DDDDDaDDDDDDDDDDDDDDDDDDDDaDDDDO Q D D D O D .-^°'( ^% § D D " jn? ^ W c^ Q D tii ^a L ftu fa *fl □ D i HA 1 m /S "^ D D ■/■ w^\ ' ui fa in D O "^ ^W tAy 'i D B "V f^^»' 8 D D D □ □ UNIVERSITY OF MASSACHUSETTS g n D n LIBRARY D LJ D a D D n D = D D a D D D D O D D Q D D D D D D D D D D D D D D D D D D D D D □ D D D D D D D D D D D D D D D D D D O D D n D D D D O DDDDDl DDDDDaDDDDaDDDDDDDaDDDDDDDD FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 42 (No. 1) JANUARY-FEBRUARY 1977 TABLE OF CONTENTS Interregional Cooperative Research in Fruit Tree Viruses and Aspects of Control Measures: Present and Future When Should an Existing Orchard be Replaced Cleaning the Weed Sprayer A Substance that Deters Egglaying by Apple Maggot Flies Supplement - Establishment and Management of Compact Apple Trees (Part II) (6 pages) INTERREGIONAL COOPERATIVE RESEARCH IN FRUIT TREE VIRUSES AND ASPECTS OF CONTROL MEASURES: PRESENT AND FUTURE^ R.C. McCrum Department of Botany and Plant Pathology University of Maine A few commercial nurseries conduct virus indexing programs in regard to their propagating stocks and also maintain nuclear stock blocks. Individual State Experiment Stations as well have for several years cooperated in certification programs with commercial nurseries in regard to Prunus tree fruit nursery plants. There is, however, at the present no general U.S. recognized certification or regulatory program for distribution of virus-indexed or virus- free apple nursery stocks. In this respect, the U.S. orchardist is not as fortunate as his European counterpart in receiving reli- able virus-free materials. The European distribution of virus-free material, handled through regulated programs, involving both re- search and inspection agencies, results in great volumes of clean budwood from the initial source which is built up and released to the industry by the cooperating nurseries. Part of the problem in the U.S. in not duplicating this accomplishment is the reluctance of the American growers to set up a uniform, regulated approach for handling virus- indexed trees. Also, because of our numerous and separate fruit growing areas, there tends to be a larger diversity in apple cultivars due to the different climatical aspects, grow- ing seasons, temperature limiting factors, other pressing disease pathogens, soil types, processing requirements and changing con- sumer demands, each one a critical factor to specific area growers. In addition to this, there is a rapid development of patented selec- tions being offered to the trade. In spite of these handicaps, there has been considerable prog- ress in obtaining and using virus-clean apple trees and we must realize that it is only 5 years since the first introduction and distribution of the IR-2 program's virus-free apple stocks began. We are just beginning to realize that our research findings and dissemination of this knowledge, which has led to increased quar- antine interest in regard to the import of pome fruit tree mater- ial, signifies that the U.S. itself must also establish certifi- cation criteria and procedures in order to export it's own nurs- ery material to meet the expanding world competition. There is little or no control on the shipping of virus-infec- ted apple budwood or treesthroughout the United States. This has in the past led to a high incidence and spread of latent viruses, particularly in cases where new cultivars have been desired quickly, in large amounts, and have been put on older, sometimes infected stock trees for a fast buildup of material. Exchange of nursery stocks among regions and nursery suppliers, without detailed inform- ation as to original source and disease status, also helps to in- crease the problem. Part I appeared in Nov. -Dec, 1976 issue of Fruit Notes With few exceptions, you pay your money and take your chances in regard to infection with viruses when you purcliase tree stocks. Progress is being made when nurseries start from original clean source materials, but it will take several years until large numbers are built up, particularly with patented varieties. In addition, grower reluctance to pay premiums for certified virus-free trees delays the cleanup of U.S. material. This is due to the extra time and effort it takes to certify and maintain a virus-free program by the fruit tree industry. Until the purchaser demands and is willing to pay for trees certified and indexed as to trueness to name and~Freedom from virus, he has only the reputation of the seller and nursery to fall back on. Problems with stock-scion incompatibilities like the presently looming brown-line-decline syndrome with some East Mailing types are suspected to be pathogenic in nature and may be the result of a combination of viral or mycoplasmal pathogens. The relationship of stock-scion in regard to known clean materials is particularly important. It is not good to use virus- clean materials in one of the components while the virus content of the other is unknown. One may contain a latent or "hidden" virus that may damage the other clean component. This was well pointed out in the decline of Virginia Crab resulting in stem-pit- ting of the latter hardy stock material. Both parts of a two part tree must receive a clean bill of health to receive potential bene- fits of either of the components. In addition, as pointed out by van Oosten, the use of virus-free bud sources is only one of the ingredients of a healthy industry. Equally important is the care- ful attention shown to non-viral aspects of tree selections. Fac- tors such as fruit finish, trueness to name, stability of the germ- plasm and a history of the susceptibility of the selection to known apple virus infections are other important and desirable facts. Given this information, the grower has a better guarantee of what the potential of his purchased trees will be in his future orchards. In today's competitive markets, with increasing production costs, all factors that can be ascertained should be made available to the orchardist especially in regard to purchasing his basic ingred- ient, his trees. Tests at the Maine Station have demonstrated that considerable differences in regard to fruit finishing characteristics occur in selections of Golden Delicious even though they are free from virus infection. Some virus-free selections produce badly russeted fruit year after year compared to others which develop good fruit finish when growing side by side in the same orchard and receiving identi- cal production practices. (Table 1) 3 - Table 1, Non-viral fruit russet in selected clones of Golden Delicious, in lbs per bushel. Clone C Clone H Russeted Clean Russeted Tree Heavy Light Heavy Light Clean 1 3.5 7.9 3.4* 2.4 4.9 28.5 2 8.0 21.0 7.6 2.3 17.3 16.5 3 22.6 11.4 1.9 .0 8.7 27.7 4 15.5 11.7 1.5 6.2 17.0 12.5 5 23.7 11.3 .0 2.2 13.9 20.5 6 13.5 21.6 2.3 .9 7.4 24.8 7 18.1 14.6 1.0 .2 12.2 23.9 8 7.2 3.5 .0* 5.9 17.2 9.8 9 10.7 15.6 10.7 2.6 13.2 20.2 10 2.4 17.8 18.9 2.7 13.7 13.2 *Less than a bushel Both clones could be marketed as virus-free Golden Delicious. It goes without saying that good "seed" produces better crops than poor "seed." A successful potato farmer insists on knowing the disease rating and potential of his propagative seed and knows what the odds are of planting poor seed. It is paradoxical that apple trees are bought and planted for future envisioned high- yielding crops often without knowing their possible inherent faults or capabilities or virus content simply because there is no "pedi- gree" or labeling system to prevent this from occurring. Somehow a standard system has to be developed to insure that superior germ plasm is protected from viral reinfection as well as to insure that the grower receives specific information certifying that the prod- uct he receives is the quality product the nursery originally started with. Progress has recently been made in reducing certain yellows diseases of fruit trees originally thought to be viral in nature but now known to be caused by mycoplasmal pathogens (ultramicro- scopic bodies contained in phloem cells and transmitted by leaf- hoppers). There are also similar sized rickettsial and bacterial type pathogens transmitted by leaf hoppers that affect woody plants. Fruit trees infected with these pathogens respond to antibiotic in- jections and disease symptoms are frequently arrested. Such con- trols are only stop-gap measures as they do not entirely eliminate infections and must be repeated. With viral infections there are not even stop-gap chemicals and a tree once infected in the orch- ard or infected when planted stays infected for the life of the tree. It is true that the possibility of reinfection with a virus may occur with insects as in other plants; however, to date, this has not been shown to happen with the apple virus entities. We, still do not know what relationship the so-called latent and seem- ingly inocuous apple viruses have to other plants and should not continue to spread these around in infected budwood sources. Tools to handle virus-free superior propagative material are available. UTiat is needed is an industry-wide cooperative program establishing checks and controls backed up by regulation and in- spection measures to insure quality of product from the originator to the purchaser with proper certification and identification of tree material. It should be handled by industry so as to keep it flexible and receptive to changes as they are needed, particularly with the patented scion and new stock selections, since these must be controlled by the patent holder. We have the expertise and the knowhow, all we need is the initiation of a system. In conclusion, as one old career orchardist was heard to say, "It takes a lot of Saturday nights without a paycheck before a newly planted orchard starts to show a profit." The first and most important aspect of this orcharding business is what you put into that hole in the ground as the basic investment to live with, grow with and build upon. *************** WHEN SHOULD AN EXISTING ORCHARD BE REPLACED Robert L. Cristensen Department of Food and Resource Economics One of the questions confronting an apple producer is that of the optimal replacement period. Should the old orchard (or some portion with trees of the same age) be torn out and replaced now or at some time in the future? This question has become in- creasingly important because of the trend to compact trees and higher density plantings. A difficulty, of course, relates to the fact that a new planting takes several years to attain production and thus a di- rect comparison of net income from the old orchard as compared to the new orchard is not possible. Perrin and Proctor (1Q74) have outlined a procedure to be used in making such a decision which takes into account net income flows over the life of the orchard. ^ R.K. Perrin and E.A. Proctor, "The Economics of Replacing Apple Trees - A Guide for Producer Decision Making", Economics Informa- tion Report No. 36, Department of Economics, North Carolina State University at Raleigh, February, 1974. - 5 - Th per yea the net value o ard to net inc come £o ized" n cipated orchard e technique r over the present va btained in obtain an " ome from st r the next et income f net income should be involves three life of the new lue of the orcha step one is amor annualized" net ep two is compar year from the ex rom the proposed for the next ye replaced. steps orcj^a rd.^ tized incom ed wi istin new ar fr First, annual net returns rd are discounted to obtain Second, the net present over the life of the orch- e. Third, the "annualized" th the anticipated net in- g orchard. If the "annual- orchard exceeds the anti- om the old orchard, the old A simple example may be helpful. The following table presents the life cycle cash flow for Red Delicious apples sold on the fresh market. Table 1 Age of Orchard Life Cycle creases at Cash Flow Per Acre (With Projected Price In- 2.9 Cents Per Bushel Per Year) Net Cash Income Age of Orchard Net Cash Income Age of Orchard Net Cash Income 1 $ -651 11 $1,277 21 $1,477 2 -174 12 1,360 22 1,490 3 -175 13 1,433 23 1,469 4 -62 14 1,446 24 1,451 5 205 15 1,459 25 1,432 6 515 16 1,462 26 1,413 7 847 17 1,465 27 1,394 8 1,033 18 1,467 28 1,350 9 1,113 19 1,469 29 1,310 10 1,194 20 1,471 30 1,269 The present value formula with uneven income streams is as follows: PV = ^1 + ^2 TT^TT (1 + i) R n (Ui) n where R^^ to R = the atinual net returns in each year i^ = the appropriate interest rate Calculating the present value of a future return is the reverse of compounding interest. If we compound 95 cents at 5-1/4 per- cent simple interest, we have one dollar at the end of the year. Therefore, the present value of one dollar received one year from now, given a 5-1/4 percent interest rate is 95 cents. "^The following costs are not considered since they are irrelevant to the replacement decision: all fixed costs for equipment and buildings and land charges. - 6 Inserting the numbers from Table 1 into the formula yields the following (the full series is not presented for reasons of brevity) : PV = (-651)+ (-174)+ (-175)+ (-62)+ (I+.IO) ,, . ...2^,. .^.3... ,„.4 (205)+ (515) (1+.10)''(1+.10)"(1+.10)'^(1 + .10)^(1+.10)^ + _(1,269^ (I+.IO) = $6,364 For the above table, the present value of the cash flow over 30 years with an assumed rate of 10 percent is $6,364.00. The annualized value formula is as follows: A + PV X 1 - (1 + i) 30 where : PV = present value i = the interest rate Using the present value computed above and an interest rate of 10 percent, the formula becomes A = $6,364 = $640 .10 1 - (I+.IO) TU Thus, if the interest rate used is 10 percent the above formu- la yields an annualized net income of $640.00. If the existing orchard yields a return net of cash expenses less than this amount, it should be replaced. Unfortunately, although this decision criteria. has the appear- ance of a "rule of thumb" it has many difficulties. Obviously, the technique requires a large amount of data. Some standardized yield pattern over time must be assumed and prices large number of years in the future. 7 estimated for a The potential errors in the Rules of thumb are difficult to attain except in rather simple decision situations. They almost always assume a number of fac- tors to remain constant and, as a consequence, often are in error, - 7 - future are, however, damped considerably by the discounting techni- que itself. That is, the effect on the present value of an error of 50 percent in net income in the 27th year will be relatively small. A reasonable manager will also consider the fact that the net return in a given year from an existing orchard can be highly vari- able due to the random effects of weather on yield as well as price. Therefore, the blind application of the $640 criterion might well be wrong. In summary: A theoretical decision model does exist for re- placement of orchards. The orchardist may use the procedure as a technique to obtain more information concerning such a decision. This knowledge together with other considerations form the total bank of information the manager uses in exercising his judgment in the decision. *************** CLEANING THE WEED SPRAYER Cleaning the weed spray between sprayings will preserve the equipment, help insure uniform spray coverage, and prevent the chance mixing of incompatible chemicals, or applying traces of the wrong chemical. Below are suggestions for cleaning weed sprayers that appeared in Special Circular 81 entitled "Weed Control Sprayers Calibration and Maintenance" and published by The Penn. State Univ. Extension Service, University Park, Pennsylvania. "After each day's use, thoroughly flush with water, both in- side and out to prevent accumulation of chemicals. "Choose your cleaning area with great care. It is important to discharge the cleaning water where it will not contaminate water supplies, streams, crops, or injure other plants, and where puddles will not be accessible to children, livestock, pets or wildlife. "When you change chemicals, or finish spraying for the season, clean the sprayer thoroughly both inside and out. "The following steps are suggested for thorough cleaning: 1. Hose down the inside of the tank completely, filling it half full of water. Then flush out the cleaning water through the nozzles by operating the sprayer. 2. Repeat the procedure in step 1. 3. Remove nozzle tips and screens. Clean them in kerosene or detergent solution, using a soft brush. Do not use a knife, wire, or other hard material to clean nozzle tips. The finely-machined surfaces of the tips can be easily damaged, causing distortion of the spray pattern and an increased rate of application. 4. Fill the tank about half full of water and add about 1 pound of detergent for every 50 gallons of water. 5. Operate the pump to circulate the detergent solution through the sprayer for about 1/2 hour, then flush it out through the boom. If you have used 2,4-D or an organophosphorous insecticide, be- fore doing step 6, follow these additional procedures: a. Replace the screens and nozzle tips. b. Fill the tank about half full of water and add 1 pint of ammonia for every 25 gallons of water. c. Operate the pump to circulate the ammonia solution through the sprayer for about 5 minutes, and discharge a small amount through the boom and nozzles. d. Keep remaining solution in the sprayer overnight. e. In the morning, flush out all the ammonia solution through the nozzles by operating the sprayer. 6. Fill the tank about half full of clean water while hosing down both the inside and outside, then flush out through the boom. "When finished with the sprayer for the season, remove and store the nozzle tips, strainers and screens in light oil. Store the sprayer in a clean, dry shed. If the pump cannot be drained com- pletely, store where it cannot freeze." *************** A SUBSTANCE THAT DETERS EGGLAYING BY APPLE MAGGOT FLIES Ronald J. Prokopy Department of Entomology In the preceding 2 issues of Fruit Notes, I have discussed how apple maggot flies locate food, mates, and egglaying sites and how this information can be put to practical use in developing traps for monitoring and (in small orchards) possibly even controlling maggot fly populations. In this article, I will discuss a unique sort of behavior engaged in by the apple maggot and its close rela- tives just after egglaying. The fly-originating chemicals associated with this behavior offer promise as a new means of controlling the apple maggot without insecticides in large orchards. - 9 - Egglaying by apple maggot females is accomplished when the fe- male arrives on a susceptible fruit, raises up on its legs, bores with its ovipositor through the skin of the fruit into the flesh, and deposits a single egg. The ovipositor is a needle-like protru- sion from the posterior of the abdomen through which the egg is passed into the fruit. Following egg deposition, the female with- draws its ovipositor from the fruit, and then proceeds to circle around the fruit for about 30 seconds, dragging its fully-extended ovipositor on the fruit surface behind itself. After this, the fe- male cleans its ovipositor for a few seconds and then flies off the fruit. About 5 years ago, I became very curious as to why the females engaged in this rather elaborate behavior of ovipositor-dragging. Actually, my observations of maggot fly oviposition in nature re- vealed that only about half the cases in which females were seen attempting to bore into a fruit culminated in ovipositor dragging while the other half did not. When I examined the fruit, I found that among females which did drag their ovipositors after attempt- ing boring, 901 had in fact deposited an egg. On the other hand, among females which did not drag their ovipositor after attempted boring, only 2% had deposited an egg. Thus, there was a clear pos- itive relation between egglaying and dragging the ovipositor after- ward. This suggested that the act of ovipositor dragging might be a mechanism for marking the fruit with some sort of substance to signify the presence of an egg. I investigated this possibility in a Wisconsin sour cherry orchard heavily infested by apple maggot flies, which attack sour cherries in that state. I held a sour cherry by a thin wire at- tached to the stem, brought the cherry to within a few inches of a female on a cherry tree, and waited for the female to fly onto the cherry. Two types of cherries were offered: (1) a clean cherry never visited or infested by an apple maggot, and (2) a cherry in which another apple maggot female had just laid an egg and dragged her ovipositor. It turned out that 621 of the females that landed on the first type of cherry attempted egglaying, while 01 arriving on the second type attempted egglaying. Clearly, there was some sort of deterrent to repeated egglaying associated with the second type of cherry. The question now arose as to whether this egglaying deterrent originated from the eggs, the flies, or the fruit. To answer this question, I offered the females 4 types of cherries: (1) a cherry in which a female had laid an egg but was not allowed to drag her ovipositor afterward, (2) a cherry with a pin prick, and the exuding fruit juice spread over the fruit surface afterward, (3) a cherry never visited by any flies, and (4) a cherry in which no egg was laid, but on which a female (transferred there from another cherry) had dragged her ovipositor. The results showed that 60-651 of fe- males that arrived on each of the first 3 types of cherries attemp- ted egglaying compared with 0% that arrived on the fourth type. - 10 - This was strong evidence that some sort of substance (which we will call a fruit marking pheromone) , secreted from the ovipositor of a female during ovipositor dragging, was preventing; other females from attempting to lay an egg. Of what advantage is it to the flies to deposit such a marking pheromone? Examination of hundreds of fruits by myself and other investigators has shown that usually only 1 maggot larva per fruit can survive to maturity if the fruit is small, 5/8 inch or less in diameter. Hawthorne fruit, the original native host of the apple maggot, and sour cherries do not usually exceed this size. There simply isn't enough food or space in such fruits for more than one larva to develop. By depositing fruit marking pheromone following egglaying, a female is in essence saying to other females arriving afterwards, "Don't bother to lay an egg here. If you do, you'll be wasting your energy and your egg. There's only room for 1 larva here, and the larva from my egg already has a head start and would outcompete the larva from any egg you might lay. You're better off if you leave this fruit and look for a different one that isn't marked with pheromone and therefore doesn't already contain an egg." Apples, which the apple maggot began to infest about 110 years ago, are of course much bigger than hawthorne fruit or cherries and can support as many as 15-20 larvae to maturity. Therefore, 15-20 fe- males can lay eggs in and deposit marking pheromone on apples be- fore the pheromone begins to become a deterrent to further egglay- ing. During the past 4 years, I (alone, or in conjunction with Drs. Volker Moericke of Bonn, West Germany and Harvey Reissig of Geneva, New York) have continued to explore various properties of this fruit marking pheromone. We have found that if pheromone-marked fruit is kept under dry conditions at normal summer temperatures, the phero- mone is remarkably stable and is nearly as effective in preventing egglaying 2 weeks after its deposition as 0 hours after. Surpris- ingly, the pheromone has proven to be water-soluble, and can be partially washed away by rainfall. This is not necessarily a dis- advantage to us, however. For example, we have been able to swish marked fruit in a container of water, spray the pheromone-water solution onto clean fruit in laboratory cages, and to a substantial degree prevent maggot fly egglaying in this fruit. If combined with an effective spreader-sticking agent, this pheromone should be able to survive considerable rainfall and remain effective under a variety of outdoor weather conditions. Recently, we have found this same sort of pheromone to exist in all 6 of the close relatives of the apple maggot that we have examined. These include the blueberry maggot, black cherry fruit fly, eastern cherry fruit fly, and western cherry fruit fly. Drs. Byron Katsoyannos and Ernest Boiler of Wadenswill, Switzerland have also recently found it to occur in the European cherry fruit fly, the worst pest of cherries in Switzerland. This past year, these workers collected marking pheromone deposited after about 1 million - 11 - cherry fly egg layings in fruit in laboratory cages. They s\\fished. this fruit in water, and sprayed 10 cherry trees in nature with 2 applications of the pheromone-water solution. The results were ex- tremely encouraging: only 61 of the pheromone-sprayed cherries had any cherry maggot eggs or larvae, compared with 100% maggot infesta- tions of adjacent unsprayed cherries. In the past 2 months, Reggie Webster and I have discovered that the fruit marking pheromone of the apple maggot acts net only as an egglaying deterrent to maggot flies but acts also as a chemical signal to Opius lectus , a parasite of the maggot eggs. The phero- mone arrests the parasite females, and elicits a strong degree of searching behavior for maggot eggs. Parasites encountering fruits sprayed with marking pheromone are therefore likely to remain in the area of the pheromone-sprayed tree for a longer time and effec- tively search out any maggot eggs that might be in the fruit. The task facing us now is the chemical identification and syn- thesis of the marking pheromone. This will require the expertise and equipment of an accomplished pheromone chemist, which are few in number. We hope in the near future to interest one of them in tackling this challenging pheromone. If some day the pheromone can in fact be obtained at reasonable cost, then the pheromone, com- bined with an effective spreader-sticker, could be sprayed onto our apple trees to prevent maggot fly egglaying. The deterred females, which we know move about frequently, might then be captured out by baited yellow rectangles and/or baited red spheres hung in specific trap trees. Native or released Opius lectus female parasites would be retained in the area by the presence of the pheromone. Thereby, an integrated approach to apple maggot management, combining deter- rents, attractants, and parasites, could hopefully be achieved. Establishment and Management of Compact Apple Trees William J. Lord and Joseph Costante University of Massachusetts Part 2 Rootstocks Commercial interest in size-control rootstocks developed in the early 1950's in Massachusetts. Presently, those in most common use are the clonally propagated Mailing (M.) and Malling-Merton (MM) rootstocks. The degree of dwarfing induced by these rootstocks is shown in Table 9. A descrip- tion of these rootstocks and seedlings follows as well as a summary in Table 10 of the characteristics of the common and less commonly planted rootstocks. Table 9. Apple rootstocks presently used in Massachusetts and their relative degree of dwarfing. Apple rootstock Dwarfing (%) of seedling trees^ M.9 M.26 M.7 MM 106 MM 111 Seedlings 30-50 45-60 55-75 75-90 80-90 100 -Degree of dwarfing will vary with variety and soil type. M.9. This is a true dwarf rootstock (Table 9) and can be use- ful for specialized orchard culture by commercial growers. It is a century old, thus well known. This rootstock has a brittle root system which means each tree will need to be supported by a post or by a trellis. It is a very suitable root- stock for high density plantings. Interest in this rootstock is increasing for use in "pick-your-own" orchards. On a good site, with good soil and management, cultivars on M.9 can be productive. Virus-tested M.9 rootstocks (free of all known viruses) are becoming available. Preliminary data from the Netherlands show that; (a) cultivars on virus-tested M.9 rootstocks grow more vigorously than those on virus-infected M.9's; (b) virus tested trees usually produce larger yields than virus-infected trees; (c) the yield efficiency (poundsof fruit/unit of growth) of the virus-tested trees is equal to or higher than virus-infect- ed trees; and (d) fruit quality is also usually better for the virus-tested trees. The stronger growth of virus-tested trees could be advantageous on poorer soil but a disadvantage for high density plantings on strong soils. Cultivars on M.9 are well suited for trellising or the slender spindle type of training with a single post parallel to the trunk for support. Apple varieties differ in vigor on M.9 with weaker growing types like Idared, Empire, Golden Delicious, and probably MacSpur easier to train as slender-spindles than Red Delicious, Mcintosh or Cortland. Slender-spindle trees will be described elsewhere. M.26. This is one of the new clones from East Mailing from a cross of M.I 6 and M.9 and introduced to the U.S.A. about 1 958. Its roots are brittle like the M.9 but trees on this root- stock have better anchorage. Whether or not trees on M.26 are going to require support is still questionable. At present, we have found temporary support necessary on windy sites and when nursery stock quality was poor. An overgrowth of M.26 forms below the graft union and burr knots (adventitious roots) form on the stock. It does not suckei as much as M.7. Trees on M.26 produce earlier than those of M.7 and it propagates well in stool beds. It is not resistant to wooly aphids or to collar rot. It is reported to be very winter hardy. M.26 requires well-drained soil for optimum performance. M.26 is gaining popularity in Massachusetts orchards but many questions about this roostock remain unanswered: anchorage, soil requirements, whether loss from fireblight will be a problem, and scion/rootstock effects on growth and fruiting. Therefore, it is suggested only for trial. We have observed no serious problems but our experience is limited to 6 years. M.26 looks very promising in Michigan. They have lost a few trees in commercial plantings, but these have been on low, wet heavy soils. Michigan reports that M.26 will sup- port a free standing tree. To the contrary, researchers in western New York are rather "cool" toward M.26 because of its susceptibility to fireblight and its sensitivity to "wet feet." It requires a well-drained sandy, loamy soil without the tendency to drought (Table 8). M.7 is the best stock we have to give a semi-swarf tree. Twenty years of commercial experience with M.7 has proven its reliability under our conditions. Cultivars on this root- stock come in bearing early and continue to produce good annual crops. M.7 is not without its faults-it produces suck- ers from the roots, it tends to lean, particularly when budded to Red Delicious, and it is susceptible to wooly aphids. Early Rootstock bearir Seedling D M.13 C- Robusta 5 B MM 104 B M.2 B M 106 A M.7 A MM 111 C- Antonovka B AInarp 2 A M.9 A+ M.26 A+ Table 10. Summary of rootstock characteristics (Letters A-E denote estimate of value: A = excellent; E = poor) Collar Rot Tolerance to: Remarks and bearing Productivity Anchorage Resistance Wet soil Dryness Low T° Recommendations Highly vigorous-90 to 100% standard c A C- C B- c B B C A- C c+ B+ A B B C A+ Medium vigor range- '60 to 85% c )f standard A C E E B c- B B 6 C B c+ A B C- C+ B B- B- C B- c a C- B + B+ B c A B B+ A A+ ? ? A B+ A ? Half -size . ? and smaller ? A A+ D A+ D C B A+ C- C- C- c A Use now limited. Does well on wet soils. Tolerates heavy soils. Very susceptible to collarrot. Never very popular. Avoid poorly drained soils. Suckers. Popular with M.9 interstem. Inadequately tested in U.S.A. Inadequately tested in U.SA. Attractive to mice. Fire blight susceptibility. VReported as not being hardy where there are mild periods during winter because it has a very short rest period. Trees on M.7 need to be budded 8 to 10 inches high in the nursery so that the trees can be planted deeper in the orchard. Deeper planting provides better anchorage and reduces suckering. M.7 produces a tap root, thus trees on this rootstock should be planted on deep, well-drained soils. In spite of higher budding, providing temporary basal sup- port by means of 3-foot long hardwood stakes driven 2 feet into the ground is advisable for Red Delicious and for all cultivars on windy sites. MM 106 has some good characteristics and some believe these outweigh its weaknesses when budded on semi- vigorous cultivars (Idared, Empire, or spur-types) and plant- ed on light loam soils. Trees on this rootstock come into production early. MM 106 also has a strong well-balanced root system, therefore, anchorage is not a problem. It is sucker-free and resistant to wooly aphids. Our Massachusetts orchards frequently have localized wet areas and in these areas we lose trees on MM 106. Furthermore, MM 106 produces large trees with such cul- tivars as Mcintosh. Loss of trees on MM 106 is commonly attributed to collar rot but may be more directly related to winter injury at the crown, soil management, or soil drain- age. (Trees on MM 106 are slow to mature in the fall and the trunk tissue near ground level, which is the MM 106 portion of the tree, is late maturing and thus more suscep- tible to low temperatures in early winter than the other above-ground portions of the tree.) MM 111. A good rootstock for sandy loam soils because it is more drought-tolerant than other size-control rootstocks. It is more vigorous than MM 106, thus it is of no value to orchardists desiring to increase tree numbers per acre. Cur- rently, MM 1 1 1 is being used as the understock for interstem trees because it produces well anchored trees. It is inter- mediate in winter hardiness. Seedling. These formerly constituted the bulk of the root- stock material used for apple trees. No two seedling root- stocks are identical in genetic makeup. Trees on seedling rootstocks are well-anchored and more tolerant to unfavor- able soil conditions than many M. and MM rootstocks. Trees on seedling rootstocks are slower to come into production than those on size-control rootstocks. Seedling rootstocks will produce trees 25 to 30 feet or more in height without restrictive pruning. Trees on seedling roots are inefficient because tree centers are unproductive or produce poor qual- ity fruit due to inadequate sunlight. Presently, seedlings are used mainly as the understock for spur-type trees and inter- stem trees. Interstem Trees The interstem tree ordinarily consists of: the understock, the interstem, and the scion variety (Fig. 2A). Interstem trees cost more, and they are usually only available by contracting two years in advance. The scheme most often practiced by the nurseryman is to bench-graft the interstem (M.9) onto the chosen rootstock (usually MM 106 or MM 111), plant this tree in the nursery and bud on to it the scion variety in 10 August. Trees consisting of four parts denoted as "C" series inter- stem dwarf apple trees are available from a nursery in Mis- souri. These have a seedling root, K-14 winter hardy trunk, a dwarfing interstem (C-6 or C-52) and the fourth part of this tree is the desired cultivar (Fig. 2B). The nursery reports that standard cultivars with C-6 produce trees about half size of standards on seedling roots. The interstem C-52 produces trees about two-thirds to three-quarters the size of the cul- tivar on seedling roots. Combining the spur-type cultivars with the C-6 and C-52 interstems reportedly produces earlier bearing, heavier yielding, and smaller trees than if standard type cultivars are used. Our experience with the "C" series in Massachusetts is limited. There is an active interest in interstem trees with M.9 interpiece because of the desire for small trees that do not require support. Tree size should be intermediate between that produced by M.9 and M.7 rootstocks. It is suggested that the M.9 interstem should be at least 6 inches long and positioned on the stem of the understock at least 12 inches from the top of the roots to permit deeper planting. Interstem trees are suggested for trial. Orchard Design Tree density defined. Terminology and planting distances used vary among researchers with compact apple trees. Below is shown the names we have chosen for this publication, the tree number in each density, and the rootstock and interstem combinations that can be utilized in each density. Rootstock and interstem combinations that can be Density Number of trees/A utilized in each density^ Low Less than 1 14 Medium 115 to 249 High 250 or more Seedling, MM 111, MM 106, Alnarp2, M.13, C-52/K-14/ seedling, M.7. MM 106, M.7,C-52/K-14/ seedling, C-6/K-14/seedling, M.9/seedling, M.9/Alnarp 2, M.9/MM 111,M.9/MM 106, M.26. M.9 Cultivar vigor and soil type are factors influencing tree spacing. Tree spacing. We cannot make firm recommendations on planting distances because our experience is too limited. Furthermore, the number of variables affecting tree size are great— orchard site, soil, severity of pruning, nutrition and tree training among others. However, as a guide we have suggested in Table 11, planting distances that seem reason- able minimum spacings for our conditions in Massachusetts. Similar tree spacings are given for both medium and low vigor cultivars which reflects our lack of experience with the spacing requirements of various cultivar-rootstock combina- Fig. 2. Interstem trees. (A) is a3-piece tree with an MM 106 understock, M.9 interstem, and Mcintosh as the cultivar. (B) is a 4-piece tree with a seedling under- stock, K-14 winter-hardy trunk, C-6 dwarfing inter- stem, and Mcintosh as the cultivar. tions. However, we have 20 years of commercial experience with M.7 and strongly believe that without restrictive prun- ing, 16 ft. X 24 ft. should be considered the minimum spacing of a permanent planting of vigorous cultivars on this root- stock and that on some soils 20 ft. x 30 ft. spacing is not too wide. We have allotted an 8 ft. alley for orchard travel and har- vest operations. If you like a 7 ft. alley, decrease the spacings between the rows by I ft. (for example, a 16 ft. x 24 ft. spac- ing to 16 ft. x 23 ft.). It cannot be overemphasized that as planting density increases, it becomes even more important that soil, cultivar and rootstock be correctly matched. When deciding on what density to plant, consider the following factors: (1) the characteristics of the site and soil— windy, poorly drained soil, etc.; (2) cultivar being planted— vigorous, spur-type, etc.; (3) time available for tree training and pruning; and (4) meth- od of marketing— "pick-yourown," processing, or fresh use. Low density tree planting. Usually allows for full tree devel- opment with a minimum of pruning to restrict tree spread. It requires the least investment per acre while production costs are below those of orchards on seedling rootstock. Massachusetts growers should consider low density plant- ings when the cultivar is a vigorous-growing (Mcintosh and Delicious) standard-type tree and the rootstock is M.7 or MM 106 because it is difficult to restrict the size of these trees. Plantings of these cultivars on these rootstocks spaced 10x18 feet, 15 x 20 feet, or 20 x 20 feet have become so dense that growers have been forced to remove trees while the orchards were still relatively young. Medium density tree planting. Thisdensity will require more careful attention to training and pruning trees than with low density planting to prevent tree crowding and maintain fruit quality. It is essential to maintain conical-shaped trees 11 (Christmas tree shape). The higher investment per acre in comparisonto low density plantings (Table 1) should be off- set by earlier, higher yields. Medium density plantings involve free standing trees-MM 106, M.7, M.26, and interstem trees. However, more experience is needed before we can be sure of the stability of trees on M.26 without support. The trees are smaller than in the low density planting, easier and less cos'tly to spray, and a higher percentage of the leaf area is exposed to sunlight which is essential for flower bud formation and high fruit quality. High density tree planting. This type of planting will require the use of M.9 rootstock with the tree individually staked or supported by a trellis. Thus cost of establishment is extremely high (Table 1). Adjustments in orchard size and/or management procedures will be necessary if sizeable acreage of high densities is planted by the established grower because of the careful attention needed in growing the trees and containing them within their allotted space. Few soils in Massachusetts are suitable for trees on M.9 without providing supplemental water. In the Netherlands, where all modern plantings are on M.9, there is a rule of thumb that states that orchard size should be governed by the number of skilled pruners on the farm. An apple orchard of 20 to 25 acres is considered large in the Netherlands and the grower sells his fruit through an auction, jumble-packed in wooden crates. To the contrary, the average Massachusetts grower has 50 or more acres, grades and packs his fruit into bags, cell count cartons or trays, and in many instances retails part of the crop. Time is such a limiting factor that many orchardists are forced to hire custom pruners to prune their bearing orchards. Orientation of tree rows. North-south orientation of tree rows is preferred because it favors maximum exposure of the leaves and fruit to sunlight. However, frequently the topography of the land and orchard boundaries dictate the directions in which the tree rows will extend. When designing the orchard, allow for service roads and sufficient space at the ends of rows for equipment maneuver- ability. Pollination. Most apple cultivars are self-unfruitful and require cross-pollination to set a commercial crop. In select- ing a cross-pollinating cultivar, the following factors should be considered: (1) Age when it begins to flower, (2) season of bloom, (3) viability of pollen produced, (4) tendency to flower annually, (5) cross-incompatibilities, and (6) adapta- bility and value of the cultivar to the region. Table 1 2 lists some of the cultivars grown in Massachusetts according to their season of bloom. These are generally suit- able cross-pollinizers for each other; several exceptions are noted. These cultivars do not always bloom in the same rela- tion one to another each year. During years when the pre- bloom temperatures are high, all cultivars are apt to bloom at about the same time; when the pre-bloom temperatures are low, the bloom is late and 7 or more days may elapse between the early- and late-blooming cultivars. Bloom peri- ods of those cultivars listed in the early- and mid-season groups should overlap sufficiently for suitable cross-pollina- tion in most seasons; the same would be true for those cul- tivars in the mid-season and late categories. It would be Table 11. Suggested minimum planting distances for various apple cultivar/rootstock combinations.^ Rootstock or interstem combination Tree spacing (ft) and trees/acre (in parentheses) for: Vigorous Medium vigor and cultivarsV low-vigor cultivars^ M.9 or M.9A M.26 M.9/MM 106 M.9/MM 111 M.9/Alnarp2 M.9/seedling C-6/K-14/seedling C-52/K-14/seedling M.7or M.7A MM 106 MM 111 8x 16 14x22 12 X 20 14x22 15x 23 15x23 15 x 23 16x24 16x24 18x26 20x28 (340) (141) (181) (141) (126) (126) (126) (113) (113) ( 93) ( 77) 6x 14 (518) 12x 20(181) lOx 18(242) 12x 20(181) 13x 21 (159) 13x 21 (159) 13x 21 (159) 14x 22(141) 14 x 22 (141) 16x 24(113) 18x 26 ( 93) ^Increase spacings by 2 feet on heavy soils. VMclntosh, Delicious, Cortland, Macoun, Puritan, Spartan. '^Most spur-type Mcintosh, spur-type Delicious, Paulared, Tydeman's Early, and Jerseymac have medium vigor. Golden Delicious, Idared, Empire, MacSpur, and Rome are cultivars with low vigor. 12 Table 12. Approximate bloom period of apple cultivars producing viable pollen for cross-pollination.^ Early lidseason Late Empire Jerseymac Julyred Lodi Mcintosh Niagara Paulared Puritan Tydeman CortlandV Macoun Delicious'* IVIelrose'' Early Mclntoshy Northern Spy, Red Spy Golden Delicious Rome, Gallia I da red Spartan Spencer ^ Bud sports or strains of an apple cultivar are not cross fruitful with each other or the parent cultivar even though they have viable pollen and functional ovules. Examples: Delicious strains such as Richared, Starking, Red Prince and Starkrimson will not pollinate Delicious or each other and vice versa. VCortland and Early Mcintosh are cross-incompatible but are suitable pollinizers for other cultivars. '^Melrose and Delicious are said to be cross-incompatible. Both are suitable pollinizers for other cultivars. The cultivars listed below are triploids; they do not pro- duce viable pollen and are ineffective in cross-pollination. Early Midseason Late Gravenstein Baldwin Mutsu Rhode Island Greening Spigold unwise to rely on early blooming cultivars to cross-pollinate a late-blooming cultivar or vice-versa. One should not rely entirely on strongly biennial culti- vars such as Early Mcintosh as cross-poliinizers for annual cultivars such as Cortland, Delicious and Mcintosh. When a strongly biennial cultivar fails to bloom, there is no suitable pollen to cross-pollinate the usual annual flowering cultivar. Hence, the annual cultivar will fail to set a commercial crop in alternate years and tends to become biennial, also. In low density plantings, the pollinating cultivar may be set either in solid rows or interplanted with the main cultivar. The former is preferred because interplanting with the main cultivar can create problems in spraying and be an incon- venience in harvesting. When the pollinator cultivar is set in solid rows, alternate 1 or 2 rows of the pollinator with 4 rows of the main cultivar. Where interplanting is used, every third tree in every third row should be a pollinator cultivar. Early Mcintosh and Golden Delicious are probably par- tially self-fruitful and it is advisable to set them in solid rows with fewer pollinating rows than with other varieties to reduce the tendency of oversetting and for convenience of spraying. To the contrary, Cortland, Mcintosh and particu- larly Delicious require a high proportion of pollinators, par- ticularly on sites where poor pollinating weather is apt to occur rather frequently. It is well documented that foraging bees tend to work up and down rows rather than across rows. When trees are planted at low densities and the trees are not crowded in the row, the bees will move between trees somewhat indepen- dently of the row. However, medium and high density plant- ings may eventually have little space between trees in the row, thus forming virtually a solid hedgerow. As a result, the distribution of pollenizer pollen across one or more rows may be seriously limited because of movement of the bees along the hedgerows instead of between adjacent rows. Thus, it may be advisable that every fourth tree in every row be a pollinator cultivar. Orchardists almost invariably rely on honey bees for pol- len dispersal, and they usually do this by renting colonies from beekeepers. We suggest that one, but preferably two colonies per acre be brought into the orchard at the time of 10% bloom. The hives may be arranged singly or in groups of 4 in various locations. Grouping is superior because colonies competing with each other increase bee activity. Bees can "set a crop" in 2 good flying days (temperature about 65° F and partial sun). After full bloom, bees should be removed as soon as possible so that you can continue your spray program. Soil Preparation Frequently, hay fields and pastures with reasonably good fertility, can be planted to trees without extensive land preparation. While it is generally true that newly-set fruit trees do very poorly in a heavy grass sod, it is possible to obtain growth equal to that obtained under cultivation by the use of herbicides. Hay fields, and especially pastures, frequently have low fertility. Fertility can be increased by applying 500 to 600 pounds of a complete fertilizer such as 10-10-10 and by application of sufficient high magnesium lime or a high cal- cium lime. A soil pH of 6.0 to 6.5 is desired for orchards. Soils which have not had frequent applications of lime will require 2 or more tons of lime per acre. (It is always advis- able to have the soil tested to determine its pH and lime requirements. Information on taking soil samples and where to send them for analysis can be obtained from your County Extension Office.) Paraquat (an herbicide) can be applied in 4 to 6 foot wide strips along the tree rows the year prior to planting or after planting to control grasses and broadleaf weeds. Residual herbicides should not be used for preplanting weed control because the trees planted in the treated soil may be killed. When paraquat is used the year of planting, the spray must not hit the v\/ood of the tree, otherwise injury may occur. Information on herbicide usage can be obtained from your County Extension Service. On newly cleared land and soils which are low in fertility 13 and are not too stony or likely to erode badly, It is advisable to build up the soil by seeding and plowing or disking under cover crops before planting trees. Spring oats, buckwheat, or millet can be sown as the summer cover crop and spring oats for the winter cover crop. This is an opportune time to apply lime because it can be incorporated into the soil during the disking of the cover crops. When the trees are planted, a mixture of grass seed and oats can be sown. During the summer, the oats can be cut and let lie or be raked around the trees for mulch. On a fairly level site which is not subjected to serious erosion, it may be possible to interplant with low growing crops such as pumpkins, for "pick-your-own" or roadside stand sales. These crops can be grown for a few years to help defray the cost of caring for the young trees until they come into production. The rows of the cultivated crops should not be planted so close to the tree rows that they interfere with growth of the young trees. Intercrops in a young orchard should be considered as a temporary enter- prise and they should be discontinued just as soon as they interfere with tree growth and care. Mapping the Orchard Once the decisions are made concerning cultivars, rootstocks, and planting distances, the orchard design should be drawn to scale on paper. Be sure to map the location of the drainage system, wet spots, and changes in soil type. After planting, record any changes in original planting plan, and record the date of planting, name and address of nursery supplying the trees, weather conditions at time of planting, and other information of value. Staking the Field A base line (the first row) is laid out on one side of the field parallel with an adjacent row of trees in an existing orchard, a fence, or a road. Stakes are placed along this line where the trees are to be planted. {I/Vhen staking the field be sure to allow sufficient room along the edges of the orchard for equipment maneuverability.) Now establish several rows of stakes at the spacing desired for the alley between trees at right angles to this row (Fig. 3). Right angles can be deter- mined with a measuring tape and stakes using the carpenter's square method in which 9 ft. X 12 ft. x 15 ft. or 12 ft. x 16 ft. X 20 ft. are the lengths of the sides of the right-angled triangle. A right triangle can be constructed out of wood strips if desired. Now that the stakes are in place, the remainder of the orchard can be staked by "sighting-in" on the stakes and with the tape measure. When staking the field only 1 or 2 months prior to plant- ing, a couple of handfuls of lime can serve as an alternative to staking each tree location. Fig. 3. A method of staking the orchard before planting. In this planting, the first row is laid out 30 feet from an existing fence and the location of the trees in the row staked (12 feet apart in the row). Right angles are determined at both ends and the middle of the first row with a 12 ft. x 16 ft. x 20 ft. right triangle. By stretching a measuring tape along the 16 ft. side of the right triangle, the location of the trees can be staked. The rows are 20 feet apart. 14 Cooperative Extension Service University of Massachusetts Amherst, IVIassachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, S300 POSTAGE AND F EES PAID U.S. DEPARTMENT OF AGRICULTURE AGR101 BULK THIRD CLASS MAIL PERMIT Available to the public without regard to race, color or national origin. FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 42 (No. 2) MARCH/ APRIL 1977 TABLE OF CONTENTS The Use of a Pressure Tester to Measure Firmness of Apples Apple Trees on M.26 Mite Predator Studies in Massachusetts Apple Orchards in 1976 Pomological Paragraphs Selecting the best spacing for the variety, rootstock and soil Early heavy cropping THE USE OF A PRESSURE TESTER TO MEASURE FIRMNESS OF APPLES William J. Bramlage Department of Plant and Soil Sciences Firmness of apples is used worldv\fide as a measure of ripeness and "condition" of the fruit. The most widely used instrument for firmness measurement is the Magness-Taylor pressure-tester (devised in 1925), although the Effegi tester (developed recently in Italy) has met some acceptance due to its compact size and convenience. Tests comparing the Magness-Taylor with the Effegi indicate that readings of the 2 instruments are quite comparable, and I shall as- sume that what is said in this article about use of a Magness-Taylor is equally true about use of an Effegi tester. With its worldwide and longstanding use, and the importance of its measurements, one may assume that the Magness-Taylor is used in a standard way and that readings by different users are closely comparable. Not so! There is no standard technique and readings are often grossly variable among users of the instrument. In 1 test in Geneva, New York, it was found that professional users of a Magness-Taylor varied as much as 3 to 4 lbs in the readings they obtained on the same lots of apples! Following an informal discus- sion at a meeting in December, 1975, where it was evident that use of pressure testers differed widely, 10 Northeastern post-harvest horticulturists-^ agreed to 'gather data on factors that can influ- ence pressure test determinations, in hopes of standardizing a tech- nique. The results of this collaborative effort, coordinated by Dr. G.D. Blanpied of Cornell University, are summarized here. The Magness-Taylor pressure tester: The instrument itself may be a cause of erroneous readings. First , there are 2 sizes of plun- ger "heads" that might be used. For apples, the larger one, with a diameter of 7/16 inch, is always used; the smaller, 5/16 inch head is for use on pears, which are much harder than apples until nearly ripe. A second problem is that the instrument may not be calibrated. Calibration is relatively simple and should be checked regularly. To calibrate, place the plunger on an accurate scale and press down slowly until the scale registers a weight that occurs on the pres- sure tester scale. Check this weight against the recorded reading on the pressure tester. Several different points on the scale should be tested in this manner. If the readings on the scale and on the tester do not correspond, the readings on apples you obtain with the tester should be adjusted accordingly, or better, the spring in the pressure tester should be replaced or the instrument sent to the factory for re-calibration, if necessary. A rusty spring should always be replaced. Collaborators were: G.D. Blanpied, Cornell Univ.; D.H. Dewey, Mich. State Univ.; R.E. Hardenburg and A.Watada, USDA, Beltsville, Md. ; M. Ingle, W.Va. Univ.; R. LaBelle d, L. Massey, Geneva, N.Y. ; G. Mattus, V.P.I and S.U., Blacksburg,Va. ; W. Stiles, Univ. of Me. and W.J. Bramlage. - 2 - Choosing a sample for testing: The user should consciously and care- fully choose the fruits that will be tested, knowing the factors that may influence the readings. A. If you are testing in the orchard, it is likely that fruit from the outside of the tree will test firmer than those toward the inside of the tree. B. Fruit size is a very important factor. In general, the larger the fruit, the softer it will be. Sometimes a 1/4 inch difference in diameter can make a 1 or 2 lb differ- ence in the pressure test! Following years of careful record-keeping. Dr. George Mattus suggests that you not vary more than 1/4 inch in diameter among the fruit you J test. Obviously, some kind of sizing device is therefore ' necessary in choosing a sample. Further, you should test a size that is representative of the majority of the crop, and specify the size you are testing. You cannot accurately compare firmness of lots of fruit if you sample 3-inch fruit in one lot and 2-1/4 inch fruit in the other. C. The temperature of the fruit can have a small but sometimes significant influence on pressure tests. Firmness tends to be slightly less when apples are warm than when they are cold. This is not nearly as important a point as is the size of the fruit, but for maximum accuracy, the user should be consistent about testing either warm fruits or cold fruits. D. A very important but controversial question is: How many fruits should you test, and how many times should you test each fruit? Obviously, 1 fruit is not sufficient, and the more fruits you test, the more accurate will be the aver- age pressure reading. But, between these 2 indisputable points there is little agreement. Many people test only once per fruit, but many others test twice -- once on each of the opposite sides (usually blush and green sides). Some people may even test as many as 4 points on an apple. (Is 1 apple tested on 2 opposite sides equal to 2 apples tested on 1 side? Probably not.) How many different fruits should you test? Most people agree that 10 fruits from a given lot is probably minimal for accuracy, but may prefer 20 to 25 fruits to reduce error. If only 10 are tested, they should probably each be tested on 2 opposite sides. I personally prefer testing 20 apples once on a designated (green or blush) side. The significant point here is, how- ever, that a large enough sample must be tested to overcome the variation within the population of fruits being samp- led. If large variation exists, a large sample size is required. Making the test: Having calibrated the pressure tester and care- fully chosen a~sample, how should you test the fruits? First, you shouldrecognize that the fruit is not of uniform firmness. Gener- ally, the blush side is firmer than the green side. This differ- ence may be as much as 1 lb of pressure. Therefore, either consis- tently test the blush side, knowing it is firmer, or the green side, knowing it is softer, or else test both the blush and the green sides and average the readings. Since the skin badly distorts a pressure test on an apple, it must be removed from the area to be tested. The depth of the cut removing this skin influences the reading: the deeper the cut, the higher the reading. Dr. Robert Hardenburg suggests use of a potato peeler (stainless steel to avoid rusting) for quick, shallow, con- sistent cuts. These cuts should be made at a point half way between the stem and calyx ends of the fruit. Never test a bruised area. For testing, the fruit should be placed on a hard surface (e.g., table top) rather than being hand-held. The plunger should be in- serted to the line inscribed on the plunger. Testing only to the "yield point" of the fruit tissue (i.e. , when it "gives") produces an erroneously low reading, and going beyond the line gives a high reading. However, the most critical feature of testing is the speed of applying the force. The faster you apply the pressure, the higher will be the reading. The proper speed is about 2 seconds, and to regulate your speed it is suggested that you say to yourself, "1001, 1002, as you insert the plunger into the fruit. This may sound childish, but it is extremely critical as can be seen simply by ap- plying force at different speeds during calibration. The user needs to frequently check himself during testing to make sure he is test- ing at the proper speed. Applying pressure too fast is probably the greatest source of false readings by users of the pressure tester. Having tested the fruit, how do you read the scale? Some read it to the nearest whole lb., others to the nearest 1/2 lb., and some may even read to the nearest 1/10 lb. It seems clear that reading to the nearest 1/2 lb. is sufficient, and if your sample size is reasonably large, the nearest 1 lb. is satisfactory. Again m.y prefer- ence is to the nearest 1/2 lb. With an accurate instrument, careful sampling, and precise testing, you should obtain a quite accurate firmness measurement of the fruits. But this accurate measurement still may not truly represent the "condition" of the apple. Some sources of error are the following. A. Nitrogen (N) level of the fruit: Increasing the N level in apples may reduce firmness of apples more than it affects postharvest "condition" of them if the apples were at the threshold of N-deficiency before treatment. Thus, you may misjudge "condition" by comparing lots of widely varying N levels. B. Watercore: The more watercore in a fruit, the firmer it may pressure test, even though increasing watercore indi- cates increasing fruit maturity. Pressure tests may indi- cate very little about "condition" of watercored apples. C. Water loss: If apples are losing water rapidly, they may "soften" due to loss of turgor, i.e., wilting. This soften- does not represent what is usually regarded as "loss of con- dition." There are probably other complicating factors, also, but these examples illustrate the importance of observing the fruit you are testing, recognizing symptoms of complicating conditions, and being careful about how you interpret the results of pressure tests. With the importance of firmness in the acceptability of apples, and the ease of using pressure testers, these instruments seem cer- tain to remain as key determinants of apple quality in the foresee- able future. Yet, it is shocking to see how erratically these de- vices are used. At present, a term, like "10-lb Mcintosh" may actu- ally mean little to anyone but the person who tested the fruit; these same apples may test 12 lbs. to another person, and 8 lbs to still a third person. Yet, Mcintosh apples truly testing 12 lbs. of pres- sure have grossly different potential than ones truly testing 8 lbs. If we are going to use firmness as a meaningful guide to apple qual- ity, we all need to re-examine our testing procedures, and do our utmost to standardize them so that our determinations can become more comparable and our interpretation can be more accurate. Here is a problem that can be overcome with good judgement and little or no expense. *************** APPLE TREES ON M.26 William J. Lord Department of Plant and Soil Sciences Observations this past year show that the vigor of non-bear- ing trees on M.26 is variable. (Assuming that all the trees are on M.26.) Trees of the same variety , within a block, may be ex- tremely variable in some orchards with some weak and/or difficult to train. This may mean that trees of M.26 react more to unfavor- able growing conditions than those on more vigorous size-control rootstocks . Roger Young, Kearneysville, West Virginia, reported at the 19th Conference of the International Dwarf Fruit Tree Association on March, 1976, that leaning in a test orchard of the trunk or leader (central leader not being upright) of trees on M.26 was a problem 5 - especially with 'Stayman', ' Rome ' , ' Winesap ' , and 'Jonathan' culti- vars. Non-bearing 'Red Prince Delicious' planted at our Research Center in 1971 or 1972 have developed leaning. The leaning appears to be caused by something other than poor anchorage. In other orch- ards, poor anchorage appears to be a problem. Trees that were pro- vided either no support or a short stake for support at planting, now require an 8-foot stake for support in some instances. This was not due to early, heavy cropping. Whether or not the stakes can be temporary or needed permanently is not known. We need a free-standing tree smaller than that produced by M.7. But I'm beginning to wonder if M.26 is the answer for some orchards. Approximately 8% of the trees in Massachusetts on size-control root- stocks are on M.26. Thus, in several years we can better evaluate M.26. *************** MITE PREDATOR STUDIES IN MASSACHUSETTS APPLE ORCHARDS IN 1976 Robert G. Hislop and Ronald J. Prokopy Department of Entomology In several 1976 issues of Fruit Notes , we described certain techniques developed by researchers in other apple growing regions of North America to reduce spraying for apple insects and mites without sacrificing fruit quality or quantity. These accomplish- ments were made possible by careful monitoring of insect popula- tions in the orchard, and selection of orchard sprays to which mite predators were resistant. In this issue of Fruit Notes, we will describe work we have been doing this past year toward a similar goal of reduced spraying for mites in Massachusetts apple orchards. Our study is long term and its objectives twofold: (1) to determine which species of mite predators occur naturally on wild or unsprayed abandoned apple trees, and (2) to determine if any of these predators occur or thrive in commercial orchards. This should provide some indication as to which types of spray programs are con- ducive to the buildup of these beneficial predators in our orchards. We knew at the beginning of our study that Amblyseius fallacis , a predatory mite known to play a key role in the suppression of red and two spotted spider mites in some commercial apple orchards in the midwest and southeast, also occurs in some northeastern states. Several of its habits are well known, such as remaining in the ground cover until July, when it moves up into the tree canopy to feed on plant feeding mites. Here it is exposed to the constant onslaught of cover sprays directed against principal insect pests. - 6 - Because of this exposure, A. fallacis eventually developed resis- tance to certain organophosphorous Tiisecticides . Portions of our orchard survey, described below, were undertaken in hopes of dis- covering this particular predator in Massachusetts orchards. Last spring, we began intensive tri-weekly sampling of mite pop- ulations from March through October in the orchard at the Belcher- town Research Center, and in 6 commercial and 3 abandoned orchards in 3 different locations across the state. In the Belchertown orch- ard, each of the materials Zolone*, Guthion*, Imidan*, and Sevin* were regularly applied by airblast sprayer to each of 3 groups of trees, with 3 groups left unsprayed for comparison. Among the com- mercial orchards, 3 used one type of spray program, while the other 3 used a different program. In each orchard, samples were taken of the ground cover under the trees, bark, and leaves of 3 'Red Delici- ous' and 3 'Mcintosh' trees. The ground cover and bark were sam- pled to determine if mite predators, especially A. fallacis , existed in these habitats at different times of the season. Bark and ground cover samples were placed in funnels under heat lamps which forced mites out of the samples into jars of pre- servative placed at the bottom. Leaf samples were brushed in a mite brushing machine, the mites landing on glass discs on which they could be readily observed. All mites were counted, including red and two-spotted spider mites, tiny apple rust mites, and preda- tory mites and insects. We also sampled the leaves of 20 other commercial orchards from which we had obtained the spray history. This sampling was conducted only once--at the peak of the mite season in August. Our results to date reveal arboreal mite predators to be widely distributed in Massachusetts apple orchards. However, Stethorus punctum, the black lady beetle important in Pennsylvania apple orch- ards , and Typhlodromus pyri , the predatory mite important in Western New York, were not found in our survey. The situation in abandoned orchards was quite different from commercial ones. In commercial orchards, fewer kinds of mite predators were found, the predominant species being A. fallacis . This predator was seldom encountered in abandoned orchards'!! Red and two-spotted mites were virtually ab- sent in abandoned orchards, which is not surprising in view of the high predator populations found there. Growth of these populations was likely aided by high abundance of one of their food sources, the apple rust mite. In many commercial orchards where the spray program included repeated applications of Zolone* and/or Benlate*-glyodin combination arboreal mite predators were scarce or totally absent. It appears that one or all 3 of these materials may have been toxic or repel- lent to the predators. In such orchards, the two-spotted spider miti *Trade name was the principal mite pest and miticides were applied repeatedly (2-4 applications) for its control. Two-spotted populations first appeared in early June, increasing thereafter until miticides were applied in July and August. In comr.ercial orchards where the above materials were not used, arboreal mite predators, particularly A. fallacis , were present in numbers sufficient to exert some suppressive effect on the spider mites. In most such orchards, the predominant mite pest was the European red mite. In 2 of the intensively studied orchards, pop- ulations of red mite peaked in late June in one orchard and late July in the other. In each case, only one miticide application was needed. A. fallacis (which appears to be only slightly suscep- tible to the principal miticides used in all sample orchards: Plic- tran* and Omite*) first appeared in the trees in July and increased thereafter in apparent response to increasing European red mite pop- ulations. The miticides undoubtedly eliminated part of A. fallacis ' food source but apple rust mites were present in sufficient numbers to provide alternate food. In the third orchard studied intensively, spider mites never reached numbers high enough to cause damage and no miticide was needed. None of the arboreal mite predators, including A. fallacis, appeared in the bark samples, suggesting wind dispersal as the pri- mary means of their getting into the tree. The ground cover samples are still being analyzed. When completed, this analysis should tell us more about the early season habits of these mite predators. We are encouraged by the wide distribution of certain arboreal mite predators such as A. fallacis in Massachusetts apple orchards. However, results to date tend to confirm our suspicion that these important predators either cannot survive or are repelled in orch- ards sprayed with certain insecticides and/or fungicides. This is of immediate economic importance to the grower, and may have serious long-term consequences as well. For example, if spider mites ever become resistant to all available miticides (which is a possibility), orchardists using these materials will almost certainly have little protection against spider mite buildup. In orchards where the build- up of mite predators is not discouraged, it is likely that miticide usage can be reduced in most cases. During the next two years, we will be continuing our field and laboratory studies so that we may more fully comprehend the poten- tail of natural enemies, particularly mite predators, in the suppres- sion of red and two-spotted spider mites in our commercial orchards. *************** POMOLOGICAL PARAGRAPHS SelectinR the best spacing for the variety, rootstock and soil. We can try, but I believe that one cannot accurately select the best spacing for the variety, rootstock, and soil under our condi- tions. To do this, one may have to use several rootstocks in the same row because of the variable nature of our soils. Even then, it would be guess work. Personally, if I make an error, I prefer that the spacing be too wide rather than too close. I believethat the average Massachusetts apple grower who stores and grades his own fruit hasn't the time nor money to fight trees too closely spaced for their natural vigor. ft************** Early heavy cropping. This is not always desirable when trees are planted at wide spacings. Early, heavy cropping may stunt the tree. This has been observed in a row of Cortland on M.26 with the severity of stunting varying considerably within the row. Therefore, we may find that in some instances heading back cuts on the extension growth of the central leader and on shoots of the scaffold (framework) branches is desirable. This procedure will stiffen the central leader and scaffold branches, promote growth, and delay fruiting. An alter- nate to heading cuts is defruiting. *************** All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State Laws and regulations in effect on the date of this publication. When trade names are used for identification, no product endorsement is implied, nor is discrimination intended against similar materials. NOTICE: THE USER OF THIS INF0R>1ATI0N ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Establishment and Management of Compact Apple Trees William J. Lord and Joseph Costante University of Massachusetts Parts Purchasing Trees Quality trees are the foundation of a successful orchard; anything less is a gannble. Thus, the following points are worthy of nnention. 1. Plan ahead (a year or two is best), thereby making it possible to plant the trees you want when you want them. 2. Tree quality rather than price should be the major consideration. One-year-old trees, 4 to 6 feet in height and at least 5/8 inches in diameter usually grow faster than lower grades. 3. Insist on 1-year-old branched trees or whips budded 14 to 16 inches above the bottom of the rootstock. Trees budded lower than this may have to be staked. 4. We suggest purchasing from nurseries that dig their trees in the fall and store them. 5. Don't accept second best even if it means waiting a year or more for quality trees on the desired root- stocks and/or of the desired cultivar. The time waiting usually can be well spent on site preparation. 6. When ordering interstem trees be sure to specify a 6 to 7 inch dwarfing stem piece grafted on a 7 to 10 inch long understock. Degree of dwarfing varies with interstem length— the longer the interstem, the great- er the dwarfing. Care of Trees on Arrival From the Nursery Check the trees to determine if tree count and cultivar/root- stock and size agrees with order and to determine if injury to the trees might have occurred in handling and shipping. Do this where it is cool and the roots will not dry out. If planting conditions are not suitable, open the bundles of trees and store them in a cool, well-ventiled area and be sure the roots are kept moist, or heal them in a shady area, or cover the roots with wet soil, peat or sawdust in an open shed. DO NOT store trees with apples or where they have been stored. It is possible that residual ethylene in the stor- age atmosphere might break dormancy of the trees and when planted they may fail to grow properly or even die. Pear trees are especially sensitive to injury. All photographs in this and subsequent parts bv Louis J. Musante. Time of Planting Fall planting of apple trees is not recommended for Massa- chusetts because there is too much risk of winter injury to the trees. The trees should be planted in the spring as soon as the frost is out of the ground and the soil easily worked. Most years, planting can commence in late April, thus the target for receiving trees from the nursery should be April 1 5. Late planting is a frequent cause of unsatisfactory tree growth. Planting The soil should be in a good workable condition at planting. Do not plant in a wet "soggy" soil. The hole for the tree should be large enough to take in the entire root system. It is important to dig the holes the right depth because if dug too deep the tree may settle after planting and the graft union will be below ground. To the contrary, the hole should be deep and wide enough so that the roots will rest on the bottom without having to "pin-them-down" with soil. Plant the trees in good loam soil. When the hole is hand-dug, place the top soil on one side and the subsoil on the other side. This will enable you to place the top soil around the roots when setting the tree. Putting 2 to 3 pounds of high calcium lime on the soil scheduled to be returned to the planting hole may improve the calcium level of the trees for 2 or 3 years. Haul in some rich soil if the soil is not good. A half bushel of good soil with 2 to 3 pounds of high cal- cium lime mixed with it will help the trees off to a good start. Planting holes are most frequently dug with tractor mounted augers. A 9-inch auger is suitable for trees on M.9 rootstock. However, a 12-inch auger is needed when the post for supporting the tree is going to be placed in the planting hole. A 2-foot auger orbackhoe is best on a poorly prepared soil and for trees on rootstocks other than M.9. Soaking the tree roots in water for 12 to 18 hours prior to planting is a good practice. During planting, keep the roots moist by covering them with wet burlap or canvas or keep them in water to prevent drying. At planting, the broken roots should be removed and the trees set in the holes so that the largest roots, and if possible, the heaviest branched side is toward the prevailing wind. Plant the tree with a slight slant in the same direction. When planting on dwarfing root- 15 stock, the graft union after tree settling should be 2 inches above ground line. Allow an additional 2 inches at planting for tree settling. After planting, the soil should be thoroughly tamped around the roots so they will be in contact with wet soil. It is not necessary to water trees unless it is extremely dry prior to and after planting. Opinions differ concerning the planting depth of 3-piece interstem trees. Some suggest that these trees should be planted with the lower graft union 2 inches above ground. Other individuals suggest deeper planting with the top of the interstem 2 inches above the ground. We have tried both methods and have observed that when the rootstock portion is less than 7 inches in length, shallow rooting can be expected when the trees are planted with the lower graft union 2 inches above the ground. The trees may be less vigorous than those planted deeper (the top of the interstem 2 inches above the ground) and frequently require support. Four-piece trees can be planted 12 inches or more in depth because the trees of this type may average 20 inches in length between the scion union and the top of the roots. However, the trees should not be planted too deeply to prevent scion rooting. Placement of sand or gravel around the tree base after planting will help stabilize the tree. It also helps to keep the area dry and thus reduces the danger of collar rot. Do not re- move soil from around the trunk, place the gravel or sand on top of the soil. (The trees will not scion root in these materi- als.) When the wind causes the trunk to sway, the gravel will trickle down and around the trunk, thus helping to stabilize the tree. Also, this will prevent the formation of an open area around the trunk where water will collect and contribute to crown disorders. Supporting Trees Tree support is now accepted as a standard procedure in apple growing. The need for tree support is dependent on rootstock, cultivar, soil type, and site. For example, all trees on M.9 need support. Delicious on IV1.7 need support whereas Mcintosh on this rootstock is generally well-anchored on deep, well-drained soils. On windy sites, it may be advan- tageous to provide at least temporary support for all trees on M.26 and M.7 rootstocks. Support methods mclude: (a) temporary basal support which is practiced so that the tree can establish a strong lateral root system; (b) permanent support by posts; and (c) permanent support by a trellis. Temporary support. This can be provided with a 3-foot long hardwood stake driven 2 feet into the ground next to the trunk at planting time. Plastic ties, nylon ties or wire can be used to fasten the tree to the post. When wire is used, the wire around the tree should be covered by a section of inner tube, a section of plastic hose, or cloth to prevent tree injury. Temporary support may be necessary for the first 5 or 6 growing seasons. Permanent post. Pentachlorophenol-treated (penta-treated) or creosote-treated posts are used for trees on l\/l.9 root- stocks. These should be allowed to weather for a year before use because of possible injury to the trees by the creosote or penta. The posts should be 8 to 8/4 feet in length, at least 2 to 2y2 inches in diameter at the base, and set V/2 to 2 feet in the ground (Fig. 4). Soon after planting, Fig. 4. A planting of trees on M.9 rootstocks after 3 growing seasons. The trees are individually supported by an 8-foot post set 2 feet in the ground. 16 Fig. 5. In this orchard, the end posts are stabilized with a wire extending from the posts to an anchor bolt. Fig. 6. End post of trellis using monofilament. A hole was bored in the end post for the insertion of the "feed through" device for the monofilament. The "feed through" device secures the monofilament and eliminates the need of stapling the monofilament. plastic or nylon ties should be looped in a figure 8 around the tree and post at about 2-foot height to provide tree support. In older plantings, 3 to 5 of these ties are used per post for tree support and to keep the leaders vertical. Trellis. Training apple trees to a trellis is quite similar to train- ing grape vines to the Kniffin system. The trees are supported on trellises of 8 to 9-foot long preservative-treated posts set 2 to 272 feet in the ground and perhaps spaced 24 feet apart in the row. The end posts are stabilized with a wire extending from about the height of the top wire of the trellis to an anchor bolt (Fig. 5) or to a "dead-man" buried 3V2 to 4 feet deep and 4 to 5 feet from the post. No. 9 galvanized wires or plastic wires stapled to the posts or passed through the interior of the posts complete the trellis (Fig. 6). The bottom wire generally is 2 feet above the ground, while the others are spaced 12 to 18 inches apart above it depending upon the height of the posts (Fig. 7). Care of Trees the First Year Heading the newly planted tree. It is difficult to find agree- ment on this very important phase of tree training. No. 1 trees of non-spur types (standard types) frequently are head- ed at 30 to 36 inches or not at all if planted early. Spur-type trees which don't branch as readily as standard types are generally headed at 28 to 30 inches. Heading spur-type trees rather severely should promote branch development which might otherwise be inadequate in number. (The lower the tree is headed, the greater the number and length of the branches.) Regardless of heading height, both spur and stan- dard types (non-spur) may still fail to produce a sufficient number of branches the first year in the orchard. As long as leaf size and color are good, the trees should develop good lateral branching the second season. When newly planted trees are not headed severely enough, they usually develop branches that are too high. The next pruning season, the trees may have to be headed again to induce branching between the height of 20 to 30 inches above ground level (the desired height of the lower permanent branches). Thus a year is lost. Pruning in the planting season. As a xu\e, all desirable branch- es on the free afp/anf/nff should be left unpruned. An excep- tion to the rule would be when a tree has one large branch. This should be removed because it may cause one-sided branch development on the tree by inhibiting the growth of Fig. 7. Tree being trained on a trellis. In this orchard, the posts are set 22 feet apart. The bottom wire is 2 feet from the ground with 2 wires above spaced 22 to 24 inches apart. The depression at the base of the trees should be filled in with soil, sand, or gravel to prevent accumulation of water. 17 4 i ] \ Fig. 8. Mcintosh on M.26 after one growing season. This tree had one strong branch at planting that should have been removed. It now competes with the leader of the tree. It should be removed and the leader headed at 28 to 30 inches to stimulate branch devel- opment. Fig. 9 shows the same tree after pruning. other branches or it may compete with the leader (Figs. 8 and 9). Pest control. An essential for optimum growth in compact orchards is adequate pest control. Too often, young plantings are sprayed inadequately because of the practice of applying what is left in the tank after spraying bearing orchards. This is an unwise practice considering the high cost of establishing orchards and the need of early returns on the investment. Growers with substantial acreage of young plantings may find smaller and less expensive spray equipment than com- monly used in older trees a good investment. The most common pest problems in young apple orchards in Massachusetts are scab, sucking and chewing insects, and tree borers. Generally, for the first 3 years, 7 to 10 sprays annually are required to control these pests. The entire tree should be sprayed including the trunk. It is well to remember this when selecting mouse guards because some types inhibit good spray coverage as well as sunlight and air movement. Young plantings can be sprayed on an alternate row Fig. 9. The same tree as in Fig. 8 after pruning. basis (spraying every second or third row and then reversing the order of travel the next spray). The first growing season of the planting, the dosage rate per 100 gallons can be 25% of that recommended for bearing trees. The dosage rate should be increased annually and by the fourth growing season, a full dosage rate and spray schedule is recommended. For information concerning pest control, contact your County Extension Office. Pest control charts are revised annually. Fertilization. Lime but not fertilizer or manures can be put in the planting hole with the roots. Lime can be added by throwing 2 to 3 pounds of high calcium (Ca) lime on the soil destined to be returned to the planting hole. A nitrogen (N) fertilizer, a complete fertilizer, or one containing N, potas- sium (K2O) and minor elements, should be applied after a rain has firmed the soil around the roots of the newly planted tree. Fertilize at the rate of 1/4 to 1/3 pound of ammonium nitrate (33% N) or its equivalent by spreading lightly in a wide circle around the tree (8 to 12 inches from the tree trunk). Calcium nitrate is gradually replacing ammonium nitrate as the common source of nitrogenous fertilizer be- cause of low Ca levels in Massachusetts apple orchards. 18 Chemical weed control. Paraquat can be applied anytime during the growing season under newly planted trees and dichlobenil is safely applied in the late fall or early winter at the end of the growing season. Apply paraquat at the rate of 1 quart plus spreader per acre in mid-May and again in mid-July taking necessary precaution against hitting the tree with the direct spray or spray drift. Drift can be a major problem when applying herbicide sprays. To reduce this problem, you can use a foaming agent (adjuvant) with the spray, avoid spraying when the wind is greater than 5 miles per hour, avoid high pressures, and use nozzles that produce coarse sprays with a minimum of fine droplets. A flooding flat nozzle is particularly good for drift control and is de- signed to operate at 15 to 20 psi. Dichlobenil (Casoron*) should be applied at the rate of 100 to 150 pounds of 4% granular per acre. Its use is de- scribed elsewhere in this publication. Guards for mouse protection. Encirclement of tree bases with hardware cloth guards to prevent mouse injury has been a standard practice for many years. Hardware cloth must have 3 or 4 wires to the inch to be mouse-proof. The guards should be 6 inches in diameter and 18 inches in height. They should be set in the ground on top of the tree's root crown. Hardware cloth is expensive and has to be cut to the desired dimensions. Plastic-lined mouse guards can be purchased precut from a local distributor. They are cut to form a circle 3 inches in diameter and 18 inches in height or a 6 inch circle with 10 inch height. Plastic mouse guards have become popular the last several years because they are more economical than hardware cloth or plastic-lined mouse guards. However, they shelter insects and should be examined annually for constriction of trunk growth. Pruning At this point, it is well to recognize the fact that pruning procedures cannot be fully and accurately described. Fur- thermore, no two trees, which appear similar at planting time, grow alike even when subjected to similar pruning and training procedures. Cultivars differ in growth characteristics and their response to pruning. Lastly, rootstocks, soil and growing conditions influence tree vigor and pruning and training requirements of trees. At best, all we can do is dis- cuss the basic principles for training and pruning and you will have to learn the finer details by experience. We suggest training and pruning trees to obtain and main- tain a conical shape (Christmas tree shape) because this form allows better penetration of sunlight into the trees and light distribution along the sides of trees. A conical tree shape is only possible with a central leader tree and only possible by removing and/or shortening the strong branches in the upper part of the tree and retaining the shorter, weaker branches. Presently, many trees in our orchards have large branches in the upper third of the trees which inhibit light penetration into the lower section of the trees. In the past, the main objective of pruning an apple tree was to produce a large percentage of Extra Fancy apples at lower costs. This is still the prime objective but many growers are now attempting to obtain the benefits of early, heavy production by closer spacings of compact trees. As a result, the problem has arisen of trying to contain the trees within their allotted spacings especially when thecultivar-rootstock- soil has not been properly matched. Training and pruning of trees becomes increasingly impor- tant as planting density increases. Growers lacking time to do detailed pruning and training, as being suggested for medi- um and high density plantings, would do well to establish only low density plantings. Such a planting system is rela- tively easy to manage and not so sensitive to variations in soil conditions, errors in pruning, and other management procedures as are medium and high density plantings 7 Season to prune. Commercial growers commence pruning some types of fruit trees in January, but home orchardists, because of limited tree numbers, can wait until the arrival of milder weather. Pruning may be done through the blos- soming period but late March or April is preferred. Water sprouts on apple trees should be removed in mid-summer and dead or diseased branches can be removed whenever they are present. Pruning systems. It appears logical to suggest the following pruning systems, based on orchard density, for Massachusetts orchards. 1. Low density orchards: minimal containment of tree spread and height. 2. Low density orchards: containment of tree height. 3. Medium density orchards: containment of tree spread and height. 4. High density orchards: staked ortrellised. Pruning low-density orchards with minimal containment of tree spread and height This system involves pruning tech- niques used in the past and described in countless pruning bulletins. The tree has a central leader and pruning involves: (1) the selection of desirable scaffold limbs; (2) the removal of undesirable limbs to eliminate whorls of branches and thus permitting only one branch to develop at a given level as shown in Fig. 10A; (3) maintaining the dominance of the leader by suppressing or removal of competing leaders; (4) restricting too rapid development of certain scaffold limbs by heading-back to an outward growing horizontal shoot or branch; and (5) on bearing trees, the elimination ^Growers may be able to increase production per man hour and per acre without the problems encountered with vigor- ous cultivars on semi-dwarf rootstocks at close spacings if M.26 and interstem trees prove reliable under our con- ditions. 19 of those tree parts which tend to bear fruit of poor size and color. Limb positioning (described elsewhere in this publication) is a very important practice on cultivars, such as Red Deli- cious, which possess the inherent tendency to develop narrow crotches. The "novice" fruitgrower should purchase (fee 25 cents) Leaflet No. 290 entitled "Pruning Fruit Trees in the Home Orchard" from the Bulletin Center, Stockbridge Hall, Univer- sity of Massachusetts, Amherst. This leaflet contains illustra- tions, photographs, and discussions which will increase the reader's understanding of basic pruning techniques. Pruning low density orchards with containment of tree height. Many growers would like to restrict tree height to about 12 feet even in low density orchards. The central leader and branch development on the central leader in the upper portion of the tree requires considerable attention in order to accomplish this goal. The following training and pruning procedures for restriction of tree height \s suggested for trial. These procedures involve the development of branches in layers on the central leader and heading the cen- tral leader annually (Fig. 1 0B) fe(/f/?of /7ea(y/>7g the past sea- son's growth on scaffold limbs as shown in this figure. Tree height can also be restricted by using pruning procedures described under the previous heading and by annual heading of the central leader as described below. Fig. 10A. Two year old tree being pruned by standard prun- ing procedures. The lowest limb should be 18 to 20 inches from the ground, all others spaced 4 to 8 inches apart vertically on the trunk and each one about 90° around the trunk from the one below it. Fig. 108. Two year old tree being pruned as suggested by the USDA. It has 2 layers of limbs. The leader will be headed annually [heavy marks ( — ) indi- cate heading cuts] . The one year old wood on the branches is headed annually until branches on which this wood is borne start to fruit. First dormant season. 1. Select central leader and remove branches competing with it (Figs 11 and 12). (This could have been done in June of the first growing season.) See Fig. 13. 2. Head the central leader by removing % to V2 of its past season's growth (Fig. 12). p a. When heading leader of a weak tree or one with no lateral branching, be aware that the first level of branches should be developed within the verti- cal spacing of approximately 1 8 to 30 inches from ground level. b. If the leader and lateral branch development is poor, head it regardless, developing both the first and possibly some of the second level of branches the following year. 3. Select lateral branches (3 to 5 if possible), well-spaced vertically around the trunk for the first level of perma- nent branches at the base of the leader. (These branches could have been positioned with spring-type clothes- pins during the first growing season.) Fig. 14 shows the use of clothespins to position branches. a. If only one branch has developed or the branches are too high or low, remove them and start over. b. If branches have developed on only one side, do the same. 4. Branches lower than 18 to 20 inches from the ground should be removed. Second dormant season. 1. A well-grown tree will have branches on 2 and 3 year old wood. However, most trees will not make sufficient growth to make possible the selection of a second level of branches 20 to 24 inches above the lower level of branches at the base of the central leader. 2. Remove all shoots competing with the previous sum mer's extension growth of the central leader. (This could have been done in June of the previous growing season. Also, it may have been possible to retain some of these competing shoots if they had been positioned with spring-type clothespins during the previous grow ing season.) 3. Head the central leader by removing Va to V2 of its past season's growth depending on tree vigor and the pres- ence or absence of lateral branches on the previous summer's extension growth of the central leader. 4. Remove all branches along the central leader for a dis- tance of 20 to 24 inches between the uppermost branch of the first layer of permanent branches and the top of the leader. (This could have been done during the "Heading— usually refers to cuts made into current season's shoots or 1 -year-old shoots. Only part of this wood is re- moved, leaving part of the same age wood on the tree. 20 Fig. 11. Jerseymac on MM 106 after one growing season. Tine tree developed wide-angled lateral branches. It is necessary to select one of the 3 upright branch- es as the central leader and head the central leader. Fig. 12 shows the same tree after pruning. previous growing season.) 5. A few trees will have lateral branches on the previous summer's extension growth of the central leader. On these trees, it will be possible to select laterals for the second layer of branches. Select 3 or 4 lateral branches for this second layer allowing several inches vertical spacing between branches. Remove excess branches. 6. Continue the selection of the first level of scaffold branches at the base of the leader. Three to five branches are needed. These should be well-spaced vertically around the trunk and the lowest limb 18 to 20 inches from the ground. 7. Position the branches at the first level to an angle of 45° with wire or wood spreaders described elsewhere in this publication. Those that developed the previous Fig. 12. The same tree as in Fig. 1 1 after pruning. growing season could have been positioned at that time with spring-type clothespins. 8. Remove upright shoots (watersprouts) that may have developed on the branches at the first level, branches growing towards the center of the tree, downward, or competing with the selected, permanent scaffold branches. 9. Heading of branches may be required on some cultivars to stiffen them and on spur-types to force lateral branching. Third dormant season 1 . A well-grown tree now has 2 distinct layers of branches (the first at the base of the central leader and the sec- ond 20 to 24 inches above the first layer) and possibly the beginning of a third layer on the previous season's extension growth of the central leader. 2. The previous summer's extension growth of the central leader is pruned and competing shoots removed as de- 21 '■■ s Fig. 13. A hormone is synthesized in the growing points of the branches in the upper parts of the tree and translocated downward. (The greater the amount of hormone, the wider the branch angles.) There- fore, crotch angles are relatively narrow in the branches highest on the trunk where little or no hormone reaches them from growing point above, and they are progressively wider toward the base of the tree as shown in this figure. Furthermore, the smaller the supply of hormone, the greater the growth. This is why the greatest growth was made by the uppermost branches of the tree shown In this figure. scribed for the second dormant season. 3. Select 3 or 4 lateral branches, if they are present, on the previous season's extension growth of the central leader for the third level of branches. These should be 18 to 20 inches above the second level of branches. 4. Continue the selection of the second level of scaffold branches (20 to 24 inches above the first level). Three or four are needed and should be well-spaced vertically (3 to 4 inch spacing) and the branches not directly Fig. 14. Spring-type clothespins used on lateral shoots the first growing season to position branches. The clothespins could have been removed after 2 or 3 weeks. Note the plastic-lined mouse guard. The gap at the bottom of the guard makes it ineffective for mouse protection. above one another. 5. Position the branches at the second level to an angle of 45°. 6. Prune the scaffold branches in the first layer at the base of the leader as described for the second dormant season. Fourth dormant season. 1 . At this time, scaffold branches should be well distrib- uted along the central leader in layers. There should be 3 distinct layers on well-grown trees and the start of a fourth layer, depending on how well the tree has grown. 2. The one-year-old and two-year-old sections of the 22 MOW TO GET THE HIGH DENSiTT TREE Off TO A GOOD STA«T MEAVr MASKS SHOW WHERE PRUNING CUTS SHOULD BE MADE 1 •y*ar-old ttoot Head tide thoolt 4-vear old lection Spreod brorich- et, remove forlred termlnoll to o lingle iheet and head that ihool Head tide thoott S-yeor-old lectlon and older If tree hat filled alloned ipare, head back where neceiiar> into 7 year-old wood to on unheaded lide ihool Avoid heading cute into 1 -year-old ihooti until the tree It fruiting well Fig. 15. A diagram of the "constructive training" program suggested by Dr. D.R. Heinicke in USQfK Agriculture Handbook No. 458 entitled "High Density Apple Orchards-Planning, Training and Pruning." (Reproduced with permission of the author.) central leader should be pruned as in the third dormant season— heading the extension growth, removal of competing lateral shoots, selection of branches for the third level, and positioning of branches in the third level. 3. The framework of the 2 lower levels of branches has been established. Remove only water sprouts and those branches which are growing toward the center of the tree, or are competing with permanent scaffold branches. Excessive pruning invigorates growth and delays formation of fruit buds. Care beyond the fourth year. 1. Prune to maintain the conical shape with short, weak branches in top of the tree. 2. Head the central leader annually. If it gets too vigor- ous, cutting into 2-year-old or older wood may be necessary. The central leader above the cropping area should not carry too many branches. 3. Try to develop new branches in the tree instead of attempting to invigorate old wood. a. Water sprouts that are growing in the direction of a vacant area can be kept to fill that section with bearing wood or as replacements for older bearing branches. Positioning of these water sprouts would be beneficial in many instances. b. An occasional new shoot, growing at an angle from a branch, can be retained to provide new bearing wood for the future. 4. Cut all dead and diseased wood, all branches that have a tendency to grow inward toward the tree's center, and all water sprouts that are growing straight up, whether in the center of the tree or from the upper surface of side branches. 5. Drooping shaded wood that has become weak and unproductive should be removed. 6. Where two branches are growing so close together that one shades the other, the less desirable branch should be removed. 7. All suckers at the base of the tree should be removed. Pruning medium density orchards. A training and pruning system for medium density orchards is described in Agricul- ture Handbook No. 458 published by the USD A. ^ We have no experience with this system in Massachusetts but since there is grower interest in it we have attempted to describe it below. The training and pruning procedures suggested in Agriculture Handbook No. 458 (See Fig. 15) may be most suitable for spur-type trees which branch less readily than standard types. Planting time. 1 . Head trees at about 28 to 30 inches. ^Agriculture Handbook No. 458 published in 1975 by the USDA and entitled "High Density Apple Orchards-Plan- ning, Training and Pruning." You can purchase this publi- cation for 65 cents a copy from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 23 Fig. 16. Mac Spur on IV1.26 after 1 growing season. Since only one branch developed at a low level (less than 18 inches from ground), it should be removed and the tree headed again at 30 inches. First growing season. 1 . When shoots average 3 to 6 inches in length: a. Select central leader plus 3 to 5 potential branches and remove all other shoots. b. Remove shoot growth lower than 18 inches from ground. First dormant season. 1. Tree is now composed of new terminal shoot growth (one-year-old section of tree) and the original whip with lateral shoots (two-year-old section of tree). 2. Select the central leader and remove all competing shoots. 3. Head the central leader by removing !4 to Vs of its past season's growth. Head it to induce branching that will be 18 to 24 inches above the branches at the base of the leader. Fig. 17. Same tree as in Fig. 16 after pruning. For those with "courage" trunk renewal is a method of get- ting weak trees to grow properly. This involves cutting back the tree to a few buds to develop a new trunk. a. If leader development is poor, head it regardless so that a strong leader will develop which can be headed at an adequate height the following year. 4. Select 3 to 5 lateral branches, well-spaced vertically around the trunk for the first level of permanent branches at the base of the leader on the two-year-old section of the tree. a. If only one branch has developed or the branches are too high or low, remove them and start over (Figs. 16 and 17). b. If branches have developed on only one side of the tree, do the same. 5. Head each branch by removing % of the past season's growth. This will keep the branches vegetative, stiff- ened and encourage development of lateral side shoots (Fig. 18). Fig. 18. Heading cuts as advocated by the USDA induces lateral branching as illustrated in (A). Branches of this type have greater fruiting potential than the unheaded branch shown in (B). Heading cuts to induce lateral branching may not be essential on non-spur type trees. (Redrawn with the permission of Don R. Heinicke.) 24 Second growing season. 1. When current season's growth is 3 to 6 inches long, remove those shoots competing with the terminal branch extension and the central leader. Second dormant season. 1. Tree now composed of 1, 2 and 3-year-old sections with one or two levels of branches (Fig. 10B). 2. The 1 and 2-year-old sections are pruned the same as the first dormant season. This consists of removing shoots competing with extension growth of the leader and selecting 3 to 5 lateral shoots to form the second level of branches on the central leader. The second level should be 18 to 24 inches above the first level at the base of the leader. Head the leader and lateral shoots (branches) by removing '/= and % of their past season's growth, respectively. 3. In the 3-year-old section: a. Position branches to open areas and spread to a 45° angle before pruning. b. Thin excess shoot growth and maintain 3 to 5 lateral branches in the lower or first level. c. Prune the lateral branches as if each were a central leader tree. 1. Single out terminal shoot and remove compet- ing shoots. 2. Head terminal shoot by removing Va of its cur- rent season's growth. 3. Thin^'-' vigorous shoots growing upright on the branch. 4. Head side shoots of the branch by removing '^ or less of the current season's growth. This won't be necessary with some cultivars. Third growing season. 1. Remove shoots the same as in the second growing season. In addition, remove all vigorous upright shoots developing on lateral branches. nird dormant season. 1. The tree now is composed of 1,2, 3, and 4-year-old sections with 2 or 3 levels of branches. 2. The 1, 2, and 3-year-old sections are handled as described before. Be sure to allow adequate space between limbs developing one above the other. 3. Some of the headed shoots on the 3-year-old section will have lateral shoots develop below the point of ^ ^Thinning refers to the removal of branches in a portion of the tree or throughout the tree to reduce competition between limbs and permit greater light and spray pene- tration. heading. If too many develop, remove some (thinning cuts), keeping those more horizontally positioned. 4. Do as little pruning as possible in the 3-year-old section of the tree. Tfie leader Is the only terminal requiring heading each year 5. In the 4-year-old section, reduce the number of head- ing cuts: a. Remove all shoots competing with terminal growth. b. With regard to shoots developing on the branches: remove over-vigorous ones, head lightly some with moderate vigor, and leave the rest of moderate and weak vigor shoots unheaded. c. Where side shoots were headed the year before, cut (thin) into 2-year-old wood to a weak side shoot or a bud, removing the vigorous terminal growth. 6. Fruiting should be confined to the 4-year-old section. Fourth growing season. 1 . Remove fruit from central leader and ends of branches to maintain tree form (may be necessary in third sea- son for some cultivars). Follow procedures practiced in the third growing season. Fourth dormant season. 1. Tree is now composed of 1, 2, 3, 4, and B-year-old sections with two to four levels of branches depending upon how well the tree has grown. 2. Encourage fruiting rather than growth, so, do as little pruning as possible. 3. If possible, avoid heading into 1-year-old wood in sections where fruiting is to be encouraged. 4. In 5-year-old section: a. If tree has filled allotted space, head back where necessary into 2-Year-old wood to an unheaded side branch. b. Avoid heading cuts into 1 -year-old wood until the tree is fruiting well. Care beyond the fourth year. 1 . Keep a vegetative terminal shoot on the central leader. It may be necessary to cut back into the older wood to renew the terminal shoot. 2. Make mainly thinning cuts by removing an entire branch or cutting back into older wood to a side shoot (1 -year-old wood) or branch. 3. Follow procedures 4 to 9 as outlined in section entitled "care beyond the fourth year" for low den- sity orchard with containment of tree height. 4. Cultivars, such as Cortland and Golden Delicious with flexible wood, often need to be headed back to 25 a more horizontally growing branch near the trunk. Branches of Cortland tend to droop and this cultivar has a tendency to lose its dominant central leader. Thus, particular attention must be given to keeping the leader dominant. Mcintosh and Jerseymac should present no serious problem if well trained during the first 4 years. Cultivars, like Delicious, Early Mcintosh, and Macoun, need limb positioning because they are inclined to develop strong upright limbs. Pruning high density orchards with trees staism Fig. 22. Richared Delicious on MM 106 showing excessive vegetative growth and the lack of limb positioning. angle from the central leader would mean the limb is hori- zontal to the ground). Spur-type trees need clothesplnnlng more than the standard type cultivars. Limb positioning with the wire or wood spreaders can be done at any season of the year, but is best used during the dormant season. The basic design of the tree is easily determined during the dormant season and thus decisions are easier to make concerning the need of spreading. Limbs that are too crowded can be saved by spreading; perhaps the greatest benefit of spreading Is the omission of pruning (Fig. 23). 29 -»■*'; - —OS* >.-- Fig. 23. The best control of vegetative growth can be ob- tained by combining mininnal pruning and limb positioning. Tree Nutrition Fertilizer, either nitrogen (N) alone, a complete fertilizer, or a fertilizer containing N and potassium (K2O) and minor elements, should be applied 3 to 4 weeks prior to bloom and at a rate of 1 /4 pound of ammonium nitrate or its equiv- alent for each year of age. Reduce or omit N on young, vigorous Mcintosh trees when they start to bear fruit, if the trees appear very vigor- ous, to avoid excessively large, poorly colored apples. With this cultivar and all other cultivars, start participating in the Leaf Analysis Program when the trees start to fruit in order to determine the fertilizer requirements of the trees. (Information concerning the Leaf Analysis Program and specific details on orchard fertilization can be obtained from your County Extension Service.) Boron deficiency is more apt to be a problem with young than older bearing trees. Therefore, boron should be applied as a ground application or a foliar spray once the trees com- mence to fruit if this element is not already present in suffi- cient amounts in the fertilizer being applied annually. Exces- sive N levels are particularly disastrous with bearing Mcintosh trees and low Ca levels are a problem in all Massachusetts apple orchards. Once every 3 years, take soil samples and send them to the West Experiment Station, University of Massachusetts, Amherst, for determination of soil pH and lime requirements. Directions fortakingsoil samples can be obtained from your County Extension Service. Weed Control Chemicals (herbicides) are frequently used to control grasses and broadleaf weeds under apple trees. Herbicides should be used in such a manner that they provide early-season con- trol of weeds, but not necessarily control for the entire season. Regrowth of weeds in August and September can be advantageous for the following reasons; (1) The weed regrowth will help slow down growth of vigorously growing trees and thereby lessen the chance of winter injury. (2) The weeds will provide some protection to the tree roots against low temperature injury. (3) They will reduce soil erosion. The current recommendations for their use under apple trees can be obtained from your County Extension Service. In addition to chemical weed control, sand or gravel can be applied around the base of trees to reduce weed growth and/ or an area in the vicinity of the trunk can be cleared of weeds in the late fall. Calibration of sprayer with tractor-mounted boom. The sprayer can be calibrated by making a trial run over some known area. (One acre contains 43,560 square feet. When spraying a 4-foot swath, you must travel 10,890 feet to treat an area equivalent to an acre.) The easy way to calibrate the sprayer is to fill the tank completely or to some other known level, spray 1/10 of an acre (1090 feet x 4 feet) and then accurately measure how much water is required to refill the tank to the previous level. Multiply the gallons used by 10 to get the gallonage per acre. If for example, the sprayer delivered 60 gallons per acre and the herbicide is used at a 4-pound per acre rate, 4 pounds of the herbicide should be added for every 60 gallons of water in the spray tank. Calibration of granular herbicide applicator Granular appli- cators must be calibrated with the herbicide actually being applied. The best way to calibrate is to operate the applicator over a known area such as 1/100 of an acre (436 sq. ft.). You must catch dichlobenil* while operating over the known area and weigh it. The usual way is to disconnect the spinner and to collect the output from the applicator in a bag or bucket. Weigh the dichlobenil very carefully because the amount collected is quite small. When using a hand-operated granular applicator, fill with a known weight of dichlobenil*, operate the applicator over a known area, and then weight the herbicide remaining in *The only granular herbicide in common use. 30 Table 13. The number of trees that can be ground-sprayed with 100 gallons or 1 gallon of spray mixture when applied at the rate of 100 gallons per acre and spraying around the tree trunk the stated number of feet. Distance sprayed from middle of the truni< No. trees/I 00 gals. Calculated Calculated as a square as a circle Approx. no. trees/gal. Calculated Calculated as a square as a circle 3 feet 4 feet 5 feet 6 feet 7 feet 1210 681 436 303 222 1539 868 555 385 283 12 7 4 3 2 15 9 6 4 3 Table 14. Ounces of dichlobenil required per tree when applying this herbicide by hand. Area treated around the base Square area 6 ft. X 6 ft. 8 ft. X 8 ft. 10 ft. X 10 ft. 12 ft. X 12 ft. 14 ft. X 14 ft. Circular area 6 ft. diameter 8 ft. diameter 10 ft. diameter 12 ft. diameter 14 ft. diameter Ounces of dichlobenil G-4 At rate of 100 lb/A 1.3 2.4 3.7 5.3 7.2 1.0 1.8 2.9 4.2 5.7 At rate of 150 lb/A 2.0 3.5 5.5 7.9 10.8 1.6 2.8 4.3 6.2 8.5 the applicator. Calibration of a handgun on a hydraulic sprayer or a com- pressed air knapsack sprayer. When applying the herbicide with a handgun and to a limited area around each tree, calibration is relatively simple. First, determine how long it takes to deliver one gallon of spray. Then choose from Table 13 the plot size to be sprayed and note the number of plots that a gallon will cover. Finally, determine the length of time to spray one plot. Example; (a) The hand gun delivered 1 gal. in 63 seconds. (b) The distance sprayed from the middle of the trunk will be 4 feet. When calculated as a circle, 1 gal. will spray 9 areas of this size. (c) Seconds to deliver 1 gat. /Trees per gal. = 63/9 = 7 seconds/tree. (d) The data show that each plot should be sprayed in 7 seconds. Applying dichlobenil by hand. Some growers apply dichlo- benil by hand on an individual tree basis. Table 14 above indicates the ounces of dichlobenil to apply per tree based on area to be treated. For example, if you plan to apply dichlobenil at the rate of 100 pounds per acre and to treat a circular area of 6-foot diameter under each tree, one ounce of dichlobenil should be applied under each tree. Mouse Control Three general methods of bait application for mouse control are available: hand trail baiting; mechanical trail baiting; and broadcast baiting. Hand trail baiting, placement of zinc phosphide-treated grain baits in natural mouse trails and burrows, gives excellent control of both meadow and pine mice but is slow and tedious especially when mice ^re not abundant or surface signs of pine mice are obscure. Treat 2 to 4 spots with teaspoonful quantities of bait 31 around the dripline of each tree. Pay particular attention to low areas, rock outcrops, fence rows and orchard borders. Bait should be placed near holes to underground burrows or in active runways and under vegetation or artificial covers. Apply at the rate of 2 to 3 pounds per acre. For pine mice, bait should be applied to holes and burrows for best results. Mechanical trail baiting. A tractor-drawn trail-building ma- chine constructs artificial runs in which bait is distributed. If properly done, 95% of meadow mice and 80% control of pine mice can be expected by the trail builder method. A trailbuilder should be operated so that the trail made by the machine is just inside the drip line on both sides of the trees. Apply at the rate of 2 to 3 pounds per acre. Check machine accuracy for proper operation. Broadcast application of bait by hand, cyclone seeder or aircraft will provide control of meadow mice but control of pine mice may not be adequate. Broadcast application by tractor-drawn equipment is rapid but more bait is used than with hand or mechanical trail baiting. Broadcast methods give poor control when the ground cover is very dense, including a heavy mat of leaves, as the bait fails to penetrate into the mouse runways. Apply the zinc-phosphate-treated baits at the rate of 6 to 10 pounds per acre. Choose a period, immediately after harvest, of the least human activity in the orchard and warm, clear weather for applying the baits. This is the period when mice will be most active and most apt to consume the applied baits. A thorough and conscientious job is essential for good mouse control. NOTE: Before applying any toxic baits, a permit must be obtained for bait application from: Massachusetts Division of Fisheries and Game, 100 Cambridge Street, Boston, Massachusetts 02202. Pesticide regulations are always sub- ject to change, therefore, always contact your local County Extension Service for the latest information on rodenticide and pesticide usage. 32 Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT Available to the public without regard to race, color or national origin. FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 42 (No. 4) JULY-AUGUST 1977 TABLE OF CONTENTS Considerations in Attempting to Improve the Calcium Content of Apples 2,4-D for Problem Weeds in Strawberries The Plum Curculio: An Introduction and Summary of Preliminary Field Observations, 1976 C02 Treatments for Mcintosh at the Begin- ning of CA Storage ese CONSIDERATIONS IN ATTEMPTING TO IMPROVE ^ THE CALCIUM CONTENT OF APPLES 2 Heather A. Betts and William J. Bramlage Department of Plant and Soil Sciences Apples are subject to many diseases and physiological dis- orders after harvest, all of which must be controlled to provide a product acceptable to consumers. The mineral nutrient composi tion of fruit at harvest greatly influences the occurrence of th problems, and it is now widely recognized that calcium (Ca) content is a key factor. Low Ca levels are implicated in development of corking disorders such as bitter pit, cork spot, and Jonathan spot, both before and after harvest. In addition, watercore, internal breakdown, low temperature breakdown, lenticel breakdown, scald, and rot may be intensified when fruit Ca levels are low. From among these problems, bitter pit and internal breakdown have been most extensively studied for their relationship to Ca nutrition. Bitter pit has long been recognized as a Ca-def iciency prob- lem. It is influenced by many environmental, orchard management, and storage factors such as water stress, pruning, mineral balance, and time of picking, and many of these influences may actually be acting through modification of fruit Ca levels. Usually, the lar- ger the fruit and the drier the growing season, the more bitter pit is found. Some success in reducing bitter pit has been obtained with calcium chloride (CaCl2) and calcium nitrate (CaCNOj)^ sprays 4 to 7 times during the growing season; CaCl2 is usually the pre- ferred material since Ca(N02)2 adds nitrogen to the tree, which can intensify a Ca deficiency. Sprays typically reduce the incidence from 40% to 10% in 'Cox's Orange Pippin' apples in England. Since mobility of Ca in the apple tree is very low, the Ca must be ap- plied directly to the fruit for the treatment to be successful. Ca dips after harvest have also been used to increase the Ca content and decrease bitter pit occurrence during storage. Internal breakdown usually occurs after harvest and is often more prevalent in late-picked fruit. High relative humidity in storage accentuates the disorder. It develops as extreme soften- ing of the tissues, with brown discoloration that can become dark- chocolate colored with time, and with the vacular bundles standing out prominently as dark-brown strands. Recent studies show that internal breakdown is greatly influenced by Ca nutrition. In Eng- land, Perring determined that 'Cox's Orange Pippin' apples contain- ing greater than 4.5 mg Ca/100 g fresh weight of flesh will usually ^This is a review article. Our current suggestions for increasing Ca level in apple trees can be found in the May-June, 1977 issue of Fruit Notes. 2 Present address: 200 Sullivan Street, Claremont N.H. 03743 - 2 - be free from breakdown during storage, whereas at 3 mg/100 g fresh weight the fruit is very likely to develop breakdown early in stor- age. In Canada, Lidster, et al . determined that nearly this same Ca level (4.5 mg/100 g) was required for maximum protection of •Spartan* apples from breakdown in storage. Spraying and dipping apples with Ca solutions before storage have frequently been effec- tive in reducing internal breakdown. One spray program raised the Ca level of the fruit from 3.7 to 5.4 mg Ca/100 g of fruit flesh, and correspondingly reduced the occurrence of breakdown in storage from 16% in the controls to 0% in the treated fruits. In Massachu- setts, we have consistently found in recent years that in a given situation, greatest incidence of internal breakdown occurs in the apples with the lowest Ca content. There is, therefore, strong reason for a fruit grower who is having difficulty maintaining fruit quality during storage, to be concerned about Ca nutrition of the fruit. Unfortunately, it is not easy to substantially increase Ca levels of apples. Ca is one of the most abundant minerals in most soils, yet fruit frequently contain inadequate amounts of this mineral. Apple tree roots do not readily take up Ca from the soil, and what they can take up is influenced by numerous soil conditions. Thus, lime and Ca fertil- izers do not quickly or markedly increase Ca levels in apples. Leaves seldom show Ca deficiency symptoms even though fruit may be severely deficient. What Ca is absorbed from the soil is transported very slowly within the tree, and what is transported is apparently directly by water use in the tree. Movement is largely within the xylem (the water transporting system) . Early in the season, small apples are using large amounts of water, and relatively large amounts of Ca move to the fruit with this water. By mid-season, however, apples are using much less water and are also serving as a large depository for sugars and other organic nutrients coming from the leaves. These nutrients are moving through the phloem (the food transporting system) , in which Ca is relatively immobile. Therefore, little Ca is transported to the fruit late in the season, since the fruit are being supplied large- ly by the phloem system. As a result, 901 of the apple's Ca may move in during the first 6 weeks after full bloom. When water stress occurs in the apple tree, water may be drawn from the fruit to the leaves, and simultaneously Ca may be withdrawn from the fruit. In this way, water stress may create or intensify Ca defi- ciency in the fruit. The average Ca level in the fruit is considerably lower than that in the rest of the tree. Within the apple fruit itself there are large differences in the concentration of Ca. In the cortex (outer flesh) of mature apples, Ca concentration declines steadily from the stem end to the calyx (blossom) end, which is probably why bitter pit and internal breakdown usually begin to develop (and develop most intensively) at the calyx end of the apple. The apple - 3 peel has al-out 3 times more Ca in it than has the flesh. Because of this uneven distribution, Ca concentration is sometimes extreme- ly low in the fruit tissues most sensitive to physiological disor- ders. An understanding of these characteristics of Ca nutrition of apples is important in designing a program to improve fruit Ca lev- els. Much work has been done worldwide to increase Ca levels in apples. Soil treatments have been of little measureable benefit. Tree sprays of Ca salts such as CaCl2 and Ca(N07)2 have given some success in increasing Ca levels and reducing disorders. Their ef- fectiveness usually increases with concentration of the salts in the spray mix and with the frequency of spraying, A common cause for unsatisfactory results is poor spray coverage; because of the low mobility of Ca to fruit within the tree, thorough and uniform coverage is essential. This problem may be intensified by appli- cation of Ca in concentrate sprays. Postharvest dips have the advantage of being able to complete- ly cover the fruit with solution. In England, researchers in one trial got similar control of bitter pit with a postharvest immer- sion for 1 minute in 0.05 M Ca(N03)2 as with 4 summer sprays of the same solution. However, CaCl^ again is considered to be a more effective salt for dips than CaCNO)-, at least in part because CafNOj)^ will support bacterial growth and leave an undesirable residue on fruit after storage. Other substances have been added to the dipping solution in order to increase the penetration of Ca into the fruit, with varying and often conflicting results. The most striking effects have been obtained by adding "thickeners" to the dipping solution. Mason and his colleagues in Canada have used arrowroot flour and the commercial thickener keltrol with great success. With 'Mcintosh,' dips in 41 CaCl2 plus keltrol al- most tripled flesh Ca during storage, and significantly reduced the softening rate of the fruit during and following storage. These thickeners apparently cause much more Ca to adhere to the surface of the apple, from which it can be absorbed into the flesh later during storage. Injury can result from excessively heavy treatments to in- crease Ca levels. Tree sprays can severely injure leaves, especi- ally early in the season or in hot weather. Postharvest dips can cause injury to the surface of the fruits, usually appearing as a burn or as black spots at the calyx end of the fruits. In most cases, fruit inury is not serious, but in a report from New Zea- land 23% of 'Cox's Orange Pippin' were injured by a 2.5% CaCl2 dip. As we learn more about the effects of mineral deficiencies on storage life and quality retention in fruit, it becomes increasingly important to develop strategies to overcome the deficiencies. Solu- tions will not be simple. Following a comprehensive study of fac- tors related to storage breakdown of 'Spartan' apples in British - 4 Columbia, Canada, Lidster, et a1 . concluded that: "The fruit and orchard profile for expected minimum breakdown incidence would be as follows: (1) high Ca content in apple flesh (minimum of 42.4 ppm fresh weight): (2) apple K (potassium) and B (boron) content to be less than 883 and 2.9 ppm, respectively; (3) small apple di- ameters [optimum diameter, 5.8 cm (approximately 2.30 inches)]; (4) low apple soluble solids (below 11.9%); (5) low to moderate tree vigor [terminal growth less than 46 cm (approximately 18 inches)]." These 5 factors accounted for 75% of the variation in breakdown among different samples, but that still left 25% to be accounted for by other factors. It will be necessary for the grower to understand the complex ity of the Ca problem in apples if the problem is to be success- fully overcome. We have attempted in this brief review to outline the key features of the Ca problem, so that as growers look ahead to the coming season they can better understand why specific ac- tions or conditions can or cannot be expected to influence the Ca levels of their fruit, and thereby influence the storage life and quality of next year's crop. *************** 2,4-D FOR PROBLEM WEEDS IN STRAWBERRIES Dominic A. Marini Southeast Regional Fruit and Vegetable Specialist Broadleaf perennial weeds, such as dandelions, can be a seri- ous problem when carrying over strawberry beds for 2 or more sea- sons. The commonly used strawberry herbicides do not control these perennial weeds and hand weeding of deep-rooted perennials is vir- tually impossible. on ol leaf f rui t gle a 0 V a t i pi ant estab to fr in 2 5 appl i growt Dow Fo d or e weeds . s , we p p 1 i c a ng the ings. 1 i s h e d u i t b u to 50 ed dur h. rmula 40* stabl i shed In the 1 are sugges t i 0 n of t h harvested Furthermo beds are ds. The r gallons o ing warm w formulation of 2,4-D is now registered for use strawberry beds for the control of many broad- 977 chemical weed control chart for small ting for the control of broadleaf weeds, a sin- is herbicide applied right after mowing or ren- strawberry bed. It should not be used on new re, spring or fall applications of 2,4-D to not recommended because of the possible injury ecommended rate is 1 to 1-1/2 quarts per acre f water. For best results, 2,4-D should be eather when weeds are young and making rapid Since many crops and ornamental plants are sensitive to only the slightest trace of 2,4-D, it should be applied under calm con *Trade name ditions when there is no possibility of drift onto nearby plants. Tomatoes, grapes, and roses are particularly susceptible to injury. Applying a dilute spray using nozzles that deliver large, coarse droplets and low pressure reduces the possiblity of drift. Clean the sprayer thoroughly after using it to apply 2,4-D be- cause trace amounts of this herbicide can injure sensitive crops. In fact, it would be best not to use the same sprayer for other crops. If this is unavoidable, rinse thoroughly with clean water and then fill the tank with a solution of 1 part household ammonia to 99 parts water and allow it to remain for 24 hours. Then pump some of this solution through the system, drain, and rinse again. A quicker method is to fill the tank 1/3 full of water and add 1/4 pound of activated charcoal and 2 to 4 ounces of laundry detergent for each 10 gallons. Agitate the mixture and swirl it around in the tank for at least 2 minutes so that it reaches all parts of the tank. Pump some through the system, drain, and rinse with clean water. Where broadleaf perennial weeds are a problem in established strawberry beds, 2,4-D can be useful for their control, but it must be used with extreme caution because of the possibility of in- jury from drift onto nearby sensitive plants and the need for re- moving every trace of it from application equipment. *************** THE PLUM CURCULIO: AN INTRODUCTION AND SUMMARY OF PRELIMINARY FIELD OBSERVATIONS, 1976 Karen I. Hauschild and Ronald J. Prokopy Department of Entomology The plum curculio is one of the most serious pests of apples in Massachusetts. It is a native species, originally found on wild plums, crabapples, and hawthorn; however, with the past cen- tury, it has adapted to most tree fruits as they have become in- troduced from Europe. Here we outline the life history as known from the literature, and discuss some of the results of our first year (1976) of research studies. Dr. Whitcomb, of the Waltham Experiment Station, conducted an extensive study of the biology of the plum curculio in Massa- chusetts in the 1920' s. He found that in some years a few adult curculios arrive on apple trees as early as the pink stage. Ac- cording to his study, feeding punctures can be found from the last week in May, while oviposition (egg-laying) occurs from late May to mid-July. Mating, he found, occurs prior to, or during the - 6 - time when the adults arrive on the trees. Eggs hatch in about a week. Larvae then tunnel into, and feed on, the developing fruits for the next two to three weeks. Most of the larval-infested fruits drop to the ground, and there the larvae leave the fruits to pupate in the soil. Adult curculios emerge from the soil approx- imately one month after that. These emerging adults feed on late apple varieties or leaves and then overwinter, unmated, in or near orchards. There is only one generation of curculios in Massachusetts. Damage caused by the plum curculio is of several different types. Early in the season, curculios feed on and lay eggs in young fruits. These fruits are then scarred with surface wounds. Small round holes are the result of feeding punctures, while cres- cent-shaped yellowish scabs are the result of egg-laying activities. The most important injury is larval tunneling inside the fruits and the correspondent fruit drop. Feeding scars of the adults in the fall and adult feeding damage on blossoms in the spring are other types of injury. Controlling this pest has been a frequently difficult as well as expensive task, even with modern insecticide sprays. Research- ers in other states are working on alternatives to chemical con- trol of the plum curculio, but to date no practical means of con- trol other than insecticides have been developed. A reduction in the number of chemical sprays against the curculio would not only save growers' money, but in addition would postpone the onset of possible pesticide resistance, and decrease pesticide contamination in the environment. Beneficial insects such as pollinators, preda- tors, and parasites would also undoubtedly benefit from reduced numbers of insecticide sprays. One of the purposes of our plum curculio project here in the Department of Entomology is to study the activities of the adults to determine whether there is any behavioral trait which could be used in the development of a curculio trap. Although some aspects of the biology and life cycle of the curculio are reasonably well understood, there is little information on its behavior. A trap- ping device such as is used for apple maggot or lepidopterous pests (for example, the codling moth) would (coupled with informa- tion on how many curculios an orchard could tolerate without affect- ing crop quality or yield) aid the grower in determining whether and when he should use insecticides against the curculio. It also is possible that such a trapping device could be used as a direct control measure -- that is, the trap itself could be effective in controlling adult curculios, especially where only small popula- tions were present. The major study that was conducted last summer involved spend- ing many hours observing the behavior of adult curculios on apple and plum trees located on Orchard Hill on the UMass campus. The purpose of this study was to obtain some understanding of the cur- 7 - culios' behavior. Observations were made at varying time intervals from 8:00 A.M. to 9:00 P.M. on warm, sunny days. Once we had lo- cated a curculio we watched that insect until it moved out of sight, From these observations, we found that the main activities of adult curculios were: 1. Exploration - moving about a tree in search of food, ovipositional or resting sites. 2. Defense or camouflage behavior (These insects are very sensitive to noises or other disturbances.) 3. Resting 4. Feeding 5. Ovipositing (egg-laying) An adult curculio appears to have little recognition of places it or other curculios had previously visited, as individuals spent considerable time re-exploring the same areas. Curculios were rarely observed flying, spending most of their exploratory time crawling. It appeared that they were able to distinguish fruits from twigs and foliage only upon direct contact, and not by dis- tance vision or smell. In terms of egg laying behavior, females spent several moments "drumming" their antennae and tarsi (feet) on the fruit before they would attempt to lay eggs. These observations would suggest that curculio behavior is rather complex, and for this reason it will take considerable time to discover what methods curculios use to find their host trees, food and mates. It appears that this insect has comparatively little dependence on vision. For this reason, we doubt that a trap employing only visual stimuli would be very effective. Also, since within-tree flight appears to be of minor importance, traps aiming to capture curculios flying within trees would likewise probably not be very effective. Traps based on insect flight to visual stimuli are relatively easy and quick to develop and use, and we have indeed experienced some success with such traps for tarnished plant bug, sawfly and apple maggot. We are closer to an understanding of plum curculio behavior than we were a year ago. However, many further long term studies on the behavior of adult plum curculios will have to be carried out to uncover some behavioral trait which would lend itself to an effective, efficient and reliable trapping device. 8 - I CO2 TREATMENTS FOR 'McINTOSH* AT THE BEGINNING OF CA STORAGE William J. Bramlage Department of Plant and Soil Sciences Perhaps you have read about the CO2 treatments that are being used in Washington to slow dovm softening of 'Golden Delicious' apples in CA storage. This procedure has gotten a lot of publi- city and is working very well in commercial storages in that state. If you have read any of these reports, you have surely wondered if the same treatment will work on 'Mcintosh'. So have we, and in earlier Fruit Notes articles (Sept-Oct, 1973 and Sept-Oct, 1975) we reported results of our preliminary studies with this procedure. In 1975, we also reported that a large-scale test was to be conduc- ted to determine the feasibility of this "COo pretreatment" of 'Mcintosh*. This test has now been completed and its findings can be reported. The 'Golden Delicious* treatment simply consists of raising the CO2 level in the storage to 15% during the first 8 to 10 days of CA storage, then scrubbing it down to the normal CO2 level for CA storage. It results in much slower softening of the apples and allows the growers to market crisp fruit into late spring and early summer. In preliminary tests with 'Mcintosh', both in Massachusetts and in other areas where this variety is important, the trials in- dicated that softening of 'Mcintosh' could also be slowed down by CO2 pretreatment, but that there was considerable danger of COo in- jury from the treatment. To evaluate as broadly as possible the potential benefit and potential danger from such a treatment, a co- operative study was made at 5 locations where 'Mcintosh' is an im- portant variety: Massachusetts, New York, Michigan, Ontario, and British Columbia. At all 5 locations, a treatment that had appeared in prelim- inary tests to be about optimum for 'Mcintosh' was tested. It con- sisted of liarvesting the apples at peak time for CA storage, quickly cooling them to 38°F, and as quickly as possible sealing them in CA where COo was brought to 12%. This 12% CO2 atmosphere was main- tained for 2 weeks and then the apples were put under normal CA conditions of 5% COo and 3% O2. The samples were kept in CA for up to 8 months before Being compared with other CA samples that had not received the 12% CO2 pretreatment. Besides conducting this test of what was believed to be about the best treatment for 'Mcintosh* , each participant tested the effects of 1 or more of the following factors that might influence response to the CO2 treatment: harvest date; delaying treatment after harvest; slow cooling during treatment; temperature, humid- ity, and O2 level during treatment; increased CO2 concentration; and, increased length of the CO2 treatment. - 9 - The results from these tests clearly demonstrated that the CO2 pretreatment can delay softening of 'Mcintosh' in CA storage. At every location, treating them with 121 CO2 for 2 weeks produced apples that were 1 to 2 lbs firmer than untreated CA samples after 4 to 6 months in storage. However, the effect gradually wore off; after a week at room temperature these differences had largely dis- appeared, and after 7 to 8 months of storage even the fruit right cut of storage showed only small differences. Nevertheless, these differences would be well worth the treatment if no problems arose from the treatment. But there are problems! Both external COo injury (a scald- like burn) and internal CO2 injury (a form of internal breakdown) developed. The extent of these injuries was variable among loca- tions; external injury occurred everywhere except in Michigan, and internal injury was distinct only in British Columbia. However, the problems were sometimes overwhelming; in British Columbia, 431 of the fruit had external injury, and 53% had internal injury, and in New York 30 to 351 of the apples had external injury. In Massa- chusetts, we've found the extent of injury to vary from year to year, sometimes not occurring at all and in other years occurring to a serious extent. We also find different samples varying great- ly in the amount of injury that they develop from the same treat- ment. Just as it was obvious in these tests that the CO2 treat- ment can delay softening of 'Mcintosh', it was also obvious that the treatment has the potential of causing very serious damage to the stored apples. What about other factors that might influence results? We found that increasing the CO2 level from 12% up to 15% resulted in a bit more fruit firmness after storage, and that increasing treatment time from 2 weeks to as much as 6 weeks did likewise. However, both of these modifications increased the amount of CO2 injury as well as increasing firmness of the apples. Harvesting the fruit 1 week earlier than peak time increased treatment bene- fit, but again it also increased the amount of injury. Harvesting 1 week later than peak time reduced benefit from the treatment. Treating the apples at 32°F rather than at 38° reduced both bene- fit and injury. In tests in New York, treatment was begun when the apples were still warm (55°) and they were cooled to 38° dur- ing the 2-week treatment; the CO2 treatment was of no value in de- laying softening of these warm fruit. In Michigan, apples were kept at 70°F for a week, or at 32° for 1 or 2 weeks, before they were treated; any delay reduced treatment benefit, and 1 week at 70° eliminated any benefit. The O2 level and the humidity in the storage during the CO2 treatment had no effect on the delay in softening brought about by the CO2 pretreatment. It was rather clear from the results of these tests that rais- ing the CO2 level to 12% for 2 weeks at the beginning of CA storage has no magic effect on the apples; it simply slows down their rate of ripening even more than CA alone does. Anything that increases - 10 - ripeness (late harvest, slow cooling, delayed treatment, etc.) be- fore treatment takes away from the benefit obtained from the treat- ment. Benefit from treatment is increased when less ripe apples are treated. However, factors that increased the ability of the treatment to delay ripening and softening also increased their sus- ceptibility to CO2 injury. The only exception to this was storage humidity. We found that by not humidifying the storage until after the COt treatment, injury was reduced but firmness was not. Later tests m British Columbia support this finding. However, it re- mains to be determined if this technique is practical, and if it produces new problems. After examining the results of these tests, it was the unani- mous conclusion of those who participated in them that for 'Mcin- tosh', the possible benefits to be gained from the CO2 pretreat- ment did not outweigh the possible losses that might result from CO2 injuries. Unfortunately, 'Mcintosh' seems to be more sensi- tive to CO2 than are 'Golden Delicious' in Washington. Unless a way can be found to reduce the risk of injury without reducing the delay of softening, CO2 pretreatment of 'Mcintosh' cannot be recom- mended for commercial practice. *************** All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State Laws and regulations in effect on the date of this publication. When trade names are used for identification, no product endorsement; is implied, nor is discrimination intended against similar materials, NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whalev Director Cooperative Agricultural Extension Worl< Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol 42 (No. 5) SEPTEMBER/OCTOBER 1977 TABLE OF CONTENTS The National Controlled Atmosphere Research Conference Monitoring Traps for Blueberry Maggot Flies Pomological Paragraph Ethephon' s use to promote early-ripening of Mcintosh Some Details to Consider When Harvesting and Storing Apples I i I 4 THE NATIONAL CONTROLLED ATMOSPHERE RESEARCH CONFERENCE William J. Bramlage Department o£ Plant and Soil Sciences On April 5-7, 1977, a National Controlled Atmosphere Research Conference was held at Michigan State University, bringing together nearly 100 persons with professional interests in controlled atmos- phere storage of various commodities. The last such conference was held in 1969, and the main objective of this meeting was to re- view the changes that have occurred since then. The focal points of the meeting were the consideration of new techniques and new problems, and an update on our knowledge of the responses of differ- ent commodities to CA. The full proceedings of the Conference will be available soon, but in this article I will touch on the points that may be of most interest to our readers. Storage construction. Probably the biggest concern today with storage construction, is the problem of how to fireproof polyure- thane satisfactorily. Flame retardants have been of limited value, and some of the approaches that are being taken either are not prac- tical in a storage or are of unproven durability. Several speakers concluded that the most reliable way to fireproof urethane is to cover it with one-half inch of cement mortar. Mr. Keith Clarke, of Vineland, Ontario suggested that at a minimum, a urethane-sealed storage should be dealt with as a highly flammable structure: Treat it as a farmer does his haymow, he suggested. Some storages have burned because their owners were using them as workshops! Construction methods were discussed by Mr. D.L. Hunter of Yakima, Washington. Of considerable interest today is how to con- serve energy in the storage. He pointed out that large rooms (e.g., 40,000 bu capacity) are most efficient, as are large capacity re- frigeration units. However, large units give you less air move- ment per unit. One common mistake in storage is to put fans in front of cooling coils. This arrangement adds the heat from the fan to the room air. Mr. Hunter also described the use of a rubber gas seal that can be sprayed on behind the insulation. Rubber gas seals have been very successful where they have been applied carefully. The first storage to use this material was built in 1969 in Kelowna, British Columbia; this storage has been expanded three times since then, always with th-e rubber vapor barrier, and over a million bushels of apples are now stored in it. The operator of this stor- age was at the Conference and verified the successful use of this gas seal. - 2 - Storage operation. Since a storage operator can choose from a long list of scrubbbing techniques, a common question is: Which is best? Lime boxes are not used in many areas, partly because they are considered to be a nuisance, but they are very effective. We have been urging growers not to put lime in the storage because it keeps the CO2 level so low that the CO2 is not providing its maximum effect m delaying ripening of the fruit in storage. How- ever, tests in New York showed no adverse effect on the fruit from having lime in the room. This technique of course provides protec- tion from CO^ injury, but you must consider that it displaces some fruit. Dr. G.D. Blanpied, of Cornell University, compared data on costs for various scrubbing systems. Water scrubbers are very effec- tive, but corrosion of bearings, motors, and switches from the brine raises operating costs. This can be avoided by having a separate water scrubbing system, which costs more to install but which saves money in the long run. Surprisingly, Dr. Blanpied' s analyses indi- cated that in the long run the least expensive scrubbing system may be the commercial scrubbing devices that use charcoal as CO2 adsorb- ant. While they are expensive to purchase and install, their oper- ating expenses are very small and they have a long operating "life." Another operation technique of considerable interest is the possible use of high-C02 treatments at the beginning of CA storage. This question will be considered in a separate article. Commodity responses to CA storage. In the U.S., about 38% of the apple crop is stored in CA. In the Northeast, the percentage is much higher than this and has probably reached its peak, but in the Southeast and Midwest the "growth areas" for CA storage of apples only a small percentage of the crop is stored in CA. The question we can now ask is, what about storing commodities other than apples? In the West, many pears are stored in CA, but in the East a greater susceptibility to CO^ injury almost rules out CA storage of pears. Progress is being maae in developing techni- ques for CA storage of peaches and nectarines, but there is no com- mercial application yet. Sweet cherries may be stored in CA, but there is little evidence that it is better than storage in air if good temperature control is maintained (29-30°F is optimum). Avo- cados are being successfully stored commercially in Florida, but the potential for development is limited. Much effort has gone into tests for CA storage of citrus, but without success. Vegetables are extensively transported in CA-equipped trucks and vans. One of these systems ("Transfresh") ships 5 million pounds of foodstuffs per week, mostly by truck, and another ("Sea- land") is involved primarily in ocean transport. However, these are short-term treatments aimed specifically at transportation problems. Long-term storage of vegetables in CA has not proven fea- sible. There is often interest in storing tomatoes in CA, but this is very dangerous because tomatoes can easily be injured by a stor- * 3 - age environment. Root crops (carrots, beets, potatoes, etc.) have been extensively tested and simply are not suited to CA storage. Frequent mention is made of CA storage for flowers, but laboratory successes are very difficult to put into commercial practice, due in part to the vast number of flower species, varieties, and grow- ing conditions that can all influence storage responses. On the national scene CA storage is moving into some new areas. Some excellent results have been obtained from nut and grain tests with CA, and commercial storage is now practiced. The object here is mainly to control insects. Also, use of CA during transit of meat is growing rapidly, and 401 of the "Transfresh" shipments are with meat. In this case, the object is mainly to control bacteria growth and discoloration of the meat. To the Northeast storage operator, however, it is evident that CA storage today is still an apple industry. Hypobaric storage. During the past 10 years, a new concept in storage has emerged. It is called "hypobaric storage", "low pressure storage," or simply "LPS." This approach involves storing produce under a strong vacuum, which removes gases (like the ripen- ing ethylene) from the produce almost as fast as they are formed. It also greatly reduces the amount of oxygen they are receiving, and removes COo as fast as it forms. This type of storage has pro- duced some remarkable results with storage of many commodities, in- cluding apples and pears. 'Mcintosh' apples in March are said to taste like they were just harvested. There are many engineering problems involved with applying the technique. It would require whole new approaches to storage construction. Tests with this new storage method have now been made on small scales in a number of different places, and results were critically evaluated at this Conference. It seems clear that LPS can work, and work well, on a number of crops. Grumman Allied Industries, Inc. (basically, an aerospace industry) is developing 40-foot long units for transporting produce in LPS, but they are still experiencing technical problems. Even when it becomes tech- nically feasible to commercially build and operate LPS systems, they will be expensive. How economically competitive LPS will be with CA remains to be determined. The recurring theme of reports given on the use of LPS was that the spectacular effects first re- ported for this system led to expectations that were too great. More realistic assessments now state cautious optimism that LPS will take its place in post-harvest horticulture, but that CA and other systems now being used have not been made obsolete. Summary. This 1977 National CA Research Conference brought together a great deal of knowledge, and some controversy, about - 4 - the use of CA in today's horticultural industry. Proceedings of this Conference should be of interest and value to everyone in- volved in CA storage. We will inform you in Fruit Notes how to ob- tain copies when they are published. *************** MONITORING TRAPS FOR BLUEBERRY MAGGOT FLIES Ronald J. Prokopy and William M. Coli Department of Entomology The blueberry maggot, Rhagoletis mendax, is generally consid- ered the most important insect pest of commercially grown highbush blueberries in the eastern and mid-western United States. The adults look identical to apple maggot adults, but are a different species. They emerge from overwintering cocoons about the time earliest-ripening berries are turning reddish blue. They feed for about 10 days-principally on insect honeydew on foliage, mate, and then commence laying eggs into the berries. The eggs hatch in about 4 days, and the larvae (maggots) feed for about 2 weeks on the flesh of the berry, causing it to rot. Infested berries may look in fine condition on the outside but be soft and mushy inside. When no measures are taken to prevent injury, 501 or more of ripe berries may be maggot infested. The standard method of controlling the blueberry maggot is application of 3-5 insecticide treatments against the adults. At present, the treatment schedule followed by most growers is a type designed to prevent any possible maggot injury, irrespective of whether or not maggot flies are actually present. If there were a method available for accurately assessing fly abundance in the plantation and eventually relating fly density to level of larval infestation, then the decision as to whether or not insecticide should be applied could be made on a firm cost-benefit basis. Un- necessary and uneconomical sprays could be eliminated, resulting in (a) monetary savings to the grower, (b) less pesticide residue on and in the fruit and in the environment, (c) less selective pressure for rapid development of maggot fly resistance to insecti- cides, and (d) greater opportunity for natural enemy buildup. Un- til now, no effective method for assessing blueberry maggot fly abundance has been available. In 1976 and 1977, we studied the reactions of blueberry mag- got flies to visual and combined visual-odor stimuli. When we tested their responses to 6 x 8 inch painted cardboard rectangles Graduate Student in Department of Plant and Soil Sciences - 5 - hung from highbush blueberry branches, we found that the flies were more attracted to yellow enamel ones than to enamel green, blue, orange, red, white, gray, black, aluminum foil, or clear Plexiglas ones. We then found that the maggot flies were even more attracted to daylight fluorescent yellow rectangles than to enamel yellow ones. These color responses of blueberry maggot flies were virtually identical to the color responses of apple maggot flies in earlier tests (see Sept. -Oct., 1976 issue of Fruit Notes) . We believe that the reason the flies are so attracted to bright yellow color is because they perceive yellow as if it were super-bright or super- intense foliage on which to find food. In another test, we hung 1.3 and 3- inch diameter red spheres and found the blueberry maggot flies highly attracted to both, but especially to the 3-inch ones. This is very similar to our findings on apple fly response to red spheres (see Nov. -Dec, 1976 issue of Fruit Notes) . We believe that the reason the flies are so attrac- ted to 3-inch red spheres is because they perceive such spheres as if they were super-large blueberries on which to find mates or lay eggs. We then coated 6 of the 6x8 inch daylight fluorescent yel- low rectangles and 6 of the 3-inch red spheres with Bird Tangle- foot (a clear sticky substance that captures and holds arriving flies) and hung them from highbush blueberry branches in a planta- tion in Munson, Mass. from July 13 to August 11. We caught a total of 1547 blueberry maggot flies on the rectangles and 3309 on the spheres. When ammonium acetate crystals (an odoriferous bait attrac- ting food-seeking flies) was added to a second set of 6 yellow rec- tangles, 2206 maggot flies were captured. This was more than on the unbaited yellow rectangles, but fewer than on the unbaited spheres . These findings indicate the sticky-coated daylight fluorescent yellow rectangles and 3-inch red spheres are effective traps for capturing large numbers of blueberry maggot flies. Hence, they can be profitably employed to monitor maggot fly population levels and activities in commercial plantings. Their use will aid in better timing of maggot fly sprays, and avoidance of unnecessary applica- tions when no maggot flies are present. Proper positioning of the traps is critical to their fly-cap- turing effectiveness. They must be hung so that the flies can clearly see them. Therefore, all foliage, twigs, and berries within 8-12 inches of all sides of each trap should be removed. But be- yond this distance, there should be as much fruit and foliage as pos- sible (especially below and to the sides) to attract flies into the general area. Although we have not yet established any firm rela- tionship between maggot fly trap captures and fruit infestation levels, we would suggest that capture of 5 flies per trap per week may warrant insecticide treatment on highbush berries grown for - 6 - the fresh market. At least 1 trap per acre should be employed. Berries grown for processing may require treatment when fewer than 5 flies per trap per week are captured. Where can the traps be purchased? Sticky-coated, ammonium- acetate-baited fluorescent yellow rectangles can be bought from Zoecon Corporation, 975 California Avenue, Palo Alto, California 94304, at a cost of about $1.00 each. Each rectangle will prob- ably need replacing with a new one at mid-season owing to accumu- lation of large numbers of other large insects which may cover up and obscure the smaller maggot flies on the trap. Sticky-coated 3-inch red spheres, likewise baited with ammonium acetate, may be purchased for about $1.00 each from New England Insect Traps, Box 301, North Amherst, Mass. 01059. Such spheres are quite selective, capturing relatively few other insects. They will last many sea- sons and require coating with Tanglefoot only at the beginning of the season and perhaps again after a series of heavy rains. Which- ever type of trap you choose to use, it should, over the long term, pay you dividends in reduced spray costs for this insect. *************** POMOLOGICAL PARAGRAPH Ethephon's use to promote early-ripening of Mcintosh. Our sugges- tions for ethephon use on Mcintosh are based on 3 time periods for sale of ethephon- treated fruit prior to normal harvest time (Labor Day or shortly after), during normal harvest, and after sev- eral months of storage. To have well-colored Mcintosh by Labor Day, we suggest applying ethephon at 2/3 to 1 pint plus 20 ppm 2,4,5-TP 8 to 12 days prior to anticipated harvest. These suggestions have worked well at our Horticultural Research Center. In 1975, we ap- plied 1 pint of ethephon plus 20 ppm 2,4,5-TP with an airblast sprayer on August 27 and had adequate color for harvesting by Sep- tember 2. In 1976, we applied the same mixture on August 16, and harvested the fruit August 26. *************** SOME DETAILS TO CONSIDER WHEN HARVESTING AND STORING APPLES F.W. Southwick Department of Plant and Soil Sciences Pre-Harvest Conditions Harvest Abnormally high temperatures during the few weeks prior to harvest tend to make most apple varieties more suscep- tible to storage scald in both regular and CA storage. Preharvest drop tends to be most severe when: (a) hot weather prevails; (b) trees have a large crop; (c) foli- age is damaged by drought, frost, insects and diseases; (d) trees are deficient in boron, magnesium and potassium; and (e) trees have a high nitrogen level. The preharvest drop control materials NAA and 2,4,5-TP are effective when applied before damage to the foliage occurs - not afterward. Apples continue to increase in size as long as they re- main attached to the tree. A significant increase in total bushels harvested is possible by delaying harvest ,.,u^^^,,^^ ^..^u r.^^.A — ^,,4-1-^ your marketing strategy. Of whenever such action suits course, preharvest drop control, fruit maturity and sus- ceptibility to various fruit disorders must be kept in mind. There is no single optimum maturity date for a variety during the picking season for fruit to be sold through- out a 9-month marketing period. For example, the desired maturity of apples for immediate post-harvest sale may be much more advanced than for regular or CA storage. Mcintosh for CA storage shou from 15-17 pounds and posses color. Such fruit will be 1 scald and be in a firmer, ju May than more mature, later Mcintosh placed in regular s ruary) will develop less sea mature at later picking date the less mature fruit is inv scald regardless of whether storage. Id range in s at least ess suscept icier condi picked appl torage (unt Id when the s. With ot ariably mor it is held flesh firmness 50 percent red ible to storage tion in April and es. However, il January or Feb fruit is more her varieties, e susceptible to in regular or CA 8 - Immature fruit of all varieties is subject to more bitter pit, shriveling, and brown core during storage than more mature apples. Overmature fruit is more susceptible to water core, inter- nal breakdown, flesh softening and rots than less mature fruit either prior to harvest or during storage. Avoid excessively large fruit of a given variety when selecting apples for long-term storage. Such fruit have much poorer keeping quality than smaller sizes. Usually fruit from light bearing older trees and from very young trees are often unsuited for CA storage because of their large size. Alar-85*-treated Mcintosh scheduled for storage should be harvested at the same time as untreated fruit even though the Alar- 85- sprayed fruit may be a pound or two firmer than similar apples which have received no Alar-85. Most of the flesh firmness advantage Alar-85- sprayed fruit pos- sesses at harvest is lost during the first few months of storage. The prime value of Alar-85 on bearing Mcintosh trees is to provide superior preharvest drop control dur- ing the latter part of their picking season rather than serve this purpose when Mcintosh for CA storage should be harvested (early part of the picking season) . The magni- tude of preharvest drop is often relatively minor early in the Mcintosh harvest season and can be controlled quite well with NAA (naphthaleneacetic acid) . Late varieties which may be frozen on the trees should never be harvested until the fruit thaws completely. Har- vesting frozen fruit will result in visible injury at points where they are grasped by pickers and wherever they come into forceful contact with other fruit in pick- ing or storage containers. Apples which have been frozen can be expected to have hastened flesh softening (even if no visible injury is present after thawing) and a short- ened storage life. The lower the freezing point between 22° and 28"F, the greater the potential loss of flesh firmness. Dispose of such fruit as rapidly as possible. If the fruit temperature falls below 22°F, visible injury to the fruit tissue can be expected once thawing takes place. All varieties subject to storage scald should be treated prior to storage with a suitable inhibitor if they are to be stored beyond early January. Suggestions for prestor- age treatments to control storage scald and decay organ- *Trade name Storage 9 - isms can be obtained from your Regional Fruit Specialists Harvested fruit should be moved into storage no later than 12 to 24 hours after picking. Long delays between harvesting and storage result in greater susceptibility of CA Mcintosh to scald, other senescence disorders, and loss of flesh firmness. 1. Ideally, apples placed in storage should be cooled from field temperatures to 32°F within 24-36 hours. Rapid cooling of apples following harvest is of major importance in maximizing their marketable life. Rapid removal of the field heat from fruit stored in bins or boxes requires recognition and understanding of proper stacking proce- dures to obtain the best possible rate of heat exchange from fruit in the center of these containers to the cool- ing unit. If an extended period is required to reduce the temperature to 32°F, one can expect a much more rapid deterioration of the fruit from senescence disorders and loss of flesh firmness than would result following fast cooling to 32°F. 2. When apples are placed in CA storage, we recommend a de- lay in sealing the room until the fruit is cooled to 32°F even though the CA room (as for Mcintosh) will be held at 38°F after the room is sealed. However, complete load- ing and proper cooling of an individual CA room should be accomplished in about 2 weeks. Any extension of this per- iod, particularly for Mcintosh, may result in a substan- tial increase in their storage scald susceptibility. Gen- erally, CA storage tends to reduce the scald susceptibil- ity of Mcintosh as compared to similar fruit held in reg- ular storage. However, delaying the sealing and CA at- mosphere development for 3 to 5 weeks beyond the time Mcintosh are initially loaded into a room may make this variety about as susceptible to scald as similar fruit placed in regular cold storage. Of course, if long per- iods of time are required before a CA room for Mcintosh can be sealed, the application of a scald inhibitor is essential . 3. Since questions are frequently asked concerning the at- mosphere and temperature requirement for CA storage of apples, the following table represents our present recom- mendations. 10 Variety Cortland* Macoun Mcintosh Baldwin Cortland* Delicious Empire Golden Delicious Idared Northern Spy Rome Beauty Spartan Carbon dioxide Oxygen Temperature (Percent) (Percent) 3 (Degrees F) 5 38 5 3 38 5 3 38 2 3 32 2 3 32 2 3 32 2 3 32 2 3 32 2 3 32 2 3 32 2 3 32 2 3 32 *Cortland listed. may be stored at either CA atmospheres and temperatures Varieties with the same CA atmosphere and temperature require- ments can be stored together providing the room can be fully loaded, cooled and ready for sealing in approximately 2 weeks. isicicicitii*1:1ei:iciticit'k Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, S300. POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE AGR101 BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 42 (No.6) NOVEMBER-DECEMBER 1977 TABLE OF CONTENTS New England Fruit Meetings and Trade Show Mulching Strawberries for Winter Protection Proceedings of the National Controlled Atmosphere Research Conference A Visitor's View of the Apple Industry in British Columbia Apple Aphid Control Through Natural Enemies Trends of Michigan Tree Fruit Industry — Part I Fruit Notes Index for 1977 NEW ENGLAND FRUIT MEETINGS AND TRADE SHOW The New England Fruit Meetings and Trade Show will be held at the New Hampshire Highway Hotel, Concord, New Hampshire. The meet- ings are scheduled for January 4 and 5, 1978. The hotel is accessible from all major highways. Routes 3 and 93, which lead to Concord, are accessible from anywhere in Mass- achusetts. Persons coming from Western Massachusetts and Southern Vermont may find the most convenient route to be Routes 9 or 10 to Keene, New Hampshire, and then Routes 9 and US 202, 89 and 93 to the Highway Hotel. *************** MULCHING STRAWBERRIES FOR WINTER PROTECTION Richard Marini, Research Technologist University of Vermont, Burlington, Vt . Winter injury is often one of the most limiting factors for strawberry production in northern regions. Although most New Eng- land growers mulch their plants in the fall to prevent winter in- jury, it may still occur, especially when snow-cover is lacking. Nevertheless, growers recognize the value of mulch but are often unsure when to apply it and how much to use. A brief review of the physiological changes occurring in strawberry plants during the fall may help eliminate some of the confusion. Plants generally develop hardiness in response to fall envi- ronmental conditions. Strawberries cease growing and enter rest in late-summer and early-fall as daylength and temperatures decrease. During this time, sugars accumulate in the leaves and roots, leaves become less upright, and red color may develop in petioles and leaves. Hardiness increases significantly after exposure to several frosts, but may be reduced by subsequent warm, weather. Cool weather is then needed to regain the lost hardiness. Strawberries usually continue to harden into mid-winter. Because hardening conditions are not the same each fall, the rate of hardiness development and the degree of hardiness attained differs from year to year. If mulch is applied before near freez- ing temperatures occur, plants often fail to harden sufficiently, and may be injured more severely than unmulched plants. Therefore, mulch should not be applied according to the calendar date, but on the basis- of fall weather conditions. Researchers in Minnesota (1) found plants mulched in early October were killed when exposed to 27°F, while those mulched in early November survived 18°F. Although the critical temperature varies with the variety, well-hardened - 2 plants may be severely injured or killed when exposed to 10°F, while blossom primordia in the cro\>ms may be injured at 25°F. A good rule to follow is to mulch after several days of near-freez- ing temperatures, but prior to severe cold. Many materials are used for mulch. They should be free of weed seed, and be loose and light so as not to mat down, but heavy enough so that it will not blow away. Canadian researchers (2) found straw provided better protection than sawdust or wood chips. Marsh hay appears to be as effective as straw. Both of these ma- terials lose much of their insulative properties when they become wet, ice-filled, or matted down. We have monitored strawberry crown temperatures under several mulching treatments (Table 1). Table 1. Minimum air temperatures, minimum temperatures of straw- berry crowns of mulched and unmulched plants, and snow depth. Data were collected in 1966 and 1975. Air temp. Snow depth Straw mulch C°F) (inches) (tons/A) 197 5 -6 8 3 -6 8 6 -6 8 0 -6 0 0 1966 -18 0 6 -18 0 0 -12 7 6 -12 7 0 With an air temperature of -6% plant crown temperature was 27°F under both 3 and 6 tons of straw/A, with 8 inches of snow cover. Plants with 8 inches of snow but which were not mulched had crown temperature of 24°F. Plants that were not mulched and lacked snow cover were at 3°F, which is below the critical temper- ature for strawberry plants. Crown temperatures are influenced by the present temperature as well as the temperature of several pre- vious days. For example: in 1975, there were 5 consecutive days when the temperature fell below 15°F. The next day was -6°F and at that time the crown temperatures were 3°F. In 1966, however, sever- al warm days followed by a temperature of -18°F produced a higher crown temperature of 5°F. The data in Table 1 suggest that mulch provides little addi- tional protection when plants are covered with 7 inches or more of snow. Whfen snow cover is lacking, however, 6 tons of straw per c rown t (°F) emp 27 27 24 3 20 5 25 22 3 - acre may provide up to 15*? protection. Mulching at rates greater than 3 tons/A would probably add little protection especially in areas where snow cover is reliable. LITERATURE CITED 1. Brierley, W.G. and R.H. Landon. 1944. Winter behavior of strawberry plants. Minn. Agr. Exp. Sta. Bui. 375. 2. Collins, W.B. 1966. Effects of winter mulches on strawberry yields. Proc. Am. Soc. Hort. Sci. 89:331-335. *************** PROCEEDINGS OF THE NATIONAL CONTROLLED ATMOSPHERE RESEARCH CONFERENCE In the Sept. -Oct., 1977, issue of Fruit Notes, we presented some of the points discussed at the National Controlled Atmosphere Research Conference held in April, 1977. The full proceedings of the conference are now available. They consist of 300 pages of in- formation on CA and hypobaric storage structures and equipment, transport research and applications, quality maintenance, prestor- age treatments with CO2, atmosphere modification, and insect and disease control during^ storage. It concludes with specific re- quirements and recommendations for transport and storage of indi- divual crops. These proceedings are available for $8. 00, postage paid, for U.S. and Canadian delivery, and $9.00, postage paid, for overseas delivery. Please request Horticultural Report No. 28, and enclose a check or money order written to the order of Michigan State Uni- versity. However, this order should be sent to the Department of Horticulture, Michigan State University, East Lansing, Michigan 48824. *************** A VISITOR'S VIEW OF THE APPLE INDUSTRY IN BRITISH COLUMBIA Duane Greene Department of Plant and Soil Sciences The major fruit growing area in British Columbia is centered in a narrow band in the Okanogan Valley extending from the Washing- ton State border north about 100 miles. Orchards in general are - 4 - quite small and many growers depend upon apple production as a sup- plement to other income. Expansion of the industry will be limited because most good sites are now in production and orchards estab- lished further north are likely to be damaged by periodic winter freezes. There are about 33,000 acres of fruit trees in British Columbia, with 25,000 of these being planted to apples. Apple production gen- erally ranges between 9 and 10 million bushels. Approximately 401 of the apples are Delicious, 30% Mcintosh, 10% each of Golden Deli- cious and Spartan and the remaining 101 miscellaneous varieties. The acreage of Spartan is not expected to increase due to a serious problem with internal breakdown in storage. There are relatively few old orchards due to freezes during the past 10-12 years. This has made possible the replacement of these older orchards with more acceptable varieties and strains. Most fruit growers are planting trees on size-controlling root- stocks. One of the most important factors when choosing a rootstock in British Columbia is its susceptibility to collar rot. Many of the commonly-planted rootstocks in Massachusetts, including M. 7 and M.106, are too susceptible to collar rot to be planted extensively. However, the vigorous rootstock M.4 has been used successfully because of its resistance to the disease. Recently, M.26 has become popular because it induces early bearing, partial dwarfing, and has resistance to collar rot. Under British Columbia conditions, it produces a tree similar to or slightly smaller than one on M.7. Orchards in British Columbia are being planted heavily to spur- type Mcintosh and Delicious. It was estimated that for every non- spur Mcintosh being planted there were 10 spur-type Mcintosh going into the ground. Tree spacing in British Columbia is generally closer than that presently suggested in Massachusetts. A number of growers have planted spur Mcintosh 8 x 18 ft or spur Delicious 10 x 20 ft on M.4 roots, with the intention of removing every other tree when the trees begin to crowd. However, a poor orchard often results because tree removal is delayed and the lower limbs become weak. The fertilizer program followed in British Columbia differs in many respects from that in Massachusetts. All orchards are defi- cient in boron C^) . A lack of B can result in poor tree growth and a light crop of misshapen fruit. It is recommended that broadcast applications of B be made every third year in early August. However, many growers apply B solely in the spring as a spray application. B deficiency appeared in many British Columbia orchards in 1977. In many cases, the injury was severe enough to reduce the crop. This situation occurred, in most instances, in orchards where no late-fdll irrigation was applied and where the grower had not applied B to the soil for many years because of primary reliance on a summer spray application of B. Generally, annual applications of nitrogen (N) are made. Growers are steadily changing from the use of ammonium nitrate to urea. In many instances, N applications are split, with half being applied in November and the remainder being spread in the spring. Calcium, zinc and magnesium may also be deficient and re- quire application in British Coltombia orchards. Both pesticides and plant growth regulators are applied with sprayers delivering about 50 gal/acre. Most growers do not have spray equipment to make dilute applications. Chemical thinning of apples, including Mcintosh, is often done with dinitro materials (Elgetol*). This is applied during the full bloom period. Elgetol* acts by burning the stigmas of unpollinated flowers and thus reducing the number of fruit that set. If the weather turns excessively moist or cool during the first 4 days af- ter the spray application, serious overthinning and leaf burning may occur. Sevin* is not used as a thinner because of its detri- mental effects on the predator mite population. Consequently, the thinning results I saw in British Columbia on Mcintosh were much poorer than we would expect to have in Massachusetts. Often there was overthinning of the bottom limbs and clustered fruit at the top of the tree. Clusters of fruit were generally broken up by hand- thinning after June drop. The major stop-drop compound used on Mcintosh is 2,4,5-TP. Very serious carryover effects of 2,4,5-TP showed up in the spring of 1977 from applications made late in the summer of 1976. Delayed foliation at shoot tips, small leaf size, and reduced fruit set and fruit size were all symptoms of the carryover effects. This problem was serious enough to reduce the Mcintosh crop in British Columbia in 1977. The problem may have been particularly severe in 1977 because the application of 2,4,5-TP in 1976 was made prior to and during a period of very hot weather, and also because the 2,4,5-TP was applied as a concentrate spray. Alar-85* is normally not used as a stop-drop material and NAA apparently is not effec- tive enough. Approximately 300,000 boxes of Mcintosh each year are treated with ethephon to advance ripening for sale of these fruit soon af- ter harvest. It is recommended that both NAA and 2,4,5-TP be inclu- ded with the ethephon and that these chemicals be preceded by an ap- plication of Alar-85* in mid-summer. Growers are experiencing increasing problems in establishing trees on old sites. It now is recognized that the poor growth is due to soil acidity where trees previously grew. Lime has not been added routinely in the past because the fruit-growing area is arid and thus the soil has had a pH of 7.0 or greater. In existing *Trade name orchards, soil pH between the rows may still be near neutral. How- ever, in the soil within rows the pH may be well below 5.0. It is now recommended that lime be added in the rows of an older orchard before it is removed. Using this method, the lime may be added more precisely in the areas that require lime and not in the areas between rows that do not require pH adjustment. In conclusion, it was interesting to observe the innovations and contrasts of 'Mcintosh' culture in an area where orchards are generally small and the weather during the growing season is dry and sunny. Growers in British Columbia have cultural problems but they are in many instances different from the ones in Massachusetts, *************** APPLE APHID CONTROL THROUGH NATURAL ENEMIES Roger G, Adams, Jr, and Ronald J. Prokopy Department of Entomology Aphids are small soft-bodied, pear-shaped insects that may be either winged or wingless. They may cause considerable injury to apple and are most easily recognized by the presence of a pair of tube-shaped structures known as cornicles at the end of their abdo- mens. In this article, we discuss the apple aphid Aphis pomi and its natural enemies in Western Massachusetts apple orchards. We focus in particular on our research on the ecology of its major predator, a midge. We conclude with new findings on spray mater- ials which are least toxic to the midges and allow their build-up. The apple aphid, formerly known as the green apple aphid, may be found in dense colonies on apple throughout the growing season. Serious losses may result in commercial orchards if populations are not suppressed. Apple aphid injury may be caused in a niimber of ^ays . Feeding on fruits may result in the production of "aphis apples," while foliar feeding may result in leaf curling and stunt- ing of terminal growth. Aphid excretion of honeydew (a sticky, sugary waste product visible as clear spots about 1/16 inch in diam- eter on leaf and fruit surfaces) and subsequent growth of blackish sooty mold fungus on the honeydew can result in reduced photosyn- thetic activity of leaves and contamination of fruit. Recent evi- dence that the apple aphid can artificially transmit the organism causing fire blight in apples could lower the economic threshold level for this pest. Currently, several sprays are required in local orchards to assure successful control. One of the aims of our apple pest management program is reduction in spray appli- cations without increased aphid injury. To achieve this aim, we are hopeful that aphid natural enemies will play a greater role in aphid control than they now do. The most frequently reported natural enemies of aphids are lady beetles, lacewing larvae, syrphid fly larvae, and anthocorid bugs. However, while studying the natural enemy complex of the apple aphid in a Western Massachusetts apple orchard, we found quite a different species to be the dominant predator: the larval stage of a cecidomyiid midge by the name of Aphidoletes aphidimyza. The adult midge is a small delicate, fly-like insect which can lay up to 100 eggs in aphid colonies. The eggs are tiny and orange, resembling particles of paprika. They hatch into larvae in about 3 days. The larvae are small (about 1/10 inch long), bright orange colored maggots that feed on many species of aphids. Larval devel- opment is completed in 7 to 10 days, at which time they drop to the soil to form cocoons. The complete life cycle from egg to adult usually takes about 3 weeks. The species overwinters in the soil as a larva within a cocoon. Population densities of the apple aphid and its natural enemies were recorded from 1974 through 1976 in an unsprayed section of an apple orchard at the Belchertown Fruit Research Center. Throughout the study period, the cecidomyiid was by far the most abundant pred- ator found. A total of 1902 individuals appeared on sampled foli- age. Syrphids were next most common, with 177 individuals found. Lacewing larvae, lady beetles, and anthocorids appeared only occa- sionally. The cecidomyiid was responsible for high apple aphid mortality and dramatic aphid population reductions. Apple terminals were caged with various aphid to cecidomyiid density ratios to study the feeding behavior of the larvae. In every case, those aphid colonies caged with cecidomyiids were either reduced or decimated within 12 days. The overall mean number of aphids killed per ceci- domyiid during its larval development was 28, ranging from 4 to 65, depending on predator and prey abundance. During feeding, cecido- myiid larvae paralyze aphids by injecting salivary toxins. Since there is no struggle by the aphid, killed aphids appear as shriv- elled, blackish bodies with the mouthparts still anchored in the leaf. Our studies showed that predaceous cecidomyiids appear in Western Massachusetts apple orchards in mid-June. However, by early June, apple aphid populations have already reached injurious levels in some orchards. Therefore, despite control of summer apple aphid populations by the cecidomyiid, it appears too late in the season to prevent damage due to early-season aphid activities. Why don't cecidomyiids appear until mid- June? Where do they overwinter - within or outside the orchard? To find answers to these questions, emergence cage studies were conducted during the spring of 1976. Tent-like cages, containing yellow sticky traps used to capture emerging cecidomyiid adults, were placed in the Belchertown orchard under leaves which harbored cecidomyiid larvae the previous fall. On June 11, 4 cecidomyiid adults were captured within such cages. Thus, a portion, if not the majority, of the cecidomyiid population overwintered within the apple orchard, but adults did not emerge until mid-June. This last finding agrees with the observed first appearance of cecidomyiid eggs on foliage sampled in previous years. Therefore, due to the lack of biologi- cal synchrony between predator and prey, the cecidomyiid is unable to prevent early season aphid damage. The cecidomyiid is still in the soil in the cocoon stage while early damage is occurring. For season-long control, apple aphid populations need to be maintained below economic threshold levels until the cecidomyiid predator arrives to control summer aphid populations. We believe that the economic threshold level of the apple aphid (that is, the point at which some remedial action should be taken) is approxi- mately 50 apple aphids per terminal leaf. Drs. Madsen, Peters, and Vakenti of the Summerland Research Station in British Columbia were able to reduce the number of sprays needed to obtain apple aphid control by monitoring aphid populations, Their results are presented in an article entitled "Pest Management: Experience in Six British Columbia Apple Orchards," which appeared in the August, 1975 issue of the Canadian Entomologist. Sprays were recommended when 50 per cent of the leaves sampled were aphid infested. Pesticide sprays have been shoi\m to have a detrimental effect on many natural enemies of pests. For example, syrphid flies are abundant in late May and June in many commercial orchards. They lay oval, white eggs about 1/16 of an inch long on apple foliage in or near aphid colonies. The eggs hatch into grayish-white larvae which are ferocious aphid predators. However, syrphids are often though not always, killed by pesticide sprays. Further studies are needed to determine which materials allow syrphid survival. We are currently in the process of studying the toxicity of orchard pesticides to the predaceous cecidomyiid to determine its susceptibility, tolerance, or resistance to some of the more recom- mended materials. Cecidomyiid eggs collected from the Belchertown orchard were placed on adhesive tape affixed to glass slides. The - 9 - slides were dipped for 5 dosages equivalent to IX chemical was replicated 5 mortality was determined pesticides to young larva mortality) was determined 72 hours after treatment, termined by immersing thi mixtures for 10 seconds, ment. seconds in chemi concentration in times with 10 e 72 hours after t e hatching from by counting the Toxicity to la rd and fourth in Mortality was c cals mixed with water at an orchard sprayer. Each ggs per replicate. Egg reatment. Toxicity of treated eggs (early larval dead larvae on microslides te instar larvae was de- star larvae in pesticide hecked 96 hours after treat- Table 1. Laboratory toxicity of orchard pesticides to eggs and larvae of the predaceous cecidomyiid, Aphidoletes aphidimyza. Pesticide Imidan 50 WP Guthion 50 WP Guthion 50 WP CFitchburg) Sevin 50 WP Zolone 3 EC Thiodan 50 WP Systox 6 EC Phosphamidon 8 EC Plictran 50 WP Omite 30 WP Thiram 50 WP Captan 50 WP Glyphosate 4 EC Check Check (Fitchburg) % early Dosage/100 % egg larval gal spray mortality mortality 1-1/2 lbs 5/8 lb 5/8 lb 1 lb 1-1/2 pts 1 lb 5 ozs 1/4 pt 5 ozs 1-1/2 lbs 2 lbs 1 lb 4 qts larval mortality 8 86 6 72 4 6 8 34 14 6 6 8 4 5 "2T 14 38 21 0 29 57 27 0 2 0 2 6 0 18 18 6 10 46 32 16 12 8 6 10 8 3 Per ce Guthion (Be and 7 2% of was moderat toxicity of mortality o Marshall Fa low (6%). in Aphidole The Marshal Guthion tre lb/100 gal. which Aphid had not rec nt mortality was gener Ichertown population) the eggs, respectively ely toxic to Aphidolet Guthion to Apnidolete f eggs collected from rm in Fitchburg, MA an Thus, differential Gut tes populations collec 1 Farm apple orchard i atments annually for 7 The section of the B oletes eggs were colle eived insecticide or m ally low with the exception of the and Sevin treatments, where 861 , failed to hatch. Phosphamidon es eggs. In contrast to the high s eggs collected from Belchertown, a" commercial apple orchard at d treated with Guthion was very hion resistance appears to exist ted from 2 areas of the state, n Fitchburg has received 7 to 8 years at the dosage rate of 1/2 elchertown apple orchard from cted for use in toxicity tests iticide treatments for 6 years. - 10 - A few materials that were of low toxicity to Aphidoletes eggs were moderately or highly toxic to young larvae hatching from treated eggs. Such early larval mortality was highest (571) for Systox treatments, while Imidan, Thiodan, and Guthion (Fitchburg) were of moderate toxicity (24 to 38%) to young larvae. Thiodan was found to be most toxic (46% mortality) to late instar larvae while Systox was of moderate toxicity (321). The fungicides Captan and Thiram, the miticides Plictran and Omite, and the herbicide Glyphosate were all of low toxicity to Aphidoletes eggs and larvae. These results show that Guthion, Systox, and Sevin had very detrimental effects on the predaceous cecidomyiids from Belchertown. Phosphamidon treatments were moderately toxic to Aphidoletes eggs and young larvae hatching from treated eggs, thus resulting in over- all high mortality. Zolone was the only insecticide tested that had little effect on the eggs and young larvae of Belchertown ceci- domyiids. However, Zolone has been found to be very highly toxic to the most important mite predator in Massachusetts, Amblyseius fallacis (Robert Hislop, personal communication) (see March-April, 1977 issue of Fruit Notes for more information on this mite preda- tor). Thiodan and Imidan were moderately toxic to Belchertown cecidomyiids and, according to recent lab tests by Robert Hislop, of rather low toxicity to A. fallacis. Therefore, Imidan should be the broad-spectrum insecticide of choice and Thioaan the aphi- cide of choice if one desires good insect and aphid control while allowing at least moderate survival and build-up of our most im- portant aphid and mite predators. The more abundant these preda- tors, the fewer pesticide applications that are needed. We emphasize that these findings are based on tests of a sin- gle population of cecidomyiids which has its own unique genetic structure and has been exposed over the years to a certain array of pesticides. The genetic structure and pesticide exposure his- tory of cecidomyiids undoubtedly varies from orchard to orchard. Indeed there is some indication from our field observations that cecidomyiid populations in certain commercial orchards in Massa- chusetts may be more tolerant of Guthion treatments that Belchertown populations. We are currently studying this aspect. In conclusion, we reiterate that the more abundant the aphid predators, the fewer aphicide applications that are needed. *************** - 11 TRENDS OF MICHIGAN TREE FRUIT INDUSTRY Jerome Hull, Jr. Department of Horticulture Michigan State University Part I. Composition of the Industry Michigan's fruit industry includes about 66,000 acres (A) of apple, 41,000 A tart cherry, 13,600 A sweet cherry, 18,000 A peach, 8,000 A plum and 6,500 A pear. Pear acreage has declined rapidly because of pear psylla and fireblight control problems, low yields, and declining markets. Peach acreage has also decreased because of winter injury, 'valsa canker, X-disease, lack of satisfactory chemical fruit thinning compounds, and need for seasonal labor for pruning and multiple selective harvesting. The future of the sweet cherry industry is uncertain. About two-thirds of the crop is brined for maraschino cherries and the future of this market depends on development of a satisfactory alternative to the dye that was recently banned for artificially coloring maraschino cherries. Many Michigan orchardists grow small acreages of plums because they are relatively easy to produce and can be readily machine-harvested with cherry harvesting equipment. About two-thirds of the crop is processed. Michigan produces two-thirds of the nation's sour cherry crop and this crop continues to increase in importance. Several major changes in this industry offer it an optimistic future. The crop is mechanically harvested, eliminating a major harvest labor con- cern. Expanded grower processing provides the producer increased control over the marketing of his product. The industry has mar- keting legislation to provide for diversion or "set-aside" in sur- plus years for market stability, and has a promotion program to encourage market expansion. The industry has some production and marketing problems but appears to have a very stable future in Michigan. With 66,000 A, apples are the largest tree fruit crop in Michigan. In the most recent tree survey C1973), the 5 leading varieties were Delicious (24%), Jonathan (22%), Mcintosh (111), Golden Delicious (101) and Northern Spy (81). About 801 of the state's apple acreage was on seedling rootstocks and 20% on size- control rootstocks. Approximately 14% of the acreage was planted between 1968-1972 and two-thirds of these trees were on size-control rootstocks. ■'■Presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association on July 13, 1977. - 12 - The 1973 tree census data indicated that Delicious should re- place Jonathan as the major apple variety. However, much will de- pend upon the performance of this variety on size-control rootstocks, since 72% of the Delicious non-bearing acreage in 1973 was on these types of rootstocks. Delicious is extremely vulnerable to frost and fruit set is frequently poor. Mcintosh has been one of Michigan's leading apple varieties for many years, but non-bearing trees represented a very low per- cent of the total Mcintosh trees in 1973. This fact plus antici- pated tree removals indicate that Mcintosh production in Michigan will decline in the future. The fruit are easily bruised during harvest and many growers experience difficulty obtaining adequate red color on this variety. Recent plantings have been primarily spur-type Mcintosh. Northern Spy is not being planted heavily. It is very slow to come into production and is grown primarily for the processing mar- ket. Growers are more interested in dual purpose apple varieties and summer varieties. Idared is becoming very popular, since it bears at an early age, has a semi-spur type growth habit, produces large attractive fruit which have excellent packout, and stores well. It has returned a premium to Michigan growers during late- season marketing periods. We anticipate an increased production of summer apple varie- ties because young-bearing trees and non-bearing trees represented a very high percentage of the total for summer varieties in Michi- gan orchards in 1973. Paulared and Jerseymac predominate in re- cent plantings of summer varieties. Irrigation Young trees have limited root development and are readily stunted by prolonged drought conditions. Thus, many orchardists have found that trickle irrigation is beneficial in young plant- ings. Dr. A.L. Kenworthy, in our Department of Horticulture, has also obtained some interesting results applying nitrogen (N) through the trickle system. He cooperated with 2 commercial orchardists in northern Michigan and applied N in 4 applications at weekly in- tervals during June. The treatments consisted of N applied at the same rate used by the growers when applying a ground applica- tion in late fall or early spring, and at rates equal to 50 or 25% of the grower rate. Ammonium nitrate or urea was used depending on the grower's preference. He found no significant differences in leaf N among the 3 N rates applied through the trickle irriga- tion and the ground application applied by the growers. Half as much nitrogen applied through the trickle irrigation system ap- peared as effective as the grower's soil application. No yield differences have been observed. - 13 - The drought in the siaimner and fall o£ 1976 markedly affected Michigan's 1976 apple crop. In a niimber of orchards fruit did not mature uniformly on the trees suffering from severe moisture stress, with those around the periphery of the tree ripening earlier than fruit in the interior of the tree. This phenomenon was not as pronounced in irrigated orchards. Harvest Market demands for larger, redder apples increases the hazard of internal breakdown of Jonathan fruit. Control of internal breakdown is now achieved by a pre-storage water dip or drench treatment with a 4^ calciiun chloride solution. Unfortunately, calcium chloride is corrosive to most metals; thus, application equipment must be cleaned after use. Corrosion of nails or other bin fasteners also can be a problem. A fungicide is added to the calcium chloride solution to control storage rots. The solution can be utilized until it becomes excessively contaminated with accumulated soil or debris. For many years, Michigan growers obtained adequate scald con- trol on stored fruit by using DPA at 1000 ppm. In recent years, it has been necessary to increase the rate to 2000 ppm except for Jonathan, Idared and late-picked Rome Beauty, for which 1000 ppm appears to give adequate scald control. Storage scald is controlled best when fruit is treated at nor- mal orchard temperatures within a day or so after harvest. Cold fruit directly from the orchard or from storage for up to 2 weeks after harvest can be effectively treated for scald control but the maximum concentration of DPA must be applied. The chemical becomes less effective as the treatment is delayed but it is better to make a late application of the material to apples intended for long term storage than not to treat at all. A fungicide, either thiabendazole (TBZ) or benomyl, is added to the scald inhibitor solution to pre- vent widespread development of blue mold, soft rot and gray mold diseases on apples during subsequent storage and handling. Ethylene is a gaseous plant hormone that causes fruits to ripen. It is produced at a constant low rate during the last few weeks of growth and development of immature fruit. The ethylene production rate abruptly increases immediately preceding the onset of ripening, causing the internal atmosphere ethylene concentration to increase from about 0.1 ppm to 10 to 100 ppm over the course of several days. Dr. D.R. Dilley has developed a colorimetric technique that enables storage operators to detect high ethylene levels in fruits as they begin to ripen. About 20 fruits are placed in a 10 liter dessicator, which is then filled with water. A vacuum is applied for about 5 minutes to withdraw gas from within the fruit. A sam- - 14 - pie of this gas, which collects in the head space of the desicca- tor, is introduced into an ethylene indicator tube which changes color from yellow to blue-green as the chemical indicator reacts with ethylene. A 200 ml. gas sample is tested. Fruit testing about 0.5 ppm of ethylene or less is utilized for longest term storage. Apples testing about 2.5 ppm or less are considered satisfactory for mid-term CA and those testing greater than 5 ppm are used for short-term storage. Making such prestorage ethylene analysis and storing fruit accordingly has markedly improved the fruit firmness situation for one of our major long-term storage operators. Marketing A unique experience to Michigan fruit growers in the last few years is a marketing and bargaining bill known as Public Act 344. This state legislation provides for the establishment of a grower marketing organization possessing exclusive marketing con- trol over a fruit crop when 51% of the growers of a specified mar- keting unit request certification to be the marketing agency for that commodity. The legislation pertains to marketing of produce for processing, not fresh market outlets. Processors, desiring to purchase the product of the grower marketing organization, must bargain with the organization on price and other terms relative to marketing of the grower's produce. All growers pay a fee, de- ducted by the processor, to the association for its bargaining ser- vices. The constitutionality of the legislation is being challenged in Michigan courts and growers have varying opinions about it. It has disrupted some long established grower-processor relation- ships. In 1976, bargaining returned more money to the Michigan producer of processed apples than that returned to growers in other competing areas in the eastern part of the country. There are some problems to be resolved in the marketing procedures but the other states are closely observing the performance of PA 344 in Michigan to determine if similar marketing legislation has merit for their respective areas. Expansion of farm marketing through pick-your-own and retail farm markets has increased and been important to the success of many orchardists in recent years. It is more intensive in south- eastern Michigan near the metropolitan Detroit area. However, it is being performed very successfully by many enterprising fruit growers throughout Michigan. (Will be continued in the January-February ^ 1978 issue) *************** - 15 - FRUIT NOTES INDEX FOR 1977 (This index of major articles has been prepared for those who keep a file of Fruit Notes. The number in parenthesis indicates the pages on which the item appears.) January -February Interregional Cooperative Research in Fruit Tree Viruses and Aspects of Control Measures: Present and Future Cl"4) When Should an Existing Orchard be Replaced (4-7) Cleaning the Weed Sprayer (7-8) A Substance That Deters Egglaying by Apple Maggot Flies (8-11) Establishment and Management of Compact Apple Trees (Part II) March-April The Use of a Pressure Tester to Measure Firmness of Apples (1-4) Apple Trees on M.26 (4-5) Mite Predator Studies in Massachusetts Apple Orchards in 1976 (5-7) Establishment and Management of Compact Apple Trees (Part III) May-June Suggestions for Fertilization of Apple Trees in 1977 (1-4) A One-Two Punch for Weeds in Strawberries (4-5) Reasons for Deformed Strawberry Fruits (5-6) Why Irrigation for Strawberries? (7-8) Alternate Row Spraying for Apple Pests (8-10) Establishment and Management of Compact Apple Trees (Part IV) July-August Considerations in Attempting to Improve the Calcivun Content of Apples (1-4) 2,4-D for Problem Weeds in Strawberries (4-5) The Plum Curculio: An Introduction and Summary of Preliminary Field Observations, 1976 (5-7) CO2 Treatments for Mcintosh at the Beginning of CA Storage (8-10) Sept ember -October The National Controlled Atmosphere Research Conference (1-4) Monitoring Traps for Blueberry Maggot Flies (4-6) Some Details to Consider When Harvesting and Storing Apples (7-10) November -Dec ember Mulching Strawberries for Winter Protection (1-3) A Visitor's View of the Apple Industry in British Columbia (3-6) Apple Aphid Control Through Natural Enemies (6-10) Trends of Michigan Tree Fruit Industry (11-14) Part I - 16 - All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State laws and regulations in effect on the date of this publication. When trade names are used for identification, no product endorsement is implied, nor is discrimination intended against similar materials. NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 Official Business Penalty for Private Use, $300 BULK THIRD CLASS MAIL PERMIT DR. WM. J. LOT^D PLANT & SOIL SCIENCES FRENCH HALL FN 0100^ FRUITpf NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS. UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. W. J. LORD AND W. J EDITORS BRAMLAGE Vol. 43 (No. 1) JANUARY /FEBRUARY 1978 TABLE OF CONTENTS Varieties of Peaches for Massachusetts Trends of Michigan Tree Fruit Industry (Part II) Pomological Paragraph Supplies for trellising apple trees or growing them as slender spindles Shelf Life of Pesticides in Common Use by Fruit Growers European Apple Sawfly: Biology and Development of an Adult Monitoring Trap I VARIETIES OF PEACHES FOR MASSACHUSETTS J.F. Anderson Department of Plant and Soil Sciences Variety Recommended Flesh App roximate for color harvest date* C § H W -42 T Y -41 T Y -41 C a H Y -40 T Y -38 C § H Y -32 H Y -32 C 5 H W -30 C ^ H Y -28 T Y -25 T Y -25 C ^ H Y -23 C Y -18 C 5 H Y -16 T Y -12 C 5 H Y - 7 C Y 0 T Y + 3 Erly-Red-Fre Garnet Beauty Brighton Sunhaven Harbelle Jerseyland Reliance Raritan Rose Redhaven Harken Harbrite Triogem Sunhigh Richhaven Canadian Harmony Cresthaven Elberta Jerseyqueen C - Commercial H - Home garden T - Trial Varieties so marked are not necessarily equally adapted to all sections of the state. Y - Yellow flesh * - Days before or + after Elberta W - White flesh about 9/15 Variety Notes Erly-Red-Fre An attractive, white-fleshed, freestone peach of medium to large size. The flavor is excellent. The tree is vigorous and above average in bud hardiness. Garnet Beauty* A bud sport of Redhaven. Resembles Redhaven in color and texture. It is a semi-clingstone. The tree is vig- orous, productive and hardy. Brighton* An attractive, high-quality, yellow-fleshed peach. The fruit is roundish, uniformly medium in size and highly colored. The flesh is medium firm, juicy, with very good flavor. The pit is semi-cling. The tree is vigorous, productive and medium-hardy. *Recommended for trial on basis of performance in other areas. Sunhaven An attractive, highly colored peach of good quality. The fruit is variable in size, medium to large. The tree is productive and above average in bud hardiness. Harbelle* The fruit is large, attractive, with deep yellow ground color and a bright red blush. Flesh is a rich yellow, medium in firmness, of good quality. The stone is semi-free. The tree is productive and medium in vigor and bud hardiness. Jerseyland A large, firm, juicy, freestone and of good flavor. The tree is large, upright and very productive. Bud hardi- ness is above average. Reliance A medium-sized, roundish, yellow-fleshed freestone peach of fair to good flavor. Reliance is recommended as a very hardy variety for the home fruit planting. Raritan Rose The fruit is large, round, attractive. The flesh is white, firm, and juicy. The tree is large, upright-spreading and productive. Bud hardiness is above average. Redhaven The medium-sized fruit is highly colored, attractive and has firm flesh and fair flavor. The tree is very productive and requires heavy thinning. Harken* A large, attractive, yellow-fleshed peach. The flesh is FTrm, juicy, of good quality and the stone is free. The tree is said to be vigorous, productive, and equal to Redhaven in bud hardiness. Harbrite* A large, attractive, yellow- fleshed peach. The flesh IS medium-firm, juicy and of good flavor. The stone is free. The tree is said to be very productive, hardy and moderately vigorous. Triogem The fruit is medium to large and well-colored. The flesh IS smooth, firm and has a very good flavor. The tree is medium to large, fairly vigorous and productive. The buds are of average hardiness. Sunhigh A large, highly colored, freestone with firm flesh and excellent flavor. The tree is medium in size, productive and susceptible to bacterial spot. Richhaven A large, attractive, highly colored freestone of very good quality. The tree is large, vigorous and productive. Bud hardiness is above average, Canadian Harmony* A large, highly-colored, yellow-fleshed peach. The flesh is firm, juicy and of good flavor. The tree is vig- orous, productive, and about equal to Redhaven in bud hardiness. Cresthaven* A large, oblate-shaped peach with a dark-red blush. The bright yellow flesh is firm, juicy and slightly fibrous, there is some red at the pit. The flavor is very good. The tree is vigorous, productive and medium in hardiness. Elberta The fruit is large, fairly attractive and a freestone. Flesh is firm, juicy and has fair flavor. The tree is large, vigorous and productive. The tree has wide soil and climatic adaptibility . Jerseyqueen A large, attractive, oval-shaped peach. The flesh is yellow, firm and very good in flavor. The stone is free. Jerseyqueen is moderate in bud hardinesSo *************** TRENDS OF MICHIGAN TREE FRUIT INDUSTRY (PART II} Jerome Hull, Jr. Department of Horticulture Michigan State University Rootstocks Trees on dwarfing rootstocks have been planted extensively by Michigan apple growers in recent years. Nevertheless, clonal rootstocks have not solved all of our apple production problems. In fact they have introduced additional problems. Clonal rootstocks used initially were M.2 and M.7. M.2 tended to be too vigorous and M.7 develops suckers from the rootstock and gives poor anchorage to the more vigorous varieties, notably Deli- cious. MM 106 and IM 111 were popular rootstocks when they became available in the early 60's. MM 106 is a very productive and pre- cocious rootstock but often produces a larger tree than antici- pated, particularly with Mcintosh and Paulared varieties. It also has been sensitive to cold injury and collar rot, particularly when planted on poorly drained soils or on some of Michigan's heav- ier textured soils. MM 111 has not been as dwarfing as desired and has been slow to initiate bearing on young trees. M.9, popular for high density plantings, is not well adapted to Michigan's light textured orchard soils. Trees on this root- stock are readily stunted by drought and weed competition. The ■'-Part II of talk presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association on July 13, 1977. 4 - stunted trees fruit early and fail to produce adequate vegetative growth for ample bearing surface. Many orchardists are now planting trees on M 26, about which we have little experience or knowledge. There is also much renewed interest in M.7 budded higher than in older plantings on this root- stock, to enable deep planting for better anchorage. MSU has developed several new apple rootstocks from seed of open pollinated trees of the Mailing 1 through 16, Alnarp 2 and Robusta 5. These have been named the MAC (Michigan Apple Clone) series. The more dwarfing, well-anchored clones are MAC 1,4,9,10, 25,39 and 46. MAC 9 is the most dwarfing, producing trees slightly larger than M.9 but with better anchorage. Trees on these root- stocks will soon be under evaluation in commercial orchards. Research and grower experience with apple trees on clonal rootstocks indicates such plantings should be placed on the most desirable fruit sites. Because the trees are smaller, bloom is much more susceptible to frost injury. Orchardists have learned that trees on clonal rootstocks re- quire excellent management practices if tree performance is to equal grower expectations. This includes site selection, soil preparation, planting techniques, weed control, soil and moisture management and early training. Some growers have erred and planted trees too close together, resulting in crowding before trees begin to produce fruit. This has prompted interest in transplanting of established trees and in summer pruning. Frost Control High density plantings on size-control rootstocks have accen- tuated the concern for ideal planting sites for apple orchards be- cause the smaller tree is much more vulnerable to spring frosts. Growers with less than ideal sites often find it necessary to con- sider some method of frost control in high-density plantings. Frost protection with oil and propane gas has become very expensive. Overtree sprinkling has been demonstrated to be an effective way of preventing frost injury. This technique along with wind machines and helicopters, may become more popular in the future with orchard- ists requiring occasional frost protection. Research with a foliar application of rhizobitoxin suggests it may delay bloom several days to minimize frost injury. Tree Management Spur-type Delicious are very popular in both clonal and seed- ling rootstock plantings. Unfortunately, these trees have not al- ways performed to grower expectation. The primary cause for disap- pointment probatly has been management rather than rootstock, tree density, or a choice of strain. - 5 - Early training of young trees to prevent development o£ vigor- ous upright growth is important as a means of encouraging early fruiting. Spring-type clothespins can be attached to the leader above lateral shoots to force the laterals to grow more horizon- tally. (The snap portion of the clothespin is attached to the trunk when new lateral branches are 3 to 5 inches in length.) The clothespins are left in place 3 to 4 weeks. An apple picking bag is an excellent container for carrying clothespins when you place them in the trees or remove them later in the season. Round tooth- picks can also be used on succulent lateral shoots for the same purpose. They are less expensive than clothespins but take more time to position in the trees. Either technique promotes develop- ment of wide-angle scaffold branches. Many trees require branch spreading the second season. Wire spreaders 6 to 8 inches in length and cut with a sharp point on each end work well on upright growing branches in the second sea- son. If additional spreading is required in subsequent years, wooden spreaders should be used. Orchardists use either wooden spreaders with nails inserted in each end of the spreader or wooden slats with V cuts in each end. Scrap lumber, sawed into varying lengths with deep V cuts in each end, work satisfactorily. Wooden spreaders with shallow V cuts are difficult to anchor in the tree and tend to slip along the scaffold and the leader. Delicious is not the only variety that requires this detailed training. Paulared, a popular and heavily-planted summer variety, requires scaffold spreading over several years. Early spreading is particularly beneficial with this variety as established scaf- folds split readily at the point of attachment to the leader during spreading in subsequent seasons with wooden spreaders. Our experience with Paulared indicates that it is a rather_ vigorous variety and trees propagated on MM 106 tend to make fairly large trees. We also note a tendency towards biennial bearing. Fortunately, chemical thinning seems to overcome this difficulty. An application of 50 ppm NAD at petal fall or 7.5 ppm of NAA about 10 days after bloom has provided acceptable chemical thinning of young Paulared trees. When planting trees on the less vigorous rootstocks (M.9 and M.26), we usually head the trees at 24 to 30 inches to encourage scaffold formation at the desired heighth on the trunk. Orchard- ists heading these trees at 30 to 36 inches often fail to obtain scaffold development within 2 feet of the soil surface and have "top-heavy" trees. Removal of the shoots just beneath the apical bud is an effective method of preventing formation of vigorous com- peting scaffolds. Establishment of such vigorous scaffolds makes it very difficult to maintain small tree stature. Growers observe that leaving more than the usual number of scaffolds on Starkrimson Delicious results in more consistant an- nual production. - 6 - Summer Pruning Interest in summer pruning has increased as orchardists have experienced difficulties with excessive tree vigor in high density plantings . Summer pruning of fruit trees means different practices to different people. Some orchardists consider summer pruning to be nothing more than removal of water sprouts, which are removed by hand or with pruning equipment in mid-season. This pruning removes the vigor- ous upright current season's shoots developing on the scaffolds and interior of the tree, especially in the vicinity of large prun- ing cuts that were made during dormant pruning. Some clonal rootstocks and some of the interstem trees tend to grow numerous suckers from the rootstock. Orchardists who prune these off during the summer often refer to the practice as summer pruning. Occasionally, an orchardist will perform dormant season-type pruning during the growing season. This involves moderate to heavy pruning with selective branch removal, including heavy cuts. Apple trees subjected to such pruning in June can be severely weak- ened or stunted and fruit may fail to grow to optimum size. Flower- bud initiation may be reduced and there is the possibility of tem- porarily throwing the tree out of production. Summer hedging is the summer pruning concept of a few orchard- ists, but it has presented some problems. Initially, summer hedg- ing was done in mid-season after the initial flush of growth. Re- growth occurred the same season in the vicinity of the pruning cuts resulting in development of "crows feet" type growth on the tree's periphery. Excessive shading in the tree's interior occurred. When summer hedging is delayed, less regrowth occurs, thus the most successful summer hedging of apples is normally performed in mid- August. Follow-up dormant pruning is also necessary but this con- sists of numerous fine cuts, thinning out the growth around the periphery of the tree plus removal of large branches causing crowd- ing. Summer pruning of young, vigorous, closely-planted apple trees that are crowding has consisted of selective heading-back and selec- tive removal of shoots to reduce tree vigor. Upright vigorous shoots originating on the main scaffolds are removed. Cutting to a lateral or to an apple is most dwarfing. Delaying this pruning until August results in less difficulty with regrowth whereas if performed in June or early July, regrowth beneath the cut usually occurs, especially if pruning stubs remain. Summer pruning to control tree size of bearing trees can af- fect shoot growth and flowerbud development. Shoots are usually - 7 pruned back to an apple and non-fruiting limbs are thinned out by cutting to a lateral branch. Suckers and upright growth are re- moved. Improved fruit color results and stronger flower buds de- velop in the interior area of the tree. Some orchardists leave about two inches of the current season's growth. Buds on this ba- sal stub often regrow if cuts are made before August. Peach trees respond more favorably to summer pruning than do apple trees. Pruning is usually delayed at least until bloom. Pruning cuts heal more readily when performed at this time of the year and the seasonal application of fungicides helps to reduce canker difficulties. Pruning at this time of the year also accom- plishes some fruit thinning. This pruning is best described as dormant season-type pruning performed in early summer. Summer hedging of peach trees has some advantages. The hedge- row concept of peach culture being researched at Purdue University involves summer pruning to dwarf the tree. Some Michigan orchard- ists have practiced mechanical topping of peach trees not trained to a hedgerow. The trees are mechanically topped and sometimes hedged in late July to control tree height and to admit liglit into the tree. There is very little regrowth the same season. Growth in the top of the trees the following season is less vigorous than that normally experienced with dormant-season hedging. Some vibra- tion of the tree occurs during mechanical hedging and the nearer to harvest the practice is performed, the more fruit is shaken from the tree. Experience suggests that the tree should be very vigor- ous before being subjected to hedging. Mechanical topping and hedging stiffens the scaffold branches and more growth occurs in the lower part of the tree. Admitting light to the interior of the tree has made possible the retention of more fine wood over a longer period of time. After several years, one peach grower had to thin-out the bottom area of the topped trees to enable pickers to reach fruit in the lower inter- ior of the tree during harvest. Peach trees subjected to severe early-season summer hedging have sometimes been severely winter-injured the following winter if extreme winter temperatures occur. (Will he continued, in the Maroh-April^ 1978 issue) *************** POMOLOGICAL PARAGRAPH Supplies for trellising apple trees or growing them as slender spindles^ WT. Loren dT Tukey, 103 Tyson Building, University Park, Pa. 16802, has compiled a listing of commercial suppliers of mater- ials used in training trees on trellises or as slender spindles. You can obtain a copy of this list from Dr. Tukey. SHELF LIFE OF PESTICIDES IN COMMON USE BY FRUIT GROWERS Jeffrey Carlson Assistant Pesticide Coordinator Department of Entomology University of Massachusetts Fruit growers frequently ask how long pesticides can be stored and still be effective. To answer this question, we have obtained information on 10 fruit pesticides in common use by consulting the manufacturers of these chemicals. The information below can give only a general idea of the shelf life as it is ultimately deter- mined by conditions of storage, as well as chemical stability. The following storage conditions should be observed, also, please con- sult the label for any specific conditions for particular chemicals. 1. Store pesticides in a dry, well-ventilated place at tem- peratures above freezing. 2. Always keep a pesticide in its original container and make sure it is tightly sealed. 3. Store granular or powdered materials above the ground to avoid dampness. 4. Keep the temperature under 100°F if storing volatile com- pounds. 5. Keep volatile herbicides separate from other pesticides to avoid contamination. 6. Keep an accurate inventory of the stored chemicals. It is to your benefit to use up the pesticides that you've purchased as soon as possible. Don't forget about them in the back room. Rotate stock; use older materials first! Common Name (Trade Name) Shelf Life Comments phosmet,WP (Imidan) 2-3 years Good stability under nor- mal storage conditions. dodine,WP (Cyprex) 2-3 years Could be stored up to 5 years provided container is tightly closed and the room is kept cool and dry. azinphos-methyl,WP 2 years Under normal storage con- (Guthion) ditions. thiram,WP (Thylate) 4 years If kept dry, package is sealed tightly, and is stored at temperature un- der 100°F. - 9 Common Name (Trade Name) Shelf Life simazine,WP (Princep) Indefinite ammonium sulfamate, sol' uble salt (Ammate X) carbaryl.WP (Sevin) At least 2 years several years Comments Has been stored as long as 9 years under good conditions . No low temperature limit but keep dry and under 100°F. Wettable powder formula- tions have been stored up to 5 years without loss of effectiveness. captan,WP paraquat, liquid (Paraquat CL) captafol, flowable (Difolatan) 3 years Indefinite at least 3 years Settling may occur in flowable formulations. It is important to shake the container in order to re-suspend components be- fore using. Under normal storage. Extremely stable, no prob- lems with storage. After 2 years will tend to settle, needs good agitation. *************** EUROPEAN APPLE SAWFLY: BIOLOGY AND DEVELOPMENT OF AN ADULT MONITORING TRAP Elizabeth D. Owens and Ronald J. Prokopy Department of Entomology One of Massachusetts' more serious apple insect pests, the European Apple Sawfly (EAS) , is a recent invader of North America. It was first discovered on Long Island in 1939, and may have been introduced there in the cocoon stage in root balls of ornamental crab apple trees imported from Europe. Since its introduction, it has spread through many of the fruit growing areas of the Northeast and is particularly troublesome in the New England states. EAS adults first appear in apple orchards during full pink. The small, inconspicuous, wasp-like insect is not often observed by orchardists. When seen among the open flowers, it appears lit- tle different from other small insect pollinators, being dark-bod- ied with a yellowish head and underside, and having clear wings. - 10 - It is during bloom that female EAS deposit their small white eggs in the developing fruit. The egg-laying scar appears as a tiny- brownish spot near the top of the caylx cup. The larvae hatch in about 10 days, with the first visible larval feeding damage being a small dark brown trail tunneled near the surface of the fruit. As a sawfly larva develops, it takes on the appearance of a dark- headed white caterpillar which migrates from fruit to fruit, tun- neling directly to the core and feeding. Later larval damage is characterized by large masses of dark-colored frass at the feeding tunnel entrances. Most EAS-damaged fruit is lost during June drop. However, some remain on the tree and appear at harvest scarred with long yellowish scabs originating at the caylx and winding around the fruit surface. It takes about 3 weeks and 4 to 5 fruits for a sawfly larva to mature. It then drops to the soil where it forms a cocoon, re- maining in that state until adult emergence the following spring. Thus, there is only one generation annually. Most commercial apple orchards do not have a population of sawflies arising from within the orchard, the reason being that standard pesticide spray programs include a petal fall spray which, if applied at the appropriate time, kills most or all of the lar- vae. However, since most New England orchards are surrounded by areas dotted with wild or abandoned apple trees, there is a contin- ued threat of invasion by sawfly adults migrating in from the out- side. To improve the orchardist's ability to determine if EAS is active in his orchard and, if so, to aid in the appropriate timing of spray applications against sawfly, we initiated the following research aimed at development of an effective and convenient trap for monitoring EAS adult population levels. First, we spent many hours observing EAS adult activity in abandoned apple trees. Females were watched as they flew about blossoming trees on warm sunny days in May. We observed them feeding on pollen in open or partially opened blossoms and laying eggs in the caylx cup. Most adults were seen to land near or di- rectly on the blossoms. This information led us to study (with the aid of a spectrophotometer) the visual reflectance pattern of apple blossom parts and to field test white surfaces that might prove to be effective blossom mimics. In our first experiment, conducted in an abandoned orchard, we compared 6x8 inch rectangles hung vertically from apple tree branches and coated with the following colors of enamel paint: white, gray, black, yellow, green, blue, orange, or red. Clear plexiglas and aluminum-foil-covered rectangles were also tested. All traps were coated with a thin layer of Bird Tanglefoot*, a clear sticky substance that captures alighting insects. The results (Table 1) show that more EAS were captured on the white rectangles than any others tested. The fact that white captured *Trade name - 11 more than clear plexiglas ( = a neutral surface ) indicates that EAS captures on white were the result of positive attraction and not simply random collision. Table 1. Comparative captures of EAS adults on rectangles of var- ious colors. 7 replicates. Rectangle Total No. EAS adults captured White 61 Gray 25 Clear plexiglas 18 Yellow 3 Aluminum foil 1 Black 1 Red 1 Green 0 Orange 0 Spectrophotometer analysis of light reflected from apple blos- som petals and all other blossom parts (stamen, pistal, etc.) showed all flower parts to be high in reflectance at wavelengths from 400- 650 nm, and very low in reflectance in the ultra-violet part of the spectrum (300-400 nm) . The human visible spectrum is 400-700 nm; the insect visible spectrum is 300-650 nm. In our second test, we therefore compared 5 types of white rectangles: zinc oxide, Day Glo primer, white enamel, lead oxide, and Zoecon pre-dyed white cardboard. The first three were low in ultra-violet reflectance (as were apple blossoms) and the last two were high in UV reflectance (unlike the blossoms). The results (Table 2) showed that zinc white, which most close- ly mimics apple blossoms in color reflectance pattern, captured the most EAS. Day Glo and enamel whites captured nearly as many EAS as the zinc white, but Zoecon and lead white, which were poor mimics of apple blossom reflectance patterns, were not at all attractive to EAS. These results indicate that sticky-coated rectangles coated with either zinc oxide white or Day Glo primer white could be used to monitor EAS activity. Table 2. Comparative captures of EAS adults on rectangles of vari- ous white surfaces. 10 replicates. ^__^ Rectangl? Total No. EAS adults captured Zinc white 90 Day Glo primer 62 White enamel 49 Zoecon white 3 Lead white 0 - 12 LTTlUm Although further work is necessary to determine the optii shape and placement of the traps, our research to date has resulted in an effective and convenient monitoring trap for adult EAS during apple bloom. Because most orchardists use domestic honeybees for pollination, it should be noted that the rectangular zinc white or Day Glo primer white traps were not very attractive to bees. In the next issue of Fruit Notes, we will discuss our research showing that such white traps are also effective for monitoring tarnished plant bug adult populations in apple orchards. *************** All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State laws and regulations in effect on the date of this publication. When trade names are used for identification, no product endorsement is implied, nor is discrimination intended against similar materials, NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AN LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300. POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 43 (No. 2) MARCH /APRIL 1978 TABLE OF CONTENTS Varieties of Raspberries and Blackberries for Massachusetts Pomological Paragraph Publication Available Partial Budgeting of Management Alternatives for Fruit Growers Pomological Paragraph Apple Production Costs in Pennsylvania in 1975 Trends of Michigan Tree Fruit Industry - Part III Tarnished Plant Bug on Apple: Damage and Monitoring Traps I VARIETIES OF RASPBERRIES AND BLACKBERRIES FOR MASSACHUSETTS James F. Anderson Department of Plant and Soil Sciences Variety Gatineau Heritage Madawaska Taylor Latham Sumner Heritage Clyde Brandywine Bristol Type Recommended for Red C 5 H T C 5 H limited C 5 H Harvesting Season C C Purple Black Very early Very early Early Midseason Midseason Late Late Sept. Late Late Early T = Trial H = Home garden C = Commercial Varieties so marked are not necessarily equally adapted to all sections of the state. *It is recommended that only Registered or Certified plant stock be used in establishing new raspberry plantings. Gatineau Heritage Madawaska Taylor Latham Variety Notes The fruit is large, firm, good quality and moderate- ly attractive. The plant is vigorous, productive and moderately winter hardy. Most often grown for the fall crop only. The summer crop is said to be moderate in production and the fruits slightly smaller than those produced in the fall. Produces large, firm fruit of good quality and medium red color. The plant is vigorous, productive and winter hardy. It is susceptible to spurblight. Has been grown successfully on a commercial scale in the high elevations of Worcester and Franklin counties. Where it remains free of virus, the plants are tall, vigorous, hardy and productive and the fruits large, firm and have very good flavor. The fruit is of good size, bright red in color and of average firmness and flavor. The plants are vigor- ous, productive and hardy when spurblight is con- trolled. Latham is susceptible to spurblight. - 2 - Sumner The fruit is medium to large size, firm, and have very good flavor. The plants are hardy, vigorous and productive. Appears adapted to heavier soils. Heritage The berries of the fall crop are medium-sized, very firm, coherent, attractive and of very good flavor. The plants are vigorous and productive. Clyde A large fruited purple raspberry. The berries are attractive, firm, tart, and good in quality. The plants are very vigorous, hardy and productive. Clyde is most suitable for culinary use. Brandywine A new introduction from New York. The berries are said to be large, round, reddish-purple, firm, coher- ent, tart but of good quality. The plants are very vigorous and productive. Said to make a fine flavored jam. Bristol Black raspberries are not generally satisfactory in Massachusetts because of their great susceptibility to virus diseases. Bristol is one of the more desir- able varieties. It produces large attractive, firm berries of good quality. The plants are vigorous, and productive as long as they remain free from virus diseases. Blackberry Varieties Darrow The plants are hardy, vigorous and productive. The berries are large, firm, attractive and have good flavor. Trailing types, such as Boysenberry, Loganberry and Youngberry are not sufficiently winter hardy and productive in most parts of the state. However, the Boysenberry has been reported as reasonably satisfactory in a few locations. *************** POMOLOGICAL PARAGRAPH Publication Available. Bulletin No. C-102 entitled "Establishment and Management of Compact Apple Trees" is available for 75 cents from The Bulletin Center, Cottage A, Thatcher Way, University of Massachusetts, Amherst, Mass. 01003. Make check or money order payable to the Massachusetts Cooperative Extension Service and send it to the address given above. This publication has under one cover the information on establishment and management of compact apple trees that appeared in serial form in Fruit Notes during 1976 and 1977. PARTIAL BUDGETING OF MANAGEMENT ALTERNATIVES FOR FRUIT GROWERS Robert L. Christensen Department of Food and Resource Economics Introduction Fruit growers must make many decisions o£ both a short-term or long run nature. These decisions can range from those involving replacement of blocks or choice of varieties (which are very long run in nature) or those such as selecting a spray program, deciding on the size of a picking crew and purchase of packaging materials (which are short run in impact). Decisions can be of significant magnitude in a monetary sense or relatively insignificant. It is obvious that as the magnitude of financial committment increases, the attention paid to the consequences of such a decision on profitability should also increase. The most important function of management is the planning and evaluation of the alternative courses of action that can be taken. The decision-making function is the true meaning of management. Thus, it is important that a manager become fully knowledgeable with the concepts of costs, revenues, and profits. He also must have a decision-making framework or "procedure" that he can follow in developing and analyzing his data so that the profitability of a course of action can be established. It should be clear that the exercise is one of planning or anticipating future events. This means that the manager must make some assumptions or projections with regard to expected future prices, costs, yields, and the like. It also means that if these projections turn out to be in error, then the decision made may also be in error. Thus, the importance of good information from records, farm research, or other sources should be obvious. Budgeting as a Tool for Decision Making Budgeting is the pencil and paper testing of the consequences of a decision before actually making it. It consists of projecting the costs and returns resulting from a course of action into the future and thus calculating the probable effects on net earnings. Since few managers will knowingly make a decision that is shown to be unprofitable, it is important that a manager have the best information available and that he knows how to use this information to assist him in assessing the profitability of the decision. The technique to be described and illustrated here is that of partial budgeting. It is the most easily understood and most widely applicable of all of the economic decision making tools. Some of the other advantages are as follows: - 4 - 1. Budgeting is adaptable to individual farm situations. 2. Budgeting is a framework for dealing with prices, costs and ! yields and can be used to analyze the effects of changes in any of these economic variables. 3. Budgets can be adjusted to reflect the differences in managerial ability. 4. Budgeting enables the comparison between alternatives. 5. Budgeting can be used to analyze the impact of a specific adjustment (partial budgeting) or changes affecting the entire business (complete budgeting) . Budgeting Applied to an Orchard Situation Before budgeting begins, it is necessary to select the alter- natives for which budgeting is to be conducted. In the hypothetical example illustrated in this paper, we wish to evaluate the economic consequences of full row spraying for pest control versus alternate row spraying. This is an excellent example of a decision where partial budgeting is appropriate. Partial budgeting is used when considering a change in only one aspect of the operation. The focus is on only those things that will change as a result of the decision. Thus, the information needs are identified as those changes. Identifying the nature of the changes that will occur is the first step. In the problem of evaluating the impact of alternative row spraying, we can identify the following factors : (1) Spray materials (2) Tractor and sprayer time (3) Labor time (4) Fruit damage (5) Yield There may be other factors that could be relevant but are non- quantifiable or involve information that is not available. For example, reduced soil compaction may be beneficial while increased mite or aphid populations may have a long run negative impact on vigor and yield. However, at present information is lacking on these impacts and one must, therefore, assume they have no effect. "Quantifying the Effects of the Alternative" The next step in the analysis requires the estimation or projection of the magnitude of the effects on each of the factors. This step can be illustrated by the following set of questions: 5 - 1. Mow much less spray materials would he needed? How much less sprayer and tractor time is needed? What reduction in labor would result? How much more insect damage on fruit would there be? What would be the effect on vield? rind and most one's own However , ist over of inform adopted t accurate , may not b and poor A third s the Agric These res close mon ensure th sions mus individua experienc yields . ing t accur orch this some ation he pr it i e the recor ource ultur ults itori at th t be 1 rat e of he answers to these questions is not easy. The best ate answers would be based on personal experience in ard under the specific conditions of that orchard, would imply the conduct of experiments by the orchard- period of time, which could be a risk. Another source is the experience of other orchardists who may have actice. While such information is often valid and s equally often in error. The particular circumstances same, other factors may have influenced the results, ds or memory may yield erroneous or false information. of information is the research results provided by .il Experiment Stations and Extension Services, are nearly always from controlled situations with ng and collection of data. Every effort is made to e results are valid and accurate. In many cases deci- based on information from all three sources, i.e., es of spray application and other practices and either others or research results on effects on quality and Assuming such information is available, the following illustrates how these data might be organized for further analysis: Resource Use for Alternate Spray Methods 1 Acre Block Full Row Alternate Row Difference Spray Materials ($) $120 Tractor 5 Sprayer Time (hrs) 3 Labor Time (hrs) 3 Fruit Damage (^) 2 Yield (bu.) 250 $60 1.75 1.75 3 250 -$60 1.25 hrs. ■1.25 hrs. 6 - "Converting the Data to Economic Terms" The next step in the analysis is to convert these data to economic terms. This involves putting prices or values on each of the factors. Below is a table with assumed prices for each factor and the computation of the added or reduced costs. Factor Unit Value No. of Units Total Cost Spray Materials Tractor ^ Sprayer Time Labor Time Damaged Fruit — $60.00 $5/hr. 1.25 hrs. 6.25 $3/hr. 1.25 hrs. 3.75 -$4/bu. 2.5 0 bu. 10.00 "The Partial Budget and Profitability Determination" The final step is to compile the economic data in the partial budget. The usual format for the partial budget is as follows: Added Returns: (A) Reduced Returns: CC) Reduced Costs: (B) Added Costs: (D) (A) + (B) = (E) (C) + CD) = (F) If (E) is greater than (F) then c If (E) is less than (F) then dec: iecision is profitable. Lsion is unprofitable. 7 - In the example at hand there are no added returns (A) or added costs (D) . The only categories o£ relevance are reduced costs (B) and reduced returns (C) . Therefore, the profitability relation reduces to the comparison of (B) and (C) . If (B] exceeds (C) tlie alternative is profitable. The values comprising reduced costs (B) are: Spray materials $60.00 Tractor and sprayer 6.25 Labor 5.75 Total (B) $70.00 The only value appearing in (C) , reduced returns, is a reduction in the value of fruit of $10. The value of (B) exceeds (C) by $60 which is the indicated increase in profit per acre which would result from the adoption of the alternate row spraying method. "Determination of the Economic Parameters" The above procedure is quite simple in concept and application but it avoids the issue of how some of the economic parameters are obtained. Specifically, the entire question of how equipment costs are estimated and placed on an hourly basis is not treated. Two classes of costs are involved: (1) fixed or "ownership" costs and (2) variable costs. The ownership costs include depreciation, interest on investment, taxes, insurance, and repairs. Variable costs include fuel and lubrication. Ownership costs are essentially a given value for a year and do not vary with acreage while variable costs are directly proportional to use. *************** POMOLOGICAL PARAGRAPH Apple Production Costs in Pennsylvania in 1975 were found to be $679.68 per acre, according to a study made in Adams and Franklin Counties by B. Wayne Kelly, Farm Management Extension Specialist at Pennsylvania State University. Harvesting costs were $196.37/acre for an average yield of 402 bu/acre, giving a cost harvested at $2.18/bu. Spraying materials were $91.44, and all labor (less harvesting) was $212 . 70/acre. In Western Michigan, a study by Myron Kelsey, Agricultural Economist at Michigan State, indicated that production costs for a semi-dwarf planting were $518.22/acre and harvesting costs, $236.19/acre for a yield of 400 bu/acre, giving a cost harvested at $1.88/bu. Spray materials were $97.49/acre, and all labor (less harvesting) was $133.27. Although the studies were not completely comparable (differing somewhat in values and charges), their results are surprisingly close. -- L. D. Tukey, Penn State, Horticultural Reviews. 26 (No. 2). 1977. -8- TRENDS OF MICHIGAN TREE FRUIT INDUSTRY (PART III)^ Jerome Hull, Jr. Department of Horticulture Michigan State University Nematodes and Soil Fumigation Parasitic nematodes have become o£ increased concern to Michi- gan fruit growers. Many orchards are planted on light-textured soils and on these soils damaging nematode populations are being detected in an increasing number of young orchards and orchard sites. Peach trees are most susceptible to nematode injury in Michigan. However, cherry trees also are susceptible and nematodes can be a problem in apple and pear plantings, especially in orchard replantings . The root-lesion nematode is of primary concern, although the dagger, rootknot and lance nematodes may also be present. The usual nematode damage symptoms are stunted trees with poor vigor. Nema- tode numbers vary within a field; therefore, tree vigor on the site is variable. Some feeding nematodes will induce gall formations on plant roots. Root cells destroyed by nematode-feeding become dark dis- colored areas in the root system. These root-lesions increase with continued feeding and secondary invasion by other soil microorganisms occurs. Some nematodes feed on young roots and alter the traditional root branching structure. They may also devitalize or kill roottips. Soil fumigation prior to planting on old orchard sites is often essential to produce vigorous healthy orchards. Thus, a laboratory analysis of soil and root tissue is suggested to detect nematode problems. The soil and root samples are usually collected about 2 months after the initiation of tree growth in the spring and before frost in the fall (usually mid-July to mid-September) . Many fruit crops respond to soil fumigation with nematicides. This is readily apparent by improved tree growth. A long-term study in New York has demonstrated a definite financial advantage from fumigating an apple orchard. In Michigan, increased growth and winter survival of young peach trees has occurred following fumiga- tion. Furthermore, fumigation also seems to be associated with improved weed control in new fruit plantings. Nematode control is not simple. Proper soil preparation prior to soil fumigation is essential for maximum nematode control. The soil must be cultivated to promote thorough decomposition of previous Part III of Talk presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association on July 13, 1977. -9- crop debris because undecayed roots harbor nematodes, protect them from the fumigant, and interfere with fumigant application. It should be in excellent tilth and soil moisture should approach that desirable for seeding. Dry soils permit rapid escape of fumigants whereas dispersion of fumigants in excessively wet soil is poor. Fumigants do not volatilize and disperse properly at soil tempera- tures below 50°F and escape too rapidly from soils when the tempera- ture is above 80°F. Spring treatment usually delays planting so late summer or early autumn is usually best for the application of soil fumigants in Michigan. Soil fumigation is the primary treatment being utilized by Michigan orchardists. The fumigant is chiseled 6-10 inches deep into the soil with the chisels space 8-10 inches apart along the tool bar. The soil is smoothed with a drag or cultipacker immedi- ately after application to prevent the chemical from escaping. The most widely utilized soil fumigants are Vorlex*, DowFume W-85*, Telone* and Shell D-D*. Methyl Bromide also has been utilized to treat individual tree sites with an injecting soil auger in the fall prior to planting. When fumigating orchardists normally treat a 7-foot strip where the tree row will be located rather than treating the entire field. Research with granular nematicides applied with fertilizer appli- cators and rotatilled into the soil is encouraging. There also is much interest in foliar application of nematicides. Vydate-L* is a foliar nematicide that can be applied to non-bearing trees. However, 2 to 3 applications per year are necessary. Furthermore, we do not consider it an alternative to soil fumigation, although yearly appli- cations until a tree comes into bearing may help suppress nematode difficulties . Nemagon* or Fumazone* can be applied as a post-plant row appli- cation. It must be chiseled into the soil about 8 inches deep along the tree row. However, it is usually a less effective method than pre-plant soil fumigation. Orchard Replant Problems Another difficulty encountered in establishing fruit plantings is frequently referred to as the Specific Apple Replant Disease. This is observed where an apple orchard is replanted to apples. Young trees planted where the old trees stood may make poor growth, thus tree growth on the site is variable. A specific disease has been identified as the cause of this difficulty in cherry, and work continues to identify the difficulty in Apple. Chloropicrin is beneficial as a soil treatment for the Specific Apple Replant Disease. The Dutch have found that using a potting mixture in the planting hole is useful in preventing poor vigor because of the disease. * Trade name -10- The use of beneficial bacteria to promote establishment and growth of young trees is a new area of research. Spectacular bio- logical control of crown gall, caused by the bacteria Agrobacterium tumef aciens , has prevented the stunting and poor growth associated with the gall formation on crown gall-infected trees. An organism from New Zealand has been reported by the USDA and plant pathologist: at Agricultural Experiment Stations to promote favorable growth of fruit trees. Dr. A. Jones, MSU plant pathologist, is using New Zealand bacteria Agrobacter radiobacter (isolate #84) to inoculate tree roots by dipping at planting time as well as inoculating the soil in an attempt to promote growth of young fruit trees in Michi- gan by preventing crown gall infection. The exact mechanism of activity by the organism is not known. Some pathologists believe the isolate occupies sites on the plants and thus prevents other pathogenic bacteria from, invading the plant root system. *************** TARNISHED PLANT BUG ON APPLE: DAMAGE AND MONITORING TRAPS Ronald J. Prokopy, Karen I. Hauschild, and Roger G. Adams Department of Entomology The tarnished plant bug (TPB) is among the 5 most injurious insect pests of apple fruit in Massachusetts orchards. From the published literature, we know that TPB adults over- winter under duff in hedgerows. During the first warm days of Spring, they begin flying into apple orchards. There, an adult seeks out a developing flower bud, inserts its beak into the bud, and sucks up plant sap. After the beak has been removed, sap oozes from the puncture, sometimes forming a large, readily visible drop- let. The overwintering adults continue to feed in this manner until they die, usually by the time of the first cover spray. The adults rarely lay eggs in apple trees but rather in legumes and other ground cover plants. Indeed, some of our preliminary findings suggest that a large amount of vetch, alfalfa, a clover in or near the orchard may encourage substantial buildup of TPB populations. The eggs hatch into nymphs, which then give rise to second generation adults. The nymphs do not feed on apple. Neither, apparently, do the second and third generation adults -- at least not to the extent of causing noticeable injury. Research on TPB was initiated in 1976 because we wanted to learn more about this insect. Our goals were three-fold: (1) to determine what types of apple injury result from TPB feeding, and when these injuries are initiated; (2) to develop some sort of simple, effective monitoring method for estimating the size of TPB populations in apple 11 trees; and (3) to accurately relate the numbers of TPB sampled by this method to the amount of TPB injury. We hoped we could eventually construct an index or chart which would indicate to the grower that if X number of TPB adults were taken in the samples, then X amount of TPB injury could be expected. Based upon the intended market for the fruit, and therefore the amount of TPB injury the grower felt he could tolerate, the grower could then decide if it was worthwhile to spray a pesticide against TPBs. In this article, we report on our progress to date toward these goals. To study the nature an structed a large number of unsprayed section of orchar each cage was positioned to buds on a branch. We intro and sealed the ends to prev 12, 1977, the day the first buds were at green tip. Th after which they were remov further entry of insects, new cages every 4-5 days un days at bloom for pollinati correlate the stage at whic to TPBs with the nature and d occurrence of TPB injury, we first con- cages made of plastic and cloth. In an d at the Horticultural Research Center, completely surround 6-7 developing flower duced one TPB adult into each of 6 cages ent escape. The cagings began on April TPB adult was found in the orchard. The e TPBs remained in the cages for 4 days, ed and the cages resealed to prevent We repeated this procedure with TPBs in til July 1 (the cages were opened for 4 on). Using this procedure, we could h developing apple flower buds were exposed amount of ensuing injury. The data in Table 1 reveal that feeding by caged TPBs on apple flower buds at the green tip and half inch green stages caused a substantial amount of bud abscission. No detectable bud abscission resulted from TPB feeding initiated at tight cluster or afterward. TABLE 1 Time of initiation of injury by TPB adults in cages Average number of flowers per cluster at full bloom % decrease compared with check Green tip Half inch green Tight cluster onward Check (cages without TPBs) 3.1 3.7 4.5 4.5 311 18°^ 0% Most years abscission resulting from early season TPB feeding would not be an important economic consideration. However, in off- bearing years, years of severe frost damage, or poor pollination, this bud abscission could be important. The data in Table 2 reveal that feeding by caged TPBs on buds, blossoms, and fruit from mid-pink to petal fall caused dimples in a -12- large percentage o£ the apples at harvest. Most of the dimples were near the calyx. Many were deep, but some were shallow and surrounded by a small (1/16" - 1/4") tan-colored scab. Only a small percentage o£ dimpled fruit resulted from TPB feeding from green tip to early pink and from first cover or later. TABLE 2 Time of initiation of injury % Dimpled fruit by TPB adults in cages at harvest Green tip to early pink 12-0 Mid-pink to petal fall 471 First cover or later 9% Check (cages without TPBs) 0?; The economic consequences of dimpling injury caused by TPB feed- ing vary from grower to grower according to the intended market of the fruit and the severity of dimpling. When you come right down to it, the dimples are purely cosmetic injuries and affect only the appearance of the fruit. In no way do the dimples affect the eating or keeping quality of the fruit, as do injuries by apple maggot, plum curculio, and codling moth. Most Massachusetts growers with whom we have spoken feel they can tolerate 1-3% of lightly dimpled fruit in their cartons of U.S. Fancy or better fruit. Moderately or heavily dimpled fruit is usually culled. Our next goal was to develop a method for monitoring the abun- dance of TPB adults on trees throughout the period when they could cause injury: silver tip through petal fall. In many crops where TPB is a pest (e.g. alfalfa, sugarbeets), TPB abundance can be readily and rather accurately monitored by collecting TPB in sweeps with an insect net. This method is not useful for collecting TPBs on the woody twigs and branches of fruit trees, however. Because plant bugs are rather closely related to aphids, we suspected that plant bug adults, like aphid adults, might use visual cues to guide them to their host plants and feeding sites. Our approach was similar to that which we used in developing a method of monitoring European apple sawfly populations in apple orchards (see Fruit Notes 43(1): 9-12). Using a spectrophotometer (an instru- ment which records the wavelengths of light reflected from surfaces) , we measured the spectral reflectance pattern of the surface of all apple structures susceptible to TPB feeding injury. We also measured the spectral reflectance pattern of surfaces to which we had applied various enamel paints. By so doing, we were able to select particular painted surfaces which closely mimicked the reflectance patterns of 13- apple structure. The only structure which we could not mimic was the pink tissue of developing blossoms, which had a reflectance pattern unlike that of pink, red, or any other paint. We then applied the paints to 6x8 inch cardboard rectangles, coated the rectangles with a clear sticky substance (formerly known as "Bird Tanglefoot" but now called "Tangletrap") to capture alighting TPBs, and hung the rectangles by wire from low apple tree branches at knee to waist height. The results of this test showed that TPB adults alighted in greatest numbers on white, clear Plexiglas, and in lesser numbers on gray, green, blue, rectangles (table 3). TABLE 3 and yellow rectangles, red, orange, and black Color of Rectangle No. TPB adults captured Color of No, . TPB adults Rectangle captured Blue 39 Red 34 Black 31 Orange 27 White 131 Clear Plexiglas 129 Yellow 109 Gray 96 Green 71 The white paint reflected light in the same general pattern as bud scales, newly unfolding leaves, the calyx cup, and mature blossom petals. The intensity of reflection from the white w^as greater than from bud scales, etc., hence giving it the appearance of very bright bud scales, etc. The yellow paint reflected light in the general pattern of maturing leaves, but likewise, at greater intensity. The fact that clear Plexiglas captured just as many TPBs as the white and yellow rectangle suggests that TPBs were not actually attracted by the white and yellow surfaces. Rather, it appears that TPBs were repelled by colors such as red, orange, and black, which have reflec- tance patterns similar to those of twigs and bark, upon which TPBs do not feed. Additional tests revealed that like sawfly adults, TPB adults discriminate between different types of white surfaces. No apple structures reflect an appreciable amount of ultra-violet (UV) light. Consistent with this was our finding that TPBs readily alighted on white-painted rectangles reflecting a low amount of UV, but were repelled by white-painted rectangles reflecting moderate or substan- tial UV. Although to the human eye, IN and non-UV reflecting white paints are indistinguishable, to the eye of TPB, they obviously are distinguishable. As things have turned out, the same low-UV-ref lecting -14- titaniuH or zinc oxide white-painted rectangle traps that have proven so attractive to sawfly adults (Fruit Notes 43(1):9-12) are also the most effective for TPB adults. Next, we compared this sticky-coated white rectangle trap with other methods of monitoring TPB adults in orchards. Each week from silver tip to petal fall, we examined 25 developing flower buds on each of 12 unsprayed apple trees at Belchertown for evidence of TPB injury. At the same time, we counted the number of TPB adults seen on the 25 buds, and the number collected after making 25 sweeps of the ground cover foliage under each tree with an insect net. Counts also were made of the number of TPB adults captured weekly on a white rectangle trap hung in each tree. We found that the number of TPBs captured on the traps each week corresponded very closely to the amount of TPB injury that week. Thus, in weeks where few TPBs were captured, little new injury had occurred. In weeks of substantial TPB captures, substantial new injury had occurred. On the other hand, our counts of TPB numbers observed directly on the buds or taken in net sweeps bore no relation to the level of new TPB injury for the week. Our assessment of the occurrence of TPB injury in this test was not as accurate as we would have liked, because whenever it rained, the characteristic droplet of plant sap oozing from the puncture hole was washed away. In such circumstances, many injured buds could be discerned only with the aid of a hand lens to reveal the microscopic puncture. This suggests that in a "normal" Massachu- setts spring, with rainfall once or twice a week, grower reliance on visual examination of buds for presence of oozing plant sap as the sole indicator of TPB injury could be highly misleading. Our experi- ments indicate that use of the white rectangle traps is a much more reliable method. Beginning in 1978, we plan extensive studies to relate numbers of TPB captured on the white traps to level of TPB injury. Develop- ment of an accurate trap capture : injury index of TPB should be of real value to growers in making decisions about the need to apply a pesticide spray against TPB. But even in the intervening years before refinement of the index, the white rectangle traps should be useful to those apple growers having a perennial TPB problem: the traps will function as a reliable indicator of the first appearance in the spring of active TPB adults in the orchard. They should also be use- ful to peach growers for this same purpose. These white traps, which also effectively serve to monitor sawfly adult activity, can now be purchased from: New England Insect Traps, Colrain, Massachusetts 01340. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Worl<; Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, S300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 43 (No. 3) MAY/ JUNE 1978 TABLE OF CONTENTS Apple Pollination Comments Pomological Paragraph Foliage sprays containing nitrogen for fertilizing peaches Factors Affecting Shape of Apples and Increasing Their Length with Promalin* Nutritional Problems and Suggestions for Fertilization of Apple Trees in 1978 Naphthaleneacetic Acid(NAA) for Tree Training Alternate vs. Every Middle Spraying for Apple Pests in 1977 APPLE POLLINATION COMMENTS Roger A. Morse Department of Entomology Cornell University Ithaca, N.Y. To set fruit, apples must be cross-pollinated. Mcintosh pollen will not grow on a Mcintosh flower's female parts; the pollen must come from another apple variety. This is true with most apple varie- ties. Many insects may carry pollen from one apple flower to another and oftentimes flies, wasps and solitary bees are important in cross- pollination. When one has only a few acres of fruit, there are usually enough insects in the vicinity to do the job. In most years, if eight percent of the flowers on a tree set fruit, one has an adequate set for a crop. In larger orchards, those with five, ten or more acres, there are usually too few insects available to accomplish cross-pollination. This is especially true in those years when we have cool, cloudy damp weather during bloom. Large orchards need to have colonies of bees moved in to insure pollination. The wholesale price of honey has tripled since 1971. The re- tail price for a pound of table honey has moved from 45(f to 99(f: to $1.30. Many beekeepers are reluctant to move bees into orchards because they fear their colonies may swarm. Swarming weakens a colony and the beekeeper may lose his honey crop. Beekeepers who are renting bees for apple pollination are charging more than ever before and it is important that growers get the most from rented bees. There are several very simple rules to follow. Where to Place Colonies Honey bee colonies should be placed where they receive a maximum of sunlight. The entrances should face east or south. We prefer to see colonies on land which has a slight slope to the east or south. If the colonies have some protection from prevailing winds, more bees will fly than if they do not. Never place colonies under trees where they will be shaded. Sunlight warms the hives and encourages more bees to take flight. How Large A Colony to Rent It appears the price for rented colonies in New York State for apple pollination this year will vary between $15 and $35 per colony. One must not expect that colonies rented for $15 or less will contain as many bees as do those which command a higher price. We recommend that colonies for apple pollination be in at least two boxes [supers). We recommend the bees have brood in six frames in each colony. Having brood in six frames is not the same as having six frames full of brood. A brood nest is more or less the - 2 shape of a ball. When there are six frames with brood, the outer frames may not be too full. It is nearly impossible to count the number of bees in a hive, but one can count the number of frames which contain brood. If there is brood in six frames, the colony will contain about 25,000 bees, perhaps more, and be in excellent condition for apple pollination. Colonies which have brood in six frames at the outset of bloom may swarm if the bees are kept in the orchards too long. For this reason, some beekeepers are reluctant to rent colonies which are this populous. Colonies Should be Grouped We recommend that colonies be placed in groups of three to five within the orchard. By grouping colonies in this manner, the apple grower can select the better locations for bees, spots where the colonies will receive a maximum amount of sunlight throughout the day. This also allows one to select those spots which are drier and which are protected from the prevailing winds. Again, one wants to encourage as much flight as possible. Dry Bottomboards Colonies of honey bees which have wet bottomboards will send fewer bees to the field than those which have dry bottomboards. Wet bottomboards tend to cool the colony and more bees are required to keep the brood nest warm. We recommend that apple growers place pallets, old tires, cinder blocks or slabwood in the orchard on which colonies may be set. This practice will work to the advantage of both the fruit grower and the beekeeper. If the colonies of bees are six to eight inches off the ground, there will be less problem with grass blocking the entrances and hindering flight. Grass may prevent the sun's hitting the colony entrance and delay flight in the morning. A piece of tarpaper tucked under the front of the colony and extending outwards will serve to keep the grass from growing and blocking colony entrances. Dandelions, Yellow Rocket and Apples Dandelions, yellow rocket and apples all produce nectar which contains about 40 percent sugar. Thus, all three of these plants have flowers which are about equally attractive to honeybees. Dandelions produce more nectar in the morning than they do in the afternoon and so there will be fewer bees visiting dandelions in the afternoon. Apples appear to produce nectar about equally all da) as does yellow rocket. The best way to get rid of dandelions and yellow rocket is to use a weed killer. Mowing these competing plant! will help, but it is expensive. If there are a large number of dandelions and yellow rocket plants in flower in or near the orchard, one needs additional bees. At the present time, we have no method o£ discouraging bees from visiting these weed plants. Fresh Water Honey bees use large quantities of water to dilute the honey which they feed to their young. Bees may collect water from wheel ruts and depressions in the orchard. These may contain an accumu- lation of pesticides. If the bees have fresh, clean water, fewer will die. Beekeepers who rent bees for apple pollination expect to lose a small number of their bees because of pesticides and they adjust the rent price of their colonies accordingly. The grower who provides fresh water for honey bee colonies will benefit. Hand-Collected Pollen A small number of apple growers in New York State buy hand- collected apple pollen, take it to the orchard and play "little Miss Honey Bee." Hand-collected pollen may be applied to the female parts of a flower with a brush. Little pollen, if any, gets where it is needed when it is dropped from an airplane or shot into a tree from a shotgun shell. While this may be fun, it is a waste of time and money. There is nothing mysterious about cross-pollination. It involves the transfer of pollen from one apple variety to another apple variety. Honey bees can cross-pollinate apples easily, quickly and at a reasonable cost if they are given the proper management and if the orchard is properly interplanted with varieties which have pollen which will cross-pollinate each other. Neither hand-collected pollen or pollen moved by bees will grow unless the temperature is sufficiently high. Hedgerowing is a Special Problem Nearly all orchards planted today follow the same scheme. The apples are grown on dwarf rootstock and planted in hedgerows. A wind of about 12 miles per hour stops bee flight. A wind of only a few miles per hour will slow bee flight and oftentimes dis- courage bees from flying over the tops of hedgerows. We know from experience that bees prefer to fly up and down the sides of rows. Planting pollenizing varieties in the row is important because there must be an exchange of pollen to set fruit. *************** POMOLOGICAL PARAGRAPH Foliage sprays containing nitrogen for fertilizing peaches. Peach trees frequently have small pale green leaves, or yellow leaves with red flecks that develop into a mild "shothole" condition. These are symptoms of nitrogen (N) deficiency caused either by cold weather 4 - in the spring. or by failing to apply N by mid-April. These symptoms were present in many of our peach orchards in May and early June of 1977. Some growers asked if urea sprays would bene- fit growth. Unfortunately, foliar sprays of N to peach trees are ineffective. Peach leaves do not absorb N as efficiently as do apple leaves. *************** FACTORS AFFECTING SHAPE OF APPLES AND INCREASING THEIR LENGTH WITH PROMALIN* W.J. Lord and Duane Greene Department of Plant and Soil Sciences Shape of apples is known to be influenced by both climatic and non-climatic factors. The elongated shape and the 5 lobes at the calyx end of Delicious apples are particularly distinctive; thus, there is interest in studying the factors influencing their shape and the possibility of modifying that shape by chemical means. Climatic Factors Delicious grown in Massachusetts are longer some years than others and within a given year their shape will vary considerably among orchards. Shape of apples depends on cell division and cell elongation, both of which occur within 3 to 4 weeks after bloom, and is governed by growth hormones in the tree. In 1914 J. R. Shaw in Massachusetts reported on the relationship between shape of Ben Davis and Baldwin apples and the temperature following bloom; the cooler the temperature, the more elongated the apple. He concluded that during the post-bloom period, temper- ature variations between the 6th and 16th day after full bloom fitted the observed variations in shape more closely than during any other period. Non-climatic Factors As most growers know, distribution of seeds in fruit influences shape. Apples with small numbers of seeds are frequently lopsided, with the less fleshy side being the one lacking seeds. M.N. Westwood and L.T. Blaney, in Oregon, found that rootstocks, crop density, cluster position, and strain can also influence fruit shape (Non-climatic factors affecting the shape of apple fruits. Nature 200:802-803, 1963). In studies with Delicious, fruit from trees on M.l, M.2, M.16 and seedling roots were longer than those harvested from trees on M.9, M.4 and M.7. Both crop load and fruit location affected the shape of Golden Delicious. Those from trees with a light crop (whether the result of heavy thinning or light bloom) were longer than fruit from trees with a heavy crop. The "king" fruit were longer than side-bloom fruit. Fruit shape differed significantly among the 3 Delicious strains studied, with those from the "regular" Delicious trees being flatter than those from *Trade Name Starking and Starkrimson strains. Fruit Shape Alterated by Growth Regulators M.W. Williams and E.A. Stahly, in Washington, found that applications of cytokinins and gibberellins , alone and in com- bination, to Delicious apples just after full bloom affected fruit shape by increasing their length. (Effect of cytokinins and gibberellins on shape of 'Delicious' apple fruits. Jour. Amer. Soc. Hort. Sci. 94: 17-19, 1969). Cytokinin-treated fruits were longer than normal with prominent, well-developed calyx lobes, whereas those treated with gibberellins were merely longer. They postulated that the influences of temperature, crop size, and fruit location in the cluster on fruit shape were very likely related to their effects on the levels of gibberellins, cytokinins and other naturally occurring growth regulators in the developing fruits. Fruits can become flatter by application of Alar-85*. Because of this undesirable response plus possible fruit size suppression on Delicious we prefer using 2 , 4 , 5 - TP for preharvest crop con- trol rather than Alar-85. Williams in 1975 (Carry over effect of ethephon on fruit shape of 'Delicious' apples. HortScience 10: 523- 4) reported that ethephon applied to Delicious apples before harvest to improve fruit quality also can flatten fruit the following year if applied to trees of medium to low vigor. Promalin to Lengthen Delicious Promalin, a plant growth regulator formulation containing gibberellins and cytokinin, when tried in several areas of the United States, has lengthened Delicious apples, increased their weight, and improved development of the calyx lobes. We have con- ducted limited tests with Promalin because of grower interest in increasing the "typiness" of Delicious and the possibility of increasing yields due to increased volume of the fruit. In 1975, 1 pint of Promalin/per 100 gallons of water applied at late petal fall at our Horticultural Research Center did not increase the "typiness" of Richared Delicious apples. We enlarged our trials in 1976 and added surface active agents glyodin and Triton B-1956 to 2 of the treatments (see Table 1 on the next page). Fruit set was not influenced by the treatments. However, the length of the Delicious as indicated by the L/D ratio was increased by the 1/2 pint of Promalin when applied with glyodin or Triton B- 1956, and also by 1 pint of Promalin; the higher the L/D ratio the longer the apple -- a "typey" Delicious will have a L/D ratio of 1.00 or greater. It is of interest to note that although Promalin increased the length of the Delicious the difference could not be detected by visual observation before harvest but could be seen on the harvested *Trade Name --6 fruit. Furthermore, neither the fruit size nor total yield was influenced by the treatments (Table 1). Table 1. Effects of Promalin, applied at 125 gal/A when petals on king blossoms started to fall, on Richared Delicious apples, 1976. Treatment (rate/lOO gals) Fruit set (per cm. limb circ) T/D ratio^ Fruit wt (gms) Yield (bu/tre 1. Check 2. Promalin, 1/2 pt 3. Promalin, 1/2 pt + glyodin, 1 pt 4. Promalin, 1/2 pt + Triton, 1/4 pt 5. Promalin, 1 pt 5. 3a 6.0a 5. Oa 5.7a 6. 6a 0.98b 190ab 12.2a 0.99ab 175c 13.6a 1.01a 1.01a 1.02a 195a 185abc ISlbc 13.8a 14.8a 15.2a ^L/D = Length/diameter ratio A trial was also conducted in a grower's orchard in 1976, with 1/2 pint or 1 pint of Promalin applied when the petals on the "king" blossoms on Starkrimson Delicious started to fall. The results were similar to those reported in Table 1. Measurements of the L/D ratios of the harvested fruit indicated that the Promalin- treated fruit were longer than those from the check trees, but this increase in length was not evident by visual observations of the fruit while on the tree nor was there any significant increase in fruit weight or yield. In 1977, Promalin at 1 pint per 100 gallons of water plus 1 pint of glyodin was applied at full bloom or calyx of Starkrimson Delicious at the rate of approximately 150 gallons per acre. The full bloom application was not effective whereas the fruit from trees sprayed at calyx were heavier and longer. However, the difference as in 1976 was too slight to be noticeable on the tree. Summary Both climatic and non-climatic factors can influence the "typi- ness" of Delicious apples. Our most-typey Delicious are produced in orchards on high elevations where post-bloom temperatures are apt to be cooler than at lower elevations. However, temperatures are not always favorable even at higher elevations and there are growers interested in giving "mother nature" a boost by using Promalin. Our trials with Promalin are very limited and more work is needed to determine the influences of temperature. However, it does appear that a consistent favorable response from a Promalin spray may not be likely. A number of growers purchased Promalin last year but for one reason or another did not apply it. We certainly do not want to discourage Promalin use in 1978 because we need to determine its possible usefulness under our conditions. Our only suggestions concerning Promalin use other than following the directions on the label are to add to the spray mix- ture a surface active agent such as glyodin and to apply on a day when temperatures are 60° or higher. *************** NUTRITIONAL PROBLEMS AND SUGGESTIONS FOR FERTILIZATION OF APPLE TREES IN 1978''- W.J. Lord and Mack Drake Department of Plant and Soil Sciences It should be recognized from the start that it is not possible to give specific suggestions for fertilization in an article of this nature. Therefore, the suggestions below merely serve as a guide to the fruit grower for determining the fertilizer program in his orchard, It is well to remember that foliar applications are merely supnle- ments to soil applications. Nitrogen (N) : The trees severely winter injured in 1976 did not recover as well as hoped in 1977 in spite of the supplemental urea sprays. Some of these trees probably should receive an urea spray (5 pounds/lOn gallons) at about first cover in May. Apply as a separate application. Most orchards had only a medium-sized crop in 1977 while some blocks of Delicious either had no crop or a light crop due to frost. Trees which had no crop, or just a partial crop, in 1977 should receive little or no N in 1978. To the contrary, trees that had a large crop in 1977 may be low in available N for utilization this spring. The best guide to N needs of your trees is leaf analysis combined with observations of tree vigor, fruit set, and fruit ■^Unless stated otherwise all photographs are by Louis Musante, Audio Visual Dept. University of Massachusetts. 8 - color. Growers definitely are using less N on Mcintosh than in the past because we need medium-sized, well-colored apples with long storage life. Some growers have not omitted N in mature Mcintosh blocks for 5 to 8 years with no apparent harmful effects. Young vigorous trees are troublesome when they start bearing a crop because of excessively large, poorly colored fruit and poor keepability of fruit in storage. The reduction or omission of N is frequently essential. This procedure plus limb positioning (spreading) is needed on vigorous young Delicious trees to encourage bloom and fruit set. Apply sufficient N to keep bearing Delicious trees vigorous. N levels of 2.2 - 2.41 in bearing Delicious trees areprobably sat- isfactory because it is necessary to keep the tree vigorous in order to produce large-sized fruits. Furthermore, obtaining sufficient red color on the newer strains of Delicious is not a problem. The N requirement can be met by applying calcium nitrate, am- monium nitrate or urea sources of fertilizer N or a "complete" fer- tilizer. (Growers concerned about bitter pit and/or cork spot may wish to rely on calcium nitrate as the source of N.) However, the phosphorous (P) in the complete fertilizer is not needed in our orchards. Therefore, purchase a prepared mix that contains no P or purchase an N and a K fertilizer and mix them prior to applica- tion or apply them separately. Some growers apply the K fertilizer in the fall and the N fertilizer in the spring. Potassium (K) : The K requirements of apple trees with a large crop are high because the fruit utilizes about 3 times as much K as N. Since the quantity of K stored by the tree is extremely small, it seems important to supply adequate K this spring on trees that had heavy fruit set in 1977. The requirements of apple trees for K (expressed as K2O) based on potential yields are as follows: (a) less than 15 bu : 1.3 lbs/ tree; (b) 15 to 25 bu : 1.3-2.7 lbs/tree; and (c) more than 25 bu: 2.7-4.3 lbs/tree. It is necessary, however, to maintain a balance among the essential nutrients for apple trees. For example, exces- sive levels of K can reduce both leaf and fruit Ca. Therefore, we strongly urge that you participate in our leaf analysis program to more accurately determine the K needs of your apple trees^ Calcium (Ca) : Cork spot and bitter pit, which are visual evidence of low Ca levels in apples, was more prevalent than usual on Delicious during the 1977-78 storage season. The Delicious on the left in the following photograph shows bitter pit and the one on the right has cork spot. Bitter pit is most frequently associated with the calyx end of the apple and its severity - 9 - (Photograph by Russell Mariz, Photo Center, UMass. ) will increase in storage. Cork spot is not localized and will appear anywhere on the apple. The spots are more pronounced than bitter pit, being much deeper and wider. In some cases the cork spot resem- bles the inner cone of a miniature volcano, with the depressed skin area containing green or dark red pigment. Cork spot does not increase in severity in storage. Cortland continued to be troublesome in some orchards because o£ its susceptability to bitter pit, and a few orchardists were concerned this fall about this disorder on Mcintosh. It is very difficult to increase Ca content of apple trees and fruit. Although foliar sprays of Ca solutions have been shown to reduce bitter pit, they have not eliminated it. A major problem is that Ca in the soil moves very slowly into the tree and most of it is quickly tied up in an insoluble form. We suggest the following measures to increase Ca content of apple leaves and fruits. A. Continue to apply 3 tons of limestone per acre every 2 to 3 years. Where high magnesium lime was used in the last application, the use of a more soluble high Ca, low Mg lime (5-71 MgO) will act more rapidly and will provide more Ca. B. Use calcium nitrate as the source of nitrogenous ferti- lizer. Calcium nitrate increases the level of soluble soil Ca more quickly, increases the downward movement of Ca and raises the pH of the soil. C. Apply foliar sprays of calcium chloride (CaCl2) starting about 3 weeks after petal fall and repeat at 2-week inter- vals, totalling 6 to 8 applications. Apply 6 to 8 pounds CaCl2/acre/spray until mid-July. After mid-July, apply 10 pounds/acre/spray. Sprays may be applied dilute or on a trial basis up to 6X concentration. Growers desiring to paCl2 with their cover sprays should do it on a trial When combining with cover sprays , add CaCl2 last to combine basis the only, spray - in tank. If weather conditions permit going over 14 days without a cover spray, use CaCl2 spray alone. CAUTION: DURING DROUGHT DO NOT APPLY A SECOND FOLIAR CaCl2 APPLICATION UNTIL AN INCH OR MORE OR RAIN FALLS. Do not mix CaCl2 and Solubor* in sprays, Foliar injury usually is worse on Mcintosh than Delicious. There is some evidence that the combination o£ guthion and CaCl2 may increase foliar burn. Foliar injury was more severe from dilute sprays than when applied at 6X at the Horticultural Research Center in 1976 but the opposite occurred in 1977. This appears to indicate the CaCl2 injury varies with season because of such factors as rainfall and temperature. Magnesium (Mg) : Deficiency symptoms of Mg (Figure 2) are not as prevalent as in the past but this important element should not be forgotten in our anxiety to increase Ca levels. Pictu f icie the s Defic ized tween leave usual seaso toms By la which may b leave defic at ha red on the ncy symptom ymptoms on iency sympt by necrotic the veins, s on shoots ly affected n progresse appear on t te summer, the leaves e defoliate s near thei iency incre rvest . left is Mg s on pear apple are oms are ch (brown) a The olde and spurs first, an s the inju he younger the shoots show Mg d d except f r terminal ases fruit de- leaves ; similar, aracter- reas be- r, basal are d as the ry symp- leaves. on ef iciency or a few s. Mg drop gram. Mg def condit gallon sprays should apply The requirements of trees for Mg can best be met by maintaining an adequate dolomitic liming pro- Since it takes years before lime is effective in correcting iciency, Epsom salt sprays can be used to help correct the ion. Apply 2 to 3 sprays at the rate of 15 to 20 lbs per 100 s of water at the time of calyx, first cover and second cover To avoid possible incompatibilities, the Epsom salt sprays not be combined with the regular pesticide sprays. Don't Epsom salts or a lime high in Mg unless leaf analysis or visual observation indicates low Mg levels. Mg can supress Ca; Boron (B) : Toxicity symptoms of this element were observed in a few orchards in 1977. They occurred on bearing trees sprayed with a foliar application of B and on trees fertilized with B the year of planting. The picture on the following page shows typical foliar symptoms of B toxicity. The symptoms are characterized by loss of chlorophyll (green coloration) from along the midrib and larger lateral veins. The symptoms are first apparent at the *Trade Name 11 - base of the leaf blade. In severe cases, loss of chlorophyll is more extensive than shown in the picture; marginal leaf scorch develops, leaves absciss, and wood injury can occur. B def toxicity, deficiency characteri shaped les The dead c corky befo the disord (particula open calyx they matur first reco cessive pr iciency is more common than B The most common symptom of B is found in the fruit being zed by brown, round or irregular ions of about 1/4 inch diameter, ell masses become dry, hard and re harvest. Fruit affected with er will have a pebbled surface rly noticeable on Cortland) , and abnormally dark color as However, frequently the gnition of the problem is ex- eharvest drop. e. B can be supplied to apple trees either by foliar or soil applications. Use the most economical and convenient method. However, it is safest to apply all elements as a fertilizer except m emergency situations. Soil applications of boron should be applied to orchards every 3 years. The rates of application per tree vary with tree age and size. In low density orchards, apply 1/4 pound of borax (11.11 actual B) or its equivalent under young trees coming into bearing , 1/2 to 3/4 pound to medium age and size trees and 3/4 to 1 pound to large or mature trees. Be sure to note the percent actual B in the fertilizer being used to supply this element"! B containing fertilizers vary from approximately 11 to 21% actual B. In medium and high density orchards (115 trees/acre or higher), it might be best to apply B on an acre basis. We suggest the fol- lowing rates per acre of borax (11.1% actual B) or its equivalent: (a) trees 4 to 7 years of age - 12 lbs; (b) trees 8 to 15 years of age - 12 to 24 lbs; and (c) trees 16 to 30 years of age - 24 to 48 lbs. When the soil application of B is followed by a wet spring, it may be advisable to apply 2 foliar applications of B the following year. Many growers now rely on annual foliar applications of B. The usual practice is to add Solubor to the first 2 cover sprays. Fertilizer grades of borax may contain grit and should not be used in a sprayer. Mature trees should receive 4 pounds of Solubor per acre each year. Consequently, the goal is to apply about 2 pounds 12 per acre in each of the 2 applications. For young orchards, the addition of 1/2 pound of Solubor per 100 gallons (dilute basis) to the first 2 cover sprays meets the B requirement of these trees. Reports of New York State indicate that sprays can be concentrated up to 8X with satisfactory results. Leaf samples from orchards treated with Solubor have indi- cated adequate leaf boron levels but the fruit was deficient in this element. Whether or not B applied as a fertilizer more ade- quately meets the B requirement of apples than foliar-applied B is not known by us. Manganese (Mn) : The element was deficient in several orchards last summer . As sEown in the photograph below apple leaves having Mn deficiency have interveinal fading of chlorophyll with the veins remaining green. In the past we have analyzed Mcintosh apple leaves from trees showing Mn deficiency and found the leaf of this element to be 9 to 14 ppm. Mn levels of th are critically low in comparison to standard of 50-100 ppm set by othe apple trees. Mn deficiency should on trees showing considerable folia Although we haven't definite proof, ciency appeared to be associated wi fruit drop on a few trees in one or 1977. Mn deficiency can be correct applications of manganese sulfate o fungicide containing Mn. Apply man sulfate at about first cover at the lbs per 100 gallons of water. If u containing fungicide, 2 or 3 applic necessary with timings about petal and second cover. is magnitude the desired r states for be corrected ge damage. Mn defi- th excessive chard in ed by foliar r of a ganese rate of 3 sing a Mn- ations are fall, first Mn toxicity is implicated with the problem of "apple measles" shown in the photograph on the following page. The twig from Delicious at the top of the photograph shows severe symptoms of measles while the twig below has normal bark. Measles can severely injure or kill young Delicious trees. An over-application of a dormant-oil spray can induce symptoms similar to that shown in the photograph. Our only solution to the apple measle problem is raising the soil pH to 6.0-6.5. Apply lime, if needed, before planting and add 2-3 lbs of lime to the planting hole. 13 - Zinc (Zn) : Based on optimum levels of Zn established by some states, some of our orchards are low in this element. Massachu- setts growers have not used zinc sulfate sprays applied at the '•green tip" stage of bud development to increase zinc levels but some use manganese-zinc containing fungicides. These appear to be increasing Zn levels in our orchards. NAPHTHALENEACETIC ACID (NAA) FOR TREE TRAINING William J. Lord and Joseph Sincuk Department of Plant and Soil Sciences It was reported in excellent tree training the stem of newly-plant second, third, and four cut, which was not pain treatment eliminated th the trees which compete number of favorably pos and improved crotch ang the bud selected for th reportedly developed fr suggested NAA treatment procedures which involv is in competition with 1977 that II NAA in latex paint is an aid when applied as a painted band around ed apple trees (after heading) to cover the th buds. The first bud below the heading ted, became a vigorous central leader. This e cluster of vigorous shoots in the top of with the central leader and increase the itioned branches on the newly-planted trees, les of these branches. If for some reason e central leader died, a strong leader om the NAA-treated area. Basically, the is a replacement for the current training e removal by hand, in June, of growth that the shoot favored as a central leader. Directions for use indicated that the II NAA in latex paint should be applied after heading the newly-planted tree to the 14 / desired height but before growth begins, effective if made after start of growth. The treatment is not Last summer, we compared the NAA tree training technique on Marshall Mcintosh, Macoun, and Redspur Delicious with removal of buds 2, 3, and 4 immediately after planting (disbudding) or removal of shoots competing with the central leader in mid-June. The Marshall Mcintosh and Redspur Delicious were headed at 36 and 30 inches, and the Macouns at 30 inch height. All treatments were replicated at least 16 times. The NAA treatment was a complete disaster in the 3 orchards. The first bud below the heading cut, which was supposed to develop into the leader, was with only one exception either severely stunted or killed. When the bud selected for the central leader died, no strong leader developed from the NAA-treated area. Crotch angles were affected only on the Redspur Delicious (Table 1) . The trees receiving the NAA treatment and those on which the competing shoots were removed in mid-June, had wider crotch angles than the disbudded trees for each heading height. Table 1. Effect of NAA application, removal of competing shoots in mid- June, and disbudding on crotch angles. Treatment and heading height NAA, 36 in NAA, 30 in Shoots removed, 36 Shoots removed, 30 Disbudding, 36 in Disbudding, 30 in m in Cultivar Marshall Redspur Mcintosh Delicious Macoun Avg. crot ch angle (deg rees) ^ 70a 60a 67a 53bc 60a 69a 56ab 68a 56ab 59a 66a 50c 67a 44d 55a Mean separation in columns by Duncan's multiple range test, 5% level. We do not know why the results with NAA were so unfavorable although we believe the concentration was too high. However, it is obvious that Massachusetts growers should not use NAA for tree training until further experimentation shows the procedure to be reliable. Even if the NAA tree-training technique is proven to be reli- able, it has at least 3 obvious drawbacks. Spring is an extremely busy season and chances are great that the NAA will not be applied, Secondly, the treatment must be applied before growth starts. And lastly, frequently a better choice of a leader can be made in mid- June and this job can be combined with limb spreading with clothes 15 pins. Thus, at present, we still suggest the standard procedures of leader selection. This involves selection of the uppermost shoot on the windward side of the newly-planted tree when shoot growth is 6 to 8 inches in length. Shoots competing with the selected leader should be rubbed or pruned off for a distance of approximately 6 inches down the stem.. *************** ALTERNATE VS. EVERY MIDDLE SPRAYING FOR APPLE PESTS IN 1977 R.J. Prokopy, R.G. Hislop, and K.I. Hauschild Department of Entomology and R.L. Christensen Department of Agricultural and Food Economics Earlier, we reported our 1976 findings on the comparative effectiveness of alternate vs. every middle spray treatments in 3 commercial orchards (see Fruit Notes 42(5):8-10). In this article, we report on our 1977 findings , and include a cost-benefit treat- ment comparison for one of the orchards. The alternate middle treatment involves spraying alternate halves of each tree on alternate spray dates instead of both halves on all spray dates. For example, in applying the first cover spray, the sprayer would be driven up the middle between tree rows A and B and return down the middle between rows C and D, skipping the middle between rows B and C. For the second cover spray, the sprayer would be driven up the middle between rows B and C, down the middle between rows D and E, and so forth. If this pattern were followed with every spray application, it would save 50% of the spray material costs. In 1977, we compared alternate with every middle spray treat- ments in the same 4-acre blocks in the same 3 orchards as in 1976. Each block was divided into 2 plots : one receiving the alternate middle program on each spray date from pink (or petal fall) through last cover; the other receiving the every middle program. Each grower used an air blast sprayer at 4X. He followed his normal spray schedule, and used his own selection of pesticides. All trees were full grown - some on M. 7 rootstock, others on standard. The centers of the trees were fairly well pruned in all blocks. To determine the extent of pest pressure, we hung traps in each plot for monitoring tarnished plant bug adults, codling moth and redbanded leafroller adults, and apple maggot flies (see Fruit Notes 41(1) : 3-4; 41(6) :6-9; and 43(2):10-14 for information on construction of each trap type) . We caught the following average numbers/trap in each plot: 16 Tarnished Plant Zoecon phero- Apple maggot Bug Trap mone traps trap (unbaited white Codling Redbanded (unbaited Treatment Orchard rectangles) Moth leafroller red sphere) Every middle A B C Average Alternate middle A B C Average 1.3 5.0 5.7 4.0 1.0 13.0 9.3 7.8 56 110 44 120 127 205 76 145 51 185 76 111 75 157 67 151 7.0 3.0 5.7 5.2 2.7 14.5 11.7 9.7 Researchers in New York believe that when cumulative codling moth captures/trap reach 15-20 and apple maggot captures/trap reach 1, fruit injury is likely to occur unless insecticide is applied. A relation between plant bug or leafroller captures and need for spraying has not yet been established, but substantial numbers of each were trapped. Overall, the trap data show that pest pressure was considerable in both the every and alternate middle plots. To determine the actual amount of fruit injury caused by these and other pests and to determine spider mite and aphid abundance on leaves, we examined 60 fruits and 60 leaves/tree on each of 6 trees in each plot in each block every 3 weeks from mid-April until harvest. The results are given here: - 17 Spraying every middle Spraying alternate middles in orchard: in orchard: A B C Avg. A B C Avg. % leaves infested with: Mites 6.0 15.2 6.1 9.1 20.6 16.7 2.1 13.1 Aphids 1.7 2.9 2.2 2.6 0.8 3.2 1.3 1.8 % fruit injured by: Plant bug 0.3 1.9 1.3 1.2 0.3 2.9 1.5 1.6 Curculio 0 0.4 0 0.1 0.2 1.2 0.3 0.6 Sawfly 0 0.1 0.3 0.1 0 0.6 0.1 0.2 Green Fruitworm 0 0.1 0.1 0.1 0 0.3 0 0.1 All other insects 0 0 0 0 0 0 0 0 Total 1977 0.3 2.6 1.7 1.5 0.5 5.1 2.0 2.5 Total 1976 0.9 5.8 1.6 2.8 1.7 5.2 1.9 2.9 The results show that for all orchards combined, an average of 1.51 of the fruit in the every middle plots was injured by insects vs. 2.51 fruit injury in the alternate middle plots. Compared with 1976, the 1977 results show 141 less fruit injury in the alternate middle plots and 46% less in the every middle plots. Most of the 1977 difference between alternate and every middle plots was attri- butable to Orchard B, where the presence of abandoned trees nearer the alternate middle plot resulted in heavier insect pressure on that plot. As in 1976, plant bugs caused the most fruit injury. Their damage was slightly greater in the alternate than every middle treatment. However, because plant bug damage on a ripe fruit appears as a purely cosmetic injury, and does not affect the eating quality of the fruit, most growers cull only about 50% of plant bug injured fruits. The next most injurious insect was plum cur- culio. It was the only fruit insect to cause greater injury in the alternate middle than the every middle plot in each orchard. Apple sawfly and green fruitworm caused slight injury, while no fruits in any plots were found damaged by codling moth, apple maggot, or redbanded leafroller. In contrast to 1976, aphids were, on the average, slightly more abundant in the every middle than alternate middle plots. As - 18 - in 1976, spider mites were, on the average, slightly more abundant in the alternate middle than every middle plots. Some apple scab was observed in each block, but did not appear to occur in any greater amount in the alternate middle plots. A cost-benefit analysis of the every vs. alternate middle treatments in Orchard C was conducted by students in a graduate insect pest management class at UMASS (see Fruit Notes 43(2) :3-7). The results are summarized here: Dollar Costs/Acre Every Alternate Middle Middle Difference Spray materials* 135.70 67.85 -67.85 Labor (at $3/hr) 10.50 5.25 - 5.25 Fuel, oil, filters, etc. 5.00 2.50 - 2.50 Value of fruit loss owing to insect 5 disease injury** 32.72 44.72 +12.00 Cost reduction from alternate middle program*** -63.60 (Since a reduction in net costs is the same as an increase in returns, the value of $63.60 should be regarded as an increase in net returns.) * Includes cost of all insecticide, miticide, and fungicide materials. ** Fruit yield was sampled on randomly selected trees and found to be equal in the alternate and every middle plots. Total yield estimated at 750 bushels/acre in each plot. Only 0.181 and 0.06% diseased fruits appeared in the 3360 fruits sampled at harvest in the alternate and every middle plots, respectively Fifty percent of the fruits injured by plant bugs plus all fruits injured by other insects were considered as culls. Total bushels of culls per acre were 8.18 and 11.18 for the every and alternate middle plots, respectively. Culls were given an average value of $2/bushel (combination of #2 fruit and cider j apples). All undamaged fruit was given a value of $6/bushel. ' The analysis does not include possible additional costs (if any) of grading out the greater number of insect- and disease- injured fruits (11.18 - 8.18 = 3.0 bushels/acre) from the alternate middle plots. *** - 19 - The results show that grower C realized a net profit of $63.60 more per acre from the alternate middle than the every middle plot. An additional benefit was that the grower could spray the alternate middle plot in about half the time as the every middle plot. This allowed him to respond more rapidly to conditions calling for immediate pesticide application. We conclude from our first 2 years of experimentation that an alternate middle spray program in Massachusetts shows promise of effectively controlling most of the major insect pests that attack the fruit. To date, it has proven just as effective as an every middle program against those pests which are highly mobile, and hence make frequent contact with the sprayed portion of the tree: codling moth, redbanded leafroller, and apple maggot. In some situations, the alternate middle program may be slightly less effective against a pest like plum curculio, whose mobility within the tree is quite restricted (see Fruit Notes 42(4) :5-7). Where such is the case, every middle treatments for the petal fall and first cover sprays would be advisable. The alternate middle pro- gram's effectiveness against spider mites and aphids may depend on the type of pesticides employed. On the one hand, spider mites and aphids are not very mobile. On the other hand, if not killed by toxic orchard pesticides, predators are capable of effectively suppressing spider mites and aphids below damaging levels (see Fruit Notes 42(2) : 5-7 and 42(6) : 6-10) . In summary, our findings to date show that the alternate middle spray program can result in greatly reduced pesticide usage, effective pest control, and a greater net profit to the grower. For those growers interested in trying out the program, we would suggest starting with a one or two-acre block to see how the pro- gram works with your particular type of sprayer and trees, and under your particular local insect, mite, and disease conditions. We would advise against submitting large acreage to this program until you (and we) learn more about the program's long-term effec- tiveness and possible shortcomings. For example, we need much more information on its effectiveness against plum curculio and apple diseases. Present knowledge suggests that the program works best where the trees are well pruned (open centers) and spaced at recommended intervals (not wider) . Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol 43. (No. 4) JULY/AUGUST 1978 TABLE OF CONTENTS Factors Affecting Nutrient Content of Apple Foliage Pomological Paragraph Use of ethephon to promote color and ripening of apples in Massachusetts Late Summer Fertilization of Strawberries New Herbicide for Blueberries Pomological Paragraph When can the severity of russet on Golden Delicious be estimated? Use of Creosote to Prevent Deer Damage in Orchards Influence of Pesticides on Spider Mite and Predator Abundance in Massachusetts Apple Orchards — 1977 Results Apple Tree Response to Summer Pruning The Effect of Summer Pruning of Mcintosh Apple Trees on the Calcium Nutrition and Postharvest Quality of the Apples FACTORS AFFECTING NUTRIENT CONTENT OF APPLE FOLIAGE William J. Lord Department of Plant and Soil Sciences Crop size can have a considerable effect on the quantity of several elements in apple foliage. Leaves from a tree with a large crop will contain more nitrogen (N) and less potassium (K) than leaves from a tree with a light crop. Leaves from a light-crop tree may contain 0,2 to 0,3% less N than when the same tree has a full crop. Leaves may decline as much as 0.41 K in a heavy-crop year. Calcium (Ca) follows the same trend as N and exhibits about the same difference as N in leaf content between the light- and heavy-crop years. Leaf magnesium (Mg) is slightly higher in a heavy-crop than in a light-crop year. Crop size has little, if any, effect on leaf phosphorus (P) . The amount of one element may affect the amounts of other elements in the leaf. For example, leaves which are relatively high in N tend to have lower levels of K and P and higher levels of Mg and Ca than leaves from trees which have a low to medium level of N. High levels of K may depress leaf Mg and Ca, particu- larly if the soil supply of Mg and Ca are low. However, moderate levels of K do not seriously depress Mg as long as there is an adequate level of Mg . Another factor which may influence the leaf content of some elements is soil moisture or rainfall. Leaf K is generally lower in dry growing seasons than in years with adequate soil moisture. Mg is generally lower in years which have above normal rainfall during the early part of the growing season. The magnitude of the change in leaf content caused by seasonal rainfall will depend upon the relative wetness or dryness of the season and the supply of nutrients in the soil. If the soil is so wet or so dry that development of new roots is prevented, the leaf content of essen- tial elements could be reduced. **************** POMOLOGICAL PARAGRAPH Use of ethephon to promote color and ripening of apples in Massa- chusett~s^ Our suggestions for use of ethephon for promoting uni- form ripening and red color of apples have not changed from last year. These suggestions were published in Fruit Notes 40 (No. 4): July/August, 1975. Those who do not keep back issues of Fruit Notes can obtain a copy of the suggestions on ethephon usage from your Regional Fruit Specialist. **************** LATE SUMMER FERTILIZATION OF STRAWBERRIES William J . Lord Department of Plant and Soil Sciences In Massachusetts, the June-bearing varieties o£ strawberries initiate their flower buds in the fall. If conditions are favor- able, many varieties produce several flower buds in each strawberry crown and consequently produce several inflorescences per plant. The extent of flower bud development seems to be influenced by the supply of available nutrients, particularly nitrogen. A number of experiments have indicated an advantage of build- ing up the nitrogen supply in the fall from the standpoint of increased flower bud formation. However, factors such as earliness of runner plant rooting, quality of plants, soil moisture, and pest and weed control may have more effect on plant productivity than the fertilizer applications. A recent study in Minnesota showed that nutrition can affect winter-hardiness of 'Redcoat' strawberry plants. In this study 'Redcoat' strawberry plants deficient in nitrates, phosphorous, and potassium received fertilizer treatments in late-August. Arti- ficial freezing tests were conducted on the plants at the onset of their acclimation to cold weather, and in mid-winter with fully hardened plants. Plants fertilized with a complete fertilizer of 1:1:1; 2:2:2, 1:1:2, or 1:2:1 ratio made better recovery from the early and m.id- season artificial freezing tests than the non- fertilized plants and those that received a fertilizer with a 1:0:0, 2:0:0 or 1:1:4 ratio. Winter injury to strawberry plants is of frequent occurrence in Massachusetts, thus it may be worthwhile to fall fertilize* with a complete fertilizer rather than one containing nitrogen alone, as has been suggested in the past if the plants lack vigor. We suggest applying a complete fertilizer (1:1:1, 1:1:2, or 1:2:1 ratio) at the rate of 30 pounds of actual nitrogen per acre. A broadcast application of fertilizer at that time may damage the foliage unless precautions are taken. Apply on a clear day of low humidity and shake off any fertilizer adhering to the leaves, (a switch made from brush is convenient) or apply during a rain, to avoid burning of the foliage. About late August. **************** NEW HERBICIDE FOR BLUEBERRIES Dominic A. Marini Southeast Regional Fruit 5 Vegetable Specialist Terbacil (Sinbar*) is now registered for the control o£ many- annual and some perennial weeds in blueberries, and is included in the 1978 Weed Control Guide for Small Fruits. Some of the weeds mentioned on the label are crabgrass, fall panicum, foxtail, mus- tard, yellow rocket, purslane, ragweed, lambs quarters, chickweed, shepherdspurse, marestail, cinquefoil, hawkweed and quackgrass - also known as doggrass or witchgrass. As with other new materials, limited applications on a trial basis are suggested. Terbacil is sold as a wettable powder that is mixed with water and applied as a spray. Continuous agitation is necessary to keep it in suspension for uniform application. It may be applied as a band along the row and under the bushes or as a complete broad- cast application. Plants should be established for at least one year before being treated with terbacil. It may be applied in the spring or after harvest in the fall before weeds emerge, or to weeds in the early seedling stage of growth. Apply at the rate of 2 pounds of the 80 percent wettable powder per acre on light soils, and 3 to 4 pounds on heavy soils. Do not use on gravelly soils with less than 1 percent organic matter or where roots are exposed. Avoid contact of fruit or foliage with spray or mist. Blueberries may be planted in soil treated with Sinbar one year after the last application. Do no replant to other crops for 2 years, or injury may result. * Trade Name **************** POMOLOGICAL PARAGRAPH ^Tien can the severity of russet on Golden Delicious be estimated? Dr .~L'. L"! Creasy, Cornell University, Ithaca, New York, reported at the 122nd Annual Meeting of the New York State Horticultural Society that russet on Golden Delicious apples is present 30 days after petal fall, but the high pigment concentration on the fruit at this time makes it difficult to see. However, generally by mid-July russet is readily visible and the amount estimated at this time will not change through harvest. **************** •4- USE OF CREOSOTE TO PREVENT DEER DAMAGE IN ORCHARDS G. Everett Wilder Regional Fruit Agent 1499 Memorial Avenue West Springfield, MA 01089 The white- tailed deer is highly prized by hunters who spend large sums of money annually in quest of "their" deer. However, the "Buck-law" in Massachusetts, enacted to increase deer popu- lation, has not found favor with farmers because deer feed on agricultural crops. Deer favor fruit trees, especially apples, as a food source and cause considerable damage in some Massachusetts orchards. Both the female and male deer feed on apple trees during the winter months and the male deer injures trees with his horns. During the sumjner, deer feed on new shoot growth and developing fruit. Fencing, the most effective means of keeping deer out of orchards, is expensive. Therefore, many growers use taste repel- lents to prevent deer damage. These are somewhat effective when sprayed on trees during the growing season and/or during the fall and winter months. Smell and noise repellents also have been tried in Massachusetts with limited success. Recently, it has been reported from Maryland that Tabasco Sauce is an effective taste repellent against deer and rodents. Ben Tarnauskas, who operates an orchard on the Granville- Westfield town line, conceived the idea of using creosote as a deer repellent. Strips of felt approximately 3/4" x 6", with a wire attached to each strip, were dipped in creosote. (Felt weather stripping is an available and perhaps the most economical source of felt.) Ben attached one treated strip per tree on trees next to the woods. He observed that the deer avoided these trees and therefore he placed the creosote-treated strips in all young trees. The creosote has proved to be an effective repellent. Other orchardists in Granville are now using creosote-treated felt strips in their orchards. Edward Roberts has placed 2000 strips near young trees (one strip/tree 30 inches above the ground) with excellent results. No feeding by deer has occurred in trees containing the strips this past year. Mr. Roberts retreats the strips with creosote in an oil can. He suggests "touching-up" the strips about every 3 weeks during the rainy periods of the growing season. (Once seems enough for the entire winter) . This method saves on repellent and keeps the odor strong. One caution: creo- sote will burn apple tree leaves and bark. Therefore, the felt strip must be hung in such a manner that the excess creosote will not drip on foliage or wood. A safer method is to drive a 3/4- inch stick approximately 36 inches in length in the ground near the tree with the creosote strip wired to its top. **************** INFLUENCE OF PESTICIDES ON SPIDER MITE AND PREDATOP ABUNDANCE IN MASSACHUSETTS APPLE ORCHARDS--1977 RESULTS Robert G. Hislop, Charles Acker, and Ronald J. Prokopy Department of Entomology, Fernald Hall In the March- April, 1977, issue of Fruit Notes we described the results of our 1976 research aimed at reduced spraying for spider mites in Massachusetts apple orchards. In 1977, we contin- ued our search for natural enemies of mites and discovered that Amblyseius fallacis , our most important mite predator, was even more abundant and widespread than our 1976 survey suggested. Here, we discuss the results of our 1977 field work aimed at enhancing the buildup of this valuable predator in our orchards. In June, 1977, we resumed the extensive spider mite (red mite and two-spotted mites) and predator sampling program begun in 1976 but concentrated on sampling only apple tree foliage. We sampled 4 commercial orchards (A, B, C, and D) , located in 2 separate regions of the state, and 1 abandoned orchard. Two of the commercial orchards employed one type of spray program, the other 2, a differ- ent program. In addition, at the Horticultural Research Center at Belchertown, we applied either Imidan, Guthion, Zolone, or Benlate at biweekly intervals from petalfall to late August to 3 groups of trees, with 3 groups left unsprayed for comparison. All trees in the commercial and Belchertown orchards were sampled at biweekly intervals to determine spider mite and predator populations. The samples were collected, processed, and analyzed in the manner described in the 1977 issue of Fruit Notes. Results in 1977 supported the 1976 results in that A. fallacis was common only in certain commercial orchards. In the abandoned orchard its numbers were low but numerous other predator species kept red mites and two-spotted mites at very low levels. In commercial orchards A and B, sprayed with combinations of Guthion, Zolone, Imidan, Benlate, Glyodin, and Captan, two-spotted mites reached 10.7 and 14.3 mites per leaf at peak abundance (Table 1) but red mites remained below damaging levels. Popula- tions of A_^ fallacis reached maximum levels of only 0.06 and 0.04 mites per leaT'. On the other hand, in commercial orchards C and D, sprayed with combinations of Guthion, Captan, and Cyprex, two-spotted mites were virtually absent. In orchard C, red mites remained at very low levels, in contrast to orchard D, where they reached a peak abundance of 36 mites per leaf (Table 1) . A. fallacis was relatively scarce in orchard C in comparison to orchard D, probably due to the low spider mite populations. In orchard D, predacious mites reached very high numbers, (5.4 mites per at peak abundance) but yet were unable to control the red mites. In addition to the large A_^ fallacis populations in orchard D, there were 2 additional •M o 5-1 -H V) dO Q> O (U o o o CO r-l ^ +J nd -H O o 6 o O o o MD 1 o O o o rH X Si ■3 cu ^ tfl <^ •H y ^ •<* rH T-{ O a o O • rH \D O r- t: 1— ( cC o o O f-i O t--- 3 m ai JO 1— I Oj •H -^ O trt (D rH 0) o o O o 00 -^ cu rH +-> 0) -H o • o • o 00 o ■(-> >-i 2 o o o to o X o M-l 5-1 rt T3 O i-H T3 ^ — ■♦-> t/) 2 r- K1 CD o o O +-> Crt -H • 1 •g o^ o rH ^ ^ o o o ^ ■s O T3 5-1 u 0) J3 •X3 (D o o rsi o ■rj- r-l § I— 1 •>* • o o lO rt S ^ rsj o o vO I-H •H to o 5-4 4-) ■M 03 •H +-> u O rt TS (/) U •H £ •-' •H I-H C/) 00 OO \D OO !^ JSi a o P ■"• O I-H 4J 4-1 5-1 +-> •H E 5-1 4h o 1) •H (X, •^1 rH

o^ vO vO to O ^ C71 ■H +-> 1 tn O g u iu O CD <+-l ^ LO o W O pj LO LO o 'tS LO K1 LO to 5-. •H r^ c m (U 9. u O C 0) ^s o o y £> •H •HOC •H ■ R S E ■M j::'d o t:! o ^ X 3 U +J -H rH •H rH ■»-> 4-1 'T3 B a^tS ^tS 5 3 u ^ 1— ( LO r-l to O r-l 00 C7^ T3 ^-^ -s g 1 < m u Q < species of mite predators, called yellow mites, that are very slow and inefficient at locating and capturing red mite prey. These predators were considerably more abundant than A. f allacis, and it is very likely that they were interfering with its performance. In the abandoned orchard, two-spotted mites were totally absent, while red mites were always at low levels (Table 1). A. fallacis was largely absent. However, other predacious mites increased to 1.70 mites per leaf, which is a rather high level, but still con- siderably lower than predator levels in commercial orchard D. It appears that the fewer numbers of mite predators in the abandoned orchard were able to control red mites better than the larger num- ber of predators in orchard D. This was probably because the dif- ferent predator complex in the abandoned orchard was more efficient in controlling red mites. At the Belchertown Research Center, two-spotted mites were in greatest abundance (causing severe leaf injury) and A_^ fallacis in least abundance in the Zolone treated plot (Table 2). However , red mites remained below damaging levels in all plots. In the Guthion and Imidan plots, A_^ fallacis populations were high, keeping two- spotted and red mites well below damaging levels. A. fallacis levels were also high in the Benlate plot but failecPto keep two- spotted mites from reaching damaging levels (Table 2) . This is likely due to certain characteristics of Benlate (see below) which adversely affect Aj_ fallacis populations. Yellow mites were absent from all plots. The combined results from the commercial orchards and the Belchertown Research Center show that one or more of the materials Zolone, Benlate, and Glyodin have a toxic and/or other effect on populations of Aj_ fallacis . In addition, our recent laboratory findings confirm results from Michigan (Dr. B.A. Croft's laboratory), showing that Benlate, at orchard concentrations, severely reduces the number of eggs laid by A_^ fallacis . Growers using these mate- rials (Table 1) needed more miticide sprays, principally to control two-spotted mites, than growers spraying only Guthion, Imidan, Captan, and Cyprex. However, red mites can become a problem in some orchards (i.e. in orchard D) using the latter pesticides because the favorable environment may allow less efficient mite predators to increase and interfere with A^ fallacis . In the future, we plan further laboratory and field trials aimed at determining which pesticides are safest for A_j_ fallacis populations in our commercial orchards. This predator can be of great assistance in suppressing harmful spider mites if its survival can be guaranteed. In the next issue of Fruit Notes, we will describe results of laboratory tests aimed at determining the toxicity of a large variety of orchard pesticides to A. fallacis . TABLE 2. Pesticides applied to apple trees at Belchertown Research Center in 1977. Number o£ mites/leaf at peak abundance (July - August) Pesticide Rate/100 Gal Red Mites Two-spotted Mites 2 .70 3 ,60 108 .80 17 .50 1 .74 A. fallacis Imidan 50wp Guthion SOwp Zolone 3EC Benlate SOwp Check 1.5 lb 10 oz . 1.5 pts 6 oz. 7.50 5.74 6.60 8.00 3 .70 1.48 2 .00 0.25 1.47 2.14 **************** APPLE TREE RESPONSE TO SUfD^^ER PRUNING W. J. Department Lord and D. W. Greene of Plant and Soil Sciences Summer pruning has been practiced for centuries by European gardeners in order to restrict vegetative growth and to induce the formation of flowering spurs, but has not been widely applied in commercial fruit growing. Considerable research on summer pruning was conducted in the early 1900 's, and it produced widely differing results depending on type of pruning, tree vigor, and cultivar. It is very difficult to evaluate the results of these experiments because these early reports generally described their experiments too vaguely or the treatments were not replicated, but it should be noted that in some of these trials summer pruning failed to suppress vegetative growth, to increase flowering, to induce early bearing, or to increase production. In some of these trials, the summer pruning procedure was similar to that practiced during the dormant season, whereas pruning as practiced by European gardeners to induce fruitfulness involved removal of a portion of the current-season shoot rather than removing whole branches or shoots. Despite all the differences, however, it was generally agreed that summer prun- ing restricted tree growth more than an equivalent amount of prun- ing during dormancy. This flurry of research on summer pruning in the early part of the century led to the conclusion by some American pomologists that the results were too unpredictable and the practice too laborious to be of value in commercial orchards. But, now that we have greater density o£ plantings (trees per acre) than in the past, interest in vegetative growth control has been renewed. Furthermore, we have substantial acreage o£ trees on size-controlling rootstocks that are easier to prune because they are smaller, and we have mechanical pruning devices that m.ake pruning quicker. Delicious, the major cultivar in the U.S., tends to make excessive growth and to be unfruitful, and therefore needs growth restriction. And still further, as we look for ways to improve the calcium nutrition of apples we see reports from Europe indicating that summer pruning can increase fruit calcium levels. There is, therefore, ample reason to re-examine the applicability of summer pruning to commercial fruit production . What is Summer Pruning? The term summer pruning alone means little and only tells the season of pruning. It may mean nothing more than the removal of water sprouts or performing dormant -type pruning during the growing season as a means of tree training. Summer pruning could mean making detailed cuts on current season's shoots throughout the tree, using hand-held pruning tools, to restrict vegetative growth and induce the formation of flower buds on young trees. It also could mean removal of current season's shoots and/or 1-year-old wood on the periphery of the bearing tree with hand-operated pruning tools or a mechanical pruning device to restrict tree growth or increase fruit c a 1 c i um . The object of our summer pruning investigations has been: (1) to determine the vegetative and fruiting responses of young Delicious and Cortland trees; and (2) to study its influence on quality of fruit from Cortland and Mcintosh trees. Definition of Terms At this time a few terms used in this report should be defined to avoid confusion that otherwise might arise in regard to their meaning. Pinching will refer to the removal of only the tip of current season's shoots. Heading will be the term used when cutting current season' s shoots back to 4 to 6 mature leaves . Stubbing as used here is to cut upright shoots on limbs about 1/4 to 1/2 inch above their base, thus leaving a short stub. Axillary buds are borne in the axils of the leaves on current season's shoots. When a current season's shoot is pinched or headed, the axillary bud or buds directly below the pruning cut may produce growth; these are referred to as axillary spurs or shoots. We arbi- trarily classified any growth less than 1 inch long but producing a whorl of leaves as being an axillary spur. When shoots produced more than an inch of extension grovv'th they were classified as axillary shoots. The tip of an axillary spur will become either a leaf or flower bud. The terminal bud on an axillary shoot also will become either a leaf or flower bud. -10- Effect on Growth of Young Trees Pruning while the shoots are still elongating tends to cause new shoots to start growth from the axillary buds below the pruning cuts. The amount of regrowth may show little correlation with severity of pruning. We have foiond that Red Prince Delicious pro- duces more of this regrowth than Cortland. Tree vigor at time of pruning also is an important variable since the length of shoots at time of pruning is highly correlated with amount of regrowth, i.e., the longer the shoot, the greater the regrowth. Pinching did not devitalize the trees in our studies, whereas heading restricted the size of vigorous trees. Considerable regrowth follows summer pruning of vigorous young trees in late-June through mid- July. However, if substantial leaf surface is removed at this time, regrowth does not compensate for the removed surface. July and early-August appear feasible times for restricting tree size by summer pruning, but regrowth may be less when pruning is done in early-August . Pinching and heading cuts on vigorous Red Prince Delicious trees in early or mid-July frequently causes new shoots to start growth from 2 or more of the axillary buds below the pruning cuts. Thus, a proliferation of growing points occurs just as when trees are sheared with mechanical pruning devices during dormant season. Whether the proliferation of growing points can be considered an unfavorable response in all cases remains to be proven. However, clearly unfavorable responses to summer pruning have occurred. On Cortland/7A trees, 181 of the shoots headed on July 18, 1976 were dead in 1977; death of headed shoots occurred less frequently follow- ing the July 1 and August 2 pruning dates. Many current season's shoots on Cortland/7A and Red Prince Delicious/26 stubbed in 1977 failed to produce regrowth. In 1978, 71% and 50% of the stubs were dead on the Cortland and Red Prince Delicious, respectively. Some flowering from axillary flower buds and spurs has occurred in Sept- ember of the year of pruning. Summer-pruned trees also have shown a tendency to mature their wood later in the fall as evidenced by delayed leaf abscission, and this may lead to winter injury. Fur- thermore, Starkrimson trees that had been summer pruned by heading cuts in 1976 made more growth than the control trees in 1977; thus, the advantages of vegetative growth control in 1976 were lost in 1977 without follow-up summer pruning. Effect on Formation of Flowering Spurs We wanted to determine if stubbing, heading, or pinching current season's shoots in summer caused a flower bud to form immediately below the cut. Stubbing is preferred in some fruit growing areas because less regrowth is produced and thereby more chance for ini- tiating flower buds than when a longer stub is left as with heading 11- and pinching. Even though we stubbed shoots on Cortland/7A and Red Prince Delicious/26 on June 21, July 5, or July 19 many were not vigorous enough at time of pruning to produce an axillary flowering spur or shoot. As previously mentioned, many of the stubs failing to make regrowth in 1977 v\rere dead in 1978. Heading and pinching on Cortland/7A in 1976 and 1977 caused formation of some flowering axillary spurs or the development of axillary shoots with a terminal flower bud. Since Cortland normally produces some terminal flower buds, a terminal flower can form in spite of considerable extension growth of axillary shoots from the first leaf axil below the pruning cut. On Cortland we believe that summer pruning merely eliminated some potential flower buds and stimulated the formation of others since total bloom was not increased in either year following pruning. Heading and pinching procedures failed to induce the formation of flowering spurs or shoots on Starkrimson Delicious/106 and Red Prince Delicious/106 in 1976 but were somewhat successful on Red Prince Delicious/106 and Red Prince Delicious/26 in 1977, probably because conditions were very favorable for flower bud initiation as evidenced by the snowball bloom in most orchards in 1978. The Red Princ the 1st leaf axil were initiated on initiated on axill leaf axil below th 26, vvfhich had low occurred on axilla leaf axil . As wit by the summer prun pruned by heading 2nd and 3rd leaf h trees . e Delicious/10 following head this axillary ary spurs or £ e pruning. In to moderate vi ry spurs and s h Cortland, to ing . Furtherm cuts both in 1 ad significant 6 made considerable ing and pinching and growth. However, fl hort shoots developi the case of the Red gor in 1977, flower hoots from both the tal bloom was not in ore. Red Prince Deli 976 and 1977 when th ly less bloom in 197 regrowth from no flower buds ower buds were ng from the 2nd Prince Delicious/ bud initiation 1st, and 2nd creased in 1978 ciousA06 summer ey were in their 8 than the control Heading and pinching in late-June and early-July were most effective while pruning in mid-July or later had little effect on flower initiation (Table 1). TABLE 1. Time of summer pruning and percentage of tagged axillary spurs or shoots that had terminal buds that bloomed the following year. Time of pruning Bloom, 1977 of Cortland buds % Time of pruning Bloon, : Cortland % 1978 of buds on: Del/106 Del/26 21.9 a 3.3 b 1.4 b 6/21/77 7/19/77 47.6 a 42.7 a 15.7 b 25.1 a 14.2 a 13.4 b 2.1 b 4.1 b 7/1/76 7/1S/76 8/2/76 12- Its Place in Massachusetts Apple Orchards Performing dormant- type pruning during the summer has a place in young apple orchards as a means of tree training. However, summer pruning is laborious and certainly of doubtful value under Massachusetts conditions as a direct stimulus for flower bud ini- tiation on axillary spurs and shoots. To the contrary. Dr. G. E. Stembridge at Clemson University, Clemson, South Carolina, obtained substantial flower bud initiation following stubbing of 4-year-old Delicious/106 in early summer, 1974. Furthermore, many of the axillary spurs and shoots produced by late summer pruning initiated flower buds in 1975. Stembridge stated in correspondence that he thought the extra flowers produced by summer pruning were relatively inconsequential to the productive capacity of the tree. A more important consequence of the summer pruning was the removal of unwanted vigor and better light penetration. In South Carolina, growing conditions are probably more favorable for flower bud ini- tiation following summer pruning than in Massachusetts. To the con- trary, the problem of controlling vigor is probably less acute in Massachusetts than in South Carolina. Basically, Delicious is our only cultivar with which we have problems of adequate fruitfulness on young trees whereas tree crowd- ing and low fruit Ca is a problem with different cultivars in many bearing orchards. Mid-July through early-August seems a suitable timing for summer pruning to restrict vegetative growth; when prac- ticed to increase fruit Ca, early August may be best. Many answers are needed concerning the responses of our major cultivars before we can suggest this procedure on other than a trial basis only. Summer pruning is very laborious when done with hand shears, thus one of the questions is, "Can it be performed with a mechanical tree hedger?". It certainly is possible that Rome and Cortland, which produce part of their crop on 1-year-old wood, may not show favorable responses to summer pruning if a high percentage of current season's shoots are removed. Furthermore, we need to know the influence of summer pruning on sun scald of fruit, and fruit maturity and keep- ability in storage. Research on summer pruning is being conducted in many fruit growing areas and many questions concerning the practice will be answered. Meanwhile, we urge caution to the growers currently experimenting with summer pruning . **************** -13- THE EFFECT OF SUMMER PRUNING OF McINTOSH APPLE TREES ON THE CALCIUM NUTRITION AND POSTHARVEST QUALITY OF THE APPLES William J. Bramlage and Mack Drake Department of Plant and Soil Sciences As we have searched for methods to increase the amounts of calcium (Ca) in apples, we have become interested in the results from Europe indicating that late summer pruning can improve Ca nutrition of the fruit. It is logical to expect such a result from late-summer pruning, since vegetation and fruit are competing for what Ca is available within the tree, and vegetation is the much stronger competitor. Therefore, removing vegetation late enough so that regrowth does not occur should reduce much of the competition and allow more of the available Ca to move into the fruit . But, will it work? To test the idea, we adopted the pruning technique of A. P. Preston in England, which he found to work under their conditions. This is a very severe pruning technique: all current-year shoots are removed to their points of origin. We applied this technique to 8 vigorous 12-year-old Mcintosh trees on M.7 rootstock in 1975 and in 1976 within an experiment where we were testing various methods of raising the Ca level in the fruit. Pruning was done in early- August , 1 month before harvest, and resulted in no regrowth in that season. The effects of the pruning on the quality of the fruit were out- standing. Ca content of the fruit at harvest in 1975 was 15% above that of fruit from trees that had not been summer-pruned. Due to reduced foliage, light penetration was much greater and the fruit were much redder at harvest; however, there was no sun- scald on them (although sun-scald did occur on Cortlands that were pruned in the same way). After storage in either regular storage to January, or in CA until mid-April, apples from the summer-pruned trees had much less bitter pit, breakdown, and rot. In 1976, the same trees were again pruned in the same way. Again, the fruit were highly colored due to the excellent light pene- tration, but were not sun-scalded. In this second year, summer pruning increased fruit Ca by an amazing 60?;, and after storage the quality of the fruit was outstanding: bitter pit and breakdown had been virtually eliminated, and the fruit were substantially firmer than ones from trees that were not summer pruned. Clearly, summer pruning had effectively increased the amount of Ca in the apples and had correspondingly improved their postharvest quality. Should you consider using this pruning technique in your orchard? We do not think so; we do not believe that the Preston technique can be applied in New England without modification. We believe it is too severe a method of summer pruning for Mcintosh in Massachusetts. Among our concerns is the fact that in 1976 the trees produced many blossoms at harvest time. -14- These results do, however, demonstrate that summer pruning may be an important method of coping with Ca deficiency in apples. We are now considering less severe pruning methods to see if we can find a technique that is compatible with our growing conditions, and yet will remove enough vegetation to significantly improve fruit Ca levels. An important point in considering summer pruning is to recog- nize that if pruning is done early and regrowth occurs, the new vege- tation will increase the competition for available Ca ; if substantial regrowth occurs, summer pruning may reduce the amount of Ca in the fruit, and worsen their storage problems. **************** All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State Laws and regulations in effect on the date of this publica- tion. When trade names are used for identification, no product endorse- ment is implied, nor is discrimination intended against similar materials. NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. 15- MAILING LIST REVISION It is time to revise our mailing list for Fruit Notes. If you wish to continue to receive Fruit Notes, please fill in and return the attached tear sheet. Please continue sending Fruit Notes. NAME ADDRESS_ CITY Fill out and return to STATE ZIP William J. Lord Extension Pomologist University of Massachusetts French Hall Amherst, MA 01003 Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 43 (No. 5) SEPTEMBER/OCTOBER 1978 TABLE OF CONTENTS New England Fruit Meetings and Trade Show, 1979 Han/esting and Storing Apples: A Time for Observing Details Bruising of Apples After Packing Controlled Atmosphere Storage Safety Precautions Chokecherries: How to Recognize and Get Rid of Them Miscellaneous Information on Orchard Mouse Control Laboratory Toxicity of Pesticides and Growth Regulators to Amblyseius fallacis, An Important Spider Mite Predator in Massachusetts Apple Orchards NEW ENGLAND FRUIT MEETINGS AND TRADE SHOW, 1979 The New England Fruit Meetings and Trade Show, as in the past, will be held at the New Hampshire Highway Hotel, Goncord, New Hampshire, The meetings are scheduled for January 10 and 11. **************** HARVESTING AND STORING APPLES: A TIME FOR OBSERVING DETAILS W. J. Bramlage Department of Plant and Soil Sciences The apple harvest season is a hectic time for a fruit grower. His attention is often focused on his harvest labor, and perhaps on his harvest sales operation. And, unfortunately, something may have to "give". Don't let it be your storage operation! Short- cuts or mistakes in September can mean disaster in April. If a grower is to market quality fruit in the Spring, he must pay atten- tion to details in the Fall. Some comments follow on things to be watched . VJeather. Hot detrimental . mature apples coloring, esp to harvesting least 331 red effective sea period, the h room. Unless these hot app into storage weather shortly before and during harvest is generally It ripens fruit rapidly, leading to harvest of over- with shorter storage life. It results in poorer ecially if night temperatures are high, and again leads riper apples because it is necessary to wait for at color. It increases susceptibility to scald, making Id treatments crucial. If it's hot during the harvest ot apples increase the heat load going into a storage ample refrigeration is available, it is best to allow les to cool overnight in the orchard, and bring them early the next morning. If the weather is cool during harvest, the prospects for high quality fruit in the Spring are much better. Nevertheless, there is need to get apples off the tree and into storage as quickly as possible. The riper the fruit at harvest, the shorter is its storage life. With about 28° are fully ("bruises to about damage oc thaw. If the apple softening age. If of time; late varieties, freezing may occur. Apples freeze at F. If they freeze, do not pick or handle them until they thawed. Physical contact will produce visible damage ") when they thaw. Unless the fruit temperature falls 22°F, apples will survive freezing; at about 22°F,'' lethal curs and they show browning and breakdown soon after they browning and breakdown do not show up soon after thawing, s have survived the freezing. However, any freezing causes and probably leads to faster deterioriation during stor- apples freeze, do not attempt to store them for long periods dispose of them as quickly as possible. Fruit maturity. Maturity is the stage of development at harvest. If too immature at harvest, fruit will never develop top quality flavor and may be more subject to shriveling, scald, bitterpit and browncore after harvest. If overmature, fruit will deteriorate quickly and be more subject to softening, breakdowns and rots. How to identify maturity is a difficult question. Pressure test, color (especially undercolor), abscission, and flavor are helpful guides, but experience with your own fruit may be your best measure. Use of growth regulators has made this an even more difficult question. Alar* delays maturity, but not as much as many people think. Its phenomenal drop control capability and its delay of softening can be misleading. Do not delay harvest of Alar*-treated fruit; a significant amount of the firmness difference between Alar*-treated and untreated fruits will disappear rapidly during storage. Ethrel* hastens maturity, and despite our belief that Ethrel*-treated fruits can be stored if^ harvested at the right time, we think that it's hazardous to try to CA-store Ethrel*- treated apples commercially. The hormone-type Stop-drop sprays also promote maturation, and should be used with this understanding. Further complicating the maturity problem is the use of red strains and dwarfing rootstocks. Since for marketing reasons har- vesting is usually gauged by red color, the red strains are prob- ably an advantage to proper storage management since less mature (and longer keeping) fruit may be harvested. However, among the strains of 'Delicious' it is well known that some red strains mature well ahead of others. Therefore, it cannot be assumed that red strains are just like the standard strains except for color; other criteria must also be watched. It is very likely that some root- stocks influence maturity, although this must yet be defined. Again, you cannot assume that fruits from dwarf ing-rootstock trees are the same as those from seedling -rooted trees. You must watch these fruits closely. Just when to harvest apples for maximum storage life is perhaps the most frustrating question to face. In Massachusetts, flesh firmness of at least 15 to 17 lbs (if Alar*-treated, 16 to 17 lbs) is considered essential for 'Mcintosh' if they are to be stored in CA. If you are using a pressure- tester to gauge fruit maturity, be sure you are using it properly. (See: "The Use of a Pressure Tester to Measure Firmness of Apples''. Fruit Notes, March/April, 1977). In Michigan, a simple test has been~devised to measure the amount of ethylene gas being produced by apples as a means of determining whether they are suitable for long-term or for short-term storage, and it is being used commercially there, but we as yet have no per- sonal experience with this test in Massachusetts. Most of the problems due to harvesting slightly immature apples can be dealt with, and these fruit will have the potential for long storage. Most of the problems due to harvesting overmature apples * Trade Name cannot be dealt with except by rapid disposal o£ them. It is better to pick a little too soon than a little too late. Over- naturity is perhaps the greatest source of storage problems . Pre-storage operations. It is absolutely essential that apples be cooled quickly and thoroughly after harvest. Ideally, they should be cooled to 32°F within 24 to 36 hours, but in practice it is sufficient to completely cool them in 7 days. However, few growers have any idea what the temperature of their fruit actually is in storage. (Air temperature is a poor gauge of fruit tempera- ture.) Some growers who have measured fruit temperature during storage with thermocouples have been shocked to learn how slowly they are cooling. Many refrigeration systems are designed to maintain temperatures after the apples are cool, and therefore do not have the capacity to rapidly cool large volumes of fruit. These rooms can only cool fruit adequately if they are loaded slowly and carefully. Use of bulk bins increases the cooling problem, since contact of moving cold air with the fruit is reduced. Fur- thermore, bins are often arranged in the storage without regard for air-flow patterns. Cold air must move over the surface of an apple if it is to cool quickly. Inadequate cooling is undoubtedly a major source of storage problems. Varieties susceptible to scald should be treated with an inhibitor before storage if they are to be stored beyond early January. Postharvest dips are very effective if used properly. Diphenylamine, at 1000 ppm for Mcintosh, 1000-1500 ppm for Delicious, and 2000 ppm for Cortland, is generally the preferred inhibitor except for Golden Delicious, but Ethoxyquin at 2700 ppm may also be used. Tests in New York indicate that liquid-concentrate DPA is more effective than wettable powder DPA, since it is more stable in suspension and less toxic to the fruit, although it requires addi- tion of a defoaming agent. Surveys in New York revealed that many dip tanks contained considerably less inhibitor than recommended, due to dilution of solution by wet apples, removal of inhibitor on the surface of treated fruit, and breakdown of inhibitor in the dip tank. New York recommendations now suggest that when DPA dips are being replenished (brought back to volume), double- strength solution should be added to the tank, to compensate for this diminished con- centration of the inhibitor. If a postharvest dip is being used, it is wise to add a fungi- cide. A circular on "New England Suggestions for Postharvest Fruit Rot and Storage Scald Control" is available from your Regional Fruit Specialist. Benlate* has given excellent decay control on apples, but it should be noted that Benlate* seems to be unusually conducive to development of resistant strains of fungi. If Benlate* has been used during the growing season, there is a possibility that a resis- tant strain is present on the fruit. Furthermore, it is suggested that treated fruit be removed from the dipping area as quickly as feasible to avoid buildup of resistant spores. Much can be done to reduce storage decay problems by preharvest sanitation treatments; this was carefully described in Fruit Notes by Dr. C. J. Gilgut in 1972 (Fruit Notes, Sept .-Oct. :pp 2-7) . -4 If a postharvest dip is used, calcium chloride (CaCl^) may also he added to the solution. Adequate calcium levels in the fruit are essential for long storage life. If calcium treatments have not been applied during the season, or if significant amounts of cork or bitterpit are present in the fruit, 24 to 32 lbs of CaCl^/100 gallons may be added to the dip solution. The calcium residue oft the surface of the fruit will continue to enter the apples during storage, and can substantially reduce the development of fruit disorders. Storage operations. CA rooms should be filled and sealed as quickly as the apples can be thoroughly cooled. The longer the fruit remain in air after harvest, the less benefit CA will have on them. It should be no more than 2 weeks between the time you start loading a room and when that room is sealed. However, to accomplish this you must have sufficient refrigeration capacity in that room to ' remove the field heat, or else have a special room with extra cooling capacity m which you do the initial cooling of the fruit. If you must choose between thorough cooling and early sealing, choose thorough cooling. Don't overload your cooling capacity to get an early seal. The exact temperature at which you store your fruit is a criti- cal factor in determining how well they will keep. You must have a highly reliable, calibrated thermometer in the storage room, and you must store the fruit a_t the recommended temperature, not near It. A storage temperature that is only 1° or 2°F above the recom- mended temperature will significantly reduce the storage life of your fruit. Traditionally, a relative humidity of 90 to 95% has been recom- mended for apple storages. It has been clearly shown in recent years that if the R.H. is very near 1001, apples are more subject to break- down disorders; on the other hand, if R.H. is below 90% the apples will shrivel. However, we know of no storage that is equipped to monitor R.H., and doubt if very many storage operators ever measure R.H. (a slmg psychrometer is a good tool for measuring humidity). In this situation, we feel that storages are more likely to have too low humidity than too high a humidity, since it is not easy to maintain an atmosphere close to 100% R.H. Therefore, we recommend that storage operators do everything possible to maintain as moist an atmosphere as possible in the storage. For CA storage, our recommended conditions are the same as in recent years. Mcintosh and Macoun should be stored at 1% 0. , 5% CO?, and 38°F. Baldwin, Delicious, Empire, Golden Delicious, Idared, Northern Spy, Rome Beauty, and Spartan should be stored at 3% 0^, 1% COo, and 32°F. Cortland may be stored under either regime, but store best as part of the latter group of varieties. Careful observations and record keeping do not end with attain- ment of the CA condition. Atmosphere and temperature should be monitored and recorded daily. If the 0, falls below 3%, it should be brought back up immediately. Storage conditions should be watched closely and recorded. (The gas analyzer, the aspirator bulb, and all sample lines should have been carefully checked before seal- ing, and any indication of malfunction during storage should be checked-out immediately. Porous aspirator bulbs, which result in higher O2 readings than actually exist in the room, have been respon- sible for severe low O2 injury to fruit.) It is well to sample fruit periodically during the storage season. (See: "The Soft Mcintosh Problem", Fruit Notes, Sept. -Oct. 1974: pp. 1-4) Successful storage operation requires attention to details, from the beginning of harvest to the sale of the last apples. Any mistake or oversight can be disastrous, especially with the trend to longer storage periods: the longer apples are kept, the more important are the details. The successful operator should recog- nize a problem as it develops, and adjust his marketing practices accordingly. For example, if cooling in some fruits has been inade- quate, these fruits should be disposed of as quickly as is feasible. Long-term storage should be attempted only with apples that have "everything going for them". Long-term CA does not correct mistakes; it only underlines them. **************** BRUISING OF APPLES AFTER PACKING W. J. Bramlage Department of Plant and Soil Sciences Dr. George Mattus has been conducting extensive studies in recent years on the condition of apples in the distribution centers and retail stores of Virginia. He has often observed a great deal of impact bruising on apples, indicating damage that is occurring during handling of the packed fruit. To determine some of the factors associated with this bruising and to try to find ways of reducing it. Dr. Mattus conducted a series of tests this Spring that pro- duced some impressive results. Some of his findings are reported here. In one series of tests, carefully harvested apples of 5 dif- ferent cultivars were packed in fiber or foam trays, which were packed in cartons. Both 88- and 100-size packs were tested. In addition, 6 different cultivars were packed in 3- lb poly bags, which were placed in 12-bag cartons. Two different cartons for the bags were tested: 1 carton had 12 single cells, 1 for each bag, whereas the other carton had only 4 cells, so that 3 bags were packed in each cell -- 2 vertically and 1 horizontally. Each carton was dropped once, from either a 6- inch or a 12- inch height. Injury to the fruit was tabulated and is shown in Table 1. TABLE 1. BRUISING OF APPLES, PACKED IN TRAYS OR POLY BAGS, FOLLOWING A SINGLE DROP OF A CARTON. DAMAGE TO FRUIT Sq . cm . Packing Height „ -.^ !J°-.°^ of bruised %with variable o£ d?op t ^^^^ bruises area per cuts or ^ bruises per apple apple punctures CARTONS CONTAINING TRAYS Type of Tray Fiber 6" 64 0.9 62 0 Foam 6" 52 0.7 42 0 Fiber 12" 70 1.0 116 0 Foam 12" 54 0.7 54 0 BAG-MASTER CARTONS No. of Cells 12 6" 68 1.1 109 2.9 4 6" 69 1.2 127 2.2 12 12" 77 1.4 223 3.5 4 12" 80 1.5 240 4.0 The results dramatically demonstrate the potential for damage to fruit after packing. A single 6 -inch drop of a carton (measure it!) bruised over 50^ of the fruit. Apples packed in foam trays bruised less than those packed in either fiber trays or poly bags. Apples packed in poly bags, rather than in trays, received more bruises from the drop, and these bruises were much larger than those on tray-packed fruit. In addition, the apples in poly bags received cuts and punctures from the drop, even the one from only a 6- inch height. Interestingly, the 12-inch drop was not much worse on the fruit than the 6-inch drop. Also, it made little difference whether the poly bags were packed in 4-cell or 12-cell cartons. In another series of tests. Golden Delicious apples in either fiber or foam trays were packed in a number of different ways to find out more about what influences bruising. In these tests, the cartons of apples taken directly out of cold storage were all dropped once from a 12-inch height. Results are shown in Table 2. These tests shcv/ed that (1) more injury occurred in dry fiber trays than in moist fiber trays; (2) more injury occurred in shallow fiber trays than in deep-cell fiber trays; (3) damage to fruit packed in fiber trays can be reduced by individually wrapping apples in paper, padding the bottom of the carton, and especially by putting pads between layers; and (4) cold apples are more subject to bruising than are warm apples . Clearly, the way apples are packed influences the amount of damage inflicted by impact upon the carton. However, the clearest m.essage from these studies is: Don't drop cartons of apples! TABLE 2. EFFECTS OF MODIFICATIONS OF TRAY PACKING ON BRUISING OF GOLDEN DELICIOUS APPLES AFTER DROPPING A CARTON OF 100-SIZE TRAYS 12 INCHES. DAIvIAGE TO FRUIT Packing variable % with bruises Dry fiber trays Moist fiber trays Foam trays 83 72 70 No, of bruises per apple Sq . cm . of bruised area per apple Deep-cell fiber trays 62 1.7 1.6 1.4 1.1 210 169 102 77 Dry fiber trays-- + paper wraps on all apples, OR 69 2 pads in bottom of carton, OR 72 filled paper pad on each layer, OR 59 Urethane sheet on each layer 57 ing 20"C apples 71 1.2 1.2 0.8 0.9 1.3 100 98 41 93 A************ ft** 8- CONTROLLED ATMOSPHERE STORAGE SAFETY PRECAUTIONS G. D, Blanpied, Pomology Department and L. D. Baker, Agricultural Engineering Department Cornell University [Editors' Note: Earlier this year, a life was lost in the Hudson Valley Region of New York due to lack of precautions when enter- ing a CA room. We urge that this article be prominently displayed so that a repeat of this tragedy may be avoided.] Occasionally, someone must enter a CA storage to obtain fruit samples, to replace a broken fan belt, burned out motor, to check for plugged nozzles, or to make other equipment repairs. The atmosphere in the CA room probably contains less than 5% oxygen. Outside air is about 21% oxygen. Do you know what happens to you in a CA storage? Symptoms of Asphyxia'^ 17% oxygen 12-16% oxygen - 10-14% oxygen candle is extinguished. breathing increased and pulse rate accelerated. ability to maintain attention and to think clearly is diminished, but can be restored with effort. muscular coordination for finer skilled movements is somewhat disturbed. consciousness continues, but judgement becomes faulty. severe injuries (burns, bruises, broken bones) may cause no pain. muscular efforts lead to rapid fatigue, may permanently injure the heart, and may induce fainting . 6-10% oxygen - nausea and vomiting may appear. legs give way, person cannot walk, stand, or even crawl. This is often the first and only warning, and it comes too late. The person may realize he is dying, but he does not greatly care. It is all quite painless. 9- less than 6-6 oxygen - loss of consciousness in 30-45 seconds if resting, sooner if active. breathing in gasps, followed by convulsive movements, then breathing stops. heart may continue beating a few minutes, then it stops. REMEMBER: THE CA STORAGE CONTAINS LESS THAN 5% OXYGEN To avoid problems, plan ahead. Before Sealing the Room (1) The manhole in the gastight door should be at least 24 X 30 inches high to accommodate a large person with breath- ing equipment strapped to his/her back. (2) There should be a ladder inside the room, near the refrigeration unit. When loading the room, leave sufficient space to move and use the ladder around the equipment. (3) Place a danger sign on each gastight door. "DANGER - OXYGEN TOO LOW FOR PEOPLE TO BREATHE" or other suitable warn- ing should be printed on the sign using letters at least 1-1/2 inches high. Entering a Sealed CA Room If you have a New York State CA registration and need to break the seal before the end of the initial 90 day period, notify the New York Department of Agriculture and Markets in advance. If you must go to a place in the CA room where you cannot be EASILY DRAGGED TO THE DOOR, open the room and vent with air until the oxygen is 21% before entering (see item 6 on next page) . If you need to enter a sealed CA room (one from which you can be easily drag-rescued) proceed as follows: (1) Have at least 2 sets of tested breathing apparatus ready. If you don't own your own equipment, know where functional breathing equipment can be borrowed or rented. The breathing equipment should be fed with air (compressed or fan blown) not pure oxygen. The mask should be held in place with straps. Scuba diving equipment is dangerous to use because the mouthpiece may fall from your mouth if you fall. -10- (2) Check the breathing apparatus. Does it deliver air to the mask? Is the tank full of air? The two individuals using the equipment should put on the breathing equipment in normal air and use up a tank of air while doing routine tasks, They can then become accustomed to the apparatus, learn some- thing about its limitations and hear the alarm when the air level in the tank is nearly exhausted. The tanks should then be refilled prior to use in the CA storage. (3) Review the symptoms of asphyxia so you won't take any chances . (4) Remove the window in the gastight door of the CA storage room. (5) The repair person enters the CA room with breathing apparatus. The back-up person must keep the repair person in sight. If this can be achieved from outside the CA room, the back-up person should be ready to enter the CA room, but not use the air until necessary. The back-up person may need to enter the CA room to keep the repair person in sight. If both people are in the CA room and one person's warning bell rings to signal the tank is almost empty, then both people should exit the CA room. If one must climb the ladder, the second should stay on the floor. If both need to climb the ladder to maintain visual communication, drag-rescue cannot be accomplished. Open the room and vent with air. (6) If you vent the CA room with air and then need to restore the CA atmosphere, but do not have access to an oxygen burner, you can flush out the oxygen with nitrogen gas. Order the nitrogen gas in the liquid form (large thermos bottles), in trailer truck cylinders, or in regular cylinders with a manifold. A tightly packed room will require about 2 cubic feet and a room with plenty of free air space will require about 3 cubic feet of nitrogen gas per bushel to lower the oxygen concentration from 21% to 5%. Use a garden hose to deliver the nitrogen gas to the intake of the blower in the CA room. Leave the porthole open to relieve pressure in the room. * The description of asphyxia was taken from Noxious Gases and the Principles of Respiration Influencing Their Action by Yandell Henterson § Howard W. Haggard. Reinhold Publishing Corp . , 330 West 42nd Street, New York, N.Y. **************** 11 CHOKECHERRIES: HOW TO RECOGNIZE AND GET RID OF THEM Georgene Moizuk Bramlage Leverett, MA The importance of being able to identify chokecherry trees is that they serve as alternate hosts for X-disease, a very destructive disease of peach, nectarine, sweet cherry, and tart cherry trees. If the leaves of a wild cherry tree turn red or yellow in July or August when the leaves of other trees are still green, this is evidence that the tree is an X-disease -infected chokecherry. Control of X-disease of stone fruits demands control of choke- cherries. All chokecherry trees within at least 500 feet of any stone fruit trees or future stone fruit site should be completely eradicated. However, since neither the rum cherry nor the pin cherry harbors X-disease, these trees are perfectly harmless to stone fruit orchards . Illustrations and descriptions of these three kinds of cherry trees can be found below^ The easiest way for the "novice' is by their fruit and fruiting habit is borne in an umbel to identify the cherry trees The fruit of the pin cherry The fruit raceme the both the ^ rum cherry and but the calyx rum cherry. choke cherry is cup persists on borne in a the fruit of Prunus serotino block/ rum cherry Fig. 1. The leaf shape of cherry is long and narrow, the rum and the turn inward, with shiny serrations are dull and The leaves are thick and dense, reddish brown pubescence (fuzz) along the back of the midrib. The glands on the leaf stem are either small and inconspicuous, or absent. The fruit is borne in a raceme and ripens in late summer. The calyx cup persists on the Truit. Rum cherry may grow into a tree up to 50 feet or more, and the bark on a two year old or older tree is dark brown to black, and the lenticels on the bark are small and numerous. Fig. 1 -12 Fig Fig. 2 _. The cherry is bro leaf shape of the rhoke- ad with the sharp saw- like teeth pointing outward. The leaves are fa compared wiTE there is litt The glands on and prominent young leaves, a raceme and before that o irly dull and thin when the rum cherry , and le or no pubescence . the leaf stem, are large , especially on large The fruit is borne in ripens in mid-summ e r f the rum cherry The calvx cup does not per sis on the frui- Chokecherries shrubs up to are usually found as 15 feet tall with red- brown to dark bro\\Ti bark, and only a few large lenticels on the shiny bark, Fig. 5. The leaf shape of the pin cherry is long, pointed, and narrow with the serrations small and fine, and sharply hooked. There is little or no pubescence (fuzz) on the backs of the leaves. The glands on the leaf stem are either small and inconspicuous, or absent. The fruit is borne in an umbel anxT ripens in mid- summer. Pin cherry may also grow into a tree up to 50 feet or more, and the bark on the older trees is distinctly reddish brown, and the lenticels on the bark are few and large . Fig Eradication If you find that chokecherries are in the vicinity of your stone fruit trees, what is the best way to eradicate them? The chokecherry is difficult to kill due to its habit of sprouting freely from the roots. Cutting or mowing is not effective; it merely results in a thicket of sprouts which require further cut- ting. Satisfactory treatment requires use of a chemical agent that will be carried down to the roots and kill them, thus pre- venting further sprouting. The suggested material for this is Ammate-X* (AMS) , at the rate of 4 lbs per gallon of water. It may be applied as either Trade Name ■13- a stump treatment or as a "frill" treatment. Stump treatment is the application of the chemical to freshly cut stumps, thoroughly drenching the entire stump surface. "Frill" treatment is done by making cuts above the ground around the tree, using an axe or hatchet in a downward motion to expose the "growing region" of the trunk, and to leave openings to hold the material. These cuts are then filled with the chemical. Frill treatment is a con- venient and effective way to kill trees of larger diameter. Eradication of chokecherry with Ammate-X* is effective any time of the year except when the ground is frozen, or when there is snow or water on the ground around the trees. However, when using this chemical, follow the instructions on the label care- fully. For further information on brush control, you may obtain tHe "1978 New England Chemical Brush Control in Non-Food Crop Areas and in Christmas Tree Stands" circular from your Regional Specialist . **************** MISCELLANEOUS INFORMATION ON ORCHARD MOUSE CONTROL Edward R. Ladd U. S. Department of the Interior Fish and Wildlife Service We have checked a few orchards for meadow mice and find the population is about the same as 1977. If it continues at this level, orchardists can expect a high level of tree damage this winter unless an adequate baiting program is performed. The bait application should be made in October after harvest of the apple crop. Early application is usually not advisable since meadow mice continue to reproduce until Fall. Consequently, the mice that remain after an early bait application can easily regain their reduced numbers by Fall. Meadow mice must have a dense cover of grass or other plants for their survival. Thus, close and complete mowing of the entire orchard will remove much of this needed cover and make the area less attractive to mice. Time the mowing so that it will make distribution of baits easier. In addition to mowing and baiting it is advisable to perform these practices in buffer strips around as many tree blocks as possible. In the past few years there have been several instances where the outer rows of trees have received damage by mice in spite of a good baiting program within the orchard. In these cases, the mice may have moved in under snow cover from surrounding areas. Although a buffer strip is not totally effective, it does increase the travel distance for the mice and frequently will reduce damage from mice migrating into the orchard. -14 Assuming that a mid-winter thaw will occur, make plans to check those orchard areas known to have high mouse populations. Have sufficient bait available to hand treat those blocks that* have mouse holes and runways in the snow. This spot treatment should reduce possible mid-winter tree damage. Do not exceed label restrictions when baiting and distribute them carefully. Baits, when properly placed, should be in vege- tation at soil level; this is where the mice are. Baits on bare ground or suspended in the vegetation are wasted and may be easily found by animals other than orchard mice. **************** LABORATORY TOXICITY OF PESTICIDES AND GROWTH REGULATORS TO AMBLYSEIUS FALLACIS, AN IMPORTANT SPIDER MITE PREDATOR IN MASSACHUSETTS APPLE ORCHARDS Robert G. Hislop, Charles Acker, Nancy Alves, and Ronald J. Prokopy Department of Entomology, Fernald Hall University of Massachusetts In the last issue of Fruit Notes (July/August, 1978), we described results of 1977 studies aimed at determining the toxicity of orchard pesticides to field populations of Amblyseius fallacis, a key predator of red and two-spotted spider mites in Massachusetts apple orchards. Combined results from several commercial orchards and our Belchertown research plots demonstrated that application of orchard concentrations of Zolone, Benlate, and perhaps also Glyodin reduced populations of A. fallacis in the trees, resulting in spider mite outbreaks. On tEe" other hand, use of Imidan, Guthion Captan, and Cyprex permitted buildup of A. fallacis, usually result- ing in effective suppression of spider mTtes, especially two- spotted mites. Here, we discuss results of laboratory tests, carried out in conjunction with our 1977 and current field trials, aimed at deter- mining the direct and residual toxicities of pesticides to a strain of A^ fallacis from the Bishop orchard in Shelburne. Three principal experiments were performed: (A) toxicity tests of orchard materials at recommended field rates; (B) toxicity tests of principal pesticides (i.e. those in greatest use) at three different rates; and (C) tests of the influence of pesticide resi- dues on the reproductive capability of A^ fallacis. Direct Toxicity of Spray Materials to A, fallaois To determine the direct toxicity of orchard spray materials to A- fallacis, we used double-stick tape to affix adult females to microscope slides. The slides were then dipped into solutions of 15- the spray materials, which included a variety of insecticides, miticides, fungicides, herbicides, and growth regulators. There were five replicates (18 mites per replicate) for each rate of each material. Control slides were dipped into water. Mortality of A. fallacis was determined at 48 hours after treatment. Results with materials tested at recommended field rates are presented in Table 1. Materials with a toxicity of 70-100% are considered highly toxic, 30-70% moderately toxic, and O-SOI of low toxicity. Materials of high toxicity were: Zolone (both EC and KP), Systox, Sevin, Diazinon, Carzol, Paraquat, and Roundup. Materials of moderate toxicity were: Phosphamidon (4 oz. rate, and 1 oz. rate), Kelthane, Plictran, and Alar. TABLE 1. TOXICITY OF ORCHARD SPRAY MATERIALS AT RECOMMENDED FIELD RATES TO Amblyseius fallacis (BISHOP STRAIN). MATERIAL RATE/ 100 GALS MORTALITY ("O TOXICITY RATING INSECTICIDES Zolone (phosalone) 3EC Zolone (phosalone) 25WP Systox (demeton) 6EC Sevin (carbaryl) 5 0WP Diazinon 50WP Phosphamidon (dimecron) 8EC Phosphamidon (dimecron) SEC Thiodan (endosulfan) 50WP Malathion 2 5WP Imidan (Phosmet) 50 WP Guthion (azinphosmethy 1) 50WP Methoxychlor 50WP MITICIDES Carzol (formetenate 1.5 pts 100 High 4.0 lbs 87 High 3.0 oz 100 High 1.0 lb 100 High 1.0 lb 70 High 4.0 oz 46 Moderate 1.0 oz 32 Moderate 1.0 lb 19 Low 2.0 lbs 15 Low 1.5 lbs 10 Low 10.0 oz 10 Low 3.0 lbs 3 Low hydrochloride) 92SP 8.0 oz 85 High Kelthane (dicofol) 35WP 1.3 lbs 56 Moderate *Plictran (cyhexatin) 50 WP 6 .0 oz 33 Moderate Omite (propargite) 30WP 1.5 lbs 9 Low Vendex 50WP 0.5 lb 8 Low FUNGICIDES Glyodex WP 0,5 lb 28 Low **Glyodin 30%EC 1.5 pts 21 Low Dikar WP 1.5 lbs 15 Low Benlate (benomyl) : 5 0 WP 6 .0 oz 15 Low Thiram (thylate) 65WP 1.0 lb 12 Low TABLE 1. (Continued) 16 MATERIAL RATE/ 100 GALS MORTALITY TOXICITY RATING FUNGICIDES (cont'd) Phygon WP Captan 50WP Ferbam 76WP Cyprex (dodine) 65WP 0.5 lb 2.0 lbs 1.5 lbs 6 .0 oz 5 9 1 12 HERBICIDES Paraquat CL (paraquat) 2 lbs/gal 2 .0 qts Roundup (glyphosate) 2 lbs/gal 1, Princep (simazine) 80WP 3, GROWTH REGULATORS Alar-85 (deminozide) 85WP 1.0 Ethrel (ethephon) 21.61 liq 0.5 Fruitone-N (naphthaleneacetic acid) 1/4 lb = 10 ppm Amid-Thin W (naphthaleneacetamide) 1/4 lb = 25 ppm FOLIAR NUTRIENT SPRAY CaClo gal lbs lb pt 10.0 ppm 2 5.0 ppm 3.0 lbs 100 100 5 33 6 Low Low Low Low 14 High High Low Moderate Low Low Low Low * Proved to be of low toxicity to Carlson orchard strain of A. fallacis . ** Proved to be of moderate toxicity to Carlson orchard strain of A. fallacis . All of the other materials tested, inc calcium chl oride foliar nutrient spray high toxici ty of Zolone 3EC contrasted Imidan and Guthion, thu s supporting ou din was of low toxicity to this strain additional results indi cated that it w the strain of A. fallacis from the Car Further fie :ld trials wi th Glyodin are late was of low direct toxicity to thi severe anti reproductive effects (see b luding all fungicides and , were of low toxicity. The with the low toxicity of r 1977 field results. Glyo- of A. fallacis, although as oT~"moderate toxicity to Ison orchard in Harvard, currently in progress . Ben- s predator, although it had elow) . Sprays highly toxic -17- to A. fallacis are not recommended for use after bloom, and those witH~"moderate toxicities of 401 or greater are not recommended for use after the first cover spray. Although most Aj_ fallacis are still in the ground cover at the time of the first cover spray, even small amounts of highly toxic materials falling on the ground cover can severely injure them. Results with principal orchard pesticides tested at three different concentrations are given in Table 2. Five of the m.aterials (Imidan, Guthion, Cyprex, Captan, and Benlate) were of low toxicity to A^ fallacis even at double the recommended field concentration. Zolone 3EC was highly toxic even at half the recom- mended field rate, while Glyodin 30% was moderately toxic at double the recommended field rate. TABLE 2. TOXICITY OF PRINCIPAL ORCHARD PESTICIDES AT THREE DIFFERENT RATES (ONE-HALF, ONE, AND TWO TIMES THE RECOMMENDED RATE) TO Amblyseius fallacis (BISHOP STRAIN) . MORTALITY (?6) 1/2 TWICE RECOMMENDED RECOMMENDED RECOMMENDED PESTICIDE RATE RATE* RATE Imidan (phosmet) 50WP 2 10 15 Guthion (azinphosmethyl) 5 0WP 4 10 12 Zolone (phosalone) 3EC 94 100 100 Benlate (benomyl) 50WP 7 15 14 Cyprex (dodine) 65WP 5 12 15 Captan 50WP 4 9 18 Glyodin 30IEC 5 21 48 * See Table 1. Influence of Pesticides on Reproductive Capability of A. fallacis To test the influence of pesticide residues on the reproduc- tive capability of A_^ fallacis , adult females were placed on detached living bean leaves which had been previously dipped into a solution of pesticide at the recommended orchard rate and allowed to dry for 3 hours. We daily offered the predators two- spotted mites as food and counted their eggs over the succeeding 2-week period. (The two-spotted mites caused only slight damage to the leaves.) Each treatment, (including water-dipped check leaves) was replicated 14 times. The results are given in Table 3. Five of the pesticides tested (Imidan, Guthion, Cyprex, Captan, and Glyodin) had little or no apparent effect on A^ fallacis reproductive ability. However, the presence of Benlate residues totally destroyed the ability of 18- of this predator to develop and/or deposit eggs. At the end of the two-week test period, not even a single predator mite regained reproductive capability. Therefore, we do not recommend use of Benlate after the first cover spray, when A^ fallacis are entering the trees. Leaf residues of Zolone 3EC killed all A. fallacis, thus preventing successful completion of this test. TABLE 3. INFLUENCE OF PESTICIDE RESIDUES REPRODUCTIVE CAPABILITY. ON Mblyseius fallacis PESTICIDE* AVERAGE NO. EGGS/A. fallacis FEMALE** TREATED LEAVES CHECK LEAVES Imidan (phosmet) 50WP 17.5 Guthion (azinphosmethyl) 50WP 21.6 Zolone (phosalone) 3EC dead Benlate (benomyl) 50WP 0 Cyprex (dodine) 65WP 21.0 Captan 50WP 21.0 Glyodin 30%EC 19.8 20.7 19.1 23.4 22.6 22.2 20,4 21.5 * Applied at recommended orchard rate (see Table 1). ** 14-day egg totals. Conclusions The laboratory data presented here thus support our sugges- tions based on earlier field studies that certain orchard spray materials are harmful in different ways to populations of A. fallacis . For example, combined field and laboratory resuITs clearly demonstrate that the directly toxic effects of Zolone (both EC and WP) and Sevin, and the indirectly toxic (antirepro- ductive) effects of Benlate can have serious consequences to to populations of A_^ fallacis , thus creating spider mite outbreaks Care should therefore be taken when deciding which orchard spray materials to use for sound pest management. In the future, we will continue our field and laboratory testing of the influence of orchard spray materials on population buildup of our principal mite predator, Amblyseius fallacis, in our apple orchards. **************** NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Cooperative Extension Service University of Massachusetts Amherst. Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUITpf NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. W. J. EDITORS LORD AND W. J. BRAMLAGE Vol. 43 (No. 6) NOVEMBER/ DECEMBER 1978 TABLE OF CONTENTS Winter Trunk Injury to Apples Evaluation of Alar and Ethrel on the Cold Hardiness of 'Mcintosh' and 'Delicious Apple Trees Quince Rust on Apple Spider Mite Substances Influencing Searching Behavior of the Mite Predator, Amblyseius fallacis, on Apples Fruit Notes Index for 1978 WINTER TRUNK INJURY TO APPLES D. A, Kollas, Extension Pomologist University of Connecticut Storrs, Connecticut In the spring and summer of 1976, many orchardists became aware of extensive winter injury to the trunks of apple trees. Winter cold injury has not appeared on such a large scale in Southern New England for many years. This article is written to review some of the cur- rent knowledge about cold injury and to relate it to the winter injury of 1975-76. In reviewing the literature it is apparent that we still lack a good understanding of cold injury and cold hardiness. For many years, the standard way to study cold hardiness has been to collect samples of shoot, bark, or bud tissue at various times during the year, and expose it under controlled laboratory conditions to freezing temperatures. The resulting damage is then related to conditions that might influence cold hardiness. The researcher has only limited control over conditions under which the tree stood in the orchard. Every season is unique in its sunlight, temperature, rainfall, wind and snow conditions. Consequently, pro- gress in relating cold hardiness to any single one of these, and other factors, is very slow. Many studies of cold injury have led researchers to conclude that when low temperature causes direct injury to woody plant tissues it is either because ice has formed within the tissue cells, or because the tissue has dehydrated due to ice formation. Cells of living tissues contain protoplasm, the stuff that carries on basic life processes. A major constituent of protoplasm is water. If this water freezes to ice in the protoplasm, the protoplasm is destroyed and death is assured. Woody plants that survive New England winters are able to avoid ice formation within the protoplasm as a result of a process known as acclimation. The acclimation process can be initiated by the shortening day length of August or September, and by temperatures below about 28°F. Only nongrowing (dormant) plants can acclimate, and become hardy to sub-freezing temperatures. Just what changes occur during acclimation that make survival to freezing temperatures possible are still not known. It is known that the acclimation process takes time. Exposure of the plant to temperatures below about 28°F can, over a period of several days, result in hardiness to temperatures of near zero °F if other factors are favorable. Exposure, for a couple of weeks can result in maximum cold hardiness. But all tissues in a plant do not develop hardiness in the same way, or to the same degree. Dormant apple flower buds, for example, are hardy to 0°F long before trunk bark develops much cold resistance . Other factors affect the acclimation process, so that resis- tance to very low temperatures does not always result from exposure to below freezing temperature. It is pretty well established that conditions which favor accumulation of carbohydrates in the bark and woody tissue also favor acclimation to low temperature. Maxi- mum accumulation of carbohydrates depends on active photosynthetic activity in the whole tree for the whole growing season. Foliage diaease or injury, inadequate water or nutrition, shading, severe hail damage, or a growing season shortened by early frost will obviously limit photosynthetic production of carbohydrates. It is also recognized that a heavy fruit crop will draw off carbohydrates that would otherwise be available for storage in the tree tissues. There is some evidence also that chemicals produced by the crop seeds may directly inhibit cold acclimation. Reports of cold hardiness studies indicate that we cannot assign any specific safe temperature minimum to a tree at any given time. Duration of exposure to the temperature minimum must be considered. Injury increases with the length of exposure to cold as the lethal temperature is approached. Also, repeated freezing and thawing has an amplifying effect on injury, A given level of cold hardiness is subject to change toward less hardiness if the day or nighttime temperature gets much above freezing. Just how much hardiness is lost undoubtedly depends on length of exposure and how high the temperature goes, but these relationships have not been clarified. In peaches it appears that deacclimation (loss of the acclimated condition) is minimal during the rest period, but can take place very rapidly on exposure to a few hours of warm temperature any time after the rest period is completed. The rest period is usually completed in late January or early February in New England peaches. Pruning in the fall or early winter makes trees more suscepti- ble to cold injury. Again, an acceptable explanation of why this is so has not appeared. Early pruning was obviously a major contribut- ing factor to the trunk injury in some orchards in the 1975-76 winter. At Storrs, the only trees to show trunk damage were those (18-year-old Jerseyred) that had been heavily pruned in late Novem- ber and early December. No further pruning was done until early February. Comparable Jerseyred trees pruned similarly in February showed no damage. Injured trees lost 50-901 of the bark around the trunk in the spring of 19 76, These observations indicate the damage must have occurred during December or January. December temperature went to zero or lower on two days; Christmas Eve (0°F) and Christmas M Day (-1°F) at Storrs. In January, 4 subzero readings were recorded: -1° the 18th, -3° the 19th, -8° the 23rd, and -5° the 24th, In February the lowest minimum was +5° on the 3rd. The fall of 1975 was unusual in that it remained quite warm through the middle of December. The lowest for November was 27° and daytime highs were over 60° as late as the 21st and 22nd. December continued the warm trend with 61° Dec. 1st, and 60° the 15th. The only minimums through Dec. 15 that were below 20° were 15° and 18° early in the month. After the 60° temperature o£ Dec. 15, there was a drop to 16° on Dec. 17, and minimums remained low for the next 9 days with read- ings of 20, 7, 6, 10, 17, 17, 0, -1, and 5°. The first snows came during this period, accumulating to 9" between Dec. 21 and 23. For the rest of December, January and February, temperature records show favorable conditions for acclimation. A high of 52° on Dec. 27 cooled gradually and single number temperatures did not appear again until January 5 and 6. During that 9 day period maximums did not go above 41°. By January 23, when the winter's lowest temperature (-8°) was recorded, trees should have been well acclimated. The temperature fluctuations during January were not great, nor as rapid as in Decem- ber. However, trunk injury was associated with pruning done as late as the 3rd week of January in some orchards. In most years, trees pruned in the second or third weeks of January do not suffer cold injury. Since January temperatures in 1976 were not unusual, it must be supposed that the injured trees were not as well acclimated as in most years. Non-pruned trees withstood subzero temperatures, but the hardiness-reducing effect of pruning was sufficient to raise their critical temperature level into the subzero temperatures experienced in January. Possibly injury would also have occurred on trees pruned in February if subzero temperatures had occurred in February. The tree tissues that were injured at Storrs, and other orchards in Connecticut were the bark or cambium of the trunk and lower scaf- fold limbs. Bark separated from the wood in some cases, and remained attached in others. In both cases the bark died and decayed in the spring and summer. On some trees, bridges of live bark remained between dead areas, connecting across the injured zone. In Connecti- cut, these injured trees produced a normal crop in 1976, indicating that the conducting tissue of the wood was not seriously harmed. Completely girdled trees died during 1977, but some trees with very- little connecting bark remained alive, and even looked pretty good except for crop. Studies of cold hardiness have shown that bark and wood tissue of acclimated apple trees survive cold temperatures by two different mechanisms. Acclimated wood tissue is capable of a phenomenon called deep supercooling. Supercooled water in the protoplasm remains liquid even when its temperature is far below the normal freezing point. It is a phenomenon that can also be shown by pure water when small droplets are dispersed in a low-freezing-point liquid. Researchers suspect that in the woody stem or trunk tissue, proto- plasmic water may be somehow isolated from ice nucleation that occurs outside the cell walls. A temperature is finally reached, however, at which this protoplasmic water (or the finely dispersed water droplets in a non-living system) will suddenly freeze to ice. This temperature is around -40° F for fully acclimated tissue or -4- dispersed pure water. Apple trees do not survive where winter temperatures frequently drop below about -40° because below that temperature ice forms in the living wood cells, causing death. Apple bark, cambium, and bud tissues, do not depend on deep supercooling. Investigations have shown that these tissues survive our winters by moving the freezable protoplasmic water outside the cells to sites where ice formation does no apparent damage. As the temperature drops below freezing, ice begins to develop in cracks in the bark, in intercellular spaces, and between bud scales. This creates a vapor pressure gradient favoring movement of protoplasmic water toward the ice. The protoplasm becomes dehydrated rather than freezing, but considerable dehydration does not harm acclimated tissue. Experimentally, apple bark, cambium, and bud tissues have been subjected to temperatures more than 100°F below zero without injury if the temperature drop is not too rapid. The ability of these tissues to survive is thought to be limited by the rate at which water can move out of the protoplasm when temperature drops. If the temperature drops at a rate of degrees per minute these tissues can be injured by ice formation within the cells even when fully acclimated. Air temperature drop in nature is normally at rates of degrees per hour. The temperature fall on the morning of December 17, 1975 was about ICF in 5 hours (2°F per hour;) between 26° and 16°F. If the bark and cambium had been fully acclimated on December 17, 1975, we would not expect that intracellular ice could have formed, in response to the 2° per hour temperature drop. On the other hand, the 60 °F temperature of December 15 may have deaccli- mated the tissue. Then the tree would have had only 5 or 6 hours of exposure to temperatures below 28°F before the 16° temperature occurred. Recall that a period of days or weeks at sub-freezing temperature is needed to induce much acclimation. Temperatures of bark and cambium tissues apparently do some- times drop at rates faster than water can move out to safe freezing sites. It can happen in winter v>?hen air is calm and well below freezing, and the south, or southwest, side of the tree trunk is exposed to direct low angle sunshine. Tissue temperature can go to 70 or 80°F under these conditions. When the sunlight is suddenly cut off by shading, or sunset, the bark temperature returns to ambient air temperature very quickly. This sometimes results in bark or cambium kill on the south or southwest side of tree trunks. It can be prevented by applying a reflective white latex paint to the trunks. Knowledge of the relative hardiness of different tissues at different times of the year can be helpful when trying to determine when injury might have occurred, if it is discovered much later. It has been shown that sapwood is the hardiest tissue in the early fall. But by midwinter, cambium is the hardiest tissue, bark tissue is slightly less hardy, and sapwood is least hardy. Discovery of blackheart in the sapwood, without any bark or cambium injury would indicate severe midwinter cold. Many New England Baldwin trees have blackheart as a result of the extremely low temperatures of 1933-34. Finding injured cambium or bark but normal sapwood points to fall or early winter cold. Injury to both cambium and sapwood could result from unusually low temperature at any time in trees that were not well acclimated. Southwest trunk injury could also occur at any time in the winter months. In summary, the factors that seem to have been most involved in the 1975-76 winter injury seen in Southern New England were: (1) a mild fall encouraged late growth activity, and discouraged acclimation; (2) warm temperature in mid-December may have deaccli- mated the tissue just prior to a period of low temperatures; (3) a very heavy 1975 crop load on some trees limited the development of cold hardiness; (4) pruning of trees prior to occurrence of critical temperatures reduced the trees' ability to withstand cold. From the experience of 1975-76, and other winters, it should be reasonable to conclude that pruning before late February entails risk any year, but when conditions have not been favorable for development of cold acclimation by late December, early pruning is especially hazardous. Growers should learn to recognize seasons in which early pruning must be avoided. A suggested guide, until something better is developed, might be: (1) Don't prune before Christmas, because mild temperatures are likely to occur before then that can deacclimate the trees. (2) Keep a record of minimum and maximum temperatures, begin- ning November 1. Delay pruning until February if there have been 2 5 days with minimums of 28°F or lower by December 25. (3) Don't prune within 10 days following maximums of 55°F or more that occur before Christmas. (4) Leave for late February and March, the pruning of all trees that bore especially heavy crops and those that were weak or had reduced leaf surface for any reason. Use of a guide such as this will not eliminate the possibility of injury due to unusual temperature extremes, but it should minimize the risk of cold injury that is associated with pruning. EVALUATION OF ALAR AND ETHREL ON THE COLD HARDINESS OF 'MCINTOSH' AND 'DELICIOUS' APPLE TREES William W. Jenney and Bertie R. Boyce Department of Plant and Soil Science University of Vermont Burlington, Vermont It is well known that the development of cold hardiness in plants is primarily a function of the type or variety of plant and the weather conditions, especially temperature and day length, during the autumn. The degree of hardiness that a plant develops, however, may also be modified to a limited extent by other factors such as cultural practices or use of various plant growth regulators. Although Alar and Ethrel are used as growth regulators in many apple orchards, we have little knowledge of whether or not their use influences the cold hardiness of the trees. The purpose of this investigation was to determine if the hardiness of bearing-age trees is either increased or decreased by their use. The work was carried out over 2 seasons, from June, 1975 to March 1977, on 30 Mcintosh and 30 Delicious trees located at the University of Vermont Horticultural Research Center. All trees were on M. 7 rootstocks, approximately 25 years old, and uniformly vigor- ous . Five Mcintosh and 5 Delicious trees were used for each of 6 treatments. The treatments were: (1) unsprayed controls; (2) Alar at 2#/100 gal applied in early June; (3) Alar at 2#/100 gal applied in early August; (4) Ethrel at 2-1/2 pts/100 gal applied about 10 days prior to normal harvest; (5) the June Alar application plus the Ethrel application, and (6) the August Alar application plus the Ethrel application. Terminal shoots collected at monthly intervals from August to March 1975-76 and again in 1976-77 were frozen in the laboratory to several different temperatures and the amount of injury occurring was measured by determining the electrolyte release from the injured cells. As expected, the Mcintosh shoots were injured less by freezing than were the Delicious shoots; however, very few significant differ- ences in hardiness between the treated trees and controls were found with either variety. Slightly less injury occurred in both varieties at mid-winter of the first year when trees had been treated either in June or August with Alar. The same treatments brought about a slight increase in injury when the shoots were frozen in March. Ethrel appeared to have even less influence than Alar in altering the hardi- ness of apple shoots. Shoots of Ethrel-treated trees had slightly less injury than the controls when frozen in November, 1976, and slightly more injury when frozen in March. -7- Although statistical differences in shoot hardiness were occa- sionally detected as a result of the application of these materials, the differences were small and of little practical significance. Based,on these 2 years' data, it appears that Alar and Ethrel had only limited and erratic effects in altering the cold hardiness of Mcintosh or Delicious shoots, and the use of these materials probably does not significantly increase or decrease the possibility of low temperature injury, even though they do alter the physiology of the tree . **************** QUINCE RUST ON APPLE Daniel R. Cooley, Extension Technician Plant Pathology University of Massachusetts Quince rust (caused by the fungus Gymno sporangium clavipes] appeared as a problem on Red Delicious in Massachusetts this past season. It was also present in the Hudson Valley area of New York. Generally, the disease is of little importance, but outbreaks can cause serious damage. Quince rust shows on the fruit as a sunken, dark green, mis- shapen area near the calyx end. The disease often extends into the fruit, discoloring areas as far as the seed cavities. Fruit may also redden prematurely. The disease seldom affects apple leaves. Quince rust is related to cedar apple rust. Both fungi require two hosts in order to reproduce. During July and August, infections on apples (or on related plants, such as quince, hawthome, amelan- chier or crabapple) produce spores. Wind blows these spores to the next host plant, the red cedar or native juniper, where infections are started. After 2 years, wet weather in May or June will release spores from the juniper and red cedar infections. These spores will infect apple or related plants, and the cycle repeats itself. Removing red cedars and other junipers located within 2 miles of the orchard makes rust control much easier. Widening the juniper- free area to 4 or 5 miles can completely control rusts. However, in most cases, it is more practical to apply a fungicide. A grower should note that while some scab fungicides also provide good rust control (Dikar, manzate, polyram) , other good scab fungicides do not control rust (benomyl, captafol, captan, dodine, glyodin) . Other fungicides give good rust control, and fair to poor scab control (ferbam, Niacide-M, thiram, zineb)*. Fungicides to control quince rust and cedar apple rust should be applied from the time of pink buds to the third cover. -8- * A listing of the activity spectrums of apple fungicides is avail able from the Plant Pathology Department, Fernald Hall, University of Massachusetts, Amherst, MA 01003. **************** SPIDER MITE SUBSTANCES INFLUENCING SEARCHING BEHAVIOR OF THE MITE PREDATOR, Amblyseius fallacis, ON APPLES Robert G. Hislop, Nancy Alves, and Ronald J. Prokopy Department of Entomology, Fernald Hall University of Massachusetts In the preceding two issues of Fruit Notes , we described our laboratory and field results on effects of various orchard spray materials on the survival and reproduction of Amblyseius fallacis, the most important mite predator in Massachusetts commercial apple orchards. We observed that even in orchards using materials com- paratively safe for /u_ fallacis , this predator's performance was often less effective against red mites than against two-spotted mites. We suggested that factors such as late-season competition from other predators might partially explain this difference. Furthe observations, however, suggested that this reduced effectiveness against red mites might also be due to particular early-season habits of A^ fallacis which could possibly allow red mites to build up uncheclceH^ in the Spring and early Summer. Adult A. fallacis females spend the Winter in orchard surface litter. In'~Spring, warming temperatures bring them out of their Winter shelters up into the ground cover vegetation where they feed on two -spotted mite prey. In early Summer, they invade the apple tree foliage in search of red and two-spotted mites. Because two- spotted mites (but not red mites which were introduced here from Europe) are believed to be the native prey of A_^ fallacis, we theo- rized that perhaps this predator had evolved certain capabilities allowing it to locate two-spotted mites more efficiently than red mites. If this were true, and A^ fallacis could more readily locate two- spotted mite infestations, particularly in the orchard understory then it would seem that A^ fallacis might become preoccupied feeding on this host. Red mites could then escape predator detection while building up in the trees. The purpose of this research described here was to examine the possible influence of physical and chemical substances deposited by red and two-spotted mites on the host searching behavior of A. fallaci As we will show, such behavior- influencing substances do in Tact exist At the conclusion of thie article we outline how, in the future, spray applications of the synthetic equivalents of these substances to apple trees might enhance the ability of A_^ fallacis to better con- trol red and two -spotted mites. -9- In our first experiment we allowed equal numbers of red and two- spotted spider mites to infest separate 1/2 inch diameter apple leaf discs for 2 days, after which all spider mite prey (including eggs) were removed. Each leaf disc was then placed in a simple, single choice observation chamber. We then placed a single starved A. f allacis female at the edge of the chamber and allowed it to enter and leave the disc at will. Data and observations were recorded over a ten-minute time period. The results (Table 1) show that A. f allacis females spent an average of 312 seconds per visit on discs having previous two-spotted mites compared with only 58 seconds per visit on discs having no previous prey (an approximate 5-fold dif- ference) and 156 seconds per visit to discs having previous red mites (a 2-fold difference). These data strongly suggest that both species of spider mites deposit substance(s) that function to arrest host searching Aj_ f allacis, and that the substance (s) deposited by two- spotted mites was more than twice as active as that deposited by red mites. In this experiment we noticed that a large amount of silk (a white thread-like material very similar to the sort of silk spun out by spiders) was left behind by the two-spotted mites. We suspected that this silk might be playing a role in the observed behavior of A. f allacis . TABLE 1. FREQUENCY AND LENGTH OF VISITS BY A^ f allacis FEMALES TO APPLE LEAF DISCS HAVING PREVIOUS PREY. (20 replicates) Avg. no. A. fallacis Avg. time visits per apple (seconds) per Previous prey leaf disc visit on disc Two-spotted Mites 1.5 312 European Red Mites 2.6 156 None (check 3,4 58 Therefore, in our second experiment, we examined the possible influence of two-spotted mite silk on the searching behavior of A. fallacis . We manually placed the silk spun by 50 two- spotted mites over a 24-hour period onto 1/2 inch diameter filter paper discs. Each disc was placed in the observation chamber with a single starved A. fallacis female and data recorded as before. The results (Table 2) show that host searching A^ fallacis females spent 142 seconds per visit on discs containing two- spotted mite silk, compared with 12 seconds per visit on discs having no silk (a 12-fold difference). This result strongly suggested that physical and/or chemical properties of two-spotted mite silk function to arrest host searching A. fallacis females. -10- TABLE 2. FREQUENCY AND LENGTH OF VISITS BY A^ fallacis FEMALES TO FILTER PAPER DISCS HAVING TWO-SPOTTED MITE SILK. (20 replicates) Condition of disc Avg. no. A^ fallacis visits per disc Avg. time (seconds) per visit on disc With silk Without silk 3.5 6.1 142 13 In our final experiment reported here, we ex influence of solely chemical substance (s) deposit mites on the host searching behavior of /u_ fallac spotted mites on 1/2 inch diameter filter paper d after which all mites and eggs were removed. We discs in one or another of four different types o water, methanol, chloroform, and hexane. The was were then centrifuged at high speed to remove any such as silk, that might influence /u_ fa.llacis ho We reapplied each extract to a series of fresh fi each of which was dried and placed in the observa single starved Aj_ fallacis female. The searching females was then recorded over a ten-minute perio amined the possible ed by two-spotted is . We placed two- iscs for two days, then washed ten such f chemical solvents: hings (= extracts) physical substance St searching behavior. Iter paper discs, tion chamber with a behavior of the d. The results (Table 3) show that host-searching A^ fallacis females'' visited discs treated with the methanol extract an average of 8.2 times, nearly three times more frequently than they visited control discs treated with solvent alone (= 3.3 visits). Although the average length of each visit was approximately equal on each disc type, the length of time between visits to discs treated with the methanol extract was only 34 seconds, less than 1/3 the time between visits to check discs (= 112 seconds) . These data, coupled with our observations suggests that host-searching A^ fallacis females were stimulated to repeatedly return to discs treated with methanol-extracted chemical substances deposited by two-spotted mite prey. TABLE 3. FREQUENCY AND LENGTH OF VISITS AND RETURNS BY A. fallacis FEMALES TO FILTER PAPER DISCS TREATED WITH CHEMTCAL EXTRACTS OF SURFACES PREVIOUSLY VISITED BY TWO-SPOTTED MITE PREY. (20 replicates) Avg . No . A_^ fallacis Solvent visits per disc Average time (seconds) per visit on disc between visits Extract 3.6 Control 5.3 Extract 32 Control 26 Extract 54 Control Chloroform 86 Hexane 4.1 3.9 16 24 118 80 Water 7.4 5.9 27 44 64 52 Methanol 8.2 3.3 28 31 34 112 -11- We have thus discovered in these experiments two sorts o£ behavioral reactions of host searching A^ fallacis females while in the neighborhood of substances deposited by red and two- spotted mite prey: (1) stimulated searching activity in the vicinity of extracted chemical substance (s) , and (2) arrestment in the presence of two-spotted mite silk. In nature, it is likely that such chem- ical substance(s) secreted by red and two-spotted mites, is utilized by A^ fallacis adults as a cue aiding in more rapid and better detec- tion of nearby areas infested by prey. Contact with the physical structure of the silk of the prey slows down the host searching activity of A. fallacis adults, arresting them in the immediate locale of an indiviHual prey. These results also support our hypothesis that A. fallacis could become preoccupied for relatively long time perio3¥ searching within areas of two-spotted mite infestations, thereby having the effect of preventing the predator from exploring new areas harboring other hosts such as red mites . Chemical substances that are deposited by prey and that influence the host searching behavior of predators such as A.« fallacis are called "kairomones". Eventually, they could be of significant value to pest management programs. For example, if one were to identify and synthesize the kairomone secreted by two-spotted mites and spray it on apple trees together with artificial alternate food substances for A^ fallacis, the result could possibly be greater retention of A. fallacis on the apple foliage during times when natural prey densi- ties are low. Such artificially maintained populations of A^ fallacis could function to "guard" against possible spider mite outbreaks . FRUIT NOTES INDEX FOR 1978 (This index of major articles has been prepared for those who keep a file of Fruit Notes. The number in parenthesis indicates the pages on which the item appears.) January/February - Vol. 43(1) Varieties of Peaches for Massachusetts (1-3) Trends of Michigan Tree Fruit Industry (Part II) (3-7) Shelf Life of Pesticides in Common Use by Fruit Growers (8-9) European Apple Sawfly: Biology and Development of an Adult Monitoring Trap (9-12) March/April - Vol, 43(2) Varieties of Raspberries and Blackberries for Massachusetts (1-2) Partial Budgeting of Management Alternatives for Fruit Growers (3-7) Trends of Michigan Tree Fruit Industry (Part III) (8-10) Tarnished Plant Bug on Apple: Damage and Monitoring Traps (10-14) 12- May/June - Vol. 43(3) Apple Pollination Comments (1-3) Factors Affecting Shape of Apples and Increasing Their Length with Promalin* (4-7) Nutritional Problems and Suggestions for Fertilization of Apple Trees in 1978 (7-13) Naphthaleneacetic Acid (NAA) for Tree Training (13-15) Alternate vs. Every Middle Spraying for Apple Pests in 1977 (15-19) July/ August - Vol. 43(4) Factors Affecting Nutrient Content of Apple Foliage (1) Late Summer Fertilization of Strawberries (2) New Herbicide for Blueberries (3) Use of Creosote to Prevent Deer Damage in Orchards (4) Influence of Pesticides on Spider Mite and Predator Abundance in Massachusetts Apple Orchards -- 1977 Results (5-8) Apple Tree Response to Summer Pruning (8-12) The Effect of Summer Pruning of Mcintosh Apple Trees on the Calcium Nutrition and Postharvest Quality of the Apples (13-14) September/October - Vol. 43(5) Harvesting and Storing Apples: A Time for Observing Details (1-5) Bruising of Apples After Packing (5-7) Controlled Atmosphere Storage Safety Precautions (8-10) Chokecherries : How to Recognize and Get Rid of Them (11-13) Miscellaneous Information on Orchard Mouse Control (13-14) Laboratory Toxicity of Pesticides and Growth Regulators to Amblyseius fallacis , An Important Spider Mite Predator in Massachusetts Apple Orchards (14-18) November/December - Vol. 43(6) Winter Trunk Injury to Apples (1-5) Evaluation of Alar and Ethrel on the Cold Hardiness of 'Mcintosh' and 'Delicious' Apple Trees (6-7) Quince Rust on Apple (7-8) Spider Mite Substances Influencing Searching Behavior of the Mite Predator, Amblyseius fallacis, on Apples (8-11) **************** NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVE- STOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director ;ooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business 'enalty for Private Use, $300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 3ULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 44 (No. 1) JANUARY /FEBRUARY 1979 TABLE OF CONTENTS Varieties of Strawberries for Massachusetts Pruning Macspurs Pomological Paragraph Stub pruning Pruning Peach Trees Control of Water Sprouts and Suckers with Tree-Hold* U.S. Apple Exporters Expect Another Good Year Following Record Showing in 1977/78 Integrated Management of Apple Pests in Massachusetts- 1978 Results: Insects I ERRATUM IN NOVEMBER/DECEMBER ISSUE An error that should be corrected occurred on page 5 of the Nov./ Dec. issue of Fruit Notes. Item 2 of the suggested pruning guide states "Delay pruning until February if there have been 25 days with minimums of 28°F or lower by December 25". This should have read "Delay pruning until February if there have not been 25 days with minimum of 28°F or lower by December 25". **************** VARIETIES OF STRAWBERRIES FOR MASSACHUSETTS James F. Anderson Department of Plant and Soil Sciences Varieties Recommended for Harvesting Season Ear li dawn Darrow Earliglow Sunrise Midland Holiday Raritan Midway Catskill Redchief Guardian Garnet Sparkle Delite Vesper T = Trial C T T C C 5 H H H H H a H 5 H ^ H T C H = Home garden Very early Early Early Early Early Early-midseason Midseason Midseason Midseason Midseason Midseason Mid-late Mid- late Late Very late C = Commercial Varieties so marked are not necessarily equally adapted to all sections of the state. Earlidawn Darrow Earliglow Sunrise Variety Notes The fruits are of medium size and of fair to good flavor. The plants are productive and of moderate vigor. Earlidawn is not recommended where red stele is present. The fruits are medium to large, firm, glossy and have a deep red color. Primary berries tend to be rough. The plants are moderate in fruit production, vigor and runner production. Darrow is highly resistant to red stele and partially resistant to Verticillium wilt. The fruits are medium to large, firm, have a uniform, symmetrical shape and medium to dark red color. The flavor is very good. The plants are productive, make a good bed and are highly resistant to red stele and Verticillium. The berries are medium in size, glossy bright red, firm and have a symmetrical conic shape . The plants are vigorous, fair in production and resistant to red stele and Verticillium. -2- Midland The berries are large, firm, dark red and have very good flavor. The early fruit tends to be coarse. Midland is susceptible to both red stele and Verti- cillium. Holiday The berries are large, attractive, glossy, medium to dark red, very firm and fair to good in flavor. The plants are vigorous, make a good bed and are productive. Holiday is susceptible to red stele but had partial resistance to Verticillium. Raritan The berries are very attractive, bright red, glossy, firm, medium to large and have very good flavor. The plants form a good bed and are productive. Raritan is susceptible to both red stele and Verticillium, Midway The berries are of good size, a deep red color, glossy and very good in flavor. The plants are vigorous, productive and resistant to red stele. Midway is susceptible to Verticillium. Catskill The berries are large, have a good strawberry flavor. The berries have a tender skin and rate only fair in firmness. The plants are very productive and are resistant to Verticillium but are susceptible to red stele . Redchief The berries are medium to large, attractive, firm and have good flavor. The plants are vigorous and pro- ductive. Redchief is highly resistant to red stele and intermediate in resistance to Verticillium. Guardian The berries are large, glossy and light red in color. The primary berries tend to be rough. The berries are firm and have good flavor. The plants are vigor- ous and productive. Guardian is highly resistant to both red stele and Verticillium. Garnet The berries are large, attractive, moderately firm and have good flavor. The plant is vigorous, forms a good bed and is productive. Garnet is susceptible to both red stele and Verticillium. Sparkle The berries are medium to large, firm, dark red and have very good flavor. Berry size tends to decline rapidly. The plants are vigorous, productive and have partial resistance to red stele but are suscep- tible to Verticillium. Delite The berries are medium to large, long conic to long wedge in shape, bright red, glossy, firm and have good flavor. The plants are vigorous, productive and are highly resistant to both red stele and Verticillium. 3- Vesper The berries are very large, attractive, moderate in firmness and good in flavor. The plants are vigorous and productive but are susceptible to both red stele and Verticillium. **************** PRUNING MACSPURS Department William J. Lord of Plant and Soil Sciences On bearing Macspur trees, it is common to find weak scaffold limbs with few lateral branches. Scaffold limbs of this type have small potential bearing area. Branching can be induced on these limbs with stubbing cuts into 2- or 3-year-old wood. Figure 1 illustrates the response to such a stubbing cut. On this figure, the arrow points to where a branch on Macspur was stubbed during the previous dormant season. Note the vigorous upright growth during the following growing season that was stimulated by the cut. The branch in the upper-right-hand corner is one that possesses inade- quate lateral branching. During the dormant season following stubbing, the vigorous vege- tative growth behind the stubbing cut, portrayed in Figure 1, should be selectively pruned leaving only those which have the potential to become horizontally-oriented lateral branches. This is illustrated in Figure 2 . Don' t make stubbing cuts unless they are needed to induce branch- ing, reduce the length of limb, or stiffen unheaded limbs, because it has been shown with Delicious that stubbing can convert fruiting spurs into non-fruitful, vigorous shoots. Figure 1 Figure 2 **************** -4- POMOLOGICAL PARAGRAPH Stub pruning. We haven't mentioned stub pruning since it was discussed in the February, 1964 issue of Fruit Notes. However, while pruning branches on the windward sides of Delicious trees planted on a windy site this past winter the practice was brought in mind. We know that branches on the windward side are apt to "hug" the leader until crop- ping holds them down. Leaving extra limbs on the windward side of trees on windy sites will help keep the branches more horizontal because of competition. However, to keep from restricting the central leader and/or inhibiting the development of desirable scaffold limbs, do stub pruning. Stub pruning involves reducing the length of undesirable limbs instead of removing them. Many of the stubbed branches will have to be removed or again restricted during the next pruning season. **************** PRUNING PEACH TREES William J . Lord Department of Plant and Soil Sciences Pruning peach trees correctly is one of the most important opera- tions in peach growing because Valsa canker, winter injury, and limb breakage are problems associated with poor pruning practices. Peach trees may be pruned as either open center or modified leader type trees. The open center system consists of 3 main scaffold limbs arising at approximately the same point on the trunk. The modified leader type tree has 3 to 5 branches vertically spaced 4 to 6 inches apart along the trunk, with the modified leader also carrying side branches. The writer prefers the modified leader type tree, the prun- ing of which is described below, because it is less time consuming to train during the formative period and in our experience, results in less limb breakage during periods of high winds. Following a wind- storm in August, 1976, damage to open-center trees in one orchard was so severe that the grower had to remove them, whereas trees trained as modified central leader trees were retained. Pruning at planting: A 1-year-old peach tree as it comes from the nursery normally has several side branches. After the tree is set, all branches within 18 inches of the ground should be removed. Any narrow-angled side branches should be cut off. Then, 3 or 4 branches which come out at wide angles, vertically spaced about 6 inches apart, should be saved for main scaffold branches. All other limbs should be cut off flush with the trunk. The leader should be cut back to the top-most side branch and the lateral branches should be cut back to short stubs, 2 to 4 inches long, with each containing 1 bud. Pruning during the formative period: Delay pruning of both the young and bearing tree until late spring (near bud swell) . After pruning, spray the trees with a fungicide before a rain occurs to help prevent or reduce damage from Valsa canker. (Information on fungicides for Valsa canker control can be obtained from your County Extension Ser- vice.) Since Valsa canker is frequently associated with poor pruning practices and winter injury, other control measures include avoiding or eliminating narrow crotches, making pruning cuts so as not to leave stubs, and avoiding late growth. Pruning during the formative period consists of making the final selection of scaffold branches. These branches should be chosen after the first season's growth. Most v/ill be the same branches that were selected originally, with some slight readjustments. Subsequent prun- ing should develop an open bowl -shaped tree by removing branches that tend to grow inward and those which are growing straight up through the center of the tree. Head back slightly only those selected scaf- folds where growth has exceeded 30 inches with little or no branching. On scaffolds which have made less than 30 inches growth with several side branches, cut off all but 2 or 3 well-spaced side branches. Lat- erals on a scaffold branch which will grow out and slightly up from left and right are most desirable. Those which tend to grow towards .the ground should be removed. All branches which arise from the trunk, other than scaffolds, should be removed. From the second to the fourth year, cut off annually those branches which interfere with the growth of the scaffold limbs but avoid severe pruning, which will delay the time when the tree will start to produce a profitable crop. Pruning bearing trees: When pruning bearing peach trees, keep in mind that peaches are borne laterally on shoots that grew the previous year. Therefore, the stimulation of 1-year shoot growth by fertilization and pruning is essential for maximum yields of fruit. On a vigorous 1-year shoot, usually 3 buds will be produced at each node. The 2 plump out- side buds will be flower buds and the smaller bud in the center will be a leaf bud. On less vigorous shoots there may be but 1 flower bud and a leaf bud on a node . In pruning a bearing tree the following branches should be removed: 1. Those which are broken or diseased. 2. Those which are slender and weak especially on the inside of the tree. 3. Those which grow toward the center or straight up. 4. Those which grow doxmward so as to interfere with mowing or cultivating equipment. After these branches are removed, it may be necessary to thin out a few of the more vigorous branches where they are too numerous. "Leggy" branches (those which grow out for a considerable distance without branching) need to be headed back in order to induce the development of side branches nearer the trunk. To overcome the peach tree's growth habit of producing bearing wood further and further from the trunk, retain a few young branches on the inner parts of the tree. These brancher: should be located so that they will subsequently replace older -6- wood. To keep the tree at a convenient height, head back upright branches to an outward growing lateral branch when they reach a dis- tance of approximately 8 feet from the ground. Pruning Winter- Injured Trees : Peach trees may suffer winter injury from low temperatures by killing of the flower buds, and by killing of the wood. Under Massachusetts conditions, the critical winter tempera- ture for the killing of flower buds is about -15°F. The exact tempera- ture at which flower buds will be killed depends upon the variety, as some are more hardy than others. The extent of flower bud injury can be determined by cutting several buds and noting if they are bldck in the center. If all of the buds are killed, an opportunity is provided to reduce the proportion of old wood without affecting the crop since there would be no crop the following summer anyway. This will tend to stimulate the development of new growth nearer the trunk. With more severe temperature (-20°F or lower) the wood may be injured in addition to the buds. This condition is indicated by the inside of a branch turning dark brown or black. When this condition exists, it is best not to prune the tree until after growth starts. Then, only weak shoots on the interior of the tree and dead branches ishould be removed since the tree will need every healthy leaf to help recover from the winter injury. **************** CONTROL OF WATER SPROUTS AND SUCKERS WITH TREE-HOLD* William J. Lord and Duane W. Greene Department of Plant and Soil Sciences Water sprouts, which generally are removed to maintain tree form and prevent shading, are particularly troublesome on standard-type Delicious and following heavy pruning. Unfortunately, their removal becomes more time consuming in succeeding seasons because of the pro- liferation from the stubs created by pruning. Sucker growth from the trunks and roots of mature seedling trees and in plantings of M.7 and M,7A is a serious problem in Massachusetts. Suckers are costly to remove, increase in number annually, provide mouse cover, and are a haven for insects and diseases. We now have a 24-C State Registration for Special Local Needs for Tree-Hold Sprout Inhibitor A-112 (Amchem Products, Inc., Ambler, PA) for the control of water sprouts and suckers in apple and pear orchards in Massachusetts. This formulation contains 15.11 ethyl ester of naphthaleneacetic acid and is equivalent to 13.2% naphthaleneacetic acid by weight (1 lb/gal) . This formulation must be diluted before use, with either water or white interior latex paint. * Trade Name -7- Tree-Hold diluted in a combination o£ water and water-base, interior-grade, white latex paint has given good control o£ water sprouts at our Horticultural Research Station in Belchertown. However, more experience is needed to determine its effectiveness when used alone or in combination with herbicides for the control of suckers because failure of Tree-Hold to control dense sucker growth under mature trees has been reported. Thus, we suggest the use of Tree-Hold on a trial basis only for sucker control. Mixing for Water Sprout and Sucker Control For the control of water sprouts use 10 fluid ounces (2/3 pt) of Tree-Hold and make up to a volume of 1 gallon with a combination of water and interior-grade latex paint. The latex paint "marks" the treated areas and makes the mixture more viscous, thus restricting the NAA to the treated area. It has been our experience that at least 4 pints of latex paint should be used in each gallon of treating solution. Be sure to use an interior-grade latex paint and one that does not con- tain a mildewcide. For spraying suckers on a trial basis, mix 10 fluid ounces of Tree- Hold with sufficient water to make 1 gallon of spray mixture. Eight gallons of Tree-Hold are required for 100 gallons of spray. Control of Water Sprouts Prune water sprouts and then apply Tree-Hold mixture thoroughly over the cut surfaces. It can be applied with a paint brush or a small compressed air sprayer. We found that a 1-1/2 gallon compressed air sprayer with a 12-foot hose worked well, and that attaching a sponge to the nozzle was useful for swabbing the mixture on pruning cuts. The treatment can be applied anytime weather permits before growth starts in the Spring. Areas where pruning cuts have been made should be covered thoroughly, but drip on to other parts of the tree should be avoided. The Tree-Hold mixture can kill buds. Be sure to follow the label . Control of Suckers Prune the suckers during the dormant season. The Tree-Hold mix- ture can be sprayed on the stubs during the dormant season or when the new shoots from the suckers are 6 to 12 inches in height. However, the most effective timing is when the suckers are actively growing. Since the Tree-Hold mixture contains 10,000 ppm NAA, the label restricts its use from bud swell through 4 weeks after petal fall to eliminate the possibility of fruit thinning and leaf damage. Therefore, the Tree- Hold mixture should be sprayed in late-June to mid-July when the suckers are 6 to 12 inches in height. Coverage should be thorough. The Tree-Hold mixture is too expensive to apply as a band applica- tion under the trees. Since the population of suckers is generally more dense near the trunk and very troublesome inside wire mouse guards, the spray may be limited to these areas using a compressed air sprayer, a weed sprayer with an air gun, or a weed sprayer and boom with a trunk- directed nozzle. Maintain low spray pressure to avoid drift of the Tree-Hold mix- ture. Spray on tree trunks is of no concern but drift onto scaffold limbs will damage foliage and fruit. Although annual sprays of Tree- Hold mixture may be required, the number of suckers should be gradually reduced. It is of interest to note that researchers in New York State reported in 1978 that 3 consecutive annual applications of Tree-Hold has had no harmful effect on tree growth or productivity. Summary Tree-Hold Sprout Inhibitor A-112 is a useful chemical tool for the control of water sprouts and suckers in our apple orchards. We are reasonably sure of its effectiveness for water sprout control but need much more experience with its use on suckers. The new registra- tion will allow growers to evaluate the effectiveness of Tree-Hold for sucker control under a variety of conditions. Grower experiences with Tree-Hold for sucker control will add to the information currently being obtained at our Horticultural Research Center and by James Williams, Regional Fruit Specialist in Northeastern Massachusetts. **************** U.S. APPLE EXPORTERS EXPECT ANOTHER GOOD, YEAR FOLLOWING RECORD SHOWING IN 1977/78 Gilbert E. Sindelar, Director Horticultural and Tropical Products Division Foreign Agricultural Service U.S. Department of Agriculture Washington, D.C. 20250 After a banner 1977/78 season, U.S. apple exporters are prepar- ing for another good year in 1978/79. More normal crops in major markets of Western Europe following shortfalls last season conceiv- ably could keep U.S. apple exports from reaching the record sales of $66 million achieved in 1977/78 (July-June). But sales promise to be brisk as markets in Latin America, the Middle East, Far East, and other areas are developed further. Another bumper U.S. crop -- estimated at 3.3 million metric tons, the same as last year's -- will allow ample supplies for export while intensifying pressure to sell abroad. Moreover, the crops are abundant in traditional exporting areas such as the Pacific North- west, New England, and eastern New York State. The status of the U.S. dollar also will have a bearing on U.S. trade. Prior to its recent strengthening, the U.S. dollar was declining against many currencies of the world. For instance, the Reprinted from November 13, 1978 issue of Foreign Agriculture with permission from the author. British pound in mid-October 1978 was worth about $2.08, compared with about $1.85 a year earlier. Given a landed duty-paid price of $12 per carton (42 lb) for both years, U.K. importers would have paid about ^ 5.77 for U.S. apples in October 1978 -- some 11 percent less than a year earlier. Some further examples of the prolonged deterioration in the value of one U.S. dollar vis-a-vis foreign currencies (as of October 27, 1978) include: October 1977 1978 f2.4 fl.9 F2.2 F1.5 DM2.2 DM1.8 Nkr5.4 Nkr4.8 S$2.4 S$2.1 M$2.4 M$2.1 Netherlands Switzerland West Germany Norway Singapore Malaysia Currently, it looks as if total U.S. apple exports in 1978/79 could add up close to last season's recent high of 7.9 million car- tons. Exports in 1978/79 were well above the exceptionally good showing of the preceding season (1976/77), when 6.3 million cartons moved into foreign markets. At the start of last season, U.S. apple shippers were faced with a very inviting situation. The important European producers were then reporting exceptionally small apple crops, which for all Europe amounted to only about 5 million tons, compared with 6.4 million in 1976. This meant that the United States had an excellent opportunity to help fill the vacuum on the Continent -- aided by a temporary reduction in the EC common external tariff on apples from 14 percent to 6 percent. Additionally, the area's leading producer, France, was not able to reach distant markets with the same intensity of former years. As it turned out, France's apple crop in 1977 was down some 27 percent from the previous year to 1.2 million tons. This decline greatly limited the country's export potential while opening up new outlets for the United States in Europe, the Middle East, and other markets . Despite loss of shipping time during the first of last season because of the dock strike on the east coast, U.S. apple exports went on to score a 25 percent gain in volume and a 57 percent increase in value over the 1976/77 levels. On a price per carton basis, export sales to all destinations averaged $8.42 per equivalent 42- pound carton, versus $6.71 per carton in 1976/77. This is a far cry from the depressing prospects that confronted U.S. exporters in the 1960's and early 1970's. Around 1962, for -10- £or instance, there were strong signs that the United States poten- tially could be squeezed out of the world apple market. Plantings in France and other nearby countries in Western and Eastern Europe had been exceptionally heavy, portending a future explosion in pro- duction. Shortly after the inid-1960's, the explosion hit. Once-viable U.S. markets in the United Kingdom and Scandinavia collapsed. Pros- pects appeared bleak to impossible in Latin America and the Far East. Canada -- like the United States a leading producer and exporter -- was plagued with similar problems. And, to compound the problem still further. Southern Hemisphere suppliers such as Australia and New Zealand began to eye the U.S. late winter through early summer market with greater interest. They also were having access problems in Western Europe. Coinciding with these developments was burgeoning production in the United States of Red Delicious and other types. U.S. exports during that time did fall considerably -- averaging about 2-2.5 million cartons in the late 1960's and early 1970's. However, a nucleus of grower-shippers simultaneously were searching for new markets and making quality improvements needed to compete. Gradually, the situation improved, and today U.S. apple exporters are shipping reasonably large volumes to the Far East, Latin America, and the Middle East. Last year's record showing capped this rebound, as most major markets came through with larger purchases than in 1976/77. CANADA -- largest single market for U.S. apples -- was one of the exceptions to this generally upward trend and probably will show another slight decline in 1978/79. The current forecast: 2.4 million cartons, against 2.6 million shipped in 1977/78. However, U.S. sales there last year were larger than expected, coming in just 300,000 cartons under the unusually high level of 1976/77. The major limiting factors for 1978/79 will be the slightly larger Canadian crop and price gains resulting from the weakness of Canada's currency against the U.S. dollar. The Canadian dollar in October was worth slightly less than 85 U.S. cents, compared with 93 in August 1977. In WESTERN EUROPE, U.S. shippers cannot expect to repeat their strong 1977/78 showing of 1.4 million cartons in view of the 22 per- cent gain estimated for apple production in 11 key countries there over the unusually low level of 1977. The current estimate for 1978/79 exports: 600,000 cartons, or some 15 percent above the 522,000 cartons shipped in 1976/77. -li- on the positive side, expected output still is some 4 percent below that of 1976, and crops in the key European producers -- France and Italy -- are off 4 percent and 19 percent, respectively, from 2 years ago. Italy's crop, in fact, is some 5 percent below the small outturn of 1977. LATIN AMERICA (including the Caribbean and Mexico) should con- tinue its gradual growth as a market for U.S. apples. Exports there in 1978/79 are forecast at 1.9 million to 2.0 million cartons, against 1.5 million last year. Shippers will probably at least equal last year's showing in Mexico and Venezuela -- which together take about half of all U.S. exports to the region -- and make further gains in Central America, the Caribbean, Colombia, and possibly Brazil . In contrast to diminishing sales opportunities a few years ago, when France was encroaching on many traditional U.S. markets, Latin America recently has become an attractive outlet. U.S. shipments there last year rose 12 percent over the 1976/77 level. In the FAR EAST AND PACIFIC -- a recent growth market that did not, however, participate in last year's advance -- sales are expected to exceed the 1.4 million cartons in 1977/78. A large crop in the U.S. Pacific Northwest means plentiful export supplies. Hong Kong should continue to be a high-volume market, with any plus conditioned in part on currency relationships -- the Hong Kong dollar has been slightly weaker so far this year. Taiwan, Malaysia, and Singapore also look better than they did last season, when sales to Taiwan and Singapore fell significantly. The region as a whole took 155,000 fewer cartons in 1977/78 than during the previous year. This was the first interruption in the steady upward trend in sales since 1970, when only 210,000 car- tons were sold to the Far East. Exports to the MIDDLE EAST -- which opened up abruptly last year in response to smaller exports from its traditional supplier, France -- should at least match the 1 million cartons of U.S. apples shipped in 1977/78. France and Italy have long dominated this market and will prob- ably try to reclaim their traditional shares. However, some trade sources predict that the United States will exceed last season's performance in this area by a significant margin. **************** -12- INTEGRATED MANAGEMENT OF APPLE PESTS IN MASSACHUSETTS - 1978 RESULTS: INSECTS K. I. Hauschild and R. J. Prokopy Department of Entomology University of Massachusetts, Amherst, MA 01003 In 1978, the United States Department of Agriculture Extension Service made monies available for the study of integrated pest management (IPM) on major crops grown in the United States. We applied for and received such a grant to study integrated manage- ment of apple pests in Massachusetts. Although apples rank 6th in economic importance of agricultural crops in this state, pesticide usage ranks highest. Reduced spray programs have been discussed in previous issues of Fruit Notes [41(1), 41(2), 41(3), 42(3) and 43(3)1. The major objective of our IPM program was to utilize data obtained from trap captures of pest adults and other methods (such as sampling leaves for mites and observing leaf and fruit clusters for aphids and their predators) to better time, and hopefully decrease, the number of spray applications aimed against fruit and leaf pests while main- taining fruit quality. METHODS During the growing season of 1978, we scouted 24 orchards in the four major fruit growing counties (Middlesex, Worcester, Hamp- den and Franklin) in Massachusetts. Eight orchards were in the IPM program, wherein we told the growers when and what materials to spray. Eight were check orchards in which the growers sprayed their usual program with whatever materials they wished to use. Four were abandoned orchards which we used to observe presence and rela- tive numbers of insect pests. Four were alternate-middle vs. every- middle spray orchards. (We will discuss the 1978 results of the alternate vs. every-middle program in the next issue of Fruit Notes.) Every week 10 trees in a 10-acre block in each IPM and check orchard were scouted for beneficial and pest insects. We looked at 45 leaf clusters and 45 fruits from all parts of each tree for aphids, aphid predators, other leaf and fruit pests and any injury. Later in the season (from mid-June to harvest) we took leaf samples which we brought back to the lab and brushed for predator and leaf-feeding mites [see Fruit Notes 43(4) ]. We also used visual traps to monitor tarnished plant bug and European apple sawfly adults in all orchards [see Fruit Notes 43(1) and 43(2)], pheromone (sex odor) traps for codling moth and leafrollers, and unbaited sticky red spheres, sticky j,red spheres baited with ammonium acetate (a food mimic), and Zoecon AM Standard baited yellow rectangles for apple maggot flies [see Fruit Notes 41(5) and 41(6)]. In the IPM orchards, decisions We would like to thank Ted Bardinelli, Kevin Beswick, Victoria Ciarcia, Sylvia Cooley and Thomas Luippold for their assistance in this program, as well as the MFGA and participating fruit growers . -13- as to whether or not to spray were made on the basis of trap captures and visual observations o£ pest and predator insects. Decisions on all insecticide and aphicide applications were made in the orchard. Leaf samples for mites were brought back to the lab and processed. A decision on whether or not to spray for mites was made within 24 hours . RESULTS A summary of our 1978 results is given Average numbers of tarnished plant bug (TPB) (EAS) , apple maggot fly (AMP) , codling moth roller (RBLR) and obliquebanded leafroller in the 8 IPM orchards than in the 8 check or these higher numbers, fruit injury levels at infesting insects) averaged 44% lower in the of 2.6% injury) than in the 8 check orchards injury). At the same time, the 8 IPM orchar insecticide sprays aimed at these pests. We in injury to better timing and avoidance of cations. In addition, the 8 IPM orchards av than in the previous 2 years. in Table 1 (see below) . , European apple sawfly (CM) , redbanded leaf - (OBLR) adults were higher chards. But, in spite of harvest (for all fruit- 8 IPM orchards (an average (an average of 4.81 ds averaged 311 fewer attribute this decrease unnecessary spray sppli- eraged 27% fewer sprays TABLE 1. Summary of Overall Results - IPM and Check Orchards TPB y Average Number/Trap EAS X AMP ,w CM ,v RBLR u OBLR Average Fruit Injury Average No. Insecticide Sprays 1978 1976,1977 8 IPM Orchards 8 Check Orchards 6.0 5.3 8.5 122.6 166.0 5.5 4.5 4.3 5.7 89.9 98.5 4.5 2.6% 6.7 4.8% 9.6 9.3 Difference +33% +23% +47% +36% +18% +22% ■44% -31% Does not include materials directed solely at aphids (e.g., endosulfan, phosphamidon) ^ TPB = Tarnished Plant Bug X w u EAS = European Apple Sawfly AMF = Apple Maggot Fly CM = Codling Moth RBLR = Redbanded Leafroller OBLR = Obliquebanded Leafroller -14 On the basis of these results, we've calculated (see Table 2) that with the average reduction in number of insecticide applications (3) in the IPM orchards, these growers saved between $173.70 and $322.50 (depending on material and rate) on insecticides alone in each 10-acre IPM block. TABLE 2. Savings Attributable IPM Orchards for the Comparisons Based on to Decreased Insecticide Usage in Two Most Commonly Used Materials. 3 Applications Saved. Chemical Cost^/Lb. Rate/100 Gal. Savings/A^ Savings/10-A Block 1 Applic. 3 Applic, Guthion Imidan $4.30 $1.93 1/2 lb. 5/8 lb. 3/4 lb. 1 lb. 1-1/4 lb. $ 8.60 10.75 5.79 7.72 9.65 $ 86.00 107.50 57.90 77.20 96.50 $258.00 322.50 173.70 231.60 289.50 Does not include aphicide use, costs of labor, gasoline or equip- ment . ^ Costante, J. 1978. Insecticide guide for control of major pests and cost comparison. Univ. of VT (mimeo) . X Based on 400 gal. /A dilute for IPM orchards Table 3 gives a list of the major apple- infesting pests. This list was based on an on-tree harvest survey of 2,000 fruits per orchard (100 fruits per tree on each of 20 trees) . In both the IPM and check orchards, TPB accounted for the greatest percentage of fruit injury. (However, we found no good relation between TPB trap captures and TPB injury levels at harvest.) In the IPM orchards, EAS ranked second in terms of injury level. (We found that EAS trap captures and EAS injury levels are highly related, and for this reason we will be able to even more accurately time and predict need for insecticide applications aimed against EAS next year.) In the check orchards, San Jose' scale and green fruitworms caused more injury than EAS and other pests except plum curculio. We attribute better control of GFW in the IPM orchards to our careful monitoring of the presence of the larvae. In the IPM orchards, we attribute the excellent control of AMP with minimum insecticide usage to the information obtained from AMF captures on the unbaited spheres. Captures of AMP on these spheres were considerably greater and much better related with AMF injury to fruit at harvest than were captures on the baited spheres on Zoecon yellow rectangles. In one IPM orchard, no mature female AMF were captured until August 14, and few CM were captured. Based on our recommendations stemming from these trap captures, no insecti- cide was applied between June 6 and August 16. The result: no fruit injury whatsoever from AMF, CM, or any other fruit pest except early season TPB. We found almost no codling moth and leafroller injury on fruits at harvest in any of the other orchards. 2 .33% (1) 0 .54% (4) 0 .17% (5) 0 .08% (6) 0 96% (2) 0 C8) 0 05% (7) 0 59% 0 (3) -15- TABLE 3. Major Pest Species and Average Injury Levels^. Numbers in Parentheses Indicate Relative Ranking o£ Injury Level Pest IPM Orchards (8) Check Orchards (8) Tarnished Plant Bug 1.60% (1) European Apple Sawfly 0.68% (2) Plum Curculio 0.17% (3) Apple Maggot Fly 0.13% (4) San Jose Scale 0.03% (5) Codling Moth 0.01% (6) Leafrollers 0.01% (7) Green Fruitworm 0 (8) Other 0.01% Based on on-tree surveys of 2,000 fruit per orchard (or orchard block) at harvest (100 fruit on each of 20 trees) . The mite results in our IPM orchards were also encouraging. Our 8 IPM orchards averaged 1.2 miticide applications as compared with an average of 1.6 applications in the 8 check orchards, and at the same time had slightly more predator mites (Table 4) . We attribute the slightly increased number of predator mites to selective use of pesticides in the IPM orchards. (We asked growers not to use chemi- cals that had previously been shown to be toxic to mite predators [Fruit Notes 43(5)]). In Orchard A (Table 5), which had a high num- ber of predator mites (both A^ fallacis and yellow mites) , no miticide application was needed this year. In Orchard B, in which an herbicide shown to be toxic to A. fallacis was used, 3 miticide applications were needed. As the eTfects of selective use of pesticides non-toxic to predator mites take hold in IPM orchards in future years, we expect increasing predator buildup and gradually decreasing need for miticide application. TABLE 4. Summary of 1978 IPM and Check Orchard Mite Results Orchards European Mites Red Two- Spotted Mites Predatory Mites A. fallacis Yellow Mites oil No. Treatments Miticides 8 IPM 8 Check 2.1 2.4 5.3 0.7 0.07 0.01 0.05 0.01 0.8 0.8 1.2 1.6 ■16- TABLE 5. Mite Results in 2 IPM Orchards in 1978 IPM Orchard European Red Two-Spotted Predatory Mites Mites Mites A. fallacis Yellow Mites Avg. No. Treatments Oil Miticides 0.2 0.03 0.06 0.07 B* 11.4 0.08 0.01 * Sprayed under trees with Amnate in June. Our plans for 1979 include increasing the number of IPM orchards and the IPM acreage in each. (The number of check orchards to be scouted will probably decrease.) Since we have better predictive tools for monitoring HAS and AMF adults, our results next year should be even better. The combined efforts of Dr. William Manning and Ted Bardinelli of the Plant Pathology Department will also provide an IPM approach to disease control. In conclusion, our integrated insect pest management program in 1978 resulted in substantial overall savings of grower money and time, through a reduced number of spray applications, and at the same time, resulted in very high quality fruit production. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts Ross S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for Private Use, $300. POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERMIT FRUITpc NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 44 (No. 2) MARCH/ APRIL 1979 TABLE OF CONTENTS Monitoring Apple Maggot Flies. Sawflies, and Plant Bugs with Visual Traps Rootstock Testing on an International Basis Treatment of Girdled Fruit Trees Nutritional Problems in 1978 and Suggestions for Fertilization of Apple Trees in 1979 Pomological Paragraph Deeper planting may reduce suckering from the rootstock on interstem trees. Apple Disease Incidence in Massachusetts in 1978 MONITORING APPLE MAGGOT FLIES, SAWFLIES, AND PLANT BUGS WITH VISUAL TRAPS Ronald J. Prokopy Department of Entomology Introduction With the advent o£ integrated pest management programs in commercial apple orchards inMassachusetts and other apple-growing regions of the United States, there is increased emphasis on the ability of growers, orchard scouts, and extension agents to accur- ately monitor population levels of injurious apple insects and mites . Certain pests, such as aphids, spider mites, leafhoppers, leafminers, and scale insects attack principally or exclusively the vegetative parts of the tree and can be tolerated in small or even moderate numbers without economic injury. Their popu- lation levels can be monitored with reasonable accuracy by direct visual examination of foliage or branches. Other pests, such as green fruitworms and oblique-banded, red-banded, and fruit-tree leafrollers feed, as larvae, from the exterior of the fruit. While even a few larvae may cause economic injury, larval populations and the readily discernible injuries they cause, can be rather accurately monitored by direct visual examination of fruit. Still other pests, such as tarnished plant bug, European apple sawfly, plum curculio, apple maggot, and codling moth, feed as adults or larvae on developing buds or fruit. They can not be tolerated in appreciable or even small numbers with- out economic injury. Except for plum curculio, their feeding and egglaying activities are rather difficult and tedious to accurately detect by direct observation. Populations of these pests are best monitored in the adult stage. The monitoring method must be sensitive, so that detection of very low popu- lation densities is possible, and pesticide application, if nec- essary, can be made before the occurrence of economically un- acceptable feeding injury or egglaying. In the 8 commercial apple orchards in our 1978 integrated pest management (IPM) program in Massachusetts, it was the lat- ter 5 pests which accounted for nearly all of the insect injury on the 16,000 apples examined at harvest: 1.601 by plant bug, 0.68°^ by sawfly, 0.17% by plum curculio, 0.131 by apple maggot, and 0.01% by codling moth, with all remaining insect injury to the fruit totalling 0.051 (see Fruit Notes 44(1) for further in- information on the 1978 results of the apple IPM program in Massa- chusetts). This same sort of insect injury pattern is probably characteristic of several other eastern states as well. During the past few years, we have been attempting to develop effective trapping devices for accurately monitoring adult popu- lation levels of plant bug, sawfly, apple maggot, and plum curcu- lio. Most entomologists who have sought to develop insect traps have been primarily interested in uncovering highly stimulating odors, such as sex pheromones, which can attract an insect from a considerable distance. In recent years, this approach has met with outstanding success. Witness the development of sex phero- mone traps for male codling moths, leafrollers, fruitworms, and leafminers by Dr. Wendell Roelofs and colleagues at the New York State Agricultural Experiment Station at Geneva. In many instances, however, sex pheromone traps are so power- ful that they attract individuals from distances well beyond the borders of the orchard. Hence, it has often proven rather diff- icult to accurately relate pheromone trap captures in an orchard to the number of pest adults actually present within the orchard. Our approach has been an attempt to uncover attractive visual stimuli. Such stimuli, when incorporated into a trap, would lure insects only from a distance of a few yards or less. Theoretically, therefore, visual traps would have the advantage of providing estimates of only those pest adult numbers actually present with- in the orchard. Thus far, this approach has yielded 2 sorts of effective visual traps for apple maggot flies, one for European sawfly, and one for tarnished plant bug. Some of the research that led to the development of these visual traps has been outlined in recent issues of Fruit Notes: 41(5), 41(6), 43(1), and 43(2). In this article, I tie together elements of our previously described findings and present new findings on the relationship of levels of trap captures to levels of injury caused by each pest. Specific Ingredients of Our Approach (^x^^^ -juxL^.v-i-mj.'w.j. iii-j~i.\^y rv \^ o.uu'^iiiUL- \,\J iii-LiiiJ-\_ („ii\_,o\_- vj.oiacj-j. j.v_-a.-i-v--\^i ance patterns with pigments or paints having the same type of re flectance pattern. Fourth, we apply these pigments or paints to objects whose shape and size is similar to that of the correspond- ing tree structures. Finally, the objects are coated with a clear sticky substance (such as Tangletrap*) which captures alighting insects, and are hung in apple trees to assess the responses of the adults. n Trade Name -3- Apple Maggot Flies Apple maggot flies, prior to reaching sexual maturity, make frequent visits to apple tree leaves, where they feed on insect honeydew and other surface substances, and rest. After reaching sexual maturity, they make frequent visits to the fruit, where they mate and lay eggs. Visits to the twigs and branches are infrequent. A green rectangle of medium size (6x9 inches) roughly mimics the hue reflectance pattern and form of clusters of apple foliage. While apple maggot flies will alight on such a green rectangle, they alight in much greater numbers on yellow rect- angles, which have the same sort of hue reflectance pattern as apple leaves, but reflect light at a much higher intensity than leaves. It seems as though the flies perceive yellow rectangles as being super-bright or super-normal clusters of foliage. Day- light fluorescent yellow is an especially bright and attractive hue . When baited with an odoriferous substance such as an ammon- ium acetate-protein hydrolysate combination (which apparently mimics the smell of insect honeydew), and coated with Tangletrap, daylight fluorescent yellow rectangles are excellent for monitor- ing populations of food-seeking flies. A yellow or green 2-inch diameter sphere closely mimics the hue reflectance pattern, form, and size of a developing apple. While mature apple maggot flies readily alight on such spheres, they alight in considerably greater numbers on red, violet, and black spheres 3-5 inches in diameter. It seems as though these dark colored spheres, on the basis of greater contrast against the background, are more readily detectable by the flies than are the light colored ones -- much the same as humans can more easily locate red apples than yellow or green apples in a tree. Apparently the flies view large spheres as being super-large or super-normal apples. Our studies have shown, however, that if a sphere is overly large--for example, 12 inches diameter--it is less likely to be viewed as an apple and in fact attracts fewer flies than a 3 1/2-inch sphere. When coated with Tangletrap, 3 1/2-inch diameter red spheres provide excellent traps for monitoring populations of apple maggot flies seeking mating and egglaying sites. In 1978, we compared 6x9 inch odor-baited yellow rectangles (sold commercially as Pherocon AM Standard Traps by Zoecon Corp., Palo Alto, California) with 3 1/2-inch diameter dark red spheres coated with Tangletrap in 16 commercial and 4 abandoned Massa- chusetts apple orchards. Although early-season maggot fly cap- tures in the abandoned orchards were slightly greater on the yel- low rectangles than on the spheres, captures in the commercial orchards were consistently earlier and consistently greater in weekly and total numbers on the spheres than on the rectangles. -4- In commercial orchards, the great majority of apple maggot flies are immigrants, and apparently are more in search of mating and egglaying sites than in search of food. Hence, the greater effect- iveness of the spheres for monitoring apple maggot flies in comm- ercial orchards. European Apple Sawflies European apple sawfly adults make frequent visits to apple blossoms, where they feed on the pollen and lay eggs in the recep- tacles. Some mating and resting also occurs on the blossoms. They make comparatively few visits to the leaves and branches. Certain white paints which reflect little or no light in the ultraviolet part of the spectrum closely mimic the hue reflect- ance pattern of apple petals, although they reflect at a higher intensity, than tlic petals. Medium size rectangles (6 x 8- inches) coated with such paint plus Tangletrap attract and capture large numbers of sawfly adults. Evidently, the sawflies perceive the white rectangles as being super-bright or super-normal clusters of apple blossoms. However, not just any white surface will attract sawflies. For example, white paper, white cardboard, and lead white paints reflect considerable amounts of ultraviolet light, which, although not visible to humans is readily visible and in fact quite repulsive to sawflies. Fortunately, the white rectangles attract and capture few honeybees. Tarnished Plant Bugs Tarnished plant bug adults make frequent visits to apple buds and blossoms, where they feed. Less frequently, they visit leaves and branches, where they rest. Mating and egglaying seem to be rather infrequent on apple trees, principally occurring on ground cover vegetation. Just as they mimic the hue reflectance pattern of apple blossom petals, certain non-ultraviolet-reflecting white paints also approximate the hue reflectance pattern of developing apple buds. As with sawflies, 6 x 8-inch rectangles coated with such paints plus Tangletrap capture considerable numbers of plant bug adults. However, our research indicates that plant bug adults are substantially less visually specific in orientation to the hue or form of apple tree structures than are apple maggot flies and sawflies. Hence, visual traps may ultimately prove of somewhat more limited value for precise monitoring of plant bug populations Where to Purchase Visual Traps These visual traps for apple maggot flies, sawflies, and plant bugs can be purchased at modest cost from New England Insect Traps, Leyden RFD, Bernardston, MA 01337 ($1.25 per 3 1/2-inch red wooden sphere with accompanying Tangletrap; $1.00 per non- ultraviolet white cardboard rectangle, pre-coated with Tangletrap) -5- How to Position Visual Traps in Trees Proper use o£ visual traps demands more careful attention to trap placement than is the case with sex pheromone traps. The visual traps, best hung from branches on the south side of ap- ple trees at heights of 20-40 inches for plant bugs and 6-8 feet for sawflies and maggot flies, must be readily visible to insects approaching from any direction. It is advisable, there- fore, to remove all foliage and fruit within 12 inches or so of the sides, top, and bottom of a trap. Beyond this distance, however, there should be as many buds, blossoms, leaves, or fruits as possible to attract insects into the general area. Presently, we are using one visual trap of each type per 2 acres of trees in our pest management orchards. Relation Between Trap Captures and Insect Injury Levels The ultimate proof of the usefulness of such visual traps lies, of course, in the accuracy with which trap captures esti- mate numbers of injury-causing adults actually present in the orchard. In 1978, we therefore made an attempt to establish indices relating levels of trap capture to levels of injury caused by each pest. We hung 6-10 traps of each type in each of 16 commercial orchards. The results showed the following correlation values of trap captures with injury levels (+ 1.00 would be a perfect positive correlation, indicating a perfect relationship of trap captures to injury levels): (a) apple maggot captures on red spheres with apple maggot egg-laying stings, + 0.87 (b) sawfly captures on non-ultraviolet reflecting white rectangles with sawfly injury scars on mature fruit, + 0.82; and (c) plant bug captures on non- ultraviolet reflecting white rectangles with abscission of devel- oping buds caused by plant bug feeding, + 0.67. These high positive correlation values are very encouraging and suggest that prospects are good for establishing reliable indices relating visual trap captures to insect injury levels, and therefore for using visual trap captures as a basis for de- ciding if or when pesticide treatments against plant bugs, saw- flies, and apple maggot flies are economically merited in a given block of trees. We hope that our studies during the next 2-3 years will refine and validate the initial indices obtained in 1978. Until then, the principal value of the visual traps will be in detection of the first appearance and the disappearance of these pest adults in orchards. -6- ROOTSTOCK TESTING ON AN INTERNATIONAL BASIS William J. Lord Department of Plant and Soil Sciences In the past, rootstock studies were uncoordinated efforts and results have varied from state to state with little chance of iso- lating the influences due to climate and soil differences. In 1976 the North Central Regional Cooperative Project NC-140 entitled "Scion/Rootstock and Interstem Effects on Apple Tree Growth and Fruiting" was initiated with the following objectives. Objectives : 1. To evaluate the production efficiency of available and potentially useful rootstocks or interstems for fruit trees which are potentially precocious, dwarfing, free standing, easy to propagate and adapted over a wide range of climatic conditions in the North Central Region. 2. To determine the propagation practicability of new root- stocks and interstem material and ascertain the anatomical and physiological factors in graft unions that determine compatibility. 3. To ascertain the cause and prevention of the decline of new and existing rootstocks and interstems and evaluate the influence of various cultural practices on rootstock survival and performance. Under Objective 1, a uniform interstem planting was establish- ed in 1976 in Illinois, Indiana, Iowa, Kansas, Massachusetts, Mich- igan, Missouri, Ohio, and Wisconsin, and a partial planting was established in Kentucky. 'Millerspur Delicious' and ' Empire ', with 8-inch interstem of M.9 on either Antonovka, MM. Ill or Ottawa 11 rootstock, are being evaluated. Currently, NC-140 is being expanded so that a 1980 rootstock planting will be established by at least 20 cooperators in U.S.A. and Canada. At each location a planting of 'Redchief Delicious' (spur- type) on M.9, Ottawa 3, EMLA27, EMLA9 , EMLA7 , EMLA26, MAC9, MAC24, and OARl will be established. (The EMLA's are virus-free clones of M.9, M.7, etc., the MAC's are Michigan State apple clones, and the OARl is a clone introduced by Oregon State Agricultural Experiment Station.) Other Cooperative Rootstock Plantings will be established later in the 1980's. Hopefully, our NC-140 project will prove to be a benefit to growers and apple tree nurserymen, since coordinated research should lead to clearer information about apple rootstock performance . ************ -7- TREATMENT OF GIRDLED FRUIT TREES William J. Lord Department of Plant and Soil Sciences Girdling or partial girdling of fruit trees occurs annually in spite of orchard sanitation, poison baits and mechanical pro- tectors, and may be particularly severe in years of heavy, persist- ing snowfall, as occurred during the winter of 1977-78. You can help prevent damage when snow accululates above the wire or plastic guards by tramping the snow to lower its height. Determining the Treatment 1. Trees not worth saving should be removed and replaced. 2. If apple, pear or plum trees with injury above the graft union are only 1- or 2-years old, they can be cut below the girdled area. Shoots will then develop from the re- maining stub. One of these can be selected during the following spring for a new tree. B£ sure the selected shoot originates above the graft union. In case of inter- stem trees the shoot must originate above the interstock. 3. If apple or pear trees are 1-1/2 or 2 inches in diameter they can be cleft grafted. Cleft grafting is less likely to be successful on stone fruits. 4. Trunks of girdled apple, pear or plum trees more than 2 inches in diameter can be bridge grafted. Peach trees usually do not respond satisfactorily to bridge grafting. 5. When the roots of an apple tree are so badly injured that scions cannot be readily attached to them, inarching can be done. 6. Repair of girdled apple trees is complicated by planting of interstem trees. Girdling of the interstem portion, usually M.9 (it is reported that mice prefer M.9), means that when bridge grafting, cleft grafting or inarching is done part, if not all, of the dwarfing influence of the interstem will be lost. A solution to this problem is using scion wood and rootstocks from a stool bed of M.9 maintained on the farm. Season for Repair Grafting Repair grafting by bridging or inarching should be performed when the bark is slipping readily. Under Massachusetts growing conditions, the bark may not begin to slip readily until mid-April. Cleft grafting can be done earlier (March) since it is not necessary for the bark to slip. However, when the scions for bridge and cleft grafting or the nursery tree for inarching are kept dormant in storage, grafting can be successfully done even though the trees have made considerable growth. Selection of Scion Wood for Bridge Grafting It usually is necessary to obtain scions in advance of their use in order to have them dormant. Water sprouts or well-ripened one-year terminal growth make good scions for bridge grafting. Scions can vary in size from that of a lead pencil to one-half inch in diameter, the largest scions being used on larger wounds. Scions may be taken from the same tree or any other available compatible sort, but preferably from a winter hardy variety such as Cortland or Mcintosh apple. Trees for Inarching Use dormant nursery trees 3 to 6 feet in height. Mechanics of Repair Grafting Farmers' Bulletin Number 1369 of the U.S. Department of Agriculture gives detailed instructions for bridge grafting and inarching. A limited supply of this publication is available at your County Extension Service. Also available from your County Extension Service is our publication on cleft grafting. Grafting Compound For the protection of grafting wounds, many growers now use asphalt emulsion instead of a grafting wax. It can be obtained from most distributors of farm and gardening supplies. Asphalt emulsion should be applied on the tip ends of the scions and the cut stub of the trunk when cleft grafting, and over the area where the scions or top of the inarched tree meets the stock of the girdled tree. Applying the emulsion on the injured section of the trunk is also advisable to prevent weathering. The Number of Scions The following are about the right number of scions for dif- ferent sized trees: (1) Tree 2 inches in diameter, 3 scions (2) Tree 3 inches in diameter, 4 scions (3) Tree 6 inches in diameter, 6 scions (4) Tree 10 inches in diameter, 8 or 10 scions. On partially girdled trees use a proportionate number of scions. A tree one-quarter or more girdled should be bridge grafted, -9- Care of Scions After Grafting Inspect repaired trees periodically after grafting and recoat with grafting compound any areas where cracking has occurred. This phase in the process of bridge grafting and inarching is most apt to be neglected. Thus, the following procedure should increase the reliability of coverage. Place masking tape over the graft- ing compound- coated areas (where the scions or top of the inarch tree meet the stock of the girdled tree). Then, coat the masking tape with grafting compound. The scions used for bridge grafting and the trees used for inarching must be kept from producing shoots. As buds on the scions swell, rub them off. When inarching, let 1 bud develop into a shoot, preferably the bud nearest to the graft. When you are sure the graft has "taken", it should be removed. General Considerations 1. As soon as the injury is discovered, it may be possible to save some of the cambium layer cells (where new cells are pro- duced in the trunk) by promptly applying the asphalt emulsion or grafting wax to the injured area. 2. Occasionally suckers are present or arise later from the area below the wounds. Suckers that extend above the wounded surface may be used as "inlay scions" at the top end. 3. Trees leaf out and often fruit the first season after the bark and cambium layer are destroyed around the tree trunk. How- ever, the vigor of these completely girdled trees varies con- siderably. On some trees the foliage and fruit appear normal, on others, foliage may be light in color but fruit size normal, and on some other girdled trees, the foliage may be light in color and sparse, and the fruit small. The reason why completely girdled trees leaf out and often fruit the first season after the bark and cambium layer are des- troyed around the tree trunk is because water and other materials which are taken up by the roots from the soil pass up to the leaves through the wood. In the leaves the water and the carbon dioxide taken from the air by the leaves are united chemically, through the action of sunlight, into sugar. After the manufacture of the plant foods by the leaves, they move to other parts of the tree through the phloem which is found in the bark. When the phloem has been destroyed by girdling, this food cannot move to the roots. Roots will continue to grow and take up water and minerals only as long as their food supply holds out, and the above-ground portion will continue to grow only as long as it continues to receive water and minerals from the roots. Reserve food stored in the roots enable the roots to function for some time, often a year or 2, thus keep- ing the top of the tree alive. However, a completely girdled tree , unless repaired, will eventually die Trom starvation of the roots . -10- NUTRITIONAL PROBLEMS IN 1978 AND SUGGESTIONS FOR FERTILIZATION OF APPLE TREES IN 1979 William J. Lord and Mack Drake Department o£ Plant and Soil Sciences Prospects for a heavy bloom in 1979 are not too likely follow- ing the large crop in 1978, However, there are ample flower buds for a good crop in 1979 if weather is favorable at bloom. The analysis of leaf samples from commercial orchards showed that potassium (K) and manganese (Mn) were deficient in some orchards in 1978, and boron (B) was generally low. Foliar calcium (Ca) levels were considerably higher than most years; nevertheless, bitter pit on Cortland was very prevalent in some orchards and we were surprised to find a serious amount of cork spot in some Red Delicious fruit, and Empire. With the above observations in mind, we present the following suggestions as a guide for fertilization in 1979, Nitrogen (N) : Most orchards had a large crop in 1979, there, fore, the trees may be low in available N for utilization this spring. We suggest higher rates than normal of N this year unless the trees were excessively vigorous in 1978 or were heavily pruned this past winter. Potassium (K) : K was low in many orchards and even deficient in some in 1978, probably due to the demand for this element by the large crop, or because the dry weather reduced its availability. The leaf scorch symptoms of K deficiency may be confused with the leaf margin burn from calcium chloride sprays. However, unlike leaf burn from calcium chloride sprays, the scorch of leaf margins due to K deficiency progresses from the older leaves to the younger leaves of current season shoots as the season advances. The scorch may turn gray in color and leaf fall may occur late in the growing season. The K requirements of apple trees with a large crop are high because the fruit utilizes about 3 times as much K as N, Since the quantity of K stored by the tree is extremely small, it seems important to supply adequate K this spring on trees that had heavy fruit set in 1978. The requirements of apple trees for K (expressed as K-,0) , based on potential yields, are as follows: (a) less than 15 bu. 1.3 lbs,/ tree; (b) 15 to 25 bu: 1,3 to 2,7 lbs, /tree; and (c) more than 25 bu: 2,7 to 4,3 lbs, /tree. It is necessary, however, to maintain a balance among the essential nutrients for apple trees. For example, excessive levels of K can reduce both leaf and fruit Ca, Therefore , we strongly urge that you participate in our leaf analysis program to more accurately determine the K needs of your apple trees. -11- Calcium (Ca) : The use o£ calcium chloride (CaCl2) sprays to increase the flesh Ca content o£ our apples is rapidly becoming a standard practice in commercial orchards. Our suggestions for their use in 1979 are as follow: Apply foliar sprays of CaCl2 starting about 3 weeks after petal fall and repeat at 2-week intervals, totalling 6 or 8 applications. Apply 6 to 8 pounds CaCl^/acre/spray until mid-July. After mid-July, apply 10 pounds/acre/spray. Use a technical grade CaCl2 such as Allied Chemical Flakes, 77-801 CaCl^- Other brands may be equally suitable. Experience in Massachusetts has shown that CaCl2 can be combined with pesticide sprays. However, there is limited evidence that the combination of Guthion (azinphosmethyl) 50 WP and CaCl^ may increase foliar burn. Do not mix CaCl- and Solubor sprays. Always dissolve the CaCl^ in a~p^ail of water and add this last and when the spray tank is nearly full. Foliar CaCl^ sprays may be applied dilute (300 gallons/acre) or up to 6x concentration (50 gallons/acre). In our tests, flesh calcium has been increased more by 6x concentration than by dilute. In 1977 the effectiveness of foliar CaCl^ sprays at 6x and lOx was compared on Mcintosh. The concentrations were equally effective for increasing flesh calcium, and foliar burn was not excessive. CaCl^ sprays can cause burn of leaf margins. Foliar injury usu- ally is more serious on Mcintosh than on Delicious. If foliar injury occurs, do not apply again until 1 inch of rain falls. Foliar burn was more severe from dilute sprays than when applied at 6x at the Horticultural Research Center in 1976, but the opposite occurred in 1977. This appears to indicate that CaCl, injury varies with season because of such factors as rainfall and temperature. Boron (B) : B can be supplied to apple trees either by foliar or soil applications . Use the most economical and convenient method. How- ever , it is safest to apply all elements as a fertilizer except in emergency situations. Soil applications of boron should be applied to orchards every 3 years. The rate of application per tree vary with tree age and size. In low density orchards, apply 1/4 pound of borax (11.11 actual B) or its equivalent under young trees coming into bearing, 1/2 to 3/4 pound to medium age and size trees and 3/4 to 1 pound to. large or mature trees Be sure to note the percent actual B in the fertilizer being used to. supply this element. B- containing fertilizers vary from approximately 11 to 211 actual B. In medium and high density orchards (115 trees/acre or higher) , it might be best to apply B on an acre basis. We suggest the following rates per acre of borax (11.11 actual B) or its equivalent: (a) trees 4 to 7 years of age - 12 lbs; (b) trees 8 to 15 years of age - 12 to 24 lbs; and (c) trees 16 to 30 years of age - 24 to 48 lbs. When the soil application of B is followed by a wet spring, it may be advisable to apply 2 foliar applications of B.the following year . -12- Many growers now rely on annual foliar applications of B. The usual practice is to add Solubor to the first 2 cover sprays. Fertilizer grades of borax may contain grit and should not be used in a sprayer. Mature trees should receive 4 pounds of Solubor per acre each year. Consequently, the goal is to apply about 2 pounds per acre in each of the 2 applications. For young orchards, the addition of 1/2 pound of Solubor per 100 gallons (dilute basis) to the first 2 cover sprays meets the B requirement of these trees. Reports of New York State indicate that sprays can be concentrated up to 8X with satisfactory results. Leaf samples from orchards treated with Solubor have indicated adequate leaf boron levels but the fruit was deficient in this elementT Whether or not B applied as a fertilizer more adequately meets the B requirement of apples than foliar-applied B is not known by us. Manganese (Mn) : Apple leaves from trees showing Mn deficiency in 1978 had 12 to 15 ppm of this element which is much below the desired levels of 30 to 60 ppm. Mn deficiency symptoms are charact- erized by interveinal fading of chlorophyll with the veins remaining green. For those who are unfamilar with the symptoms of Mn deficien- cy, we refer you to the photograph that appeared in the May-June 1978 issue of Fruit Notes. Mn deficiency should be corrected on trees showing considerable foliage damage. Although we have no definite proof, Mn deficiency appeared to be associated with excessive fruit drop on a few trees in one orchard in 1977. Mn deficiency can be corrected by foliar applications of manganese sulfate or of a fungicide containing Mn. Apply manganese sulfate at about first cover at the rate of 3 lbs. per 100 gallons of water. If using a Mn-containing fungicide, 2 or 3 applications are necessary with timings about petal fall, first and second cover. Zinc (Zn) : Based on optimum levels of Zn established by Maine, some of our orchards continue to be low in this element. Dr. Warren Stiles, University of Maine suggests a dilute spray of Zn chelate (EDTA) at the rate of 1 to 2 lbs. per 100 gallons of water at tight cluster or first cover in orchards low in this element. He considers 25 to 50 ppm to be the optimum range for zinc in apple tree foliage. AAA************** POMOLOGICAL PARAGRAPH Deeper planting may reduce suckering from the rootstock on inter- stem trees. Dr. James Cummins, New York State Agricultural Experi- ment Station, Geneva, N.Y. is examining the interaction of interstem length and planting depth. The interstems vary from 10 to 25 cm (1 inch = 2.54 cm) in length and planting depths vary from 1 cm of the interstem being exposed above ground, to the entire interstem -13- being exposed. The most s that the numbers of rootst increasing length of inter had little effect on numbe suckers are troublesome in ing the trees with only th above ground may reduce su to prevent scion rooting, inches of interstem are st soil or gravel around the it is to lift the tree if around a tree planted too water to collect near the ignif icant ock sucker stem expos rs of suck some plan e top 4 in ckering an Even if t ill above trunk if t it is too deep resul trunk. ] ft********* results after 3 years are s increased directly with ure, while length of interstem ers. [Editor's Note - Root tings of interstems. Plant- ches of the interstem being d should be a sufficient height he tree settles 2 inches, 2 more ground. It is easier to add he interstem is too high than low. Removal of soil from ts in "dishing" which allows APPLE DISEASE INCIDENCE IN MASSACHUSETTS IN 1978 Ted R. Bardinelli,-' Daniel R. Cooley,-' and William J. Manning- Department of Plant Pathology The apple plant pathology program in 1978 focused on disease surveys. Orchards in all parts of the state were evaluated peri- odically for disease incidence. The twenty orchards in the IPM program were the most intensively surveyed, particularly at harvest Accumulated survey data will allow us to begin to determine the incidence and relative importance of the various apple diseases and will also allow us to examine new problems and re-examine existing ones. The statewide disease survey showed the current status of dis- eases to be as follows: 1) Apple Scab Apple s 1978. Wher back to rea problems wi at critical growers exp developed i and found t To our know chusetts . cab was not e scab was sons such a th spray di times, and ressed cone n their ore hat fungici ledge, ther a serious problem in most orchards in a problem, it was possible to trace s problems with sprayer calibration, stribution, failure to apply fungicides other grower management problems. Some ern that fungicide-resistant scab had hards. We investigated these situations de-resistant scab was not the problem, e is no fungicide-resistant scab in Massa- y Extension Technicians, and y Associate Professor, Department Pathology, University of Massachusetts, Amherst, 01003. -14- 2) Quince Rust : Quince rust was unusually prevalent on Red Delicious fruits. We feel that this is due to late application of the first rust spray. The first application should be made when the pink stage is just beginning. Use of a broad- spectrum fungicide for both scab and rust might be a good idea in problem orchards. 3) Frog Eye Leaf Spot : Frog eye leaf spot (foliar stage of black rot) was unusually prevalent on early-season leaves, especially on Cortland. Be- cause of extensive early infections, most of these leaves fell off and little fruit or later leaf injury was noted. 4) Black Rot: Black rot was not severe on fruit. In older, poorly pruned orchards, however, many major tree limbs were heavily cankered or killed back by the black rot fungus. A "Yellow Bark" syndrome was noted on the trunks of some apparently healthy trees in several parts of the state. The black rot fungus was isolated from "Yellow Bark" areas. We are currently investigating the relationship of the black rot fungus to "Yellow Bark" and the significance of "Yellow Bark" to tree health and vigor. Poor Apple Growth Disease (PAGD) : We investigated six cases of PAGD in 1978. The problem with newly-planted trees either on old or new orchard sites that grow poorly and unevenly and when severely affected they may die. The cause of PAGD is unknown and we are examining possible causes under controlled conditions. Cedar Apple Rust and Powdery Mildew: Neither of these diseases was a problem this past season. Fire Blight: Scattered pockets of fire blight were noted, principally in Western Massachusetts. Mutsu and the Wayne were particularly sus- ceptible. Summer Fruit Problems: Low level incidence of black rot, bitter rot, fly speck, and white rot were noted late in the season and at harvest. The IPM survey involved 20 orchards in central and western Massachusetts. These were surveyed routinely throughout the season. Results for the full-season survey are given on the next page. -15- Table 1 .Occur reiicc percent of disease incidence in random samples of apple foliage and fruits as calculated during early, mid and late grow- ing season. Foliage Apple scab Frog eye leaf spot Cedar apple rust Powdery mildew Alternaria leaf spot Apple scab Black rot Early Mid Late 1.2 3.3 0.7 <0.1 0.2 4.5 1.4 <0.1 0.1 <.0.1 4.0 1.3 < 0.1 <0.1 <0.1 Totals 5.4 Fruit 6.1 5.3 1.0 0.0 3.2 <0.1 2.8 0.4 Totals 1.0 3.3 3.2 Apple scab and frog eye leaf spot were the major foliar diseases Apple scab was the principal fruit disease. A final fruit survey of 50,000 fruits was also performed just prior to harvest. The results given below show the total disease incidence of the fruits to be 2.81. Apple scab again proved to be the most important disease affecting 2.3% of the fruits. Other fun- gal diseases such as black rot, bitter rot, white rot, and fly speck accounted for 0.223%. Calcium deficiencies were responsible for the remaining 0. 312% . Table 2. Average percent of fruits infected by disease at harvest. Disease Causal organism % Incidence Apple scab Venturia inaequalis 2.3 Black rot Physalospora obtusa 0.2 Bitter rot Glomerella cingulata 0.1 Wh i t e rot Botryosphaeria ribis 0 . 1 Fly speck Microthyriell"a rubi 0.1 Cork spot Calcium deficiency 0. 3 Total fruit disease incidence 2.8 We will be continuing our surveys in 1979. Fruit growers that have disease problems that they would like to have surveyed or diagnosed, should contact Dr. William J. Manning in the Department of Plant Pathology or their Regional Extension Agent. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUITp^ NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 44 (No. 3) MAY/JUNE 1979 TABLE OF CONTENTS Influence of Training on Growth of Newly-planted Trees Promalin Studies in 1978 and Comments on Trial Use in 1979 Harvesting Early Ripening Apple Cultivars Chemical Thinning of Apples in 1979 Growth Regulator Spray for Growth Suppression on Apple Trees Suggestions on Use of Chemical Thinners on Several Apple Varieties (chart) Alternate vs. Every Middle Spraying for Apple Pests in 1978 INFLUENCE OF TRAINING ON GROWTH OF NEWLY- PLANTED APPLE TREES William J. Lord Department of Plant and Soil Sciences Recommendations for training 1-year-old whips the year of planting have always varied. A pruning bulletin published by the University of Massachusetts in the 1950 's, when trees on seedling roots were being heavily planted, suggested that trees planted early in the spring on good soil required no heading. Other publications suggested that trees should be shortened to a height of 30 inches at planting to cause branch development down to within 18 inches of the ground. At least one publication stated that heading height at planting was relatively unimportant, the important thing being that trees grow well during the first growing season. The more current pruning publications, which include sugges- tions for training trees on the more vigorous of the size-control- ling rootstocks, frequently suggest heading heights of 24 to 30 inches and removal of growth closer than within 18 to 20 inches to the ground. It is now common to find growers heading trees at 24 to 30 inches at planting regardless of variety or whether it is a spur or non-spur type tree. Therefore, we became interested in the influence of training on growth of newly-planted apple trees Heading Height Our studies show (Table 1) that shorter trees produce fewer lateral shoots and spurs but shoot length may be longer in some instances . Table 1. Effects of Heading Height on Growth of Newly-Planted Apple Trees, 1977. Length No. of laterals : Avg. length Total Heading of Spurs of height leader and Shoots shoots Growth shoots (in.) (in.) (in.) (in.) Marshall McIntosh/M7A 51a 57a 34a 39a 39 lib 10a 6a 7b 44a 36 12ab 9a 5a 7b 48a 30 14a 7b 3a 9a 54a Lateral growth more than 2 inches in length. ^Values not followed by a common letter are significantly different at the S% level. 36 ISb^ 10a 5b 7a 30 17a 7b 6a 8a Redspur Delicious/M7A 36 11a 7a 3a 7b 30 13a 4b 3a 9a Redspur Delicious/MMlll -2- Heading height did not influence the number of lateral shoots or the total growth (Table 1) or trunk circumference increase (data not shown) . The influence of heading height on length of leader was not consistent. Although the data in Table 1 shows that heading hei critical in regard to total growth, there are other aspe response to consider. We presently prefer that branches trees be symmetrically arranged around the vertical axis leader tree and be spaced far enough apart to avoid limb when the trees become larger. In contrast, some fruit g prefer having tiers of branches. Regardless, heading a example to 24 inches, can limit the number of permanent ches selected the first growing season to 2 or 3 if vert of 4 to 6 inches are desired. Furthermore, a whorl of c shoots may develop on trees headed at 24 inches which co the leader unless some are removed and/or spread horizon mechanical device such as wooden, snap clothespins. ght was not cts of tree of apple of the central crowding rowing areas tree low, for lateral bran- ical spacings losely-spaced mpete with tally with a We found in 1977 that the lateral shoots on Marshall Mcintosh and Redspur Delicious were more widely spaced on trees headed at 36 inches than those cut at 30 inches at planting. The wider vert- ical spacing could aid in selection of shoots because of our prefer- ence of having trees with branches symmetrically arranged around the vertical axis of the central leader, and with vertical spacings of 4 to 6 inches. Spur-type strains of Mcintosh and Delicious tend to produce short lateral growth the year of planting except dire behind the heading cut, particularly De icious. In some apple growing areas he ing heights of 24 inches are considered necessary on spur-type trees that are t be grown free-standing, to insure the d elopment of the first tier of scaffold limbs within the desired location on th tree. Spur-type trees headed at 36 inc under our conditions, generally produce short lateral shoots the year of planti but this higher heading height presents the opportunity to select more widely-s shoots. Furthermore, we have observed spur-strains headed at this height will duce a good framework of branches durin the 2nd and 3rd growing seasons even th the growth was poor the year of plantin (Figure 1) . ctly 1- ad- o ev- e hes , ng pacec that pro- ough g Figure 1. One of the Redspur Delicious/ MMlll trees used in our heading height study The tree was headed at 36" at planting in 1977. Photograph taken in December, 1978. -3- However, this may not occur in apple growing regions where spur- type trees are very precocious. Fruiting tends to restrict vege- tative growth and will complicate the process of developing frame- work branches on spur-type strains and/or weaker- growing varieties. Removal of Low Lateral Shoots Early vegetative growth of newly-planted trees is made largely from carbohydrate reserves in the woody tissue (the same is true of older trees) . Later in the growing season the carbohydrates formed by photosynthetic activity are translocated and stored in the roots and bark for growth next season. We found in 1977 that growth produced within the vertical distances of 14.5 and 19 inches from ground level on Marshall Mc- intosh and Macoun trees added considerably to the total shoot growth of the tree, particularly on Marshall Mcintosh which produced 2.4 shoots longer than 2 inches within this vertical distance in com- parison to only 0.78 shoots on Macoun. Low heading at planting com- bined with removal of growth within 18 to 20 inches of the ground could produce trees, with little total leaf surface. Leaving low branches until it becomes necessary to remove them could contribute substantially to total growth and carbohydrate reserves for growth the following season. Less distance between the first limb and the ground can be allowed on varieties like Delicious without inter- ferring with mowing and weed control practices because they have an upright growing habit than on varieties like Cortland which have spreading type growth. Limbs on Cortland within 24 inches of the ground begin to give trouble when the trees commence bearing. Recommendations Tree growth will vary considerably the year of planting regard- less of heading height. Vigorous growth is the first and most im- portant step towards the development of well-shaped trees. Good stock in dormant condition, early planting, and favorable soil con- ditions are as fundamental as training. Adjust severity of heading at planting time to the conditions of tree, soil, and season under which planting is done. Under average or better conditions heading at 36 inches on 1-year-old whips should produce satisfactory growth on both spur-type and standard strains. If shoots originating lower than 18 inches above ground level do not interfere with cultural practices, leave them. The leaves on these shoots can contribute to tree growth. Well-branched (feathered) 1-year-old trees are highly desirable. When planting this type of tree, remove only broken branches and remove or restrict shoots with no potential for being a permanent scaffold limb. Head it at approximately 39 inches. -4- Promalin Studies in 1978 and Comments on Trial Use in 1979 Duane W. Greene and William J. Lord Department of Plant and Soil Sciences Promalin* is a plant growth regulator containing gibberellin A. 7 and a cytokinin, 6-benzyladenine , in equal amounts. Its pri- mary use at this time is to increase the length (^/D ratio or typi- ness)l of Delicious apples, thereby making them more attractive to the consumer. Last year we discussed factors affecting shape of apples and our preliminary studies with Promalin (Fruit Notes 43 (3): 4-7). In this article we report our 1978 findings with Promalin and include comments to consider when using it in 1979. 1978 Studies Coverage Growth regulators commonly used in fruit production have limited translocation from the site of contact with the plant. The data in Table 1 indicate that the absorption and/or translocation of Promalin also may be limited. Table 1. The effect of site of Promalin application to'Richared Delicious' apple flowers on the L/d ratios of the fruits that developed from these flowers. Treatment and microliters of solution applied^ L/q Ratio Check .93cy Petals, 25X .94c Petals, 150 .99b Receptacle surface, 25 1.03a In calyx end, 25 1.03a ^Solution contained 50 ppm Promalin plus 0.05% X-77. ^Numbers in a column followed by different letters are significantly different at odds of 19 to 1. ^A 25 microliter droplet was large enough to wet the receptacle surface with no runoff. *Tradename : highei , . ^ . apple. A "typey" Delicious will have an L/d ratio of 1.00 or greater ''^The higher the L/d ratio (length/diameter ratio) the longer the When a 25 microliter droplet of Promalin was placed either in the calyx end of the flower or on the receptacle, fruits with large ^/D ratios were harvested (Table 1). The same amount of Promalin applied on the petals of a flower produced no response. However, when the amount of Promalin applied to the petals was increased 6-fold, fruit elongation occurred. Nevertheless, 150 microliters of Promalin appl- ied on the petals was not as effective for increasing the E,/D ratios of the fruits as 25 microliters of Promalin placed on its receptacle, Therefore, it appears that Promalin must come in contact with the flower parts that are incorporated into the final structure of the apple to be most effective. Surfactants and Adjusting pH of Spray Solution In general, we do not recommend the use of surfactants with growth regulators. Many formulated growth regulators (e.g. Alar-85, Fruitone N, etc.) already contain a surfactant. It doubtful that the addition of another surfactant to the spray mixture would be of sub- stantial benefit. In contrast, the Promalin formulation contains no surfactant. Last year we reported that glyodin and Triton B-1956 (both products that increase wetting) enhanced the response of 'Del- icious' fruits to Promalin Table 2. The effects of surfactants and pH modification on the per- formance of Promalin applied to 'Royal Red Delicious,' Shelburne, MA. , 1978. Treatment' Fruit per cm limb circ. L/D ratio Fruit weight (g) y.ia^ 6.0ab 4.9bc .95c 1.00b 1.04a 154abc 142b 146bc Check Promalin Promalin + Sorba (Mg) + Glyodin Promalin + Sorba (Mg) + Biof ilm Promalin + Buffer-X 4 4 8bc Ic 1.03a 1.02ab 156ab 161a 1 pt of each chemical was used per 100 gal. of water. Treatments applied at a rate of 125 gal/acre at petal fall of the king blossom. ^Numbers in a column, followed by different letters are significantly different at odds of 19 to 1. In 1978 trials we made the Promalin solution more acid (to pH 4.0) with Sorba-Mg2, and added glyodin or Biof ilm (a surfactant). These spray mixtures, with the pH adjusted were more effective in increasing the L/D ratio of the fruits than Promalin applied alone (Table 2) . The mixture containing Promalin and Buffer-X (contains a surfactant and lowers spray pH) produced fruit elongation comparable to Promalin A r nTnmf»"r(^ i 3 1 mi t- -r i p>n1- QTTrav -6- alone. Thus we have demonstrated in both 1976 and 1978 that certain surfactants may increase the effectiveness of Promalin and adjustment of the solution pH appeared to be of additional benefit. Since Pro- malin is a rather expensive product, we feel that the addition of a surfactant to the Promalin spray may allow growers to apply less Promalin per acre or get an enhanced response from that which would normally be applied. Other Observations Warm weather prevailed during the bloom period in 1978. Fruit elongation with an enlargement of the calyx end was apparent 3-4 days after Promalin application. It is not necessary to wait until harvest to determine if Promalin caused increased fruit length in your orchard. Calyx elongation and enlargement is perhaps most pronounced 1-2 weeks after Promalin application. The L/D ratio of fruits will vary considerably on a tree. This is due to the location of the fruit on the tree and their origin within the blossom cluster. The L/d ratio distribution of fruits from untreated and Promalin- treated trees is similar (Figure 1). I .00 L / D RATIO Figure 1 The L/D ratio distribution of fruits from Promalin- treated trees and control trees. 7- This indicates that a Promalin application increases the ^/D ratio of all fruits on the tree equally. Therefore, a grower can expect to find some rather flat-looking Delicious on Promalin- treated trees at harvest time although there should be fewer than on check trees . Delicious is not the only cultivar that can be elongated with Promalin. If pollenizers are located within the rows of Delicious being sprayed you can expect elongation of these fruit also. In- creased length of such cultivars as Mcintosh and Cortland in most cases would not be desirable. Therefore, when applying Promalin attempts should be made to avoid spraying pollenizer trees where increased calyx-end length is not wanted. We observed that the typiness of Delicious was improved re- markably by Promalin throughout Massachusetts in 1978. A response of this magnitude has not occurred every year. It was noted this year that Promalin induced other responses in addition to elongating fruit. Promalin caused thinning on 20-year-old Royal Red Delicious when adjuvenants and a buffering agent were included with the Pro- malin (Table 2) . It is estimated that the crop was reduced slightly below the load considered to be ideal. Promalin does thin young Delicious trees much 'more severely than mature trees. Seed number and fruit diameter were reduced by Promalin in some experiments but these parameters were unaffected in others. No fruit weight increases have been observed in our tests even though they have been shown to occur in other parts of the country. Increased bitter pit and cork spot were observed this year for the first time when excessive rates of Promalin were used. We do not feel that this is a problem that will be encountered under normal circumstances. However, since Promalin did increase bitter pit and cork spot, in situations where low fruit Ca levels may occur, the use of this plant growth regulator may aggravate the problem. Comments on Trial Use in 1979 We do not discourage the use of Promalin. However, we do encourage growers to proceed cautiously and apply Promalin to only a portion of their Delicious trees. As a grower gains more exper- ience with Promalin applied at his location, on his trees, and in his sprayer, and is convinced the response is good and the side affects minimal, then, is the time to move ahead and apply it on a larger portion of his Delicious trees. It is not possible to effectively evaluate the Promalin response (or the response of any other growth regulator) at your orchard without leaving some trees unsprayed. We suggest that 3 or 4 re- presentative trees should be clearly tagged and left unsprayed at 2 or 3 different locations in your orchard. This should provide a valid and unbiased basis for evaluating the effect of Promalin in your orchard. -8- We offer below some comments for your consideration when applying Promalin in 1979. 1. Use 1 pint of Promalin per 100 gallons of spray solution. Apply 125 to 150 gallons of spray per acre. 2. Apply at king blossom to full bloom. If the temperature is not expected to rise above 50OF and warmer weather is predicted within a day or two, delay the application until the first warm day. 3. If the temperature at the time of application is below 60°F, add 1 pint of Glyodin per 100 gallons of Promalin spray mixture. Other surfactants may be equally ctrective. 4. Good coverage is important. Calibrate your sprayer and apply Promalin uniformly throughout the tree. 5. We urge caution if planning to chemically thin trees sprayed with Promalin. Promalin can thin. We do not know if excessive thinning can occur should Promalin and chemical thinners be used the same year. 6. Do not apply Promalin on young trees because thinning may occur. Perhaps a good rule-of- thumb is not to apply this chemical on any trees until it is bearing heavily enough to consider chemical thinning . 7. Do not apply Promalin in combination with other pesticides or growth regulators. HARVESTING EARLY RIPENING APPLE CULTIVARS James E. Anderson Department of Plant and Soil Sciences We have observed a tendency of some growers to advance the picking date for many of the early ripening cultivars. In recent years we have seen Julyred, Vista Bella and Quinte picked in mid- July and Paulared in mid-August. Fruit picked too early are often lacking in color, size and in flavor. Based on observations at the Horticultural Research Station, I would recommend picking Vista Bella during the last week of August and Julyred and Quinte a few days later. Paulared has had better flavor and keeping quality when picked in late August or early September. 9- CHBMICAL THINNING OF APPLES IN 1979 F. W. Southwick Department of Plant and Soil Sciences University of Massachusetts, Amherst When weather conditions during bloom are favorable for bee activity, many apple varieties will overset if they have an abun- dance of blossoms. In such instances, chemical thinning with naphthaleneacetic acid (NAA) , naphthaleneacetamide (NAAm) or car- baryl (Sevin) avoids a tendency toward biennial bearing and also helps increase fruit size and color. It involves some risk since the exact degree of thinning cannot be accurately predicted in advance. Furthermore, it is realized that attempts to determine the time of application of the chemical thinning sprays on the basis of days after petal fall (PF) is not entirely satisfactory. Prevailing temperatures play a primary role in the rate of young foliage and fruit development. If the temperatures are cooler than usual after PF, the time of application should be delayed beyond the suggested treatment period or vice versa if warmer than average temperatures prevail. Weather conditions before and when applying NAA and NAAm are important. If weather conditions are cool and cloudy or rainy a week or two before spraying, the leaves developing during this time will have a very thin cuticle. Under these conditions, NAA or NAAm would penetrate into the leaf more easily and overthinning may occur. On the other hand, warm, dry, sunny conditions prior to spraying would result in a leaf having a thick cuticle that would impede the movement of NAA or NAAm into the leaf. In this case, the concentration used may have to be increased to obtain adequate thinning. Weather conditions before or after application may not greatly affect the thinning action of carbaryl since the fruit is its primary absorption site rather than the leaves as in the case of NAA or NAAm. Light frost which may not injure flowers or young fruits may injure the foliage and the use of NAA or NAAm at this time may cause overthinning and increased foliage injury. There- fore, delay treatment for several days after such occurrences and reduce the spray concentration and gallonage per tree is thinning still seems necessary. In 1978, Mcintosh blossomed quite heavily in Massachusetts and in many cases were not thinned sufficiently to produce as many fruits of good marketable size as desired. Consequently, it would not be surprising if the bloom on such trees in 1979 was only light to moderate and not require much chemical thinning. A grower should carefully observe the fruit set in his Mcintosh blocks 7-14 days after petal- fall (PF) and be reasonably certain that chemical thin- ning of Mcintosh is necessary on the lighter blooming older trees. It should be remembered, however, that trees with a light to moderate bloom may occasionally overset and be more difficult to chemically thin than trees which blossom and set heavily. -10- The use o£ Promalin at full bloom (FB) to improve the "typi- ness" of'Delicious ' (increase the length to diameter ratio o£ the fruit) has been found by Dr. Duane Greene and others to be capable of thinning this variety and its strains. The use of a chemical thinner such as carbaryl (Sevin) following an application of Pro- malin, might result in overthinning , excessive fruit size and a severe yield reduction. 'Delicious' requires freedom from frost damage and ideal crop pollination conditions for good commercial yields. It is not desirable to apply a chemical thinner (carbaryl) or Promalin (which has the potential to reduce fruit set) on young 'Delicious' which invariably set light crops. In blocks of older 'Delicious' trees having a history of oversetting the use of Pro- malin at FB may be entirely satisfactory but the use of carbaryl for thinning should be delayed for at least 14 days after PF so that the need for additional chemical thinning can be reasonably well determined. If a Promalin treatment at FB or adverse weather conditions have already limited the initial fruit set there may be no need to reduce the set further with a post petal-fall appli- cation of carbaryl. 'Delicious' apples are too valuable for such risks. NAA or NAAm thinning sprays applied when the temperature is less than 650F, are usually less effective. Temperatures of 70-75OF are necessary for optimum results. When temperatures rise above 850F, there is a rather sharp increase in NAA or NAAm penetration. If the high temperatures are accompanied by humid conditions that prevent spray droplets from drying rapidly, overthinning may result. In this case, the concentration of the thinning spray should be reduced. Once the foliage has dried after application of these materials, do not respray if rain occurs shortly thereafter. NAA or NAAm are best used alone in dilute form. NAA will often cause more foliage injury and thin more than NAAm or carbaryl. Carbaryl is the least injurious to foliage. Mixing a wetting agent with the thinning chemicals may sometimes increase thinning but invariably increases foliage injury so the addition of a wetting agent is not suggested. Since the best day to apply a treatment cannot be accurately determined in advance, it may be wise to spray a different fraction of the more valuable mid- and late-season varieties at 3 or 4 day intervals during the suggested period. An occasional grower may delay his decision to thin until 3 weeks or more after PF. Apply- ing NAAm or NAA later than 3-4 weeks after PF may result in no thinning and reduced fruit size since these compounds have some temporary fruit size inhibiting action. Carbaryl is usually ineffect- after about 21 days from PF. Most commercial formulations of NAA contain 1.0 gram of NAA per oz. (a few may have 2 grams per oz.). A material containing 1.0 gram per oz. will yield a 10 ppm concentration when 4 oz. per 100 gallons are used. Four oz. of NAAm per 100 gallons will give a concentration of 25 ppm. It is assumed that the carbaryl (Sevin) used is a 50% wettable solution. -11- A 0.21 dust o£ NAA is available for chemical thinning. The dusts should be applied dry on dry foliage under good drying con- ditions to reduce the possibility of foliage injury and overthin- ning. When applied under such conditions, NAA dusts are often less injurious to foliage and may reduce fruit set less than comparable NAA sprays. Young trees generally require less thinning than older trees. If treatment seems necessary, it may be desirable to use the lowest suggested concentration of the chemical thinner, or even reduce this amount by 1/2 to 1/4. Early fruiting on the leader of young trees can seriously affect the shape of the tree. To reduce fruit load until the tree has reached sufficient size to hold a crop of apples, chemically thin at PF with carbaryl, 1 lb. plus 15 ppm NAA. Our suggestions for use of chemical thinners on several apple varieties are included in the chart on the following page! GROWTH REGULATOR SPRAY FOR GROWTH SUPPRESSION ON APPLE TREES Duane Greene and William J. Lord Department of Plant and Soil Sciences Frequently there are blocks of young, non-bearing trees parti- cularly Delicious that are growing too vigorously because of lack _ J- C ■^J1..^ J ^ -: 11,, T „„^^^ +„^„^ ,.,-; 1 1 ^ r^ c- r^ ^-\^a^^ r-^, Young, non-spur trees. Apply 500 ppm ethephon (1-2/3 pints) plus 1500 ppm Alar-85* (1-1/2 lbs.) in 100 gallons of water 10 to 14 days after full bloom or when shoots are 4 to 6 inches long. Young spur trees or older trees with no crop. These trees are more sensitive to a growth regulator spray than young non-spur trees. Therefore, apply 300 ppm ethephon (1 pint) plus 1500 ppm Alar-85* (1-1/2 lbs.) in 100 gallons of water 10 to 14 days after full bloom or when shoots are 4 to 6 inches long. In addition to growth restriction, these growth regulators gen- erally increase bloom the year following their use. Increased bloom probably will of of no value on bearing trees that lost their crop due to frost because bloom should be adequate the following year with- out the use of these growth regulators. However, it may be more dif- ficult to obtain adequate thinning the year following their use because of excessive bloom. Additional bloom because of growth regulators use could be of value on the young, vigorous trees but unfortunately fruit set may not be increased on Delicious. We suggest that the ethephon plus Alar-85* spray not be applied on young trees until they are large enough to bear a crop. *Trade Name 12 en o (— ' ft) n o o Id 3 I h- ' -pi 1^ ^ n fa fu 3 55 B ri- cr 0) < •-h t-h a> n r+ % O 3 fD U) fD fa ►-i r+ H- CD (/I fl. 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J. Prokopy, K. I. Hauschild, W. J. Manning, and T. R. Bardinelli Departments of Entomology and Plant Pathology Earlier, we reported our 1977 findings on the comparative effectiveness of alternate middle vs. every middle spray treat- ments in 3 commercial apple orchards (See Fruit Notes 43 (3): 15-19). Here, we report on our 1978 findings in 4 commercial orchards. The alternate middle treatment involves spraying alternate halves of each tree on alternate spray dates instead of both halves on all spray dates. For example, in applying the first cover spray, the sprayer would be driven up the middle between tree rows A and B and return down the middle between rows C and D, skipping the middle between rows B and C. For the second cover spray, the sprayer would be driven up the middle between rows B and C, down the middle between rows D and E, and so forth. If this pattern were followed with every spray application, it would save 50% of the spray material costs . Each of our 4 test blocks was divided into 2 plots of 2-6 acres each. One plot received the alternate middle program on each spray date from pink (or petal fall) through last cover. The other received the every middle program. Each grower used an air blast sprayer at 4X. He followed his normal spray schedule, and used his own selection of pesticides. Except in one block, all trees were full grown - some on M7 rootstock, others on standard. The centers of the trees were fairly well pruned in all blocks. To determine the extent of insect pest pressure, we hung traps in each plot for monitoring tarnished plant bug, European apple saw- fly, apple maggot, codling moth, redbanded leafroller, and oblique banded leafroller adults (see Fruit Notes 44 (2): 1-2 for information on construction of these traps). We caught the following average numbers per trap: Pest Every middle plots Alternate middle plots Plant Bug 5.8 3.3 Sawfly 1.3 2.5 Apple maggot 2.3 0.8 Codling moth 33.0 39.0 Redbanded 50,8 58.3 Oblique banded 2.3 1.8 These results show that pest pressure from tarnished plant bug, apple maggot, and oblique banded leafroller was greater in the every middle plots, while pressure from sawfly, codling moth, and redbanded leafroller was greater in the alternate middle plots. -14- To determine the amount of fruit injury caused by these and other insect and disease pests, we examined at harvest 100 fruits per tree from 18 trees in each plot. To determine spider mite and aphid abundance on leaves, we examined 45 leaves per tree on 6 trees in each plot every 3 weeks from April until harvest. The following were the results: Avg. % leaves infested with: Every middle plots Alternate middle plots 1.5 Spider mites 6.1 Aphids 3.8 Avg. ^ fruit injured by: Plant bug 0.99 Sawf ly 0.31 Apple maggot 0.02 Plum curculio 0.03 Fruitworm 0.08 Codling moth 0.02 Leafrollers 0.05 Other insects 0 6.5 0.71 0.43 0.04 0.06 0.14 0 0 0 Total insect 1.50 1.38 Apple scab 0.73 1.61 Black rot 0.21 0.19 Other diseases 0.23 0.20 Total disease 1.17 2.00 Grand total 2.67 3.38 The results show that for all blocks combined, an average of 1.50% of harvested fruits in the every middle plots vs. 1.38% in the alternate middle plots was injured by insects. Thus, even with slightly higher pest pressure from sawfly, codling moth, and oblique banded leafroller, the alternate middle plots averaged slightly less total insect injury to fruits. The results also show that an average of 1.17% of harvested fruits in the every middle plots vs. 2.00% in the alternate middle plots was injured by disease. This difference was due largely to one incidence wherein a grower failed to apply a needed spray for apple scab, and suffered 5.67% fruit scab in the alternate middle plot vs. 2.83% in the every middle plot. This suggests that proper timing of fungicide sprays is very important to the success of an alternate middle program. Every Alternate middle middle plots plots Difference 191.56 95.78 -95.78 12.25 6.13 -6.12 5.50 2.75 -2.75 -15- The following is the cost-benefit analysis of the every vs alternate middle treatments: Dollar costs/acre Insecticide, miticide, and fungicide spray materials Labor (3.50/hr.) Fuel, etc. Value of fruit loss owing to insect and disease injury 67.29 82.39 +15.10 Cost reduction due to alternate middle spraying -89.55 This analysis shows that the decreased amount of pesticide applied, combined with consequent lower cost of fuel and labor for application of pesticides, even with a slightly greater total percentage of injured fruits at harvest (3.38% in the alternate middle vs. 2.67% in the every middle plots) resulted in an overall net benefit (savings) of $89.55 per acre in the alternate middle compared with every middle plots . In summary, our findings to date show that the alternate middle spray program can result in greatly reduced pesticide usage, effect- ive pest control, and a greater net profit to the grower. For those growers interested in trying out the program, we would suggest start- ing with a one or two-acre block to see how the program works with your particular type of sprayer and trees, and under your particular local insect, mite, and disease conditions. We would advise against submitting large acreage to this program until you (and we) learn more about the program's long-term effectiveness and possible short- comings. Present knowledge suggests that the program works best where the trees are well pruned (open centers) and spaced at recommended intervals (not wider) . ***************** All pesticides listed in this publication are registered and cleared for suggested uses according to Federal registrations and State Laws and regulations in effect on the date of this publication. When trade names are used for identification, no product endorse- ment is implied, nor is discrimination intended against similar materials . Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, $300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 44 (No. 4) JULY/ AUGUST 1979 TABLE OF CONTENTS Brown-Line Decline of Apple Poor Apple Growth Disease in Massachusetts Coating the Trunks of Fruit Trees to Reduce Winter Injury Photographs of Nutrient Deficiences Further Observations of Tree Performance on M.26 Use of Ethephon to Promote Color and Ripening of Apples in Massachusetts Pomological Paragraph BROWN- LINE DECLINE OF APPLE Daniel R. Cooley/ Ted R. Bardinelli,"'" 2 and William J. Manning Department of Plant Pathology A new disease of young apple trees has become evident in the Northeast in recent years. The disease is called brown-line or graft union necrosis. Isolated trees in young plantings decline suddenly, may appear to be girdled, and can be snapped off at the point of union between scion ana rootstocK. A distinct brown-line IS evident at tne point of graft union. Researchers in New York State were able to determine that the problem occurs most often when MM106 is used as a rootstock and that it often originates in the nursery. Tomato ringspot virus (TmRSV) was isolated from diseased trees. The dagger nematode, Xiphenema americanum,was also associated with the problem. TmRSV and the dagger nematode together appear to cause brown-line decline. TmRSV is found in many plants including raspberry, grape, elder- berry, florist's geranium, and many common weeds such as dandelion, chickweed and plantains. The dagger nematode feeds on the roots of infected plants and carries virus particles to clean non-infected roots, where new virus infections are initiated. , Rootstocks and cultivars differ in their sensitivity to TmRSV. Some are tolerant and can carry the virus without showing symptoms or decline. Sensitive plants decline and die over a prolonged period. Hypersensitive plants respond to TmRSV infections by rapid destruction of cells near the point of infection. This prevents the virus from spreading further into the plant. Dr. James Cummins (Cornell University) believes that union necrosis results when a tolerant rootstock and a hypersensitive scion become infected with TmRSV. MM. 106 is highly tolerant to TmRSV and is usually symptomless. A number of apple cultivars, particularly Red Delicious, are hypersensitive to TmRSV. When the virus from the rootstock comes in contact with the hypersensitive scion, the scion reacts by killing its cells at the graft union. The result is a brown line at the graft union which prevents water and nutrient translocation into the scion. The scion dies and is easily broken off at the graft union. Cummins has rated a number of apple cultivars for brown-line sensitivity and rate of decline when grown on MM. 106. Some show 1 2 Extension Technicians, and Associate Professor, respectively. Department of Plant Pathology, University of Massachusetts, Amherst 01003 -2- rapid decline, some slow decline and others no decline at all. His rating is as follows: Rapid decline Slow decline None Jerseymac Idared Cortland Quinte Mcintosh Empire Red Delicious Spartan Golden Delicious Rhode Island Greening Stayman Rome Beauty Tydeman ' s Red York Imperial Those in the slow decline group may show increased suscepti- bility to other diseases. Stress caused by TmRSV may be a factor in predisposing trees to collar rot, caused by the fungus Phyto- phthora cactorum. A detection system for TmRSV has been developed, which can be used to detect the virus before brown-line develops. The test takes a day to complete and is useful as an advanced warning of potential problems. Inarch grafting is one possible way to prolong the life of trees with brown-line decline. Wood from a rootstock other than MM. 106 can be used to supply the aerial portions of the tree with nutrients and water. Nurseries have made considerable efforts to eliminate TmRSV, principally by means of soil fumigation to eliminate the dagger nematode. Proper site preparation by growers is also very helpful Elimination of weeds and fallowing a year before planting will help to reduce nematodes in new orchard sites. Note to Massachusetts Fruit Growers: If you suspect that you have a brown-line decline problem, please contact Dr. William J. Manning, Department of Plant Path- ology, University of Massachusetts, Amherst, 01003. POOR APPLE GROWTH DISEASE IN MASSACHUSETTS 1 2 William J. Manning, Daniel R. Cooley, and Ted R. Bardinelli^ Department of Plant Pathology Poor Apple Growth Disease (PAGD) is a new name for an old problem. It refers to poor growth or even death of newly-planted trees, whether planted in old orchard sites or in new orchard sites (especially those formerly in woodland). Scattered trees, or trees in small areas may make little growth and die during the first season. Adjacent trees may be vigorous and healthy. When new trees do not die, they differ in both size and vigor. The exact cause of PAGD is unknown. It is probably due to a combination of factors, both biological and physical. It is well-known that poorly-drained locations, and those high in or- ganic matter, especially the remains of old apple root systems, are especially subject to PAGD. Certain rootstocks, notably MM106, are also more susceptible to PAGD. A number of nematodes also contribute to PAGD. A team of scientists at the East Mailing Research Station in England feel that PAGD there is caused by the common soilborne fungus Pythium. Pythium does well in cool moist or wet soils that are high in organic matter. Dr. Geoffrey Sewell, of EMRS , feels that Pythium produces a toxic exudate in soil. This in- hibits root hair growth and function and this in turn affects the growth and extension of root tips. Growth of affected trees is considerably reduced. We investigated PAGD in 6 new orchards in Massachusetts last year. Red Delicious, Jerseymac and Mcintosh on M.7A, MM. Ill, M.26, and MM. 106 rootstocks were involved. The trees came from different nurseries in different parts of the country. We brought typical PAGD trees as well as soil from around their roots back to the laboratory and greenhouse. In the laboratory, we isolated the following potential root disease fungi: Cylindro- carpon, Cylindrocladium, Fusarium,Pythium,Rhizoctonia, and Verti- cillium. These are being used in the greenhouse to determine whether or not they can cause PAGD in apple rootstocks. Apple rootstocks have been planted in these soil samples in the green- house to allow us to follow PAGD under controlled conditions. We do not know what causes PAGD in Massachusetts. We plan to continue our laboratory and greenhouse investigations and to begin field studies in 1979. Note to Massachusetts Fruit Growers: If you have suspected PAGD problems, please contact Dr. William J. Manning, Department of Plant Pathology, University of Massachusetts, Amherst, 01003. 1 2 Associate Professor, and Extension Technicians, respectively. Department of Plant Pathology, University of Massachusetts', Amherst 4- COATING THE TRUNKS OF FRUIT TREES TO REDUCE WINTER INJURY William J. Lord Department o£ Plant and Soil Sciences Growers apply white latex paint to trunks of fruit trees to help prevent winter injury. An application to the south side of trunks and to the base of lower scaffold limbs reduces the amount of heat absorbed by the bark, lessens bark- splitting, and reduces winter injury to crotches of painted branches. Use only latex water soluble paint. Do not use oil or lead base paints soluble in paint thinner or turpentine. We have found that Glidden 3600 and Kyanize Flat White Latex Paint No. 2000, which are available in Massachusetts are safe to use. However, most high quality exterior latex paints are probably suitable. Nevertheless, they should be tested on a few trees before extensive use because some paints can be toxic, particularly to young peach trees, causing discoloration and cracking of bark and later, gum- mosis . The latex paint may be used either without dilution or as 501 dilution with water. It may be applied using a car wash mitt with a rubber glove insert, a paint roller, paint brush, or a com- pressed sprayer (if diluted). When wearing a car washing mitt, dip your hand into the paint and rub the mitt on the bark. When painting the lower scaffold limbs apply the latex in the crotches and out on the limbs for a distance of 6 to 10 inches Whitewash may also be used to coat tree trunks and branches. It is more economical than latex and can be applied as a spray. However, the durability of whitewash will be less than latex although some formulations of white wash are more durable than others . Whitewashes that are used in dairy barns and contain no insecticides or fungicides or contain an insecticide for fly con- trol are available from farm supply stores. Application in late fall seems logical because the fruit has been harvested and con- tamination of leaves is of no concern. ******************** PHOTOGRAPHS OF NUTRIENT DEFICIENCES William J. Lord Department of Plant and Soil Sciences Nitrogen and calcium are the elements of greatest concern in Massachusetts orchards. Nevertheless, each year the levels of other elements are either excessive or deficient in some orchards. The May/June, 1978 issue of Fruit Notes contained photographs and brief -5- descriptions o£ bitter pit and cork spot on apples, magnesium (Mg) deficiency symptoms on pear leaves, manganese (Mn) deficiency and toxicity symptoms on apple leaves and wood, and boron (B) toxicity symptoms on apple leaves. For your information we have included below photographs and brief descriptions of Mg and potassium (K) deficiency symptoms on apple leaves and symptoms of B deficiency on the fruit of Bosc pears. Mg Deficiency of Apple *■ Pictured on the left is Mg de- ficiency symptoms on apple leaves. Deficiency symptoms are characterized necrotic (brown) areas between the veins. The older, basal leaves on shoots and spurs are usually affected first, and as the season progresses the injury symptoms appear on the younger leaves. The deficiency symp- toms frequently become apparent in late July and early August. By late summer, the shoots on which leaves show Mg deficiency may be defoliated except for a few leaves near their terminals. Mg deficiency increases fruit drop at harvest. We consider the optimum levels of Mg in leaves to be 0.25 to 0.401. Symptoms of Mg deficiency are infre- quent in comparison with 15 to 20 years ago. Nevertheless, our leaf analysis show that levels are frequently belov/ 0.30%. Thereby, the use of high magnesium lime which has been advo- cated for years, continues to be needed in our orchards. K Deficiency of Apple Figure 2 shows leaf margin burn caused by K deficiency. This symptom can be easily confused with the leaf margin burn from calcium chloride sprays. However, unlike leaf burn from calcium chloride sprays, the scorch of leaf margins due to K deficiency progresses from the older leaves to the younger leaves of cur- rent season shoots as the season advances. The scorch may turn gray in color and leaf fall may occur late in the growing season. Never- theless, in 2 instances leaf analysis was necessary 6- in 1978 to confirm that the problem was K deficiency rather than CaClo burn, B Deficiency of Pear Occasionally B defic- iency is so acute in pear trees that the fruits be- come malformed and cracked (Figure 3) . Soil appli- cations of 13 at the rate suggested for apples is effective for preventing a shortage of this element in pear trees. ******************** FURTHER OBSERVATIONS OF TREE PERFORMANCE ON M.26 William J. Lord Department of Plant and Soil Sciences The 1976 Apple Tree Survey indicated that 8% of the trees in Massachusetts on size-controlling rootstocks are on M.26. Thus, this rootstock is common enough for us to observe its performance under a wide variety of soil and cultural conditions. Trees on M.26 react more to unfavorable growing conditions than those on more vigorous size-controlling rootstocks. Trees within a block may be extremely variable in vigor, with some of them being weak and/or difficult to train (assuming all the trees are on M.26). Spur-type trees appear weak when planted on light soils (Figure 1) , and so do Cortland trees on this rootstock. The leaders of trees on M.26 often are "droopy" on non-bearing trees, and these trees tend to lean more frequently than trees on other rootstocks (Figure 2) . We suggest providing support for the more troublesome trees rather than trying to correct the problem with severe pruning. The objective is to maintain a central leader until the desired tree height is obtained. -7- Early, heavy bearing is causing weak growth in some instances Reduction o£ crop load by hand thinning rather than by chemical thinning appears to be the best solution to this problem because tree vigor varies considerably within a block. At present, we have not seen or heard o£ any problems with fire blight associated with M.26. Figure 1 to the left shows a six-year-old Macspur on M,26 The trees in this block are planted 14 feet x 18 feet. It is obvious that on this site the planting distance is too wide and that the trees have low vigor. In 1976 we planted a block of Rogers Mcintosh and Gardner Deli- cious (a standard- type strain) on MM. 106, M.7, and M.26 in heavy soil. The trees on M.26 are very vigorous in comparison to most blocks in Massachusetts on this rootstock. Mcintosh but not Delicious were significantly smaller in 1978 on M.26 in comparison to those on M.M.106 and M.7 rootstocks (Table 1). Mcintosh produced about 0.1 of a bushel per tree in 1978 regardless of rootstock. The Delicious had a light bloom but produced no fruit. Growers establishing plantings on M.26 will have to be more selective of soils than in the past. Shallow soils, with hardpans that prevent deep rooting, are producing trees that look like "free- standing M.9's" and the trees are subject to frost heaving. Trees on M.26 require good deep soils to good drainage and waterhold- ing capacity and even on these soils they will appear to require temporary support or permanent support on some sites. ^Ct. Figure 2 to the left shows trees on M.26 with poor an- chorage. Many o£ these trees in this orchard are now staked for support. Table 1. Growth and Yield of Rogers Mcintosh and Gardner Delicious at the Horticultural Research Center, Belchertown, MA., 1978. Bloom/cm Yield Trunk Variety Rootstock trunk circumference (bushels) circumference Mcintosh M.26 4.64a^ 0.11a 11.7b M.7 6.89a 0.12a 12.7a MT4.106 6.02a 0.12a 13.2a Delicious M.26 0.99b 0.00b 10.5c M.7 0.26b 0.00b 11.6b MM. 106 0.2 3b 0.00b 10.8bc Mean in columns not having letters in common are significantly differ- ent at the 51 level. -9- USE OF ETHEPHON TO PROMOTE COLOR AND RIPENING OF APPLES IN MASSACHUSETTS W. J. Lord and D. W. Greene The use of ethephon on early maturing varieties and Mcintosh to stimulate red color development, increase soluble solids (sugar content) , and hasten fruit maturity is now a standard practice in many orchards. However , ethephon must be used with caution. The mis-use of ethephon or an unavoidable delay in the harvest of ethe- phon-treated fruit could intensify our current problems of supply management and poor fruit condition. The placement in marketing channels of an excessive volume of ethephon- treated 'Mcintosh' apples that must be sold quickly because of over-maturity could depress prices . Successful Use of Ethephon Ethephon will not completely overcome conditions unfavorable for development of red color. Ethephon, at 1/4 or 1/2 pint may add 10 to 30% red color to 'Mcintosh' apples borne on the periphery of the trees within 7 or 8 days after application. Ethephon at 1/4 pint may promote as much fruit color as a 1/2 pint and will cause less fruit softening. Under conditions that are normally associated with poor fruit color, such as high temperatures, wet and cloudy weather, excessive vigor or dense trees, ethephon- treated fruit may not develop suffic- ient red color (50% of the surface having red color typical of the variety) within 7 or 8 days after application. Furthermore, on both young and older trees, ethephon may not bring the fruit in the interior of the tree up to a satisfactory level within 7 days after treatment. When the fruit are allowed to remain longer on the tree, however, the color difference becomes greater between the ethephon- sprayed interior fruit and the non-sprayed interior fruit. It is of interest to note that 11 days after an ethephon spray (1/2 pt/100 gals of water) in 1974, 66% of the interior fruit on 10-year-old trees had typical red color and would have graded U.S. Extra Fancy. On the other hand, none of the interior fruit on the check trees would have graded U.S. Extra Fancy due to lack of sufficient red color. By the time the ethephon fruits in the interior of most trees obtain adequate color, they will probably be suitable only for juice or immediate sale because of excessive loss of firmness. The pro- blem of obtaining adequate color on the interior of large dense trees can be corrected somewhat by pulling the water sprouts during the summer and doing some light summer pruning. These procedures should be followed by spot picking which will lighten the crop load and permit better light penetration into the interior of the tree before the application of an ethephon spray. 10- Use on early maturing varieties. Ethephon is a very useful tool on early varieties. In general, a single application applied 7-10 days before normal harvest at 1/2 pint per 100 gallons of water will increase red color development within 4-5 days. Ethephon has been used extensively on Early Mcintosh, Puritan and Milton varities by Massachusetts growers with good results. Rate of color development differs from year to year and block to block among orchards. Within a block of trees, the red color gen- erally develops more slowly on the earliest sprayed trees than those sprayed nearer to the normal harvest date. This shows that color develops more quickly in some instances than others and that there is no substitute for a careful daily check of trees. Early varieties usually ripen unevenly. Therefore, it may be advisable, for some varieties to make one picking to remove the riper fruit and then apply ethephon. This should help minimize the problem of over-ripe fruit at harvest. Some growers may want to apply ethephon, then pick the ripe fruit that day, or 1 or 2 days later. Although the ethephon label does not state a specific interval between application and harvest, the practice of spraying and harvesting within 2 days of application is not recommenc ed. Harvesting all the mature fruit and then applying the ethephon to the remaining fruit on the tree is the preferred practice. Ethe- phon applied alone accelerates fruit drop. Therefore, naphthalene- acetic acid (NAA) should be used with the ethephon to counteract this abscission effect. Use on 'Mcintosh' . Our suggestions are based on 3 time periods for sale of ethephon- treated 'Mcintosh' fruits -- prior to normal harvest time (Labor Day or shortly after), during normal harvest, and after several months of storage (Table 1) . The volume of fruits sprayed with ethephon should be based upon anticipated sales during one or more of these sale periods. The harvest of ethephon- treated fruit must not interfere with the timely harvest of fruit for CA since the placement of ethephon- treated fruit in this type of storage is not recommended. Our data and those from a regional experiment involving New York, Maine and Massachusetts, show that ethephon- treated fruit which still are in good condition will store satisfacotrily in CA, but we are concerned that apples not in good condition will be stored. However, if labor difficulties worsen, it may be necessary to extend the harvest season by advancing it through the judicious use of ethephon on CA 'Mcintosh'. Fruit to be placed in storage at 32 F must be picked at proper maturity. Fruit to be sold through January 1, should receive no more than 1/4 pint of ethephon per 100 gallons of water and be harvested 7-8 days after treatment. Although these fruit should store well until January 1, they may be softer than Alar*- treated fruit. 'Alar = Alar-85* -11 Table 1. Suggested use of ethephon for promoting uniform ripening and red color on 'Mcintosh' apple trees. Purpose Compound, timing and rate Fruit for sale 1st or 2nd week of September Alar* - mid-July at 1 lb/100 gals ethephon - 8 to 12 days prior to anticipated harvest at 2/3 to 1 pt/100 gals plus 2,4,5-TP same timing as ethephon at 20 ppm Fruit to be picked during normal har- vest and held at 32 F in air for 1 month or less Alar* - mid-July at 1 lb/100 gals plus ethephon - 7 to 8 days prior to anticipated harvest at 1/2 to 2/3 pt/100 gals plus NAA or 2,4,5-TP same timing as ethepon spray at 20 ppmX Fruit to be picked during normal har- vest and held at 320F in air as late as January 1^ Alar* - mid-July at 1 lb/100 gals plus ethephon - 7 to 8 days prior to anticipated harvest at 1/4 pt/100 gals plus NAA at 20 ppm or 2,4,5-TP at 10 ppm same timing as ethephon spray Weather and tree vigor, etc. affect color development. It may be best to allow 12 days, but be prepared to harvest sooner. y 2,4,-5TP is preferred if 2/3 pt of ethephon is used because its pre- harvest drop control capability is greater than that of NAA. X If fruit are in good condition, they will store satisfactorily in CA. *Alar = Alar-85* ******************** POMOLOGICAL PARAGRAPH Some apple growers are planning to use foliar sprays of nutraphos* or calcium nitrate in June. We recommend that they switch to calcium chloride in July and August in order to supply adequate calcium to their apples. Please refer to page 11 of the March/April 1979 issue of Fruit Notes for our recommendations on timings and rate of calcium chloride applications on apple trees. Cooperative Extension Service University of Massachusetts Amherst. Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 44 (No. 5) September / October 1979 TABLE OF CONTENTS A Preliminary Evaluation of Labor Productivity in Grading and Packing Mcintosh Apples Grown Under Integrated Pest Management Conditions Toxicity of Orchard Pesticides to the Mite Predator Amblyseius Fallacis 1979 Results Propagating Your Own Fruit Trees Some Problems Than Can Reduce Storageability of Apples Pomological Paragraph Mailing List Revision A PRELIMINARY EVALUATION OF LABOR PRODUCTIVITY IN GRADING AND PACKING MCINTOSH APPLES GROWN UNDER INTEGRATED PEST MANAGEMENT CONDITIONS Henry M. Bahn Extension Specialist in Farm Management Department of Food and Resource Economics University o£ Massachusetts, Amherst In 1978 a pilot program o£ integrated management for apple pests was initiated in Massachusetts. Developed by the Coopera- tive Extension Service and Departments of Entomology and Plant Pathology, the program was designed to reduce pesticide usage while maintaining high quality fruit production. Selective pest management may result in lower production costs for pesticides, equipment and labor but may also result in higher grading and pack- ing costs and less marketable fruit due to increased damage levels. The 1979 summary for the Integrated Pest Management (IPM) pro- gram cited net benefits to the participating producers. It is un- clear, however, whether changes in insect and disease damage levels as a result of incorporating IPM growing methods will affect grading and packing costs. Studies in Michigan, the Appalachian area, and Washington State have all indicated that quality of fruit is a major influence on grading and sorting costs. Because the hand packing method is specific to the Northeast, a thorough packing cost analysis should be undertaken. V/e plan to undertake such a study in Spring, 1980. Meanwhile, preliminary applied study of the relationship between damaged fruit and grading/ packing costs was completed in Spring, 1979. By monitoring and comparing the actual packing time requirements for Mcintosh apples grown under IPM and conventional practices, some measurement of differences in labor productivity in grading and handling was est- abl ished. Yields and size of fruit produced have not been found to be significantly affected by growing under IPM methods. The major difference between IPM and conventional practices is expected to be in the quality of harvested fruit, i.e., levels of insect and disease damage. For the Massachusetts IPM pilot study, comparative data are not available for disease damage levels, but insect damage was reduced from 4.721 in the controls to 2.64% in the IPM samples. This reduction was not expected but it should be noted that this finding is based on only one year's data and a relatively small sample . Methods and Procedures To compare IPM versus conventional fruit packing costs and labor productivity, several orchards which participated in the 1978 IPM pilot program were sampled during IPM and conventional packing operations. The quantity of orchard run apples handled, culls -2- removed and quality of daily packout were noted. Total labor requirements for each day's operation for direct labor components were monitored. A simple comparison of labor productivity and labor costs was made for the two types of apples. This analysis did not identify total packing costs for either IPM or conventional fruit, but rather, the relative difference in labor productivity and costs. Results The results of the comparative analysis indicate that (1) IPM apples sampled had a higher sortout (cull) rate than the control fruit, i.e., a larger percentage of the control apples was packed as extra fancy or fancy; and (2) IPM fruit required more time per bushel for grading/packing and had correspondingly higher grading and packing costs. Fruit Injury Levels Participating IPM and check orchards were monitored throughout the 1978 growing and harvesting season. Numbers of spray applicat- ions, dosages, pest populations and injury levels were recorded. A review of the records for the orchards sampled for this study indicates that IPM blocks sustained an average of 4.6°o pest-injured fruit, while control blocks sustained 4.0% injury. Thus, the pest injury rate was 16.7% higher for the IPM fruit for the sampled orchards. For a pack of 1,000 bushels, this difference would result in 6.6 extra bushels of damaged fruit for the IPM samples. Labor Requirements A typical hand packing line for Mcintosh apples would consist of six packer/graders, a worker to supply fruit to the line and to supervise, and a carton handler to fasten and remove filled cartons. Alternatively, all activities other than grading/packing could be undertaken by one individual. Table 1 depicts the average workday for the packing lines sampled. The workday is typically 7.5 hours with a half hour lunch break and morning and afternoon breaks of 10 to 15 minutes. Although workers are paid for the 7.5 hour workday, the packing line is not operated during lunch and rest breaks. These idle periods were sub- tracted to determine the actual number of worker hours available per day. 3- Table 1. Average labor requirements -- Mcintosh apple hand grading and packing. Packing Line Operation Workday 7.5 0 hours Less lunch break @ .5 hrs. .50 Less rest breaks 2 @ .234 hrs. . 47 Packing Line Operation 6.53 hours Personnel Requirements IPM Grader/Packers 5.8^ each @ 6.53 hrs. 37.87 hours Supervisor/Carton Handlers 1.2^ each @ 6.53 hrs. 7.84 Total Worker Hours Per Day 45.71 hours Control z Grader/Packer 5 each @ 6.53 hrs. 32,65 hours Supervisor/Carton Handlers 1.2^ each @ 6.53 hrs. 7.84 Total Worker Hours Per Day 40.49 hours Fractional number of workers is due to averaging data from all sampled packing houses. According to Table 1, the IPM packing line used a larger number of grader/packers (average of 5.8) than the control (average of 5). Ordinarily, the number of grader/packers would be the same. However, on the same days the samples were taken, several control packing lines were not operating at full grader/packer capacity. The problem does not affect the comparison of labor productiv- ity for grader/packers, since productivity is based on volumne of apples packed. The supervisor/carton handler's productivity will be lower for the control fruit, however, since all packing lines were operating at normal levels for these personnel. Labor Costs The calculations for labor costs presented in Table 2 are straightforward, being merely the average wage rates on a per hour basis for the normal 7.5 hour workday.!/ In those cases where a premium or piece rate was paid, the wage rates were based on estimated hourly averages for grader/packers for each packing line. Table 2. Average daily direct labor costs -- Mcintosh apple hand grading and packing. IPM ~~ Grader/Packers 5.8^ each @ $3.42 x 7.5 hrs. $148.77 Supervisor/Carton Handlers 1.2^ each (? $6.29 x 7.5 hrs . 56.61 Total Direct Labor Costs $205.38 Control Grader/Packers 5 each @ $3.42 x 7.5 hrs. $128.25 Supervisor/Carton Handlers 1.2 each @ $6.29 x 7.5 hrs . 56 . 61 Total Direct Labor Costs $184.86 ^Fractional number of workers is due to averaging data from all sampled packing houses. Comparative Results After computing average labor requirements and costs, a comparison was made based on the number of bushels of fruit dumped and packed. In every case, the grader/packer cost for IPM fruit exceeded the cost for control fruit. This caused total direct packing costs to be higher for IPM apples in each case. Super- visor/carton handler costs, on the other hand, were less for IPM apples. This stems from the fact that the control packing lines had less grader/packers working and therefore dumped fewer apples. -'The direct labor costs used here do not include fringe benefits, taxes or insurance payments. Control 189, .0 23. ,0 87, .83 .244 • 197 047 -5- The supervisor/carton handlers for the control packing lines were, in effect, underemployed since those lines were operating at less than normal capacity. Average comparison data are presented in Table 3. Table 3. Comparison of labor productivity in grading and packing IPM pnd control Mcintosh apples.^ Activity IPM Apples Dumped (bu.) 204.0 Sortouts (bu.)^ 29.4 Packout (I) 85.58 Labor (hrs. per bu. packed) .262 Grader/Packers .217 Supervisor/Carton Handlers .045 Labor Cost ($ per bu. packed) 1.176 1.113 Grader/Packers .852 .773 Supervisor/Carton Handlers .324 .340 z Average data for all packing operations sampled. y Includes utility grade and culls. The IPM apples exhibited a sortout rate 18.4% higher than the control fruit sampled. This is only slightly higher than the difference between pest injury levels discussed earlier (16.7%). The difference may be due to more critical inspection by the grader/ packers, some unidentified deterioration of the IPM fruit during storage, or sampling error since the control fruit packed was not necessarily the control fruit monitored during growing and harvest. The grading/packing operation took slightly over 10% longer per bushel packed for the IPM apples. The Washington State study mention- ed earlier found that grading time increased as cull rates increased. The study results presented in Table 3 are consistent with those findings . By implication, if grading/packing time per bushel packed in- creases, grading/packing costs should increase relatively. Such an increase in costs was observed, being just over 10% higher per bushel for the IPM fruit than for the control sample. Implications and Conclusions The data analyzed in this study add support to the hypothesis that grading/packing costs increase as insect and disease injury rates increase. Conversely, higher quality fruit is expected to have lower overall grading and packing costs. The scope of this study is severely limited by the small sample size involved. A very small number of participating grov;ers were sampled and multiple observations were made of some participants. Thus, the data are subject to bias and should be considered as only preliminary results. Because of these limitations, management con- clusions should not be based on this report. A more complete sample should be taken on the apples grown in 1979 and a more soph- isticated statistical analysis should be undertaken to identify relationships between fruit injury levels and grading/packing costs. On a general level, however, labor productivity of graders and packers does appear to be lower for IPM grown apples. Higher quality fruit, with the accompanying lower cull rates, can apparently be packed more quickly and at loxver per bushel direct costs than fruit with a higher incidence of pest damage. Future research is needed to determine a break-even point between production cost savings of integrated pest management programs and possible increases in packing costs due to increased pest injury. ********** TOXICITY OF ORCHARD PESTICIDES TO THE MITE PREDATOR AMBLYSEIUS FALLACIS-1979 RESULTS Robert G. Hislop and Ronald J. Prokopy Department of Entomology, Femald Hall University of Massachusetts Amblyseius fallacis is the most important predator of red and two-spotted mites in commercial apple orchards in Massachusetts. It was found in 23 out of 26 such orchards surveyed by us in 1976. During the past three years we have been assessing the impact of pesticides on the survival of A. fallacis in orchards (Fruit Notes 45 (4): 5-8) as well as in the laboratory (Fruit Notes 45 (5): 14-18). We discovered that this predator can readily survive some key pesticides such as Guthion (azinphosmethyl) and Imidan (phosmet) at recommended concentrations, but is highly susceptible to certain other pesticides. For example, Zolone (phosalone) at recommended rates virtually decimated field populations of A. fallacis , thereby creating large spider mite outbreaks. Here, ive summarize our most recent laboratory results, which deal with pesticides not heretofore tested on a Massachusetts strain of A. fallacis . Two of the insecticides tested (the synthetic pyrethroids Pydrin and Pounce) have experimental permits only; we screened them to determine their effects should they become available for possible future use in integrated pest management programs in Massachusetts. Because A. fallacis spends considerable time in the orchard understory, especially m spring and early summer, careless use of herbicides can be highly detrimental to predator populations. This is the reason for inclusion of herbicides in our pesticide screen- ing program. Methods As in our previous laboratory trials, we employed here the slide dip assay technique in which A. fallacis adults (Bishop strain) were dipped into orchard concentrations of pesticide. As before, we determined the percent mortality 48 hours after dipping. Results The results are presented in Table 1. Insecticides which proved highly toxic (70-100-0 mortality) to A. fallacis were Lannate (methomyl) 1.8 EC, Cygon (dimethoate) 2.7 EC, Pydrin ^f envalarate) 2.4 EC, and Pounce (permethrin) 3.2 EC. Penncap M (parathion) 2 FM was within our range of low toxicity (0-30% mortality). Although A. fallacis has received little exposure to Penncap M in Massachusetts, this low toxicity could very well have been pre-selected by long- term exposure of A. fallacis to such chemically closely related mater- ials as Imidan (pEosmet) 50 WP and Guthion (azinphosmethyl) 50 WP . The high toxicity of the first four materials does not favor their use in integrated pest management programs. The fungicide Karathane (dinocap) 25 WP was within the moder- ately toxic range (30-70% mortality), while Polyram 80 WP, Phygon XL (dichlone) 50 WP and Manzate D 80 WP were of low toxicity. Of these materials, only Karathane would be likely to have a negative impact on orchard populations of A. fallacis . Of the herbicides tested, Ammate X (ammonium sulfamate) was highly toxic to A. fallacis , while Dowpon M (dalapon) was of low toxicity. Dowpon M and Princep (simazine) 80 WP (see Fruit Notes 43 (5): 14-18) are thus the herbicides recommended for use in inte- grated pest management programs. When applying herbicides, be care- full to preserve at least 50% ground cover under the trees to provide -8- a habitat suitable for A. fallacis buildup. With these results, the list of pesticides now known to have highly toxic effects (at recommended orchard rates) on Massachusetts strains of A. fallacis includes Zolone (phosalone) Systox (demeton) 6 EC, Sevin (carbaryl) 50 WP, Diazinon 50 WP, Lannate, Cygon, Pydrin, Pounce, Carzol (formetenate hydrochloride) 92 SP, Paraquat CL (paraquat). Roundup (glyphosate) and Ammate X. (Also, (benomyl) 50 WP has strong anti-reproductive effects on A. fallacis) . Those known to have moderately toxic effects include Phosphamidon (dimecron) 8 EC, Kelthane (dicofol) 35 WP, and Karathane. Until we learn more about possible ways in which the detrimental effects of these materials can be reduced, we discourage their use by orchard- ists aiming at an integrated program of spider mite management except where needed in emergency situations, such as San Jose scale or tentiform leafminer outbreaks. Table 1. Toxicity of pesticides to Amblyseius fallacis (Bishop strain) at recommended orchard rates . Material Rate/100 gals. Mortality, ^o Toxicity Rating INSECTICIDES Lannate [methomyl) 1.8 EC Cygon (dimethoate) 2 . 7 EC Pydrin (f envalarate) 2.4 EC Pounce (permethrin) 3.2 EC Penncap M (parathion) 2 FM FUNGICIDES Karathane (dinocap) 25 WD Polyram 80 WP Phygon XL (dichlone) 50 WP Manzate D 80 WP HERBICIDES Ammate X ["ammonium sulfamate) Dowpon M (dalapon) 0.5 pt. 100 High 1.0 pt. 96 High 2.6 oz. 100 High 2.1 oz. 100 High 2.0 pts. 12 Low 0.5 lb. 46 Moderate 1.5 lbs. 7 Low 0.5 lb. 5 Low 1.5 lbs. 8 Low 60 lbs. 78 High 2.5 lbs. 26 Low -9- PROPAGATING YOUR OWN FRUIT TREES James F. Anderson Department of Plant and Soil Sciences Fruit growers in many areas o£ the country have experienced difficulty in obtaining nursery trees. I know of several Massa- chusetts growers who have waited 2 or more years to receive tree orders and then have had to accept substitutions as to size and make-up of the tree ordered. Reasons suggested for this scarcity of fruit tree nursery stock are: (1) an increased demand for fruit trees due to both new and replacement plantings; (2) a tendency to use closer planting distances in many of these plantings; (3) loss of both understock and budded trees in the nursery due to adverse weather conditions; (4) shortages of certain understock (1 or 2 favorable and often preliminary reports on a new rootstock will create a demand that may take several years to satisfy) ; and (5) lack of qualified budders resulting in poorer stands in the nursery row. Because of this scarcity of nursery stock a number of growers have indicated an interest in propagating their own fruit trees. For those individuals contemplating such an operation I would sug- gest that they secure and read the following publications: New York Food and Life Sciences Bulletin, No. 19, June 1972; Tree Rais- ing on the Fruit Farm-An Essay on Management. by James C. Cummins, and New York State Agricultural Experiment Station Bulletin 817, May 196 7: Propagating Fruit Trees in New York by R.D. Way, F. G. Dennis and R~! M. Gilmer . Both are available from the Department of Pomology and Viticulture, New York State Agricultural Experi- ment Station, Geneva, NY 14456. There is a mailing and handling charge of 20 cents for each publication. Checks should be made out to the New York Agricultural Experiment Station. It is not unrealistic or impossible for the orchardist to pro- pagate his own trees if he is willing to carry out the necessary nursery operations on a timely basis. Those growers who currently find it difficult to complete their orchard operations on time should not attempt to propagate their own trees. An open site that has good air drainage and a well drained fertile soil is best suited for the nursery site. It would be desirable for the nursery to be located near the residence or orchard office area to provide for more efficient management and possible protection from deer damage. An isolated planting is more apt to be neglected. The orchardist growing his own nursery trees might use the following tree schedule: 1. Order the desired rootstocks at least 1 year in advance of plant- ing as the demand is often greater than the supply. -10- 2. Prepare the land at least a year in advance o£ lining-out of the rootstocks, soil fumigation might be a part of this pre- paration. 3. Line-out the rootstocks in early-Spring, April if possible. The rootstocks are set 8 to 10 inches apart in the row and the rows are 42 to 60 inches apart. The spacing between rows is determined in part by the equipment to be used. 4. Bud the trees, beginning in late July or early August. The bud wood should be collected just prior to budding. 5. During this first year the trees should be sprayed to control insects and diseases and the soil cultivated to suppress weeds. 6. The following spring the top of rootstock is cut-off just above the bud and any suckers arising from the rootstock are removed. This allows the shoot arising from the inserted bud to make maxi- mum growth. Suckers continuing to arise from the rootstock portion of tree should be removed by rubbing them off with the fingers . 7. The trees should be sprayed to control insects and the soil should be cultivated to control weeds during this second season. Herbicides might be used for weed control. 8. The trees may be dug in the late fall (November) where suitable storage conditions are available, or the following spring. DO NOT STORE THEM IN YOUR APPLE STORAGE, since gasses from the fruit may make them break dormancy during storage. The various steps necessary in the propagation of fruit trees are described in detail in Bulletin 817. Some Additional Points 1. The propagation of patented varieties is restricted. Growers wishing to propagate such a variety must obtain permission from the holder of the patent rights to it. 2. Cut budwood from trees that are healthy, vigorous, productive and true- to- type . When cutting in an orchard be especially careful, as most rows include pollenizer varieties and some may include partially top-worked trees. Keep your eyes openi 3. All nursery rows should be carefully staked and labelled so as to indicate both rootstock and variety. You should also maintain a nursery register indicating all pertinent information, 4. Budding a few trees is fun; budding for a day is hard work. The novice should start on a small scale. -11- SO^ffi PROBLEMS THAT CAN REDUCE STORAGEABILITY OF APPLES William J. Bramlage Department o£ Plant and Soil Sciences At harvest time, a fruit grower not only must gather the crop from the orchard, but he must also make dozens of decisions that will ultimately affect the quality of the product that reaches consumers. To produce a quality product, these decisions must be made with an understanding of the principles of fruit behavior and handling. Last year I reviewed what we think are the most import- ant principles as well as our basic recommendations for apple storage (Fruit Notes 43, September/October issue 1978: pp 1-5). We urge you to take a few minutes and re-read this review of the "basics", because we believe that the growers who stick as close as possible to these "basics" are the ones who year-in and year-out have the fewest storage problems. Keeping these basics in mind, I will develop here some of the information and ideas about fruit handling that have come to my attention in recent months. These considerations may help you avoid storage problems. Bruising is an important though often neglected factor in the behavior of fruit after harvest. Beside disfiguring the fruit, bruising also causes it to produce large amounts of ethylene, the hormone gas that causes ripening to begin. Dr. L. M. Massey, Jr., of the New York Agricultural Experiment Station in Geneva, has demonstrated the importance of bruising. If apples are picked be- fore ripening has begun, they are most suitable for long-term stor- age. But, if these apples have been extensively bruised during picking or handling, their potential can be shortened substantially because ripening will begin almost immediately. Even when apples are picked after ripening has begun. Dr. Massey found that extensive bruising increased their rates of softening and sugar loss during storage. He also found what we too have observed: bruising does not lead directly to breakdown or other apple disorders during storage. Careful harvesting and handling will improve fruit stor- ageabil ity . Bruising is also a major cause of fruit loss after packing. We reported last year (Fruit Notes 43, September/October issue, 1978 pp 5-7) some results from tests by Dr. George Mattus in Virginia on the amounts of bruising that result from dropping of cartons, and of the influence of different kinds of packaging on this bruis- ing. Dr. Mattus has continued these tests and has generally con- firmed last year's findings. Packages differ significantly in the amount of bruising caused by drops, but the basic message is: Don' t drop cartons of apples, not even a little bit! -12- Scald is always a worry during apple storage. We did not have serious scald problems in New England last year, but in many parts of North America scald caused very serious losses. The reason was probably high temperatures during the harvest season- - high temperature shortly before harvest increases the susceptibility of apples to scald. When susceptibility is high, conventional scald control measures may not be effective. If high temperatures have prevailed immediately before harvest, and especially if coloring is poor and you know that your nitrogen levels tend to be high, you should take extra precautions to thoroughly apply scald inhibitors at maximum dosage but not above maximumi You should also be extra careful with storage management to delay ripening as much as possible, since scald development comes with ripening, and make every effort to market the fruit as early as possible. We have also found that a high calcium level in the fruit can reduce scald development . Your fertilizer program can certainly influence your storage problems with apples. In particular, if nitrogen or potassium are quite high in your trees, or if calcium is low, you may encounter much greater problems during storage. The importance of nutrition is dramatically illustrated by a system now used in England to determine length of storage. In this system, samples of apples are collected from each orchard 2 weeks before harvest and analyzed for 5 mineral elements. Based on the analysis, the grower is informed of the maximum length of time he can store his apples and still market them cooperatively. A simpler system, based solely on fruit calcium analysis, is also being used for export apples in New Zealand. We plan to test the English system this year, but in the ab- sence of a fruit analysis, observation of your fruit can help avoid problems. If your trees have lush, dark green foliage and the apples are large and poorly colored, nitrogen levels are probably high and the fruit should not be stored late. If you see significant amounts of cork spot or bitter pit on the apples, and especially if the fruit are large, calcium levels are probably low and the fruit should not be stored late. In either case you should consider a post harvest dip treatment in calcium chloride (CaCl2). CaCl2 is com- patible with scald inhibitors and fungicides, so the treatment can easily be accomplished if you are dipping the fruit anyway. A high CaCl2 concentration (24 to 32 lbs/100 gal) is essential for success, since most of the calcium is absorbed into the fruit from residues during storage. This high CaCl^ concentration is corrosive and can cause skin injury on the fruit, but injury is much more of a pro- blem in warmer areas, such as Maryland and Virginia, than it has been in New England. Postharvest CaCl^ dips have repeatedly been shown to reduce softening and storage disorders of apples, and use of these dips is growing in many apple-producing regions. Research is also cur- rently being conducted in several areas on the infiltration, by either pressure or vacuum, of large amounts of CaCl^ into apples, but many questions remain to be answered about this method. We think that there is much potential benefit to be gained from CaCl2 dips. -13- There is growing evidence that use o£ growth regulators during the summer can have important influences on the fruit during storage. Ethrel* can of course cause earlier ripening, even when it has been applied long before harvest. Use of Alar* continues to be contro- versial its host of effects on apple development makes assessment of its overall effect hard to evaluate. During the past 2 years extensive studies have been carried out in a number of areas, but especially in New York and Maine, and they have failed to show con- sistent effects of Alar* except for greater firmness at harvest and preharvest drop control. Our own results have also been inconsist- ent. In the previous 2 years we found greater breakdown in Alar*- treated fruit, but last year there was no more breakdown with Alar* than without it. We believe that Alar* can produce greater break- down under certain conditions, but that this problem can probably be overcome by harvesting at the proper time. Do not delay harvest of Alar-treated apples; they should be harvested at the same time as if Alar had not been used. We now see evidence that Promalin* may reduce storageability of apples. Dr. Duane Greene has found in his experiments here with both Delicious and Tlclntosh that Promalin increased the amount of breakdown after storage, even when applied at low concentrations. However, Dr. Warren Stiles has found no detrimental effects from Promalin* on Mcintosh in Maine. Obviously, we have much to learn about the effects of Promalin* but it may be that the cooler temper- atures in Maine account for the differences in results. Nevertheless, we believe that growers who have used Promalin* should be extra cautious about long-term storage of these fruit. The ability to delay ripening of apples for almost a year is a marvelous thing. It is even more marvelous for Mcintosh, which is almost a summer variety. Successful long-term storage requires a lot of things being done right, and the capacity of the fruit to withstand this "test of time" can easily be eroded. Most of what has been written above has dealt with efforts to protect against these eroding influences. In conclusion it should be said that from the standpoint of fruit quality nothing is gained by long-term storage. Furthermore, the cost and scarcity of energy are sure to lead to greater efforts to conserve energy during storage operation. An obvious way to conserve energy is to store for shorter lengths of time, and just as obviously, a way to do this is to market more of the crop in the Fall. Ethrel* offers the means for starting harvest sooner, and we think that once Fall marketing has begun it should be utilized much more fully than is presently being done. A Trade name 14- PCMOLOGICAL PARAGRAPH William J. Lord Department o£ Plant and Soil Sciences Benlate* (benomyl) -tolerant storage decays. D.A. Rosenberger, Plant Pathology, Cornell University, NY reported in Cornell Fruit Handling and Storage Newsletter, July 1979 that some blue mold and gray mold rot fungi are tolerant to Benlate. Isolates obtained at several packing house-storages in the Hudson Valley, Champlain Valley, and in the Lake Ontario areas showed that the proportions of Benlate- tolerant to Benlate-susceptible fungi varied greatly among locations. Tests conducted last fall showed that a combination of 8 oz. Benlate and 1 lb. Captan per 100 gal. provided much better control of blue mold than did Benlate alone where Benlate- tolerant spores were present. Therefore, when using Benlate as a post-harvest dip or drench, we suggest adding Captan at the rate of 1 lb. per 100 gallons . *********** All pesticides listed in this publication are registered for suggested uses according to Federal registrations and State Laws and regulations in effect n the date of this publication. When trade names are used for identification, no product endorsement is implied, nor is discrimination intended against similar materials. NOTICE: THE USER OF THIS INFORMATION ASSUMES ALL RISKS FOR PERSONAL INJURY OR PROPERTY DAMAGE. WARNING: PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS AND SAFETY PRECAUTIONS ON LABELS. HANDLE CAREFULLY AND STORE IN ORIGINAL LABELED CONTAINERS OUT OF REACH OF CHILDREN, PETS AND LIVESTOCK. DISPOSE OF EMPTY CONTAINERS RIGHT AWAY, IN A SAFE MANNER AND PLACE. DO NOT CONTAMINATE FORAGE, STREAMS AND PONDS. 15- MAILING LIST REVISION It is time to revise our mailing list for FRUIT NOTES. I£ you wish to continue to receive FRUIT NOTES, please fill in and return the attached tear sheet. Please continue sending FRUIT NOTES NAME ADDRESS CITY STATE ZIPCODE Fill out and return to: William J. Lord Extension Pomologist University of Massachusetts French Hall Amherst, MA 01003 Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30. 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT PC NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol 44, No. 6 NOVEMBER/ DECEMBER 1979 TABLE OF CONTENTS Carbon Monoxide Accumulation in CA Storages Evaluation of Delicious Strains Spur-Strains of Mcintosh Variability in Macspur Strain of Mcintosh 1979 Disease Results for the Massachusetts Apple Pest Management Program Integrated Management of Apple Pests in Massachusetts Commercial Orchards - 1979 Results: Insects and Mites FRUIT NOTES INDEX FOR 1979 CARBON MONOXIDE ACCUMULATION IN CA STORAGES G. David Blanpied, Pomology Department Cornell University, Ithaca, New York Carbon monoxide (CO) is a colorless, odorless gas which causes numerous deaths each year. Almost all of these deaths are caused by CO in the exhaust from internal combustion engines. Human res- ponse depends upon the concentration of CO and the length of exposure to it. For example, you wouldn't notice 100 ppm of CO if you were exposed for 3 hours, but after 8 hours you would be nauseous and have a headache. CO at 900 ppm would cause the same symptoms after 1 hour. Exposure to 4000 ppm of CO would be fatal in less than 1 hour . The possibility of CO in CA storage was brought to my attention this past spring by Warren Stiles. He reported that workers in 2 Maine apple packinghouses had developed headaches and had become nauseous after working in an area adjacent to the door of a newly opened CA room. At both establishments an oxygen burner had been used to reduce the oxygen concentrations in the CA rooms. Analyses of the air in the areas surrounding the newly opened CA rooms revealed the presence of CO at concentrations which could cause CO poisoning symptoms to develop after exposure for several hours. We analyzed the atmosphere in 10 Hudson Valley CA rooms that had been "burned" with Anderson, Arcat, and SMB burners at harvest and/or after resealing in the spring. The 5 rooms that had been "burned" in the fall had 50-200 ppm of CO. The 5 rooms that had been recently "burned" after resealing had 250-1800 ppm of CO. Early this summer we sealed an empty CA room at Ithaca. With a new catalyst bed in an Arcat the room was "burned" to 3% oxygen. We learned that most of the CO was produced when the oxygen in the room was between 5 and 3t. Also, the faster the flow of propane to the burner, the higher the amount of CO that accumulated in the room. The take-home lessons from these observations are clear. If you are lowering the oxygen in a CA ro'om \\fith an open- flame burner, such as an Anderson burner, thoroughly ventilate with fresh air the area adjacent to the discharge from the CA room. When you open a CA room in preparation for removal of apples, ventilate with fresh air the area around the CA door if people will be working nearby. ********** EVALUATION OF DELICIOUS STRAINS William J. Lord, Richard A. Damon, Jr., James F. Anderson and Franklin W. Southwick University of Massachusetts, Amherst A planting was established in 1964 at the Horticultural Re- search Center, Belchertown, MA to evaluate the following Delicious strains on M7 rootstock: Richared, Turner Red, Jardine Red, Royal Red, Gardner Red, Red Prince, Rogers Red, Sturdeespur (Miller Strain), and Starkrimson (Bisbee strain), the last two being spurs. The experiment was a randomized block design with 6 single-tree re- plicates. The trees were planted at 20 feet by 30 feet spacing. Summarized below are our findings to date. The full report is pub- lished in the 1979 Proceeding of the Mass. Fruit Growers' Association, Volume 85, pp 76-83~] ^ '~ Color Evaluations Rogers Red, Royal Red, Starkrimson, and Sturdeespur have rated best in color evaluations. Gardner Red fruits have less intense red pigmentation than these strains and should be suitable for those who like less color intensity. Red color on Turner Red lacks somewhat in uniformity and is less intense than on Starkrimson, Royal Red, Sturdeespur, and Rogers Red. The fruits of Jardine Red are blush with some striping but lack the intensity of red needed to meet present standards for color. Production Why Delicious is unproductive in the eastern United States was the subject of a conference hosted by the USDA in 1977. Researchers in attendance stated that strains differ in fruitfulness but there was a lack of supportive data. It was reported that spur-type strains perform somewhat better than standard- type strains and that Red Prince, Richared, and Royal Red in some apple growing areas are less productive than other strains. We lost 2 of our Red Prince trees in 1972, but by statistical techniques it was possible to obtain an estimate of yields. Thus, the productivity of Red Prince in comparison to other strains in the test is reported. Early Production: Yield data were first recorded in 1970 when the trees were in their 7th year, and at this time the strains averaged at least a bushel per tree. In 1970 production per tree was similar among strains. Gardner Red produced more fruit per tree than either spur strain in 1971. In 1972, Turner Red was more productive than the spur strains. -3- Although yield per tree favored the more productive standard- type strains in 1971 and 1972, higher tree numbers per acre are possible with spur trees. Actual spacing trials provide the most reliable estimate of yield per acre. In absence of these, we arrived at theoretical tree spacings for the strains by using tree spread in 1978. Some trees of the standard- type strains have re- quired pruning to keep them in their allotted space; as a result all standard- type strains averaged 19' spread. Tree spread of Sturdee- spur and Starkrimson averaged 15' and 14', respectively. Theoretical yields per acre were determined by multiplying average yield per tree by trees per acre. The theoretical yields showed that Sturdeespur was more productive in 1970 and that there was no difference in productivity between standard-type and spur- type trees in 1971. In 1972, Turner Red was as productive as Sturdee- spur and Starkrimson. Thus, in this study yields per acre in the early fruiting years favored neither the standard nor spur-type strains Yields from 1970 through 1978: Cumulative yields per tree and per acre the first 9 years showed that Turner Red was more productive than some of the other standard- type strains. However, the producti- vity of Red Prince, Rogers Red, Richared, Gardner Red, and Royal Red, which are planted in orchards in eastern United States, was comparable. The trees of the spur-type strains are smaller than those of the standard- type strains, but production per tree of Sturdeespur, Red Prince, Jardine Red, Richared and Rogers Red was similar. Sturdee- spur had the highest production efficiency (production per area occupied) of all strains. The cumulative yields per tree indicated that Starkrimson was the least productive of all strains, but when the theoretical yield per acre was calculated it was not, because tlie trees of this strain are small. The theoretical cumulative yield per acre generally was similar for the standard-type and spur- type strains. Water Core Several indices have been used to estimate maturity of Delicious strains. We chose water core because it is of annual concern and a reliable index of maturity under our conditions. Water core is associated with mature and over-mature Delicious fruits. Fruits with this disorder may fail to meet U.S. Standards for Extra Fancy fruit and severely affected apples often develop internal breakdown during storage. In this study, Starkrimson fruits have had less water core than other strains. Nevertheless, the percentage of Starkrimson fruits with water core classified as medium and severe was not consistently less than in the other strains. Since water core can develop rapidly, this difference in water core susceptibility may be of little practical significance in some years. Summary More spur-type trees than standard- type trees can be planted per acre because they are smaller. Allegedly, yields per acre will be higher on spur-type trees but data to support this claim are limited. In this study, the spur-type and standard- type strains have been equally fruitful. Among the standard- type strains Turner Red was more productive per tree than Richared and Red Prince. Unfortunately under our conditions, red color on Turner Red fruits lacked somewhat in uni- formity. Fruits of Royal Red, Starkrimson, Sturdeespur and Rogers Red were rated highest for color. Gardner Red appears suitable for growers who like bright red color rather than dark red color. Based on the severity of water core at harvest, the fruits of Starkrimson seemed to mature somewhat later than those of the other strains. A**** A ************** SPUR-STRAINS OF MCINTOSH William J. Lord Department of Plant and Soil Sciences Spur-strains of Mcintosh are now common in Massachusetts. The question was asked about how they differ from their parent - Summer- land Red Mcintosh - and from each other. Strains common in Massachusetts are Macspur, Morspur and Stark- spur (Gatzke strain) , all of which originated in British Columbia. Dr. D. V. Fisher discussed the origin and characteristics of these strains in Fruit Varieties and Horticultural Digest, Vol. 24, in 1970. Strain B (Macspur) was discovered in a small block of Mcintosh on seedling roots planted in 1960 or 1961 in the Mervyn Greenslade Orchard in Summerland. Strain C [Starkspur (Gatzke strain)] occurred as a single tree sport on a seedling rootstock planted in about 1960 in Oyama. Six apparently identical whole tree mutants occurred in a large block in the Kelowna district. These were designated as strain D and later named Morspur. Lapins and Fisher in 1974 (Can. J. Plant Sci 54:359-361) reported that the degree of spuriness was very high in Morspur and Macspur, high in Dewar (Strain E) , and moderate in Starkspur. However, in our commercial orchards in New England, we are finding that the degree of spuriness is highly variable in Macspur, with some trees exhibiting branching and spur development characteristic of standard Mcintosh. In 1976, W. Lane and M. Maheriuk reported on a 3-year study [Can. J. Plant Sci. 56:847-851) in which they compared the fruit characteristics o£ Dewar, Macspur, and Morspur with those of Summer- land Red Mcintosh. They found no differences in stem-associated defects (short, long, fleshy) except that flat stem cavities occurred more frequently on the fruits of spur strains in 2 of the 3 years. Measurements of fruit length and diameter showed that the fruits of the spur strains were as uniform in shape as those of Summerland Red, but they tended to be longer and larger. Also in some instances, the fruits of the spur strains were softer and had less soluble solids (sugar content), probably because they were larger. In general, the study showed that the fruits of the spur strains differed slightly from those of Summerland Red and that the differences among the 4 strains were less than the variations in strains from year to year. A********* VARIABILITY IN MACSPUR STRAIN OF MCINTOSH J. W. Swales Horticulturist, Research Station Summerland, British Columbia In 1967 Horticulturists became aware of a spur-type sport of Mcintosh in the Mervyn Greenslade orchard at Summerland, B.C. That sport, a whole tree, received a great deal of publicity as it appeared to be the first spur-type Mcintosh which produced commer- cially-acceptable fruit and which possessed desirable growth char- acteristics . Propagating rights for this sport, named Macspur, were obtained by Hilltop Orchards and Nurseries of Michigan. The British Columbia Fruit Growers Association obtained propagating rights on behalf of the tree-fruit industry and nurseries of British Columbia. Since the discovery of Macspur numerous other spur-type sports have been found in various B.C. orchards. Propagating rights for those which appeared most promising were picked up by nurseries. Consequently, today there are several spur-type Mcintosh strains being propagated in North America. Macspur is the spur-type strain of Mcintosh that has been most extensively planted in B.C. during the 1970's as it is the strain selected by the B.C.F.G.A. and propagated in their budwood orchard for distribution to B.C. orchardists and nursery operators. In a few of the earlier plantings of Macspur it was noted that the occasional tree would lack spur-type characteristics. For some time it was thought that mixing of spur-type and standard Mcintosh trees had occurred. However, during the past 2 years it has been observed that the incidence of standard Mcintosh trees in plantings of Macspur has increased significantly; in one extreme case over 25% of the trees in a Macspur planting exhibit the type of growth that is characteristic of standard Mcintosh. On the other hand, there are many blocks of Macspur where the trees exhibit a high degree of uniformity. What is the cause of the problem with lack of uniformity in some plantings of Macspur in British Columbia? Is it due to bud selection? Is it due to a mixing of standard and spur-type trees? Is it due to bud mutation? To date no one has come up with the answer. It may take several years before an answer can be found. However, it can be stated that it is thought that the variability exhibited by Macspur in B.C. is related to bud selection rather than reversion since the problem has been limited to whole trees, not individual limbs. 1979 DISEASE RESULTS FOR THE MASSACHUSETTS APPLE PEST MANAGEMENT PROGRAM T. R. Bardinelli, C. W. McCarthy, and W. J. Manning 1 The 1979 growing season marked the completion of the first full year of operation of the disease component of the Massachusetts Apple Pest Management Program. The objectives of this part of the program include using and developing predictive tools to time fungi cide applications to achieve more effective management of apple diseases . Seven growers participated in the 1979 disease management pro- gram. Disease management blocks (10 acres) and control blocks were established in each orchard. This allowed direct comparison of results from control and disease management blocks located in the same orchards. Apple scab is the ma was focused on it. Seve apple scab. The best kn periods for primary appl length of wetting period during the wetting perio whether or not an infect thermograph was modified orchard temperatures. U devised that was used by decide whether an infect an eradicant kickback sp jor disease to be managed and most attention ral predictive tools are available to manage own is the Mill's Table (Table 1). Infection e scab can be determined by measuring the s and relating it to average temperatures ds . The table can then be used to determine ion period has occurred, A recording hygro- to continuously monitor leaf wetness and sing this information, a predictive table was participating growers to allow them to ion period had occurred and whether to apply ray. Extension Technician, Scout, and Associate Professor, Department of Plant Pathology, University of Massachusetts at Amherst. -7- Table 1. Approximate hours of wetting necessary for primary apple scab infection at various temperatures. Average temperature °F Number of hours of wetting 78 77 76 60-75 57-59 54-56 51-53 48-50 47 45-46 44 43 42 33-41 12 11 10 9 10 11 12 14 17 19 22 25 28 48 From: Mills, W. D. 1944. Efficient use of sulfur dusts and sprays during rain to control apple scab. Cornell Ext . Bui . No. 630. Long periods of rain in the early primary scab season made kick- back spraying difficult in most cooperating orchards. In spite of this, good scab and other disease control was achieved. Results for the seven orchards are given in Table 2 below. Table 2. Comparison of results from disease management and control blocks of seven orchards in the Massachusetts Apple Pest Manage- ment Program, 1979. Criteria Disease management Control Average number fungicide sprays Average dosage equivalent^ Average % disease on fruit at harvest Average fungicide cost/acre 10.6 9.8 0.99 $108.64 13.0 11.1 0.93 $130.93 ' . , ^ amount of fungicide used Dosage equivalent = average recommended rate of fungicide ■8- The average number o£ fungicide sprays in the disease manage- ment blocks was reduced by 2.4 or 181. Average dosage equivalents were reduced by 1.3. Fruit disease incidence at harvest, however, was the same under both conditions. Average fungicide cost/acre was reduced by $22.29/acre or 17%. When individual orchard pro- files are examined, several of the participating orchards achieved even greater reductions in fungicide applications and costs. Four other orchards have been used to evaluate the effects of spraying only every other row on disease incidence. The same fungi- cide concentrations were used as in an every row program, but applied only to every other row, alternating the rows that were sprayed. Table 3 compares these results to those obtained in blocks where every row was sprayed. By cutting all factors in half, a slight reduction in average fruit disease incidence was also obtained. Table 3. Comparison of results from four orchards using alternate row and every row spray blocks. Criteria Alternate Every Average number fungicide sprays 11.8 11.8 Average dosage equivalent 5.8 11.6 Average % disease on fruit at harvest Average fungicide cost/acre 0.23 $70.69 0.38 $141.38 7 „ . -, ^ amount of fungicide used Dosage equivalent = ^— t — j r -r—r ^ ^ - i^ ^ ^ average recommended rate or fungicide The results from our first year's program are encouraging. They are, however, only preliminary results. We need to obtain additional results over several years of varying climatic conditions. We also need to further evaluate and develop additional predictive tools for disease management for apple scab and other apple diseases. ********** INTEGRATED MANAGEMENT OF APPLE PESTS IN MASSACHUSETTS COMMERCIAL ORCHARDS- - 1979 RESULTS: INSECTS AND MITES W. M. Coli, R. J. Prokopy and R. Hislop Department of Entomology The 1979 growing season was the second year of operation of the Massachusetts IPM program"^. The major objectives of the Massa- chusetts IPM program are: 1) to produce high yields of top quality apples while decreasing the amount of pesticide usage; and 2) to encourage the use of spray materials which allow for survival of beneficial predators and parasites. Reduced spray programs on apples have been discussed in pre- vious issues of "Fruit Notes [41(1), 41(2), 41(3), 42(3), and 43(3)]. Our 1978 results on insects were summarized in Fruit Notes 44(1). Information reported here resulted from intensive scouting of 25 blocks in 20 commercial orchards in the 4 major fruit-growing areas of Massachusetts. Scouting in the 16 IPM blocks was on a weekly basis Avhile the 9 check blocks were visited bi-weekly because of gasoline scarcity. In-depth orchard scouting is the keystone of the IPM program and enables us to advise growers as to the need and optimal timing of spray applications. Materials and Methods Prior to bud break in the spring, 6 to 12 trapping stations were established in each orchard (4-11 stations per block) taking into account size of block, proximity to likely insect overwinter- ing sites and varietal composition. The majority of trapping sites were near the block periphery inasmuch as most pest pressure ori- ginates from outside the orchard. Visual traps were used to monitor tarnished plant bug (TPB) , European apple sawfly (EAS) and apple maggot fly (AMF) adults. Pheromone traps were used for monitoring red-banded leafroller (RBLR) , oblique-banded leafroller (OBLR) , and codling moth (CM) males. Mites and mite predators were monitored from mid-June to harvest using techniques outlined in Fruit Notes 43(4). Tentiform leafminer (TLM) , green fruitworm (GFW) , green apple aphid (GAA) , woolly apple aphid (WAA) and white apple leafhopper (WAL) populations were monitored by examining 10 fruit spurs or 10 terminal shoots in each of 3 tree areas-- (top, low inside and low outside) at each trapping station. (A discussion of decision making 1 Other program field staff for 1979 were: Norman Andersen, scout; Glenn Morin, scout; Annemarie Pennucci, scout; and Mary Tubbs, scout Mite brushing and counting were by Bonnie Weeks. 2 Funded by a USDA grant from 1978 through 1982. In addition, the Massachusetts Fruit Growers Association contributed $5,600. Addi- tional thanks to Mr. David Chandler, Meadowbrook Orchards, Inc., Sterling Junction for allowing us to base 2 scouts at his picker's housing throughout the summer. As a result it was possible to re- duce travel time and gasoline use. ■10- processes based on levels of pest populations as determined by the above techniques will be forthcoming in a future issue of Fruit Notes. ) Fruit injury at harvest was determined in each IPM and check block on the basis of on-tree surveys of 800-2200 fruit per block (100 fruit per tree from each of 2 trees adjacent to trapping stations). In addition, we sampled at harvest fruit injury from another block in each IPM orchard of similar tree size and varietal composition. Injury in these blocks was determined by on-tree sur- veys of 1000 fruit per block (100 fruit per tree from trees randomly located within the block) . Results Fruit Injury. Injury at harvest was divided into 2 categories: (a) permanent damage to the skin or flesh of the fruit; and (b) damage to the skin which could be removed by washing (i.e., woolly apple aphids (WAA) in the stem cavity, sooty mold (SM) , or white apple leafhopper (WAL) excrement) . Overall, permanent damage was 6% less in IPM blocks than in same orchard non-IPM blocks, and 23°o less than in check blocks (Table 1). Removable injury was 95% less in IPM blocks than in same orchard non-IPM and 93% less than in check blocks. Specifically, as in 1978, TPB was the most damaging fruit pest in Massachusetts commercial apple orchards, with IPM blocks averag- ing slightly less injury than check or same orchard non-IPM blocks. We believe that this reduction in TPB fruit injury in IPM blocks was due to better timing of spray applications rather than differences in pest pressure, since trap captures of TPB were nearly identical (13.3 per trap in IPM blocks vs. 13.6 per trap in check blocks). We attempted to develop a TPB damage grading index so as to determine how much of this TPB injury would result in down-grading of fruit value. Preliminary indications are that 321 of TPB injury would grade through as U.S. Fancy fruit, 52% would grade U.S. #1 and 16% would be culled. We plan to continue this work in 1980. Fruit injury as well as trap captures of EAS were down substan- tially from 1978, with virtually no difference between IPM and check blocks. Plum curculio (PC) injury was about the same as in 1978. Injury from PC was higher in IPM than check blocks due mainly to substantial injury (1.6%) in one orchard. San Jose Scale injury to fruit was considerably less in IPM than check blocks, where, as in 1978, scale was the second most damaging pest. Apple maggot fly (AMF) captures were down substantially from 1978, perhaps due to interference of dry weather with fly emergence from pupae. Trap captures were slightly higher in check blocks, as was injury at harvest from this pest. First captures of AMF in an abandoned or- chard in Northboro, MA occurred the week of June 1, while first captures in a commercial orchard occurred July 12. This difference -11- points out the need to monitor AMF directly in commercial orchards rather than relying on abandoned orchard captures (as recommended in Canada) to indicate the need to spray. Table 1. Average percent of insect injury on fruit at harvest in IPM and check commercial orchards in Massachusetts, 1979 ? injury Insect 16 IPM blocks 11 Same orchard 9 Check non IPM blocks blocks Tarnished plant bug 2.74 Plum curculio 0.39 San Jose scale 0.33 Apple maggot fly 0.12 European apple sawfly 0.03 Green fruitworm 0.02 Leafrollers 0.01 Codling moth 0.00 Total I of insect injury 3. 64 Average number insecticide applications^ 6.0 3. ,27 0. ,16 0. ,25 0. ,09 0. ,03 0. ,04 0. ,01 0. ,02 3.88 9.1 3.10 0.17 1.07 0.23 0.04 0.07 0.04 0.01 4TT3" 11.0 Woolly apple aphids 0.08 White apple leafhopper 0.01 Sooty mold 0. 00 Total I of insect injury 0.09 Average number aphicide applications 0.36 0.71 0.08 0.27 1.18 0.67 0.05 1.56 0. 36 1.31 0.36 GRAND TOTAL % INSECT INJURY 3.73 5.44 6.04 Does not include materials directed solely at aphids (e.g., endo- sulfan, phosphamidon) . Codling moth (CM), leafrollers (LR) and green fruitworms (GFW) were relatively unimportant pests in 1979, although injury from these insects was slightly higher in check than IPM blocks. Woolly apple aphid (WAA) injury (i.e., WAA and/or sooty mold growth on the aphid honeydew on fruit) was identical in IPM and check blocks. Speckling of fruit with white apple leafhopper (WAL) excrement was particularly high in 1 check orchard, resulting in high average injury from this insect compared to IPM blocks. Mite Populat (ERM) peak a (TSM) did no mites (ARM) bers in IPM unless in ex source for o and TSM prey of chemicals peak number ions. Overall, I nd average number t exceed very low were found in sub blocks (Table 2). cess of 300 per 1 ur major mite pre are few in numbe toxic to AF prob of AF in IPM than -12- PM blocks had lower European red mite s than the check. Two-spotted mites levels in any block, while apple rust stantial (but well below damaging)num- ARM cause no damage to fruit trees eaf and may serve as an alternate food dator Ambylseius fallacis (AF) when ERM r. Higher ARM populations and avoidance ably account for higher average and check blocks. Table 2. Average and peak number of mites per leaf (IPM and check orchards) in relation to acaricide sprays, 1979. Acaricide dosage Number of mites per leaf European Two -spotted Apple Amblyseius Orchard No . Avg . no . equivalents^ red mites mites rust mites fallacis type Blocks spray dates Oil Other Avg! Peak Avg. Peak Avg. Peak Avg. Peak IPM Check 15' 9 0.6 1.1 1.06 0.4 1.2 4.0 0.3 0.8 34.5 69.3 0.03 0.11 1.04 1.7 2.3 10.0 0.3 0.6 8.3 19.1 trace 0.01 block not included (grower did not comply with IPM recommendations) One ^p. • -1 „^ _ actual pesticide rate/100 gal. " ^ NY recommended pesticide rate/100 gal. In keeping with program objectives, IPM growers have generally avoided the use of materials which are known to be harmful to bene- ficial predators and parasites [ Fruit Notes 43(5)] . The recent ad- vent of spotted tentiform leafminer (STEM) as a major pest chusetts and use of the carbamate insecticide, Lannate*, STEM posed a serious threat to IPM objectives. in Massa- to control In one Granville area orchard this season, high counts of second generation STEM mines indicated a need to treat for this pest using Lannate*. For the remainder of the season there was a sharp decline in numbers of Amblyseius fallacis (AF) . The possibility exists that AF may survive in the ground cover if spray runoff is not excessive, although this remains to be proven. Trade name -13- Insecticide, aphicide and miticide use. IPM blocks received 46^ fewer insecticide sprays (average 6.0, range 4-7) than the checks (average 11.0, range 6-12) (Table 1). Same orchard non-IPM blocks received an average of 9.1 sprays, suggesting that growers applied some information from IPM block scouting to the rest of their or- chard. The average numbers of aphicide sprays was identical in IPM, check, and same orchard non-IPM blocks (Table 1). Fewer miticide sprays (e.g., Plictran* and/or Omite*) were applied to IPM blocks (average 0.6) compared to checks (average 1.1) [Table 2] or same orchard non-IPM (average 1.0) [date not shown]. In contrast, use of oil as an ovicide was about equal in IPM and check blocks. In addition to the substantial reduction in spray application dates, there was also a reduction in dosage equivalents for insecti- cides (42% reduction), aphicides (60'o reduction) and miticides (76% reduction) in IPM compared to check (Table 3) . Cost and benefit comparison. Table 3 summarizes the cost benefit analysis of IPM vs. check blocks. Average costs per acre for insecticide and miticide materials, respectively, were $51.64 and $14.59 lower in IPM blocks, while aphicide costs were nearly identical with the checks. IPM spray material application costs were also lower due to the reduction in number of spray dates. At harvest, IPM blocks had 23% less fruit injury due to insects, resulting in an average of $40.46 less fruit loss per acre than check blocks. As a consequence, compared with check growers, IPM growers realized an average net benefit of $122.83 per acre from the IPM program. This finding, coupled with a $71.00 net benefit from the IPM program in 1978, indicates the potential economic value to Massachusetts fruit growers of implementation of an IPM program on apples. Trade Name -14- Table 3. Cost benefit analysis of insect and mite results in 16 IPM and 9 check commercial apple blocks in Massachusetts, 1979. Observation Orchard: IPM check Difference IPM vs . check : Difference (I) Average number spray dates per acre Average number dosage equivalents for'^ Insecticides Aphicides Miticides Average cost/acre spray materials for: Insecticides Aphicides Miticides Spray applications^ Average % of insect injur/ Average value per acre of fruit loss due to insect injury Average net benefit per acre from IPM w 6.0 3.64 $90.01 11.0 4.73 $130.47 ■5.0 - 1.09 -$40.46 +$122.83 (46) 5.8 10.1 -4.3 (42) 0.2 0.6 -0.4 (60) 0.4 1.7 -1.3 (76) $53.99 $105.62 -$51.64 $ 3.46 $ 3.35 +$ 0.11 $11.25 $ 25.84 -$14.59 $19.50 $ 35.75 -$16.25 (23) p. ■ -. . actual pesticide rate/100 gal. Dosage equivalent = ^^ ^ t— 3 " . . , g^ ,, „„ t- * ^ NY recommended pesticide rate/100 gal. r Based on 15 min. time to spray 1 acre, $5.00/hour labor cost and $2.00/acre/ application for fuel and oil. Does not include injury from sooty mold, white apple leafhopper and woolly apple aphids which could be removed by washing fruit. Based on average values as of Sept. 30: U.S. Fancy fruit @ $10.50/bu., U.S. #1 fruit @ $7.00/bu., Cull fruit @ $2.00/bu. and average yields of 550 bu./acre. w ********** 15- FRUIT NOTES INDEX FOR 1979 (This index of major articles has been prepared for those who keep a file of Fruit Notes. The number in parenthesis indicates the pages on which the item appears.) January/February Vol. 44 (No.l) Varieties of Strawberries for Massachusetts (1-3) Pruning MacSpurs (3) Pomological Paragraph - Stub pruning (4) Pruning Peach trees (4-6) Control of Water Sprouts and Suckers with Tree-Hold* (6-8) U.S. Apple Exporters Expect Another Good Year Following Record Showing in 1977/78 (8-11) Integrated Management of Apple Pests in Massachusetts - 1978 Results: Insects (12-16) March/April Vol. 44 (No. 2) Monitoring Apple Maggot Flies, Sawflies, and Plant Bugs with Visual Traps (1-5) Rootstock Testing on an International Basis (6) Treatment of Girdled Fruit Trees (7-9) Nutritional Problems in 1978 and Suggestions for Fertilization of Apple Trees in 1979 (10-12) Pomological Paragraph - Deeper planting may reduce suckering from the rootstock on interstem trees. (12) Apple Disease Incidence in Massachusetts in 1978 (13-15) May/ June Vol. 44 (No. 3) Influence of Training on Growth of Newly-planted trees (1-3) Promalin Studies in 1978 and Comments on Trial Use in 1979 (4-8) Harvesting Early Ripening Apple Cultivars (8) Chemical Thinning of Apples in 1979 (9-11) Growth Regulator Spray for Growth Suppression on Apple Trees (11) Suggestions for Use of Chemical Thinners on Several Apple Varieties (chart) (12) Alternate vs. Every Middle Spraying for Apple Pests in 1978 (13-15) July/August Vol. 44 (No. 4) Brown-Line Decline of Apples (1-2) Poor Apple Growth Disease in Massachusetts (3) Coating the Trunks of Fruit Trees to Reduce Winter Injury (4) Photographs of Nutrient Deficiences (5-6) Further Observations of Tree Performance on M26 (6-8) Use of Ethephon to Promote Color and Ripening of Apples in Massachusetts (9-11) Pomological Paragraph - Foliar sprays (11) -16 September/October Vol. 44 (No. 5) A Preliminary Evaluation of Labor Productivity in Grading and Packing Mcintosh Apples Grown under Integrated Pest Management Conditions (1-6) Toxicity of Orchard Pesticides to the Mite Predator Amblyseius fallacis 1979 Results (6-8) Propagating Your Own Fruit Trees (9-11) Some Problems That Can Reduce Storageability of Apples (11-13) Pomological Paragraph - (Benlate tolerant storage decays) (14) November/December Vol. 44 (No. 6) Carbon Monoxide Accumulation in CA Storages (1) Evaluation of Delicious Strains (2-4) Spur-Strains of Mcintosh (4-5) Variability in Macspur Strain of Mcintosh (5-6) 1979 Disease Results For The Massachusetts Apple Pest Manage- ment Program (6-8) Integrated Management of Apple Pests In Massachusetts Commer- cial Orchards--1979 Results: Insects and Mites (9-14) Fruit Notes Index for 1979 (15-16) Cooperative Extension Service University of Massachusetts Amherst. Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUITpc NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 45, No. 1 JANUARY/FEBRUARY 1980 TABLE OF CONTENTS Further Trials with Naphthalene Acetic Acid (NAA) for Tree Training Winter Injury to Fruit Trees in 1978-79 Winter Injury in New Hampshire - A Grower Survey Progress Report: Height Containment on Spartan and I da red Trees Alternate vs. Every Middle Spraying for Apple Pests in 1979 FURTHER TRIALS WITH NAPHTHALENE ACETIC ACID (NAA) FOR TREE TRAINING William J. Lord and Duane Greene Department of Plant and Soil Sciences It was reported in 1977 that 11 NAA in latex paint is an ex- cellent tree training aid when applied as a painted band around the stem o£ newly-planted apple trees (after heading) to cover the second, third, and fourth buds. The first bud below the heading cut, which was not painted, became a vigorous central leader. This treatment eliminated the cluster of vigorous shoots in the top of the trees which compete with the central leader and increase the number of favorably positioned branches on the newly-planted trees, and improve crotch angles of these branches. If for some reason the bud selected for the central leader died, a strong leader report- edly developed from the NAA-treated area. Basically, the suggested NAA treatment is a replacement for the current training procedures which involve removal by hand, in June, of growth that is in com- petition with the shoot favored as a central leader. Directions for use indicated that the 1% NAA in latex paint should be applied after heading the newly-planted tiee to the desired height but before growth begins. The treatment is not effective if made after start of growth. We tried the NAA-tree training technique on Marshall Mcintosh, Macoun, and Redspur Delicious in 1977. In the May/June, 1978 issue of Fruit Notes we reported that the treatment was a complete disaster. The f irs t ~bud~below the heading cut, which was supposed to develop into the leader, was with only one exception either severely stunted or killed. When the bud selected for the central leader died, no strong leader developed from the NAA-treated area. Further tests were conducted in 1978 on 1-year-old Redspur Deli- cious trees after heading, using concentrations of 0.25%, 0.50%, or 1 . 0% NAA in latex paint. Applications of 0.50% or 1.0% suppressed leader growth, although the reduction was less than recorded in 1977. Leaders on trees painted with 0.25% NAA in latex were shorter than those on the headed control, deshooted, or disbudded trees when mea- sured on August 8, 1978 but not on September 9, 1978. Thus, it appears that trees may overcome the inhibitory effects of NAA if concentrations applied are not excessive. Thus, we concluded from our 1977 and 1978 trials that NAA, ethyl- esr.er at 0.5 to 1.0% in latex may suppress leader growth when applied as a band on newly planted or 1-year-old apple trees after heading. Furthermore, it has at least 4 obvious drawbacks. Spring is an ex',, erely busy season and chances are good that the NAA will not be -2- applied. Secondly, the treatment must be applied before growth starts. Thirdly, the present procedures of leader selection are less time consuming than the NAA treatment. And lastly, a better choice of a leader often can be made in mid-June and this job can be combined with limb spreading with clothespins. Thus, we will continue to suggest the present procedures of leader selection. This involves selection of the uppermost shoot on the windward side of a newly-planted tree when shoot growth is 6 to 8 inches in length, Shoots competing with the selected leader should be rubbed or pruned off for 0 distance of approximately 6 inches down the stem. AAA******* WINTER INJURY TO FRUIT TREES Ifl 1978-79 William J. Lord and Peter Veneman* Department of Plant and Soil Sciences Pomologists in the early 1900's considered winter injury to roots of fruit plants to be a major problem of fruit production in northern growing areas. Thus, considerable time was devoted to the study of low temperature effects on tree roots. However, a search of literature shows that root-kill on fruit trees has occur- red only once during this century in Massachusetts prior to this past winter. G.E. Stone, Botanist for the Massachusetts Agricultural Experi- ment Station, stated that root injury to apple trees occurred dur- ing the severe winter of 1903-04. No mention was made of temper- atures and snow cover in orchards that sustained injury. Minimum temperatures at Amherst in December, 1903 and January, 1904 were -3.5° F. and -26° F., respectively. The mean temperature for Janu- ary was only 14.3° F. A total of 36 inches of snow fell at Amherst in December, 1903 and January, 1904. Whether or not the snow cover was lost in the orchards where winter injury occurred is not known. During the winter of 1898-99 winter injury was widespread in Wisconsin, Iowa, Minnesota, and Canada. It was observed that where there was good snow cover there was no root injury when air temperature went as low as -50° F. The winter of 1933-34 was also unusually severe but the injury was confined to the above-ground tree portions. February was espec- ially cold with a minimum temperature of -22° F. and a mean tempera- ture of only 11.6° F. for the month at Amherst, MA. The 3 major types A Assistant Professor of Soil Sciences -3- of winter injury that occurred during the winter of 1933-34 were: killing of the sapwood in the branches and trunks; loosening and splitting of bark on the trunk; and injury to flower buds and spurs. Winter injury to above-ground portions of fruit trees has also occurred since the writer came to Massachusetts in 1955. In the spring of 1956 we found severe winter injury to the trunks and lower scaffold limbs of bearing trees, mainly Mcintosh in several orchards. The bark on the injured tree trunk was split and usually pulled away from the wood. The injury was most predominant on the south side of the tree, but no side was immune. The winter injury appeared to be associated with pruning during late December and early Janu- ary. During the winter of 1956-57 extensive wood injury and injury to both flower and leaf buds occurred on peach trees and to flower buds on sweet cherries and plums. Pruning-related injury also occurred during the winter of 1975- 76. It was found in more orchards than in 1956 and also occurred in Connecticut and New Hampshire. The trunk injury was associated with pruning done as late as the 3rd week of January in 1976 in some orchards. Cold injury and how it relates to the winter injury in 1975-76 was reviewed by D.A. Kollas in 1978 in Fruit Notes 43(6): 1-5. This past winter (1978-79) root-kill was the predominant type of injury to apple and peach trees. On peach trees the bark on the trunk at ground level or below ground also was injured. The main objective of this article is to have a written account of winter injury in 1978-79 for reference if similar damage occurs in the future. Early Studies on Root Damage Roots have been found to be the tenderest part of the apple tree although those that have been exposed throughout the previous growing season have cold tolerance equal to the above ground tree parts. D.B. Carrick in New York State (Cornell University Agr. Exp. Sta. Memoir No. 36, 1920) reported that, under laboratory conditions, apple roots frozen in October and November were more tender than those frozen in February or early March. The period of maximum re- sistance to freeze damage seemed to end before last of March. J.R. Magness in Washington State showed that bark of apple roots was killed at temperatures as high as 23° F. in November. ^Root samples taken in early December were killed by exposure to 17° F. G.F. Potter in New Hampshire reported that 16° F. was usually critical for roots of 1-year-old apple trees under laboratory con- ditions. Very rapid freezing of roots to 18° F (in a half hour or less) caused more injury than when freezing them so that the roots reached the same temperature after 6 or 7 hours. However, rate of thawing did not affect the severity of the low temperature injury. -4- In studies with peach trees, D.B. Carrick stated that it is not easy to assign an arbitrary limit within which the roots are injured by freezing. "This is because of the great variation in the root tissues. The peach cambium certainly is as hardy as the pear cambium though less so than the apple. Regardless the size of root, most of the peach material tested showed some injury at -10° C. (14° F.) , and except in unusual cases, serious injury occurred at -11° C. (12° F.)". Winter Weather, 1978-79 Temperatures in December, 1978 in Central Massachusetts (where most orchards are located) averaged 0.8° F. higher than normal, and the maximum snow depth varied from 4 to 11 inches depending on loca- tion of the weather station. Temperatures in January continued to be somewhat higher than normal and maximum snow cover varied from 3 to 11 inches. At the Horticultural Research Center (FiRC) in Belcher- town, there were 4 snow storms in January: 2 inches on the 5th and 13th, and 3 inches on the 17th and 20th. However over 8 inches of rain fell after these storms and eliminated the snow cover: 2.3 inches on the 7th and 8th, 1.1 inches on the 13th, 2.5 inches on the 20th and 21st, and 2.5 inches on the 24th and 25th. Temperatures in Central Massachusetts were 8.6° P. lower than normal in February, snow fall averaged 6 inches, and the maximum depth of snow on the ground varied from 3 to 10 inches, depending on the location of the weather station. There was one snowstorm of 2.5 inches in February at the HRC prior to -10 to -14° F. tempera- tures from the 9th through the 17th. Although the air temperatures were not extremely low, soil temperatures at 8 and 30 inch depths in one block of trees in sod were 19° F. and 30° F. , respectively, on February 16th. Symptoms of Injury Apple. The first symptoms of injury to apple trees at the HRC was observed on May 7 at the full pink stage of blossom development. Blossoms on 1 limb, 2 or 3 limbs, or the entire tree were white in color rather than pink and leaf margins were brown. Maximum air temperatures of 84° F. , 93° F. , and 91° F. were recorded on May 8th, 9th and 10th, respectively. The symptoms worsened considerably dur- ing this time, with more trees exhibiting injury, and the blossoms on the affected branches failed to open and eventually wilted and aborted, Examination of the roots revealed that the wood was brown which in- dicated winter injury had occurred. Severely affected trees died as the growing season progressed. Other trees began to exhibit light-colored foliage, with interveinal mottling that was orange in color. These trees made little terminal growth and had a light crop. It is possible that many of the severely- weakened trees will have to be replaced in 1980. Injury symptoms did not worsen on trees having only 1 or 2 affected branches. It also was of interest to note that latent buds produced growth on some of these affected branches. Peach. The injured trees bloomed and then the blossoms wilted. By late-May or early June, thousands of these trees had died or ex- hibited severe injury. In some orchards entire blocks of trees were removed in June. Weakened trees that were not removed had sparse foliage throughout the summer and few peaches. These trees should be replaced in 1980. Injury In Other Areas Winter injury in New Hampshire is discussed in separate article in this issue of Fruit Notes. It also occurred in Washington, New York, Maine and probably in other areas. According to James Ballard, Yakima County Extension Agent, Cen- tral Washington, fruit orchards and vineyards suffered severe dam- age in January, 1979. Sub-zero weather occurred during the last week of December, 1978, and temperatures remained below freezing for 24 consecutive days. Snow cover did not come until January 11, 1979, and by then the cold had penetrated root zones and soil temper- atures had dropped to 14° F. The damage was most severe on trees 5-years-old or younger, planted on rocky, cultivated ground that had little or now snow cover. Richard Norton, Fruit Specialist in Rochester, NY stated in Spray Letter No. 10, May 13, 1979 that winter injury was the major cause of: "(1) dying cherry trees - most young non-bearing trees; (2) dying lower branches in bearing apple trees, particularly un- pruned or poorly pruned trees, (3) spur dieback of young apple In July, 1979 Herbert Wave and Warren Stiles reported symptoms of winter injury in Maine. They stated that the injury was varied with malformed and/or russetted fruit, dieback of limbs and/or tops of young trees, or killing of the rootstock. Most root injury occur- red on wet soils or where there was little or no snow cover during mid-winter. Cause and Factors Influencing Injury We believe the injury to the peach trees in Massachusetts, which are generally planted on well-drained slopes, was due to lack of .snow cover which allowed deep penetration of frost and alternate thawing and freezing of the roots. At the HRC, the older bearing peach trees which had large crops in 1978 were injured more severely than younger trees commencing to bear. Paraquat had been applied annually to control grass and broad- leaf weeds under all peach trees at the HRC but they also had re- ceived periodic applications o£ hay mulch, which was last applied in 1977. Thus, mulch did not prevent damage. Frequently roots of fruit trees appear more susceptible to winter injury in dry than in wet soils. However, at the HRC, the injury to apple trees was worse on heavy, poorly-drained soil. Thus, the combination of poor soil aeration, 8 inches of rain in January and no snow cover intensified the problem of root injury. Nevertheless, trees were injured on well-drained soils both at the HRC and commercial orchards or where ledge prevented deep rooting. It was not possible to determine whether rootstocks differed in susceptibility. An interplanted block of mature trees on seed- ling roots and M.7 was equally damaged in a commercial orchard. In other blocks in the same orchard, "filler" trees on MM106 died where- as the injury to those on M.7, MMlll, or M.2 rated from none to medium. At the HRC soil rather than rootstocks appeared to be the more important factor contributing to winter injury. No Miller- spur or Empire trees with an 8-inch interstem of M.9 on Antonovka, Mlvllll or Ottawa 11 planted in 1976 on well-drained soil were injured even though soil temperature at 8-inch soil depth went to 19° F. However, Mcintosh and Delicious on MM106, M.7 or M.26 planted the same year in the same block, were severely injured where the soil is poorly drained due to a hardpan underneath. In other blocks on MM. 106, M.7 or M.26, the injury to roots was clearly associated with areas having poorly drained soil. Summary Growers have become concerned because of the winter injury to roots, especially in the absence of sod under their trees because of annual use of a contact herbicide such as paraquat plus a soil steri- lant (diuron or simazine) . Studies have shown that soil temperatures in winter can be higher under a sod or sod-plus-mulch than under bare sod. However our peach trees at the HRC were severely injured last winter in spite of a heavy residue of mulch. We are more concerned about the occurrence of soil erosion and tree heaving on bare soil, which is much more common, than possible v\rinter injury to roots. This last summer, we tagged individual limbs and whole trees at the HRC after rating the severity of winter injury. This should enable us to determine the degree of tree recovery in the orchard. Hopefully, the combination of excessive rainfall in January and bare soil in early February during a period of sub-zero air temperatures, will not reoccur for many years. WINTER INJURY IN NEW HAMPSHIRE- -A GROWER SURVEY William G. Lord Extension Specialist, Fruit University of New Hampshire Winter injury to the roots of apple trees is certainly not a common occurrence in New Hampshire, since an adequate snow cover usually protects tender tree roots from extreme low temperatures. However, throughout much of southern New Hampshire in the winter of 1978-79 snow cover was light and bare wind-blown spots were commonplace. Added to this were low soil moisture levels and long, uninterrupted periods of very cold temperatures - -all the ingredients necessary for root injury. The symptoms of severe injury have been well detailed. At about bloom, leaves and blossoms on the affected trees wilt and die. On less severely affected trees, the leaves wilt but seem to recover and injury to blossoms is less severe. New leaves develop and although the tree sets a very light crop and makes no growth, at least the tree is alive. Dam- age of these 2 types is easy to assess and tree crop losses can be accurately and easily determined. However, low level inj ury- - injury that shows up as reduced tree growth, poor leaf color, and reduced set and yields--is difficult to assess and, I feel, tremendously underestimated. This Fall a grower survey was initiated to determine the extent of injury and to correlate the incidence of injury to site, rootstock, variety, etc. The following conclusions can be made based on the survey replies: 1) Rootstock had no effect on the incidence of tree injury. Injury was reported on all the major rootstocks in use in New Hampshire- - seedling , M-106, M-7, M-26, and M- 9/MM- 106 interstems . Where more than one rootstock was present in a particular block showing injury, all rootstocks showed injury. 2) Tree cultivar likewise (and expectedly) had no effect on the incidence of injury. 3) Affected trees ranged in age from 1-year-old semi- dwarfs to 60+year-old standards. Again, no correla- tion existed between age and injury. 4) Herbicide program effects on tree injury are not so clear-cut. It would appear from the grower responses that the majority of sites reporting injury had no herbicide application in 1978, indicating that per- haps there was a slightly greater incidence of injury in blocks where no herbicides were applied. However, it seems more probable that this simply reflects the smaller number of growers who use herbicides rather than any correlation to injury. -8- 5) There appeared to be a correlation between the occur- rence of injury and site. Most injury occurred on wind-blown sites and on sites with a high-water table where the trees had previously shown symptoms o£ "wet feet". Estimating crop loss can be difficult; however, I feel we can approximate the actual crop loss using data supplied to us by growers. The grower data indicate the following crop losses. Trees Dead Trees Severely Injured Est. Crop Loss (bu) 3800 10,615 188,965* Adjusted to reflect lost crop as replacement trees develop. As substantial important as these figures seem, most v/in- ter injury went unrecorded. The injury that escaped notice was the less severe type- -the poor tree vigor and the reduced crop set and yield. This less severe vrinter injury probably will cost our growers much more in the lost production than the losses recorded above. ft****************** PROGRESS REPORT: HEIGHT CONTAINMENT ON SPARTAN AND I DARED TREES William J. Lord and Anthony Rossi Department of Plant and Soil Sciences Pyramid-shaped trees on the more dwarfing rootstocks will produce the bulk of their crop within reach from the ground, without a ladder, and should produce well-colored fruits through- out the tree. However, the most heavily planted size-control- ling rootstock in Massachusetts is Mailing 7 (M7) , on which vig- orous cultivars will produce trees 16 feet or taller. When asked what they consider to be the ideal height for trees on vigorous size-control rootstocks, the answer given by growers generally varied between 10 to 14 feet. At present there is no rootstock more suitable than M.7 for our cultivars, with the exception of Delicious. However, it may become necessary to lower or contain the height of trees on M7 in the future because of the shortage of suitable harvest labor. Therefore, questions to be answered are: (1) What is a suitable pruning method for containing tree height? (2) What is the influence of height reduction on yield? To answer these questions we established a demonstration in 1976 on 12-year-old Spartan and Idared trees on M7 planted at the Horticultural Re- search Center at 20 ft. x 30 ft. spacing. We consider trees of Spartan and Idared to have medium and low vigor, respectively. Pruning and Training Procedures The trees were not excessively tall, the Spartan and Idared trees averaging 12 ft. and / i' 1 ' i }\ I j \ \ -1 \/ / / \ \ i\ Iff/ 1 V ^ J^ V §4 V i 1 \ ' y^ \ yf ^^/ 1 ^H f 1 ^V 4 i l/ % m I-IT^^P s ^p x^^'^'^mI 1 1 n Ij 11 £t., respectively. However, the leader had lost its dominance on some trees, particularly on Spartan, and no attempt had been made to maintain pyramid-tree shape. Tree height was restricted on even numbered trees in a 25-tree row of Spartan and in a similar row of Idared. This was accomplished by cut- ting back the leader to an outward growing branch (Fig- ure 1) and maintaining tree height at this level. On odd numbered trees in each row we gradually shortened the central leader so trees of both cultivars are approx- imately 2.5 ft. shorter than the height-restricted trees. Height of the leader on the height-reduced trees averaged 8.9 ft. and 8.3 ft., respect- ively, after pruning in Feb- ruary, 1979. Height of the height-restricted Spartan and Idared trees averaged 11.4 and 10.6 ft., respectively. Figure 1. A Spartan/M7A tree planted in 1964. The central leader was cut to a lower horizontally growing lateral branch. A branch rotation program has been initiated in the top third of the tree. A comparison of the trees is shown in Figures 2 and 3. (Tree spacing appears much greater in the photographs than in reality, Trees of both cultivars are planted at 20 ft Branch spread of the Spartan trees is 17 ft X 30 ft. spacing. therefore, 17 ft. X 25 ft. spacing would be ample. Branch spread of the Idared trees is 14 ft., thus 14 ft. x 22 ft. spacing appears suitable for this cultivar.) ■10- Figure 2. Spartan trees planted in 1964; picture taken March, 1979 after pruning height of the tree on right has been gradually lowered since 1976. The height- reduced trees now average 9 ft. in comparison to 11.4 ft. on the control trees. On both the control and height - lowered trees some of the stronger branches in the top third of the trees were removed or their length restricted by cutting to a weak lateral branch. A few water sprouts were retained and spread for replacements of pruned vigorous branches. Thus, we have developed a branch rotation program which consists of removing large branches in the top third of the tree and leaving weak branches which turn will be removed when they become largei" (Figure 1). in -11- Figure 3. Idared trees planted in 1964; picture taken March, 1979 after pruning. Height of the tree on the left has been gradually lowered since 1976. The height-reduced trees average 8.3 ft. and the control trees 10.6 ft. Spreaders with nails, sharpened on an emery wheel, at each end have proven satisfactory for positioning 1-year-old sprouts (Figure 4) . The water sprouts positioned in 1976 became sizeable branches within 2 growing seasons (Figure 5). Another method used to develop new lateral branches involved leaving a short stub by making a sloping cut when a favorably positioned lateral branch originating from the central leader was removed. A shoot that develops from the stub on the central leader is retained and positioned (Figure 6) . Figure 4. Softwood sticks 3/4 X 3/4 inch or 1 X 1 inch and cut to var- ious lengths are frequently used for limb spread- ers. Regular box nails (8 or 10 penny) are driven into ends of the sticks and then the nail heads are cut at a sharp angle. Sharpen- ing the nails with an emery wheel will expedite posi- tioning of water sprouts and reduce damage . Figure 5. A limb on Spartan in November, 1977 that was spread when a water sprout in February, 1976. ■13- Figure 6 Water sprouts that develop from stubs can become valuable replacement limbs i£ positioned. The arrow points to the wooden spreader on a water sprout on a Spartan tree. Observations and Results Limb rotation in the top third of the tree, which in- volves cutting vigorous branches back to the leader or to a much weaker side branch which in turn will be removed when it becomes large, may be a suitable tree containment techni- que regardless of planting density. Retaining and spreading water sprouts to replace pruned branches appears practical and is being done in some commercial orchards. Many trees require no limb spreaders and when used, only 2 or 3 are generally necessary. A shoot originating from a stub of a branch removed from the central leader can become a valuable replacement limb. Shoots originating from the lower side of the stubs generally have the most desirable crotch angles. Therefore, when remov- ing the branch from the central leader, we suggest a slanting cut be made so that the top of the stub will be flush and the bottom of the stub will project about 1 inch. •14- The yield reduction on the height- reduced trees was not consistent until 1978 (Table 1). In 1978 and 1979 the shorter trees of both cultivars produced less fruit than the taller trees. The 2.5 foot reduction in tree height reduced yield by 2.5 to 3 bushels in 1979. This is a sizeable re- duction in yield and should be considered when reducing tree height in an established planting. New plantings can be designed with higher tree densities to compensate for bearing surface lost by keeping trees shorter. Table 1. Influence on yield from height reduction of Spartan and Idared treesz. Spartan^ Idared X Height Height Year reduced Control reduced Control Bushels/tree 1976 6.0^ 8.0a 6.2a 7.5a 1977 4.0b 5.3a 4.1a 4.8a 1978 10.4b 12.5a 10.2b 12.4a 1979 9.6b 12.9a 8.9a 11.4a z Trees planted in 1964; trial started in Feb., 1976. y Tree height 3/79: Control - 11.4'; height- reduced trees: 8.9' X Tree height 3/79: Control - 10.6'; height-reduced trees: 8.3' w Means in any row for each cultivar followed by different letters are significantly different at odds of 19 to 1. Summary We plan to maintain the 2.5 foot height difference be- tween the height-restricted and height-reduced trees in 1980 and 1981 in order to determine the yield differences. It is unfortunate that Mcintosh trees are not in this trial because it would be of interest to determine the effect of pruning on fruit color. Nevertheless, this trial and others has supplied valuable information on containment pruning, and should continue to do so. Trees on vigorous-size controlling rootstock are the predominant type tree in Massachusetts. We believe that by main- taining a dominant central leader and doing containment pruning, trees on M7, MMlll, and MM106 can be kept to a size suitable for medium density orchards (115-200 trees per acre). -15- Allornate vs. Hvtry Middle Spraying For Apple Fesi ? in 1979 William M. Coli and Ronald J. Prokopy" Department o£ Entomology In previous issues of Fruit Notes , we reported our 1977 and 1978 findings on the comparative effectiveness of alter- nate-middle vs. every-middle spray treatments for apple pest control. (See Fruit Notes 45(5) : 15-19 and 44(5): 15-35.) The 1979 results of alternate middle spraying fox apple diseases have been reported in the November/December, 1979 issue of Fruit Notes. Here, we present (a) our findings on alternate middle vs. every middle spraying for apple insects; (b) further information on diseases, and (c) a cost-benefit comparison with regard to insects, mites and disease control. Alternate middle spraying involves spraying alternate halves of each tree on alternate spi;ay dates instead of both halves on all spray dates. For example, in applying the first cover spray, the sprayer would be driven up the middle between tree rows A and 6 and return down the middle between rows C and D, skipping the middle between rows B and C. For the sec- ond cover spray, the sprayer would be driven up the middle be- tween rows B and C, down the middle between rows D and E, and so forth. If this pattern is followed on each spray date, it would save 50% of spray material and application costs. Each of four test blocks in commercial orchards was divided into 2 plots of 2-6 acres each. One plot received the alter- nate middle program on each spray date throughout the season. The other received tlie every middle urogram. Each grower used an air-blast sprayer and a concentration (IX, 4X, etc.) of his own choosing. Growers followed their normal spray schedule and selected their own pesticide materials. Except in one block, all trees were fully groivn, some on M7 rootstock, others on seedling. Pruning was generally adequate to allow for good spray penetration into tree centers. Monitoring of Pest Populations We utilized commercially available visual traps to moni- tor populations of tarnished plant bugs, European apple saw- flies, and apple maggot flies as well as pheromone traps for 1 Extension Pest Management Specialist (Entomology) and Extension Tree Fruit Entomologist, University of Massachusetts at Amherst, Other field personnel were Glenn Morin, Senior Scout; Norman Anderson, Clarence Boston, Annemarie Pennucci, and Mary Tubbs, Scouts . -16- codling moth, redbanded leafroller and oblique-banded leaf- roller. Visual inspections of fruit and foliage in all por- tions of the tree canopy were used to monitor populations of plum curculio, spotted tentiform leafminer, green apple aphids, and aphid predators. Sampling was only tri-weekly, due to gasoline scarcity. An on-tree survey of 1200 fruit per treatment block was per- formed at harvest to determine injury levels to fruit. Insect Injury to Fruit At Harvest Total insect injury at harvest averaged 2.84% in alter- nate-middle blocks vs. 3.61% in every-middle blocks (Table 1) below. Table 1. Average percent of insect and disease injury to fruit in 4 alternate-middle vs. every-middle commercial orchard blocks in Massachusetts, 1979. Insect Every-middle Alternate-middle Tarnished plant bug 3.07 Plum curculio 0.27 San Jose scale 0.19 Apple maggot fly 0.04 European apple sawfly 0.02 Green fruitworm 0.02 Codling moth 0.00 Other 0.00 Total 3.61 2.48 0.12 0.04 0.02 0.02 0.02 0.00 0.14 2.84 Disease Every-middle Alternate-middle Scab Rots Rusts Total Total injury from insects and disease 0.24 0.14 0. 00 0.38 3.99 .06 .11 .06 .23 3.07 In 1979, the most serious pest in both types of blocks was tarnished plant bug, which accounted for 2.48% injury in alternate-middle blocks vs. 3.07% in every-middle blocks. -17- Injury from the other major insect pests (plum curculio, San Jose scale and apple maggot fly) was consistently greater in every-middle than in alternate-middle blocks. European apple saw- fly and green fruitworm injury levels were identical under both treatments, whereas leafroller injury was high (0.58%) in one alternate-middle block. Disease Injury to Fruit at Harvest Apple scab was the principal disease problem in all blocks. Various rots were of secondary importance, while rusts were only occasionally present (Table 1) . Overall disease incidence was slightly greater in every-middle (0.381) vs. alternate-middle (0.23%) blocks. (For more information concerning 1979 disease results in alternate-middle vs. every- middle blocks, see Fruit Notes 44(6): 6-8.) Cost Benefit Comparison In 1979, alternate-middle spraying resulted in a savings of $62.61 per acre for insecticide and miticide materials and appli- cation costs. Fungicide materials and application costs were $70.69 less in alternate-middle blocks. Fruit loss due to insect and dis- ease injury was $19.03 and $6.70 less, respectively, in alternate- middle blocks (Table 2). Table 2. Cost benefit analysis of every-middle vs. alternate- middle treatments, 1979. Dollar cost/acre Every- Alternate- middle middle Differences Avg . cost of insecticide and miticide materials and application $125.23 $62.62 -$62.61 Avg. value of fruit loss due to insect injury $ 78.93 $59.90 -$19.03 Avg. net benefit from alternate-middle spraying for insects and mites +$81.64 Avg. cost of fungicide materials and application $141.38 $70.69 -$70.69 Avg. value of fruit loss due to disease injury $ 17.80 $11.10 -$ 6.70 Avg. net benefit from alternate-middle snraving for diseases +$77.69 Ave. net benefit from alternate-middle spraying for insects, mites and diseases +$159.33 Growers utilizing alternate-middle spraying realized a net benefit of $81.64 per acre with regards to insects and mites, and $77.69 for diseases, or a total average net bene- fit of $159.33 per acre. We believe that our 1979 results, as well as those from 1978, indicate the potential usefulness of alternate-middle spray- ing, perhaps most advantageously employed when in combination with intensive IPM weekly scouting and grower advisement. (See Fruit Notes 44(6) : 6-8, 9-14.) Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 45, No. 2 MARCH/APRIL 1980 TABLE OF CONTENTS Airblast Sprayers for Orchard Spraying Spotted Tentiform Leafminers: Biology, Monitoring, and Control More About Nematodes and Fruit Trees AIRBLAST SPRAYERS FOR ORCHARD SPRAYING-*" Kenneth D. Hickey Pennsylvania State University Fruit Research Laboratory Biglerville, PA 17307 Airblast orchard sprayers which form, transport, and deposit water droplets onto all above ground parts o£ trees are essential to the commercial production of deciduous fruit crops in eastern fruit growing areas. One characteristic which these sprayers have in common is a fan that generates the mass of air which carries droplets of pesticide suspensions to the target area. The manage- ment and control of all major orchard pests affecting leaves, twigs and fruit (diseases, insects and mites) is dependent upon timely pesticide sprays applied to all areas of the tree. In orchard spraying, the spray target often is not the specific pest being controlled (insect, mite or fungus spore) but rather the leaves or fruit on which it may be present or to which it may visit after the spray has been applied. The target, thus being the tree which is extremely variable in size, shape, density, and row spacing, has created a need for different types of sprayers. Sprayer manufactur- ers responding to these needs have produced airblast sprayers which are so diverse that a grower in America can buy just about any type he may need for his orchard operation. Because of the gradual change from standard size trees to semi-dwarf and dwarf types most growers in the mid-Atlantic states have needs for a sprayer that can be used to spray conventional size standard apple trees as well as dwarf apple, peach and cherry. The amount of spray mixture used per acre is another variable that has to be adjusted depending on tree type and size. The amount commonly used varies from 400 gal/A (gpa) in dilute sprays for mature standard apple trees to 10-20 gpa with low volume sprayers. Ultra low volumes of as little as 1.0 to 3.0 gpa have been used with special sprayers but this usage is still very limited. With this magnitude of variation in tree size and spray volume used and the wide range of sprayers available with just about any size tank, it is understandable why growers are often confused when buying a sprayer. To add to the confusion, descriptive phrases such as cfm air volume, air velocity range, dual adjustable blower, axial flow and centrifugal fans, mass median diameter of droplets, shear, disc, mistifier and spinning nozzles, touch command meters, flip over nozzle, and fluid agitation often are used to reveal the wonders of each specific sprayer. 1 Appeared in the Maryland Fruit Grower 49(4): 2-6, 1979 and the Pennsylvania Fruit News. April, ly/y. Reprinted with permission of the author. Conventional vs. Low Volume Sprayers Orchard airblast sprayers available today may for convenience sake be placed in one of three major categories, i.e., conventional, low volume and ultra low volume. The conventional type airblast sprayer commonly used today and during the past decade was designed to apply both dilute and semi- concentrate rates which ranged from 500 gpa to as little as 50 gpa. These sprayers operate at a pump pressure from 30 to 400 psi that force the spray mixture through a manifold on which several nozzles (6 to 15 per side) are located. Variable nozzle sizes may be sel- ected which regulate the sprayer delivery rate as well as the range of droplet size produced. The droplets are discharged into the airstream which range in velocity from 80 to 120 mph and in volume from 25,000 to 90,000 cubic feet of air per minute (cfm) . Air volume specifications for orchard airblast sprayers in the past have been highly controversial and their accuracy questionable to the point where they are not often used today. The droplet size produced by these machines has a wide range from 10 to 600 mu depending on pump pressure and nozzle orifice size. The conventional sprayers are effective in the application of 50 gpa or higher but are limited in the application of smaller amounts. In recent years sprayers designed to apply 5 to 20 gpa have been introduced and widely used in many apple growing areas of eastern United States. Similar type concentrate or low volume sprayers have been used for the past 20-25 years in Europe, Africa, Australia, Middle-East, Canada, and in several apple growing areas of western United States. The low volume airblast sprayer differs from the conventional type mainly in pump pressure, air velocity and air volume. Pump pressure ranges from 25 to 100 psi. Nozzles used on these machines vary from 3 to 12 per side and are either a hollow-cone swirl nozzle, a spinning nozzle, or an air jet which does not use swirl plates or discs. The spray droplets are formed when the spray mixture is injected into the airstream which may vary in velocity from 130 to 200 mph and in volume from 15,000 to 25,000 cfm. The high velocity airstream performs two major functions: 1) that of a shearing or impact action in the formation of droplets which range in size from 10 to 110 mu; and 2) as carrier of the droplets to all parts of the target areas at high enough velocity for impingement. Sprayers which may effectively dispense 1.0 to 3.0 gpa of spray mixture are available and have been proven to be equal to other sprayers in pest control. Uniform droplets are formed by a revolv- ing porous sleeve powered by an electric 12 to 24 v DC motor. Sleeves of porous metal or plastic are available which produce precisely con- trolled droplets from 5 to 100 microns. The liquid pesticide formu- lation or suspension in water are forced through the uniform pores by centrifugal force generated by the spinning nozzle. The nozzles are mounted in the airstream which may vary in volume and velocity and the droplets are sheared off and carried to all parts of the tree. The ultra low volume sprayer is the least tested to date and its use is limited by relatively few pesticide formulations which can be used. This type of sprayer has greater usage potential in the future when pesticides may be delivered directly from their pack- aged container to the tree without benefit of water as a carrier. The low volume sprayers in general use in many parts of the world are powered by the "power- take-off " on the tractor used to pull them through the orchard but also may be engine operated. They offer several advantages over the conventional sprayer: 1. Many of these machines cost less to purchase than conventional machines since most have smaller tanks, low pressure pumps and no motor. 2. They often are less costly to operate and maintain since fuel consumption is less with only the tractor motor being used in the spraying operation. Their simple design and low pressure pump which wears at a much slower rate also contributes to their low maintenance. 3. Spraying with these machines requires less total time because more time is spent applying sprays to the trees and less time in filling the spray tank and weighing out chemicals. As much as 50°6 savings in spray time can be realized with a change from 400 to 20 gallons per acre. 4. Reductions by 80-6 in the amount of water used has resulted in a significant savings on farms v/here water is scarce or must be transported for some distance. This reduction in the amount of spray mixture used also eliminates the need for a "nurse tanker" and operator often used in high volume spraying. 5. Low volume spraying generally requires about 20-40% less pesticide per acre than high volume spraying. Factors Affecting Spray Deposits Since the mass of air generated by airblast sprayers is the major source of energy dispensed in carrying spray droplets to all parts of the tree, some understanding of its character and factors affecting it should be helpful in deciding the type of sprayer to purchase. The airblast is generated by various types of fans and may vary in volume and velocity depending on the particular design or type. Droplets are either injected into the airstream through nozzles which aid in forming droplets into a range of sizes from 30 to 600 microns (1.0 micron (mu) is equal to 1/25,000 inch or 0.001 mm), or the liquid is released into the airstream under low pressure and is broken or sheared into droplets. This shearing action is typical of the high velocity low volume sprayers commonly referred to as mist-type sprayers. the rate of evaporation. A droplet moving in an airstream must have a certain minimum momentum in order to penetrate through the layers of air flowing around it. Because of the greater influence of drag force the smaller droplets traveling in relatively slow airstreams tend to follow the random turbulent fluctuation of the airstream more closely and therefore travel a more devious path than the larger droplets. Considering these facts it is evident that impingement of droplets produced by low volume sprayers would be lower during periods of low R.H. or in slow moving airstreams. Workers in New York have shown that under conditions of high evaporative potential which commonly occur during the growing season, spray droplets may lose more than 40-6 of their original volume during transport time from sprayer outlet to the foliage. They found that when the R.H. was 95% there was only about 5% water loss at 30 feet from the sprayer outlet, while 20-251 was lost when the R.H. was M% . Spray deposits in the top of trees was only 37% as much at 351 R.H. as when the R.H. was 951. Summary of Conditions Affecting Airblast Sprayer Performance A number of experiments designed to evaluate the performance of several conventional and low volume sprayers for apple pest control have been conducted in recent years. During the past 2 years Dr. L.A. Hull, Entomologist at the Fruit Research Laboratory, and I have evaluated several sprayers for control of green apple aphid and spray distribution patterns. Control levels of aphids have been correlated with chemical deposits on leaves as measured chemically using dicofol and visually using a fluorescent tracer. A number of conclusions can be drawn from these experiments and a summary of several follows: 1. Sprayer size and design directly affects spray coverage and pesticide deposits and determines the size of tree that can be properly sprayed. Conventional airblast sprayers having an airmass volume of 65,000 cu. ft. per min. or greater with velo- cities of 120 mph or more and the larger low volume sprayers may be used effectively on standard orchard trees up to 22 feet in height. Low volume sprayers of the small to intermediate size v\?hich are power take-off operated perform better in dwarf or semi-dwarf trees with heights of 12-15 feet. 2. The tree size in height and density directly affects the velo- city of the airmass by blocking or slowing air movement and subsequently affects the amount of chemical deposit. Sprayers should have sufficient air volume and velocity to blow through the top of the trees to be sprayed. m In a spraying system using air as the carrier o£ droplets several factors are operative simultaneously which affects the distribution pattern and quantity of chemical deposited. The velocity and volume of the airstream, droplet size, evaporation rate, ground speed and target distance all have individual effects on the results obtained. Droplet size and air velocity must be critically balanced to obtain effective and efficient spray application. Spray droplets of a predetermined size must travel at specific speeds in order to remain in an airstream. Many tests throughout the years have determined these critical speeds and have shown that as the velo- city decreases the larger droplets drop out first followed by pro- portionally smaller droplets as the velocity continues to decrease. The rate of velocity decrease of different airstreams has been found to be similar regardless of the volume. Thus, two airstreams with similar velocities at the point of outlet but having drastic- ally different volumes will also have similar velocities at 25 feet from the outlet and both may be only 15 to 20 percent of their original speed at this distance. In view of this rapid velocity decrease with distance from the sprayer outlet, droplet size becomes very important in the impinge- ment of droplets on leaves and fruit which directly affects the level of pest control obtained. The impingement of liquid droplets on a solid surface such as a leaf or fruit depends largely upon two factors; 1) the mass or size of the droplet, and 2) the velocity at which it is traveling. Large droplets will impinge at low velo- cities but also are the first to fall out of the airstream as the velocity decreases. The smaller the droplets the higher the velo- city required for their impingement but these droplets are carried farther in slower airstreams. In slower airstreams droplets are subjected to evaporation for a longer period than in high velocity ones, thus decreasing their size further and diminishing their chances of impingement. With conventional airblast sprayers the air velocity at the outlet may be approximately 120 mph while at 25 feet away it often drops to 15-20 mph. In these airstreams if proper droplet size is not carefully selected and distributed in calibrating the machine the larger droplets fall out on the lower parts of the trees while the smaller ones are carried farther but not deposited in the upper portion of the tree. The end result is often a poor spray distribution with heavy deposits on the lower leaves and fruit which may be phytotoxic and inadequate pest con- trol in the top of trees. The effect of relative humidity (R.H.) on spray deposition has been recognized and of concern to growers since the introduction of airblast sprayers. The effect of a high evaporation rate due to low R.H. on small droplets produced by low volume sprays is far more significant than on larger droplets because droplet size and momentum greatly affects rate of impingement. It has been shown that the rate of evaporation of the total spray volume will be pro- portional to the total sum of the diameters of the droplets compri- sing the spray. Therefore, the smaller the spray droplets the greater The rate of sprayer travel has a direct effect since air velocity loss is proportional to the forward speed. Speeds above 2.5 mph for standard trees and 3.0 mph for dwarf trees are not recommended. Evaporation rate of the droplet and droplet impingement is directly correlated with relative humidity of the ambient air. Spraying during low humidity (.35-50% R.H.) periods should be avoided, particularly with rates less than 30 gpa. Spray distribution in the tree as well as undesirable spray drift is greatly influenced by wind conditions at the time of application. No reliable tests under known wind conditions have been conducted to measure effect on pesticide distribution and deposits. The level of pest control obtained is correlated with inoculum or population pressure and the amount of pesticide applied. The lowest deposits and level of pest control are in the top of trees. It is important to keep any sprayer properly adjusted to obtain maximum performance. Frequently checks on pump pressure, nozzle wear, operator speed and air delivery are essential to dependable sprayer performance. It is particularly important that the air velocity of airblast sprayers with shear-type nozzles be checked frequently and maintained at between 165-200 mph. Accurate calibration of airblast sprayers is essential for the uniform application of orchard pesticides. (Details of proper arrangement of nozzles to obtain proper distribution pattern for conventional airblast sprayers are given in Figure 1.) Upper 2/3 Effective Airblast Noz. Discharge No GPM 6 105 5 0.83 4 0.63 3 0.45 2 0.34 -3 1-2.5 Lower 1/3 I-OFF Effective ^"2.5 Airblatt ''OFf REAR VIEW OFF-hCV 2 5-t-O OFFH-o 50%» 3.86 GPM (3.76) 35% = 2.66 GPM (2.72) IS*- I.I4GPM (113) SIDE VIEW 100 GPA - 15.2 GPM (76 GPM/side) ROMS 30 ft Speed 2.5 MPH 2 Hole Whirl Plote - 200 PSI SPOTTED TENTIFORM LEAFMINERS: BIOLOGY, MONITORING, AND CONTROL Ronald J. Prokopy, Robert G. Hislop, and William M. Coli Department of Entomology INTRODUCTION From the early 1950's until 1978, spotted tentiform leafminers (STEM) could occasionally be found in low numbers in unsprayed apple trees in Massachusetts, but were rare in commercial Massa- chusetts apple orchards. Since then, STEM have appeared in compara- tively large and damaging numbers in some commercial orchards, esp- ecially west of the Quabbin reservoir. Thus, in 1979 STEM mines were found at levels of 0.1 or more per leaf in 12 of 13 orchards sampled west of the Quabbin, but at this level in only 3 of 13 or- chards sampled east of the Quabbin. There are 2 species of STEM in Massachusetts: Phyllonorycter crataegella and Phyllonorycter blancardella. More than 901 of the STEM sampled by us in Massachusetts in 1979 were P. crataegella. Recent studies by Dr. Richard Weires of the Hudson Valley Fruit Laboratory in Highland, New York and by Drs . John Leeper and Harvey Reissig of the Geneva, New York Experiment Station have clear- ly shown that in New York, both these STEM have developed strong resistance or tolerance to azinphosmethy 1 (Guthion) , phosmet (Imidan) , phosalene (Zolone) , carbaryl (Sevin) and several other broad- spectrum insecticides commonly used in orchards over the past decade or two. On the other hand, the principal parasites of STEM continue to re- main highly susceptible to these insecticides. The result is yet another instance of pesticide- induced population explosion, compar- able to the situation we have experienced with spider mites over the past 3 decades. The pest, no longer influenced by the effects of pesticide and freed from the presence of natural enemies, is able to multiply very rapidly. Resistant populations of STEM were apparently first detected in Columbia County, New York in 1974. Since then, such populations have spread throughout most of the Hudson Valley and much of Connecti- cut, and are now being carried into Massachusetts through natural dispersal (often aided by warm southwest winds) and importation of infested leaves in bins of apples from infested orchards. Even in cases when the original introduction of STEM into an orchard may have consisted of only a few resistant individuals, popu- lation buildup may be very rapid. Each female lays an average of 25 eggs, and there are 3 generations per year. Hence, if there were no egg, larval, or pupal mortality, a single 1st generation mated female in May could give rise to more than 15,000 STEM larvae by September. Fortunately, there is considerable natural mortality, even in the absence o£ pesticide-resistant parasites or predators, so that the full biotic potential o£ this pest is rarely if ever rea- lized. In this article, we will outline the biology and monitoring methods of STLM, and suggest various possible approaches to control. Drs. Weires, Leeper and Reissig have been studying these aspects in New York since 1976. Much of what we will describe here is drawn from their excellent work, some of which is published in the 1977 Proceedings of the New York State Horticultural Society, the August 1977 issue of the Journal of Economic Entomology, the March, 1978 issue of the American Fruit Grower^ and New York Food and Life Sciences Bulletin 85 (1980")"^ BIOLOGY Description of Stages and Life History. STLM overwinter as pupae in apple leaves on the orchard floor. First generation adults begin to emerge when Mcintosh trees are in the green tip stage of develop- ment. The adults are small (about 1/8 inch long) light brown moths with white wing spots that appear as transverse bands when the wings are folded. Though frequently found resting in ground cover vege- tation during the day, they are particularly active from late after- noon through dusk, and may be found then on the undersides of leaves, the tree trunk, or interior scaffold limbs. The tiny white eggs (1/75 inch diameter) are laid singly on the undersurface of the leaves and require about 6-10 days to hatch. First generation eggs are laid predominantly on fruit-cluster leaves in the lower half of the interior of the tree. Second and third generation eggs may be laid on any leaves anywhere in the tree. In addition to apple leaves, leaves of other trees such as crabapple, hawthorne, quince, plum, and wild cherry may also serve as STLM hosts. The larva develops in the same leaf on which the egg was laid. Larvae develop first through 3 sap-feeding stages and then 2 tissue an irregular oval, circumscribing the area within which the larva will eventually develop to maturity. By the 3rd larval stage, the lower leaf surface tissue circumscribed by the trail will have a light green or whitish appearance and can be readily removed, revealing the feeding larva. Tissue feeding larvae feed just below the upper surface, producing tent-like mines with whitish spots visible when the green tissue has been eaten. The last-stage larva transforms into a pupa in the leaf tissue, with the pupal stage lasting about 10 days. The entire life cycle requires about 35-55 days, depending on weather conditions . Mines o£ 1st generation larvae can be first detected in late pink or bloom, those of 2nd generation larvae in late June or early July, and those of 3rd generation larvae in mid or late August. Generations may overlap owing to the extended period of egg-laying. Injury. STLM do not directly injure apple fruits. Rather the dam- age results from injury to the leaves caused by larval feeding. There is some suggestion, not yet confirmed that STLM larval feeding interferes with the ability of leaves to produce or transfer to fruit a hormone which inhibits ethylene production by the fruit. STLM injury may result in greater than normal concentration of ethylene within the atmosphere of the tree canopy. Principal effects of extensive STLM larval feeding on Mcintosh and other earlier-season cultivars such as Milton, Early Mcintosh, Wealthy, and Puritan may be early ripening of fruit, premature fruit drop, reduction in fruit size and color, reduction in fruit firmness and storagability , and/or reduction in fruit set the following year. Additional effects of STLM feeding may be: (a) greater sus- ceptibility of larval-infested leaves to phytotoxic effects of insecti- cides, fungicides, or calcium chloride nutrient sprays; (b) reduced capability of larval-infested leaves to absorb growth-regulator sprays applied to prevent early fruit drop or promote ripening, or (c) compounding of detrimental effects of large spider mite popula- lations, low plant nitrogen, or poor pruning. In New York, there have been little or no detrimental effects of large STLM populations on Red Delicious. Natural Enemies. Several species of tiny wasps have been found parasitizing STLM larvae in New York and Southern New England. The parasite larvae hatch out from eggs deposited in STLM mines and suck out the body fluids of STLM larvae. In Massachusetts, we have found at least 5 such parasite species, the most abundant of which is Apanteles ornigis. Among 9 Massachusetts commercial apple orchards We speculate that there might be a more or less continual immig- gration of parasite adults from unsprayed trees into commercial or- chards during the growing season. However, regular application of insecticide from petal fall through early August undoubtedly kills most adults immigrating at this time. This is borne out by the fact that both Weires and we find very little parasitism of 1st and 2nd generation STLM larvae. Adoption of integrated pest management tech- niques and corresponding reduction of unneeded insecticide applications, especially in July, could open the way to increased levels of para- sitism of 2nd generation larvae. Termination of insecticide appli- cations by early August may allow comparatively high survival of parasites attacking 3rd generation larvae. Such parasitism of these larvae, together with natural enemies feeding upon overwintering STLM pupae, could result in substantial mortality to overwintering numbers of STLM. 10 MONITORING Adults . STLM Adult seasonal activity may be monitored by employing St icky traps baited with synthetic female sex pheromone caps (obtain- able from Conrel Corporation, 110 A Street, Needham Heights, MA). Adults can also be captured on white sticky-coated visual traps used for monitoring tarnished plant bug and European apple saw- fly adults (obtainable from New England Insect Traps, Box 938, Amherst, MA). In 1980, we plan to assess which color of visual trap is most attractive to STLM adults. At present, there is no reliable means of relating numbers of adults captured in pheromone or visual traps to potential injury levels. Future research is aimed in this direction. Larvae . In most orchard situations, the most useful monitoring method to date has proven to be examination of the leaves for STLM larval mines. For 1st generation larvae, leaf monitoring should begin at late pink and continue at 4-7 day intervals until 1 week after petal fall. For 2nd generation larvae, monitoring should begin in late June and continue at 4-7 day intervals through late July. Monitor- ing of 3rd generation larvae is unnecessary, as the New York research- ers have found that while these larvae cause characteristic mines, this injury occurs too late in the season to threaten the crop or warrant additional insecticide applications. For monitoring , it is best to examine at least 10 leaves per tree on at least 1 tree per acre. For 1st generation larvae, choose fruit cluster leaves at head height in the lower half of the tree in- terior. For 2nd generation larvae, choose leaves on new woody tissue (but not water sprouts) from anywhere in the tree. It is extremely important to look carefully for evidence of earliest sap-feeding mines on the lower leaf surface. This is best done by holding the leaf toward the sky, and locating the thin wind- ing brown trail and/or the light green or whitish appearing mine. CONTROL One or a combination of the following 3 pesticide- treatment programs may be used for STLM control. Research conducted in New York and Canada shows that high levels of adult immigration and/or high overwintering mortality of STLM pupae render the previous year's level of STLM abundance in a given block of little value in predict- ing this year's STLM abundance. Thus, each grower should keep a careful eye on each block during the current growing season. A. Endosulfan (Thiodan) Program. This program is aimed at control- ling STLM adults and consists of 1 application of endosulfan (half strength) at half inch green and a 2nd application (full strength) at pink against 1st generation adults, and/or an application of endosulfan (full strength) in late June or early July timed to coincide with emergence of 2nd generation adults. 11 Pre-bloom application o£ endosulfan will also give good control of plant bugs. In some years, such as 1979, emergence o£ over- wintering adults may be strung out, and a pink application of endosulfan may not have sufficient residual activity to carry over and kill adults emerging after petalfall. Best results will be obtained if application is made in the evening, when ad- ults are most active, and if trees are well pruned to facilitate pesticide coverage. One of the major advantages of this program is that endosulfan has very little adverse effect on the principal predators of spider mites and aphids in Massachusetts, and is therefore fully compatible with an integrated pest management program. Methomyl (Lannate) Program. This program is aimed at control of STLM larvae in mines and consists of 1 petalfall application of methomyl (full strength) directed at 1st generation sap-feeding larvae and/or 1 application of methomyl (full strength) in July against 2nd generation sap-feeding larvae. Application should be made only if STLM populations reach or exceed an average of 1 mine per leaf at petalfall or 2 mines per leaf in July. Petal- fall application of methomyl will control green fruitworm and leafrollers but will not control plum curculio. The need for precise timing and proper concentration of methomyl application can not be over-stressed. Application at less than full strength may give poor control. Delay of application until many larvae have reached the tissue- feeding stage may not only result in poor control, but more importantly, may seriously exacer- bate phytotoxic effects of a variety of insecticides and fungi- cides, as well as calcium chloride sprays. To illustrate, we are familiar with a situation in 1979 when a grower applied methomyl against 2nd generation larvae after a substantial number of the larvae had already entered the tissue feeding stage. Control was fair, but the resulting large amount of phytotoxicity from subsequent fungicide and insecticide treat- ments greatly exacerbated the adverse STLM effects on premature fruit ripening and fruit drop. Methomyl may cause severe injury to the foliage of many early season apple cultivars and thus should not be applied to such cultivars. Also, methomyl is a highly dangerous compound, re- quiring careful use of a good respirator and gloves. A major disadvantage of this program is the strong toxicity of methomyl to mite and aphid predators which may result in large spider mite and woolly apple aphid population buildup in mid- and late summer. 12 ]. Oxamyl (Vydate) Program. This program is aimed at control of STLM adults and larvae and consists of 1 application of oxamyl (half strength) at pink directed against 1st generation adults and larvae and/or 1 application (full or half strength) in July against 2nd generation larvae. The latter application should be made only where sap- feeding mines reach or exceed an average of 2 per leaf. Massachusetts has received a special 24 (c) registration for use of oxamyl on bearing apple trees in 1980. Inasmuch as oxamyl will not control plant bugs, an additional pesticide should be included in pre-bloom treatments for this purpose. Oxamyl has thinning effects, and should not be applied at pctalfall or for 30 days thereafter. Because oxamyl is sys- temic and has better residual activity than methomyl, timing of application may be somewhat less critical than with methomyl. Also oxamyl may be used with much less risk of phytoxicity than methomyl on early ripening apple cultivars. There are 2 major disadvantages of this program. First, oxamyl is an extremely dangerous compound, having caused considerable sickness among a number of Hudson Valley growers in 1979. Its inhalation toxicity is many times greater than that of methomyl. Use of a good respirator and gloves is an absolute must. Second, oxamyl, like methomyl, is highly detrimental to mite and aphid predators, although it may provide some degree of spider mite control during the first years of use before resistance develops. Be prepared for eventual outbreaks of spider mites and aphids if you use oxamyl. CONCLUSIONS The information gained by New York researchers during 5 years of recent experience with STLM is of im.mense value to our ability to cope with the new insecticide- resistant strains of STLM entering Massachusetts orchards. Several of the possible measures aimed at controlling this pest pose a serious threat to the survival and build- up of spider mite and aphid predators in integrated pest management orchards. However, if growers use discretion in application of measures for STLM control, and employ control measures only when truly necessary and at optimal times, then the chances for success- ful integrated pest management in the future are greater. In this regard, treatments against 1st generation STLM larvae will have much less adverse effect on beneficial predators than treatment against 2nd generation larvae. We must be very careful not to apply excessive numbers or rates of those few materials currently effective against STLM, lest we induce rapid development of STLM resistance to these materials. Further research by colleagues in New York and other surrounding states, coupled with our own studies here in Massachusetts, will hopefully lead to less hazardous and less disruptive means of controlling STLM in the future. 13 MORE ABOUT NEMATODES AND FRUIT TREES R.A. Rohde Department of Plant Pathology A university student majoring in pomology probably wonders sometimes how, with all of the potential problems, a new orchard is ever established. Problems with soil structure and fertility, drainage, toxic decomposition products from fruit tree roots, soil fungi, bacteria, viruses and nematodes can all injure young trees. Sometimes the injury has a name such as crown gall, collar rot or SARD (specific apple replant disease) but more often the result is slov; or uneven growth that is difficult to diagnose, or even measure. Sometimes trees die from winter injury but were weakened by poor growth the previous summer. Nematodes are one of the many factors contributing to the re- plant problem. Nematodes are microscopic worms which live in the soil along with bacteria and fungi and feed on root tips. The feeding process injures or kills root tips and leads to pro- blems of water and nutrient absorption. The resulting wounds usually become infected by root rotting fungi. In addition, some nematodes can transmit virus diseases. A vigorously growing, mature tree can support a large number of nematodes without showing any symptoms. However, trees coming from the nursery, especially those in poor condition or being planted under adverse conditions, cannot tolerate this damage. Experiments at Cornell University and elsewhere have shown that the head start given to small trees by soil treatment is never lost even when high nematode populations return after a year or two . Soil samples from Massachusetts orchards always contain plant- parasitic nematodes, usually of several different species. The three most common, and most injurious, are the lesion, dagger and ring nematodes. Lesion nematodes, Pratylenchus spp., migrate through the inner root tissues breaking them down as they feed. Injury on peach trees is much more severe than on apple because peach roots contain the cyanide-producing compound amygdalin (also known as laetrile) . The cyanide produced in injured tissue increases the amount of damage. Tissues killed by lesion nematodes are quickly invaded by root-rotting fungi and bacteria. Dagger nematodes, Xiphinema americanum, have spears which pene- trate into the root tip and cause it to swell and stop growing. Dagger nematodes can transmit the virus that causes peach stem pit- ting or apple brown line and theoretically only one infective nema- tode is necessary. The virus is not common in Massachusetts, but it is present. 14 Ring nematodes, Criconemoides and Macroposthonia , are root surface feeders. Injury is not severe, but helps to slow down the growth of young trees. Other species of ring nematodes are part of the "Slow Decline of Peach" complex in South Carolina. Soil sampling. Because nematodes are distributed in clusters throughout the field, it is important to collect soil from several areas. For each 5000 sq. ft. area, 10 or more subsamples taken to a depth of 8-10" from the strip where trees are to be planted should be collected with a trowel or spade. Mix the soil in a bucket and then put one quart of mixed soil in a plastic container. If a sampling tube is used, about one quart of soil should be collected. Soi] samples may be taken at any time during the year although winter and spring populations will be low and less representative of the potential of the population to build up. Samples should be sent to one of the Regional Fruit Specialists or directly to the Department of Plant Pathology, University of Massachusetts, Amherst, 01003. Remember, dried out soil is useless. Sampling soil and extracting, identifying and counting nema- todes is time-consuming and requires a fair amount of experience and training. But the most difficult step comes next, when a prediction should be made about how much injury might be expected and what control methods, if any, should be used. The experience of the grower is invaluable at this point because he will often know if problems have occurred in this area in the past and the overall potential of the area to produce fruit trees. Soil fumigation. Treatment before planting to reduce all disease organisms is probably still the best procedure and has been discussed at length before (Fruit Notes 41 (6): 3-5, 1976). Fumigation is expensive, requires extensive preparation and special- ized equipment, and does not always fit in well with the planting schedule. Planting hole treatment. Several insecticide-nematicide chemi- cals have been used as root dips or mixed with soil around thej^p,. tree as it is planted.. All of these materials, oxamyl (Vydate^ ^ rp^ phenamiphos (Nemacur^ ^), aldicarb (Temik^ ^), carbofuran (Furadan^ ^ are highly toxic to humans and are at least partially systemic. At present time, only oxamyl is registered for use in Massachusetts, and only on non-bearing fruit trees. The "state of the art" at present calls for caution. There is enough preliminary evidence to suggest that replant problems exist and treatments will pay off. Because so many factors are involved and because each orchard, indeed each block, is a different ecosystem, small scale field trials are necessary in order to esta- blish the value of any one particular treatment. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaiey Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, $300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE. UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 45 No. 3 MAY/JUNE 1980 TABLE OF CONTENTS The Way You Fertilize Your Fruit Trees Can Affect the Quality of the Fruit You Harvest Suggestions for Use of Calcium Sprays in 1980 Suppressing Weed Growth Under Fruit Trees Pomological Paragraph Influence of Pruning Peach Trees Late in the Spring The Use of Promalin to Elongate Delicious Apples: Research Observations and Suggestions for Use in 1980 Soil Management of Peach Trees Sampling Methods and Provisional Economic Threshold Levels for Major Apple Insect and Mite Pests in Massachusetts Managing Mummy-Berry Disease of Blueberries in Massachusetts THE WAY YOU FERTILIZE YOUR FRUIT TREES CAN AFFECT THE QUALITY OF THE FRUIT YOU HARVEST William J. Bramlage, Mack Drake, and William J. Lord Department of Plant and Soil Sciences In the first half of this century, studies of the fertilizer needs of fruit trees focussed on what was needed to maximize tree growth and fruit yield. In the last couple of decades, however, attention has turned toward the effects of nutrition on the quality of harvested fruit. While the effects of calcium (Ca) deficiency have been the driving force behind the reconsideration of mineral needs, effects of nitrogen (N), potassium (K) , magnesium (Mg), boron (B) and phosphorus (P) levels in fruit on their postharvest quality have been noted. It is clear that the mineral composition of fruit at harvest is an extremely important factor in determining how well fruit will keep after harvest. Most of the research on this problem has been on apples and to a lesser extent, pears, but presumably the same relationships also have some relevance to postharvest problems with other kinds of fruit. It seems appropriate to review these relation- ships between fruit nutrition and fruit quality as we enter into a new growing season. Calcium : In 1936 bitter pit was found to be related to low Ca levels in apples. Thirty years later it could still be stated that "Inspite of the very low Ca status of many orchard so ils ... there have been few reports of direct responses by bearing apple trees to Ca..." (Temperate to Tropical Fruit Nutrition, Norman F. Childers, Editor.) Today, however, there is strong concern about Ca levels in apples and pears just about anywhere in the world that they are grown . At first, this concern was directed at bitter pit and cork spot but today we know that many physiological disorders may be at least partly related to low Ca levels in the fruit. In warmer fruit grow- ing areas, cork spot and bitter pit remain the most serious effects of low Ca, but in cooler areas various forms of internal breakdown are the most serious Ca-def ic iency problem. In British Columbia, Canada, the 'Spartan' apple industry was almost destroyed by break- down problems before methods of raising fruit Ca levels were success- fully developed. Many approaches have been taken to try to raise fruit Ca levels. Since Ca is less available in acid soils, regular liming programs are essential in areas of low soil pH. Calcitic lime is more soluble and is preferable to dolomitic lime unless Mg deficiency exists, since dolomitic lime supplies little available Ca to the soil. Use of calcium nitrate (Ca(NO ) ) as a source of fertilizer N is often recommended, and we have round that it can provide a small increase in fruit Ca levels. In areas where soil is droughty, irrigation is often recommended to maintain Ca uptake by the tree roots. Foliar sprays with Ca salts are the most direct way of insur- ing adequate fruit Ca levels during growth. There is little move- ment of Ca into fruits by the tree as long as vegetative growth is abundant, so the value of sprays is that it places Ca directly on the surface of the fruit, where it can be taken in by the fruit if conditions are appropriate. At first, Ca (NO ) sprays were recommended, but tests with many other Ca compounds have shown that calcium chloride (CaCl ) is generally the most effective material. Leaf injury from CaCl can prevent its use in many growing areas, but in Northern North America it can be used if proper precautions are taken. Frequent applications throughout the growing season are usually the most effective way of applying CaCl„. A single massive application shortly before harvest substantially raises fruit Ca and improves keeping quality of apples. This idea originated in British Columbia and we have tested it extensively, but we believe that the severe foliar damage, the potential for fruit injury or preharvest drop, and the residue that may be objectionable in hand- packing operations make it an unlikely commercial practice. Post-harvest dips in CaCl „ -containing solutions reduce soften- ing and breakdown during storage. The use of a thickening agent greatly increases the effectiveness of a dip, but thickeners leave an objectionable residue that can be very difficult to remove. High concentrations of CaCl„ must be used, and these can cause corrosion of metal and injury to fruit, and may also leave a noticeable resi- due. However, in the appropriate circumstances much benefit can be obtained from a dip. In New England, fruit growers have preferred foliar sprays, but postharvest dips are an alternative. Nitrogen . To stimulate growth of young trees, N is usually applied at high rates. Fertilizer rates should be reduced when cropping begins, but they are sometimes continued because yields can be increased. Even when N application is reduced when cropping begins, the trees may continue to be supplied with excessive amounts of N from the large reserves that have accumulated in the soil, sod and tree. We have found that high N levels in trees fall very slowly even when no additional N fertilizer is supplied. Excessive amounts of N in the tree and fruit can severely reduce fruit quality. The vigorous growth that it encourages reduces the Ca level of the fruit. Moreover, the high N fruit tend to be larger, greener, softer, more subject to preharvest drop, and to have more cork spot and bitter pit. These fruit also tend to develop greater amounts of scald, bitter pit, internal browning, and internal break- down during and after storage. Over-fertilization with N is probably very common. In the Paci- fic Northwest it has been estimated that 50 to 75% of apple orchards. and a smaller percentage of pear orchards, are excessively high in N. The effects of high N on apples are perhaps being masked at harvest by use of growth regulators, especially Alar, but growth regulators cannot mask their consequences after storage. Until recently the cheapest form of N was usually the one chosen for fertilizing orchards. It is now recognized that the form of N as well as the total amount of N that is used can influence fruit quality. USDA researchers first found that ammonium (NH.) forms of N can intensify Ca deficiency in apples by interfering with absorp- tion of Ca by roots. It has been recommended that NH. -contain ing fertilizers not be applied to apple orchards before or soon after bloom if growers are concerned about fruit Ca levels. the Use of Ca roots and a (NO ) ^as void! Is NH an N-source both supplies available Ca to interference with Ca absorption. Our experiments with use of Ca (NO ) rather than NH.NO show that Ca(NO ) may produce a small Increase in fruit Ca levels, but that this is not enough to correct Ca deficiency if it already exists. Whether the additional cost is justified by the benefit is a question for growers to decide. Our experience leads us to conclude that the total amount of N being applied to fruit trees is a more important concern to fruit quality than is the form of N that is being used. Po tassium : K deficiency reduces growth and yield of trees and severe K deficiency in apple and pear trees causes "leaf scorch", a browning of the leaves. K deficiency has only a mild effect on fruit quality, reducing acidity of the fruit and reducing red color- ation. Excessive amounts of K in fruit are a greater danger to fruit quality, since they lead to increased scald, bitter pit, and internal breakdown after storage. Fruit accumulate large amounts of K, and large yields can remove a large amount of K from an orchard. Therefore, fertilizing with K is most likely to be needed after a large crop. Nevertheless, fruit quality will suffer far more from excess K than from deficient K. Most of the effects of high K are the result of its interference with Ca in the fruit, and too much K will generally have the same effects as too little Ca. Magnes ium : Mg deficiency can produce weak and unproductive trees, and cause increased preharvest fruit drop, and its distinctive color patterns on leaves have often been observed. It may be corrected by application of dolomitic limestone or by foliar sprays with materials such as Epsom salts. There is little evidence that either too little or too much Mg directly affects fruit quality. However, excess Mg interferes with Ca just as does excess K, so excessive amounts of Mg will produce Ca deficiency effects in fruit. Phosphorus ; P deficiency can reduce tree growth and yield, and in several parts of the world it has also been shown to cause increased amounts of breakdown of apples during storage. However, in North America there has been very little evidence for P defic- iency in fruit. However, we have recently found that high levels of P in apples, especially in combination with low levels of Ca , greatly increased breakdown of apples during storage. Boron : B deficiency has occurred over much of North America, causing both internal and external cork development in fruit. Ex- cessive levels of B in fruit can cause earlier maturation and increased amounts of watercore at harvest, and increased amounts of breakdown after storage. Thus, a moderate level of B is important for good fruit quality. B also influences Ca movement in the tree. If it is deficient, less Ca is moved to the fruit and Ca deficiency can result. It is therefore important to maintain adequate B levels as a part of a program to avoid Ca deficiency. Periodic application of borax to the soil is a standard commer- cial practice in many parts of North America. A widely used alter- native is 1 or 2 foliar applications of a soluble form of B in sprays shortly after blossoming, although it is not clear how much of this B moves from leaves into the fruit. It is clear that deciding on a fertilizer program for an orchard is no simple matter. The awareness that Ca deficiency is common and that it greatly increases losses of stored fruit has caused a thor- /-i.ir>T-i ■»-Q_QTTo1.io<-n<-.r> <->f fQT-^^^^■7^:>^- ^>■ra<^^^r•oc Ue ■^^ "5 s i ^^^;^ ^>=a<;;^^J^^^^ =A • E.go ^^^ ^. ^?.E .-,^ ' —— • /^/ .^^"^z Berries bush ai mummii a mumi from •y an round surface 5^ growing blueberr ' underg grouncJ ^ -^ Apothecia mummified inch or two and on the for t f o rin at 7 e f f e c d u r i n porta mary and r ca t io commu the s are n wo CO e). to 10 t i ve g the nt pa inf ec aking n of ni cat pring o t cu vers Ther day agai bio rt i t ion und 50% ion) 0 rr en at 7 t ea f ter , int erva ns t the ss om bl n manag can b e er apo t urea pr This ther ch tly reg o 10 day inter cover s p rays Is , depending bud and twig ight stage. C ing the diseas greatly reduc heci a . Combin ills is especi is done when emicals have b is t er ed . 21 vals (the residual life of tri- are made with benomyl (Benlate) on rain. Benomyl is not very blight stage, but it is effective ultural controls can play an im- e (Ramsdell et al . , 1976). Pri- ed by cultivating between plants, ing this practice with an appli- ally effective (Stretch, personal the apothecia start to emerge in een used against apothecia, but Resistant varieties are almost non-existent. Only one numbered selection was reported resistant to both primary and secondary infections (Nelson & Bi 1 1 enb ender , 1971). Of named varieties, Bluetta, Collins and Darrow were somewhat resistant to primary infections. Jersey, Rubel, Burlington, Pemberton and Dixi are the least suscept- ible in New Jersey (Varney & Stretch, 1966), while Earliblue, Blue- ray, June, Atlantic and Ivanhoe are most susceptible. Re f er ences Nelson, J.W., and H.C. Bi t t enb ender . 1971. Mummy berry disease occurrence in blueberry selections test planting. Plant Diseas e Reptr. 55: 651-653. Ramsdell, D.C., J.W. Nelson, and R. Myers. 1974. An epidemiological study of mummy berry disease of highbush blueberry. Phytopathology 64: 222-228. Ramsdell, D.C., J.W. Nelson, and R.L. Myers. 1975. Mummy berry dis- ease of highbush blueberry; epidemiology and control. Phy to- pathology 65: 229-232. Ramsdell, D.C., J.W. Nelson, and R.L. Myers. 1976. Interaction of eradicant and protectant treatments upon the epidemiology and control of mummy berry disease of highbush blueberry. Phy to- pathology 66: 350-354. Varney, E., and A.W. Stretch. 1966. Diseases and their control. In: P. Eck and N.F. Childers (eds.). Blueberry Culture, Rutgers Univ. Press, New Brunswick, N.J. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts R. S. Whaley Director Cooperative Agricultural Extension Work Acts of May 8 and June 30. 1914 Official Business Penalty for private use, $300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 45, No. 4 JULY /AUGUST 1980 TABLE OF CONTENTS Progress Report: Scion/Rootstock and Interstem Effects on Apple Tree Growth and Fruiting Soil, Tree, and Fruit Response to Lime and Type of Nitrogenous Fertilizer Applied at Two Timings Under Sturdeespur Delicious Trees How Ethephon is Being Used to Advance the Maturity of Apples in Massachusetts Excessive Apple Bud Abscission in 1980: Was It Caused by Tarnished Plant Bug Feeding or Cold Temperatures? PROGRESS REPORT: SCION/ROOTSTOCK AND INTERSTEM EFFECTS ON APPLE TREE GROWTH AND FRUITING William J. Lord Department of Plant and Soil Sciences In 1976, in cooperation with 9 other states, we established a planting of Empire and Millerspur Delicious trees containing an 8- inch interstem of M.9 on either MM. Ill, Antonovka, or Ottawa 11 rootstocks. The trees were small and weak at planting and we have experienced significant tree losses MM Fig. 1. An a 8- inch M9 tween MJ-1.111 the scion cu white line i piece, and t is painted o of the tree, the M9 5 temp inches above trees plante duce more ro picture) tha piece is bel that the dia is larger th stock or sci interstem tree with stempiece grafted be- rootstock and Empire, Itivar. (The lower s painted on the stem- he upper white line n the scion portion ) The union between iece and MMlll is 2- ground. Interstem d at this depth pro- ot suckers (shown in n if most of the stem- ow ground. Note meter of the stempiece an that of the root- on . The significant losses of trees in this planting make most data meaningless except for overall observations. Some of the trees cropped in 1978, particularly the Empire trees. However, both in 1978 and 1979 yields were much less than in an adjacent block of Mc- intosh of the same age on MM106, M. 7 or M. 26. Stephen Long-Photo Center Measurements of the scion and interstem circumferences, tree height, and tree spread in 1979 indicate that the Empire trees are larger than those of Millerspur Delicious. The interstem portion of the trunk is misshapen on some trees (Fig. 2)perhaps due to the presence of burr knots (adventitious roots which disrupt the continuity of the bark) . The numbers of burr knots on the interstem portion vary considerably among trees. I i Fig. 2 . The presence of burr knots on the M9 stempiece (with the lower white line in its center) of interstem trees disrupts the continuity of the bark and as shown in the picture can cause distortion of the stempiece. Stephen Long - Photo Center The data from the 10 states is being summ.arized and will appear in a future issue of Compact Fruit Tree. SOIL, TREE, AND FRUIT RESPONSE TO LIME AND TYPE OF NITROGENOUS FERTILIZER APPLIED AT TWO TIMINGS UNDER STURDEESPUR DELICIOUS TREES William J. Lord, John Baker and Richard A. Damon, Jr. University of Massachusetts, Amherst 01003 A number of fertilizers are used in orchards to supply nitro- gen (N) . They may contain only an N carrier, or the N carrier may be mixed with carriers of other elements. N carriers contain nitrate N, ammonia N, a combination of both, or urea. Apple trees usually absorb N in the nitrate form because ammonium N after fixation in the surface soil is rapdily converted to nitrate N under most soil conditions. However, under some con- ditions amm.onia N may persist for considerable time. Urea is rapidly hydrolyzed to ammonia N and then behaves like ammonia. Nevertheless, apple trees can absorb urea and ammonia N if they are in solution. N sources have been compared frequently in apple orchards in the past. Differential responses have been obtained on acid soils from N carriers supplying either ammonium or nitrate N because of slower availability of ammonium N following spring application. Fixation of ammonia can influence timing of fertilization in irri- gation water during the growing season, and sodium nitrate could be harmful on soils with high sodium content. However, these are unusual situations and it is generally suggested that price per unit of actual N should determine choice of nitrogenous fertilizer for orchards. These studies preceded the concern with low calcium (Ca) levels in apple fruits and their association with cork spot, bitter pit, and breakdown of apples. Dr. Shear in 1971 reported that apple fruits had more severe Ca deficiency symptoms when nytrient-culture- grown trees received low Ca and 3/4 of their N as NH . , than when they received all NO3-N. He concluded that the effect of N -source on the differential movement of Ca into fruit and leaves could be an important consideration when determining the type of nitrogenous fertilizer for apple orchards and timing of application. Shear and Faust suggested that apple growers concerned with low flesh Ca in apples should not use ammonium N before or soon after bloom because the absorption of this element may be reduced if ammonium N is present Calcium nitrate [Ca(N03)2] was suggested as a replacement for ammonium nitrate by Eggert _et__al . in New Hampshire because it does not affect soil pH and it supplies a highly water soluble source of Ca which moves readily into the soil. To investigate the soil, tree and fruit response to lime, type of nitrogenous fertilizer, and/or time of application we initiated an experiment in 1972 with Sturdeespur Delicious trees at the Horti- cultural Research Center, Belchertown. The trees were planted in a soil having a pH o£ 6.0 to 6.5 to half lbs. of high Ca lime (40% Ca soil in the planting holes for ha (NH4NO3) , Ca(N03)2 or potassium n ally from 1972 through 1979 eithe bloom or at bloom. The trees fer also received muriate of potash s amounts of potassium (K) . Herbic in 1979 in a 3- foot band on each grass and broadleaf weeds. Paraq season from 1972 through 1975. used in mid-May of 1976, 1977, an pH were obtained within the herbi 1978 and 1979. Below are our res a 2-foot depth. Two and one- 0; 1% MgO) were mixed with the If the trees. Ammonium nitrate itrate (KNO3) was applied annu- r approximately 1 month before tilized with NH4NO3 and Ca(N03)2 o all trees received equivalent ides were applied annually except side of the tree trunk to suppress uat was applied twice a growing Paraquat-plus-simazine was d 1978. Soil samples to determine cide-treated strip in 1975, 1977, ults to date. Influence of Lime Incorporating high calcium lime with the soil in the planting hole significantly increased Ca content of the foliage in 1972 and 1973 but the differences were small (Table 1) . Although the pH of this soil was high and/or lime was incorporated into the soil, leaf Ca was still relatively low, further emphasizing the difficulty of increasing the level of this element in apple trees. Table 1. The effect of incorporating lime with soil in the planting hole on leaf calcium (Ca) of Sturdeespur Delicious trees. Treatment 1972 1973 Leaf Ca {%) : 1974 1975 1976 1977 Lime No lime 1.08a^ 0.79a 0.91a 1.30a 1.07a 0.76a 0.96b 0.74b 0.90a 1.28a 1.05a 0.74a High Ca lime 2-1/2 lbs. per tree at planting, Numbers in a column followed by a different letter are significantly different at odds of 19 to 1. Influence of N Source of Soil pH NH4NO3, as expected, increased soil acidity while soil pH under the trees that received KNO3 or Ca(N03)2 remained fairly constant (Table 2). Table 2. The influence on soil pH of three sources of nitrogen applied annually under Sturdeespur Delicious trees since 1972. Soil pH under trees receiving: "Ca(N033 2 NH4NO3 KNO^ Year soil sampled 0-6" depth 6-12" depth 0-6" depth 6-12" depth 0-6" depth 6-12" depth 1975 6.16a^ 6.09a 5.90b 5.90b 6.18a 6.15a 1977 6.05a 6.03a 5.51b 5.65b 6.20a 6.09a 1978 5.93a 5.85a 5.21b 5.20b 5.99a 5.71a 1979 6.00a 5.92a 5.20b 5.22b 6.14a 6.14a z Numbers in a row followed by a different letter are significantly different at odds of 19 to 1. In 1979 we also sampled the 20 to 24-inch soil depth and found the acidifying influence of NH4NO, at these depths but the pH was higher than at the 12-inch and 6- inch depths (Table 3). Table 3. Influence of ammonium nitrate and calcium nitrate on soil pH at different depths, 1979^. Soil Soil pH under tree receiving; depth NH4NO3 Ca(N03)2 KNO3 0-6 5.20b^ 6.00a 6.14a 6-12 5.22b 5.92a 6.14a 20-24 5.57a 6.07a 6.14a z Applied annually since 1972 y Numbers in a column followed by a different letter are significantly different at odds of 19 to 1. Influence of N Source on Elements in Leaves Leaf analyses showed that N and Mg were not influenced by N source. In 1976 KNO3 increased K and suppressed Ca probably due to the interaction between these 2 elements. In 1974, 1976 and 1977 the KNO3 trees were lower in foliar Ca than those fertilized with Ca(N03)2- This is probably an influence of K in KNO3 rather than an enhancement of Ca by Ca(N03)2 since Ca was not influenced by NH4NO3. 6. Fruit Ca levels were analyzed in 1978 and 1979. Fruit Ca was higher on trees fertilized with Ca(N03)2 on April 12, 1978(93 ppm),than those from trees that received NH4NO3 on May 22, 1978 (84 ppm) , otherwise N source and time of application has not influenced fruit Ca levels. Influence of Time of N Application on Elements in Leaves We suggest that nitrogenous fertilizers be applied as early as possible in the spring. Among the several things early appli- cation accomplishes is early absorption of N rather than late ab- sorption which could cause higher levels of this element at harvest, reduced red color of fruit, and delayed maturation. However, our data showed that with the exception of leaf N in 1974, the level of this element and Ca, K and Mg were similar in mid-July for the 2 timings of fertilization. The fertilizer application on April 12, 1974 was followed by 0.7 inches of rain on April 14, thus it probably was more rapidly dissolved and carried to feeder root depth than the May 15 application which was followed by 0.3 inches and 1.1 inches of rain on May 24 and June 1, respectively. Influence of N Source on the Incidence of Bitter Pit The trees commenced bearing in 1974, but it was 1976 before cropping was considered sufficiently uniform among trees to exa- mine the fruits for bitter pit. A frost eliminated the crop in 1977. However, in 1976, 1978 and 1979 N source did not influence the amount of bitter pit (Table 4) , which gives further evidence of the lack of differential Ca response to N source. Table 4. The influence of N source on the incidence of bitter pit Bitter pit (I): Nitrogen At harvest At harvest After storage source 1976 1978 1979 1978 1979 KNO3 lla^ 17a 9a 22a 13a NH4NO3 8a 14a 6a 18a 9a Ca(N03)2 7a 16a 6a 21a 11a z Numbers in a column followed by a different letter are significantly different at odds of 19 to 1. Summary Mixing lime with the soil used in planting hole for apple trees enhanced Ca levels for only the first 2 years. Ca(N03)2 and KNO3 are neutral in reaction and have not affected soil pH, whereas NO4NO3 increased soil acidity, N source or time of appli- cation had little influence on N, K, Mg , and Ca content of leaves, no effect on the incidence of bitter pit, and no appreciable influ- ence on fruit Ca. Thus, it would appear, under the conditions of this experiment, that no change is needed in the "old idea" that price per unit of actual N should determine choice of nitrogen fertilizers for orchards. HOW ETHEPHON IS BEING USED TO ADVANCE THE MATURITY OF APPLES IN MASSACHUSETTS 12 2 W. J. Lord , J. Williams and K. Hauschild Ethephon has been used commercially for several years on early- maturing cultivars and on Mcintosh to stimulate red color develop- ment, hasten fruit maturity, and advance the harvest season. We published a circular with suggestions on the use of ethephon in 1976. The information was up-dated last year and the suggestions appeared in the July/August, 1979 issue of FRUIT NOTES. Climatic conditions vary in the state and affect the rate of ethephon needed to obtain the desired response. Furthermore, ethephon 's use is influenced by the marketing needs of the grower. Thus, the purpose of this article is to describe how ethephon is being used commercially by some growers in Massachusetts. Horticultural Research Center. Tony Rossi, farm foreman, needs Mc- intosh apples the first week of September for sale to the University of Massachusetts dining halls. He applies ethephon at 1 pint, plus 20 ppm 2,4,5-TP, per 100 gallons of water with an air blast sprayer at IX. Tony uses 2,4,5-TP rather than NAA because it provides bette pre-harvest drop control and contributes more than NAA for advancing fruit maturity. The data in Table 1 show the 1974 to 1979 dates of ethephon application and harvest. Tony selects vigorous young trees because the fruit are larger and the ethephon effect is greater be- cause of less shading. Direct sunlight enhances the fruit color res ponse to ethephon. It can be noted in Table 1 that the fruit have been harvested 7 to 10 days after the ethephon application. Except in 1979, the fruit have been harvested in one picking. r 1 Extension Pomologist 2 Regional Fruit Specialists in Massachusetts Table 1. Ethephon usage at the Horticultural Research Center of application and harvest date. Date Application date Harvest date Days from application to harvest August 20, 1974 August 27, 1975 August 16, 1976^ August 23, 1977 August 30, 1978^ August 20, 1979 August 29 September 2 August 2 5 September 2 September 7 August 29 and September 3 9 6 9 10 8 9 14 y 1 pint of ethephon + 20 ppm 2,4,5-TP Applied earlier than usual because fruit were needed in late August Application date was delayed because of rain. Edward Roberts and Sons, Hillside Orchard, Granville. The Roberts' harvest 10 ,000 to 12,000 bushels of ethephon- treated Mcintosh apples each fall for immediate sales. Beginning the last week of August or the first week of September, they apply ethephon to ferent set of trees every 2 or 3 days, depending upon the wea a dif- ther . In 1979, the first 2 sprays of ethephon were applied at 1/2 pint per 100 gallons of water at IX (Table 2). (However some years only 1/3 pint of ethephon per 100 gallons of water was used on the earliest spray dates. The higher rate was used in 1979 in order to enhance a quicker response.) The next 5 ethephon sprays in 1979 were applied at 1/3 pint. Sprays applied September 4 or later were applied at 1/4 pint. NAA at 10 ppm is used with the ethephon sprays for pre-harvest drop control. They prefer NAA because it hastens ripening less than 2,4,5-TP. The ethephon-sprayed fruit are examined twice daily, starting 5 days after spraying, to determine color development. The fruits are harvested when they obtain 50 to 601 red color, which is generally 6 to 7 days after the ethephon application (Table 2) . (They believe that by waiting for more color, condition on the retail counter is sacrificed. ) Table 2. 1979 dates of ethephon application and harvest on Mcintosh at Hillside Orchards. Application date Harvest date Days from application to harvest August 2 2 August 24 August 26^ August 2 8^ August 30^ August 31^ September 3^ September 4^ September V September 9 September 11' August 2 8 August 29-30 September 1 September 2 September 5 September 6 September 9 September 10 Septem.ber 13 September 16 September 18 6 5 6 6 6 6 6 7 7 1/2 pint ethephon plus 10 ppm NAA y 1/3 pint ethephon plus 10 ppm NAA X 1/4 pint ethephon plus 10 ppm NAA Apples picked September 5 or later are refrigerated, packed within 2 days and shipped within 4 days of harvest. They have a market for Cortland apples in September. Therefore, 1/3 pint of ethephon plus 10 ppm NAA in 100 gallons of water at IX is applied on trees of this cultivar the first week of September. Excellent results have been obtained on young Cortland trees that produce large fruit. Atkins Farms, Inc., Amherst. Howard Atkins considers ethephon a good tool for assisting harvest and permitting sales during harvest. Ethephon is used on Wealthy, Milton, Mollie's Delicious and other early maturing cultivars as well as on Mcintosh. When used on early maturing cultivars, farm manager Stanley Kielbasa has found that the number of pickings has been reduced from 4 or 5 to 2 . On early culti- vars ethephon may be applied before first harvest or it may be applied after the fruit is first "spot-picked", so that the trees can be "stripped" at the second picking. These early maturing cultivars are sold at the roadside stand. 10 Table 3. 1979 dates of ethephon application and harvest dates at Atkins Farm. Days from Ethephon application Cultivar application dates Harvest dates to harvest Wealthy August 11^ August 25 14 Milton August 18^ September 2 15 Mollie's Delicious August 20^ August 27 7 Mollie's Delicious August 28^ September 5,6 9,10 Mcintosh August 23^ September 7 15 Mcintosh September 5^ September 19 14 z 2/3 pint ethephon plus 20 ppm 2,4,5-TP y 3/4 pint ethephon plus 20 ppm 2,4,5-TP Ethephon is applied on Mcintosh blocks scheduled for pick-your- own or for early sales at both the roadside stand and wholesale. Dates of ethephon applications and concentrations on Mcintosh and har- vest dates are shown in Table 3. Marshall Farms, Fitchburg. Marshall Farms need about 2,000 bushels of well-colored Mcintosh apples 1 week prior to the normal harvest period of the Rogers and Hermann strains of this cultivar. Fruit from trees of their own strain, the Marshall Mcintosh, should ful- fill this need in the future, but at present it is necessary to apply ethephon on some Rogers and Hermann Mcintosh trees. In 1979, the Marshall Farms delayed their ethephon application until September 4 when cool weather replaced the high temperatures of late-August and the first 3 days of September. They applied 1/2 pint of ethephon plus 15 ppm 2,4,5-TP per 100 gallons of water with a Hardy air blast sprayer at IX. The Mcintosh trees sprayed were 14-years-old on M9 , 12-years-old on M7 , and seedling trees over 50 years of age. Alfred Marshall noted that the coloring response to ethephon was best on the young trees, probably because of better light penetration. Harvest of the ethephon treated trees commenced 5 days after application. Marshall Farms in 1979 successfully stored some ethephon treated Mcintosh in regular storage for 3 to 4 weeks. As a trial they placed 11. 6 bins o£ ethephon- treated Mcintosh in CA storage. These fruit were harvested September 7, 1979 (5 days after ethephon was applied) and dipped in 25 pounds CaCl-,/100 gallons of water and placed in CA storage. The storage was opened in early April and on May 18, 2-1/2 inch apples were pressure tested and had pressure of approximately 14 pounds. Three inch apples were pressure tested on May 19 and had pressure of approximately 12.5 pounds. Marshall Mcintosh harvested on September 6 were placed in the same CA storage (untreated) on the same date. They were pressure tested on May 19, 1979 and 2-1/2 to 2-3/4 inch fruit had pressure of approximately 12.5 pounds. Marshall Farms produce about 2,000 bushels of Early Mcintosh for immediate sale from trees ranging in age and size from 14-years- old on M7 to 20, 25 or 35-year-old trees on seedling roots. Trees of this cultivar are sprayed annually about 5 to 7 days prior to normal harvest with 1/4 pint of ethephon plus 10 ppm 2,4,5-TP per 100 gallons of water at IX. This treatment improves red color and generally reduces the number of times necessary to "spot pick" trees from 4 to 2. Bolton Orchards, Bolton. Steve Ware, orchard manager, generally uses ethephon on Early Mcintosh and Puritan trees to improve red color and reduce the number of times required for "spot picking". Ethe- phon is applied at 1/2 pint plus 20 ppm NAA (for drop control) per 100 gallons of water with a Hardy air blast sprayer at IX. The first group of trees was sprayed on August 1, 1979. Ethephon was applied at 3 to 4 day intervals to different trees. Enough trees were sprayed each time to permit harvest of approximately 150 bushels. Beginning on the 4th day after treatment, Steve observes daily the color development. The fruit are generally harvested 5 to 7 days after the ethephon application and are sold at retail to satisfy early consumer demand. Wholesale buyers expressed some resistance to purchase of Mc- intosh apples treated with ethephon in 1978 because of a "dull" Ted color that Steve Ware described as "not a natural red". Carlson Orchards, Harvard. In 1979 Carlson Orchards applied 3/4 pint of ethephon plus 10 ppm NAA per 100 gallons of water with an air blast sprayer at IX on 20-year-old Early Mcintosh trees. This spray was applied at 3-day intervals on a few row of trees. The apples were harvested 5 to 7 days after the spray application. The trees were "strip-picked" because the fruits with insufficient color to meet marketing requirements were used for cider. The remainder of the Early Mcintosh apples were sold at retail and wholesale. Authors comments . The Hillside Orchard in Granville is favorably located for obtaining well-colored Mcintosh. This may partly ex- plain why they obtain good color enhancement with late-August appli- cations of 1/2 pint or less ethephon. In our early trials with 12 ethephon at the Horticultural Research Center, it was applied the 1st or 2nd week of September at 1/4 or 1/2 pint per 100 gallons, with either NAA or 2,4,5-TP for drop control. Even though the appli- cations were nearer to normal harvest than those applied at the Hillside Orchard, color did not develop as rapidly. Eight days after application, only an additional 10 to 20% of the fruit surface had red coloration. The growers used either NAA or 2,4,5-TP for drop control on Mcintosh. Our trials showed that NAA when combined with ethephon gives effective drop control for 7-10 days. On the other hand, 2,4,5-TP may cause more fruit ripening than NAA, but it does elimin- ate, in case of a delay in harvest, the chance of excessive fruit losses due to preharvest drop or the need of a second NAA application. One grower interviewed expressed concern about possible tree injury to Mcintosh when using 2,4,5-TP with ethephon. (Injury from 2,4,5-TP is noticeable the year following application. The tips of terminal shoots in the tops of affected trees appear "naked" be- cause of injury to lateral buds.) We have not observed tree injury on Mcintosh at the Horticultural Research Center from 20 ppm 2,4,5-TP. However, the same rate injured Early Mcintosh and Puritan trees when it was used with 1/2 pint ethephon to enhance ripening of fruits of these cultivars. Mcintosh and Delicious trees can be injured by 2,4,5-TP under certain conditions, one of which is over application. We believe that NAA will generally provide adequate drop control on early maturing cultivars because the fruits are generally harvested before drop becomes troublesome. However, if you do use 2,4,5-TP, 10 ppm of this material should be sufficient. When using 2,4,5-TP for drop control be sure to read the label. It is available at both IX and 2X concentration and growers have cans of both concentrations on their shelves. 13. EXCESSIVE APPLE BUD ABSCISSION IN 1980: WAS IT CAUSED BY TARNISHED PLANT BUG FEEDING OR COLD TEMPERATURES? 1 2 Ronald J. Prokopy^, Geoffrey L. Kubbell« William M. Coli , and William J. Lord At the Horticultural Research Center in Belchertown, as well as in a number of commercial orchards, we observed an unusual amount of apple bud abscission this year. The majority of abscissed buds which we observed never exceeded 1/4 inch in length and turned dark brown shortly after tight cluster. Some reached 1/2 - 3/4 inch long before abscission occurred, with the calyx cup then turn- ing yellow. In some cases, all 5-7 buds in a cluster abscissed. Usually, however, there were at least one or two healthy buds per cluster. Our examination of approximately 300 flower bud clusters in each of 8 commercial orchards revealed an average of 1.6 and 9.2% abscissed buds in 1978 and 1979, respectively. This year, an aver- age of 18.11 of the buds in these same 8 orhcards was abscissed, with one orchard reaching 36.71 abscission. Our sample consisted almost exclusively of 'Mcintosh' and 'Red Delicious' trees, with the level of abscission about the same on each. Abscission levels appeared to be greater on 'Cortlands', although we sampled few trees of this cultivar. This observation is in agreement with bloom data obtained from other experiments involving these cultivars. In an earlier study (FRUIT NOTES 42(2): 10-14, 1977), we showed that feeding by tarnished plant bug (TPB) adults on apple flower buds from the silver tip up to the tight cluster stage could result in substantial bud abscission. The large number of TPB adults captured on our white monitoring traps from silver tip to tight cluster in commercial orchards this year suggested to us that TPB adults may have been principally responsible for the high level of bud abscission. At our research block at the Horticultural Research Center, we had placed cages over several hundred dormant buds in early April to prevent entry of TPB and other insects. Abscission of uncaged buds on these trees was high (68%) , but it was nearly as great (54%) for the caged buds. The large number of TPB adults (7.2/trap by tight cluster) in this block may have accounted for most or all of the 14% difference here, but these adults obviously were not the principal cause of bud abscission. 1 Extension Entomologist 2 Research Technician 3 Pest Manager Specialist, Entomology 4 Extension Pomologist 14 We therefore believe that the majority of bud abscission in commercial orchards this year was caused by low temperatures. It is possible that the rather high temperatures from April 11-15 (590-68° F) followed by the low temperatures on April 16 (24° F) , may have been the responsible factor. It is too soon to tell if the size of the 1980 fruit crop will be affected by this abnormally high level of bud abscission. Cooperative Extension Service University of Massachusetts Amherst, Massachusetts James B. Kring Acting Director Cooperative Agricultural Extension Work Acts of May 8 and June 30, 1914 Official Business Penalty for private use, S300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 45 No. 5 SEPTEMBER/OCTOBER 1980 Table o£ Contents Progress Report: Pruning Effects on Tree Growth and Fruiting of Spartan Apple Do Calcium Chloride Sprays Affect Apple Maggot Fly Egglaying? Causes of Defects on Mcintosh Apples at Packing Sheds and Their Effects on Returns Controlling Orchard Mice PROGRESS REPORT: PRUNING EFFECTS ON TREE GROWTH AND FRUITING OF SPARTAN APPLE William J. Lord and Joseph Sincuk Department o£ Plant and Soil Sciences Small trees on size-controlling rootsto omically pruned, sprayed, and harvested than ling rootstocks. Nevertheless, training and comes increasingly important as planting den the past, we had low density orchards with s seedling rootstocks which performed well on types and there was little concern about tre We now have low, medium and high density ore and each type requires somewhat different tr cedures. The trees are spur-type, standard- and tree vigor varies considerably especiall rootstocks because of soil types. In spite trees, some growers report that pruning hour creased rather than decreased. Therefore, i several long-term trials to compare pruning in the past. Below is a summary to date of on tree growth and fruiting of Spartan apple cks can be more econ- large trees on seed- pruning of trees be- sity increases. In tandard-type trees on a wide range of soil e height and spread, hards in Massachusetts aining and pruning pro- type or interstems, y on weaker growing of the trend to smaller s per acre have in- n 1976 we initiated systems with those used a study of pruning effects trees . The Spartan apple trees on M. 7 rootstock were plante Horticultural Research Center, Belchertown, }AA in 1975. 1976, we established the following pruning programs: (A) suggested by Dr. D.R. Heinicke in USDA Agriculture Handbo (Figures IB, 2), hereafter referred to as the USDA system in tiers and central 1 annually, hereafter re as the tier system (Fi (C) minimum of pruning zagging' the central 1 ure 4) , hereafter refe the slender spindle sy (D) pruning as done in (Figure lA) , hereafter to as regular pruning, trees have been pruned method . d at the In February, a program ok No. 458 ; (B) limbs eader headed ferred to gure 3) ; and 'zig- eader (Fig- rred to as stem; and the past referred Twelve by each Fig. 1A. Two year old tree being pruned by standard prun- ing procedures. The lowest limb should be 18 to 20 inches from the ground, all others spaced 4 to 8 inches apart vertically on the trunk and each one about 90° around the trunk from the one below it. Fig. IB. Two year old tree being pruned as suggested by the USDA. It has 2 layers of limbs. The leader will be headed annually [heavy marks ( — ) indi- cate heading cuts] . The one year old wood on the branches is headed annually until branches on which this wood is borne start to fruit. Pruning and Training Methods USDA System. The system involved heading cuts and developing limbs m tiers (Figure 2). MOW TO GET THE HIGH DENSITY TREE OFF TO A GOOD STA«T HEAVY MA«KS SHOW WHERE PRUNING CUTS SHOULD BE MADE. I -yaOf'Old ttctton compiling ihooll minol ihoof R«mov« all Heod bock Hr- 2 y«ar-old t«(hon Select and h*od lateral bronchei Remove unneceiiory loteroU 3-reor-otd tection Spfeod bronch- ei, remove forked termmalt *o o lingle thoot and heod IKot moot. Head fide ihooti 4 year old tcctton Spreod branch- e», remove foried termlnall lo o lingle iheel and head H^al ihool Heod tide ihootf S-yeor old leciion and older If tree hot filled oHoned ipoce, head back where neceitory into 2 yeor-old wood to on unheeded tide ihoot Avoid heading cut» Into 1 -yeor-old thoott until the tree It fruiting well Fig. 2. A diagram of the "constructive training" program suggested by Dr. D.R. Heinicke in USDA Agriculture Handboc No. 458 entitled "High Density Apple Orchards— Planning, Training and Pruning." (Reproduced with permission i the author.) The central leader and each 1-year-old shoot on scaffold limbs were headed during dormant pruning by removing 1/4 to 1/2 of the past season's growth. The central leader was headed to induce branching so that a tier of scaffold limbs could be developed 24 inches above a lower tier of limbs. The heading cuts on shoots ' originating from scaffold limbs were made to encourage developm.ent of lateral shoots to increase fruiting potential. In May of each year, 2 or 3 vigorous shoots developed from the buds directly behind the heading cut on the central leader and later- al shoots. When shoot growth was 4 to 6 inches long, one shoot on each central leader and each headed lateral shoot was selected as the permanent extension shoot and competitors were removed. Limb spreaders were used when needed. Tier System. Pruning and training procedures were similar to those for the USDA systemexcept that none of the 1-year-old shoots on scaffold limbs were headed. Slender-spindle System. All the scaffold branches 18 inches above ground level were kept except for those with narrow crotch angles. Frequently, 2 or more branches of approximately the same size originated adjacent to each other. These whorls of branches were not eliminated until their presence appeared to be suppress- ing the dominance of the leader. At this time, one branch in the whorl was retained and the others were removed at their point of origin on the central leader. Figure 3. A 4-year-old Spartan/7A being trained with limbs in tiers, The paint, except on' the trunk, marks where heading cuts were made on the leader. Photographed March, 1979. Figure 4. A 4-year-old Spartan/7A being trained as slender spindle. Tree has received a minimum of pruning. The leader has been pruned to an up- ward growing lateral branch in attempt to zig-zag the leader. Photo- graphed March, 1979. The procedure of removing the strong vertical leader during dormant pruning and using a weak competitor as the new leader was was not successful because it became apparent that the dominance of the leader was difficult to maintain. Thus, it became necessary in most instances to establish a dominant leader and delay, until dor- mant pruning in 1979, the procedure of using a weak competitor as the new leader (Figure 4). Limb spreaders were used when needed. Regular type Pruning. This system involved selection o£ branches symmetrically arranged around the vertical axis of the tree and spaced far enough apart to avoid limb crowding when the trees be- came larger. Less temporary branches were left to provide addi- tional leaf surface than on the slender spindle trees. Whorls of branches were eliminated in order to allow only one branch to develop at a given level. The dominance of the central leader was maintained by suppressing or removing competing leaders. Results and Discussion USDA System. We found having summer . trees - Tier tr minutes was not heading by the trees b to make heading In March, 197 2.2 5 minutes; ees - 0,91 minu The time req recorded. Mos cuts on the US regular system. ut most time co the US cuts a 9, prun (b) Reg tes ; an uired t t time DA tree Few c nsuming DA system to be time consuming due to nd remove competitor shoots during the ing time per tree was: (a) USDA ular-type trees - 1.66 minutes; (c) d (d) slender spindle trees - 0.66 o summer prune the USDA and tier trees consuming during dormant pruning were s and pruning decisions on those pruned uts were made on the slender-spindle was pruning decisions. The heading cuts during dormant pruning followed by removal of competitor shoots in late May failed to encourage growth behind the area of removal in 1976 and 1977. However, in 1978 and 1979 lateral shoots behind the heading cuts were longer on the headed than on the non-headed 1-year-old shoots on scaffold branches (Table 1) , but the response was much less than that shown in photographs in USDA Agriculture Handbook No. 458. This can be noted when compar- ing branching on the tree shown in Figure 5 with that shown in Figure 6. Table 1. Current season lateral shoot growth on headed and non- headed 1-year-old shoots of Spartan apple trees^. Type of pruning on 1-year-old shoots on scaffold lii±)S Mean length of current season lateral shoots on 1 -year- old wood (cm) Current season lateral shoots longer than 4 cm on 1-year-old wood (%) 1978 1979 1978 1979 Heading cuts USDA system No heading cuts Slender- spindle trees Regular-pruned trees Trees with linijs in tiers 5.4a^ 3.3b 3.7b 3.3b 5.3a 2.3b 2.0b 1.8b 32a lib 16b 14b 26a 10b 6b 5b Trees planted in 1975. Means in columns not having letters in common are significantly at odds of 19 to 1, 5. Therefore, heading cuts do not appear worthwhile on these vigorous Spartan trees which produce adequate lateral branching because of their standard- type growth habit. At the end of the 5th growing season trees had 3 tiers of branches spaced about 5 branches per tier (Figure 5) . in 1979 the USDA-system 2 feet apart with 4 or Figure 5. A Spartan tree on which 1-year-old shoots on scaffold limbs were headed during the dormant seasons of 1976 through 1979. This tree in comparison to the tree shown in Figure 6 has more lateral branches. The paint, except on the trunk, marks where heading cuts were made on the leader and 1-year-old shoots. Photographed May, 1980. Figure 5 When the tiers were formed, 6 or 7 limbs were retained because the extra limbs provided leaf surface and permitted a choice when selecting permanent limbs. When the extra limbs were removed, limb selection was made to maximize the vertical spacing of the permanent limbs. The extension growth from the headed leaders was longer than that on the non-headed leaders in 1976 and 1978 but not in 1977 (Table 2.) The extension growth of the central leaders was not measured in 1979. Figure 6. A tree on which no heading cuts were made on 1-year-old shoots. Photographed May, 1980. The USDA system trees, in comparison to the slender spindle trees, made less trunk circumference increase in 1976 and 1977 (Table 2) . In 1978 trunk circumference increase was similar for the 4 pruning treatments probably because cropping restricted vegetative growth on the slender spindle and regularly pruned trees (Table 2). The influence of cropping on trunk circumference in- crease also was evident in 1979. Table 2. The response of Spartan trees to pruning systems initiated in 1976 at the Horticultural Research Center, Belchertown, MA^ . Year response measured Pruning system USDA Slender spindle Regular Tiers 1976 1977 1978 1976 1977 1978 1979 Length of extension growth of central leader (cm) y 103a- 98a 67a 4.3b 4.3bc 5.0a 4.6a 5.6a 5.0a 5.1a 3.9b 76b 99a 90a 97a 51b 63a Lcrease (cm) 4.8b 4.3b 4.6ab 4.2c 5.0a 5.0a 4.3ab 3.8b Yield (bushels) 1978 1979 0.00b 0.32b 0.12a 1.32a 0.09a 1.02a 0.02b 1.38a Trees planted in 1975. r Means in rows not having letters in common are significantly different at odds of 19 to 1. Yields v;ere higher in 1978 on the less - severely pruned slender spindle trees and regular pruned trees than on the USDA and tier trees In 1979, yields were higher on the slender spindle, regular and tier trees than on the USDA trees. The heading cuts on 1-year-old shoots of the USDA trees removed growth on which fruit spurs would have developed. Furthermore, measurements in 1979 indicated that the average distance of the first blossom cluster from the tip of shoots produced in 1977 was 10 cm on headed-wood in comparison to 2 cm on non-headed wood. This in- dicates that the buds directly behind the heading cuts, made in Feb- ruary, 1978 remained vegetative during the growing season of 1978 instead of producing flower buds. This appears to explain why the USDA trees were less productive than the tier trees in 1979. Trees with limbs in tiers. Trees pruned by this system responded similarly to the USDA trees in regard to growth in 1976, 1977 and 1978 and to yield in 1978 (Table 2). However, these trees were more productive than the USDA trees in 1979 and trunk cir- cumference increase was less. Pruning time has been less because no heading cuts were made on 1-year-old branches on scaffold limbs . Slender spindle trees. Pruning of the slender spindle trees has been the least time consuming of the 4 systems. The trees, based on trunk circumference increase, produced more growth than the heavily pruned USDA and tier trees in 1976 and 1977 and more fruit in 1978 (Table 2). In 1979 yield on the slender spindle trees was higher than on the USDA tree. It is well known that non-pruned trees are larger and more productive than pruned trees. The slender spindle trees are a compromise. The trees have been lightly pruned leaving as many branches as possible without stunting the growth of the central leader . Regular-type pruning. The pruning system has been somewhat more time consuming than on the slender spindle trees but less than that for the USDA trees. Yields of the slender spindle and regular- pruned trees were comparable in 1978 and 1979 (Table 2), Summ^ary The USDA pruning system has been more time consuming than the tier system, slender spindle system, or regular pruning and reduced yields in 1978 and 1979. Heading cuts caused some lateral shoot development on 1-year-old wood but much less than shown in USDA Agriculture Handbook No. 458 following similar pruning. At present we prefer the slender spindle system which involves leaving as many branches as possible without stunting the growth of the central leader. Recommendations At present we will continue to suggest the following for non- bearing trees of standard- type strains: (a) prune as little as possible without dwarfing the central leader; (b) make heading cuts only when necessary to stiffen the central leader or scaffold bran- ches, or to stimulate growth; and (c) spread branches when necessary 9. DO CALCIUM CHLORIDE SPRAYS AFFECT APPLE MAGGOT FLY EGGLAYING? 1 2 ^ Ronald J. Prokopy , Sylvia S. Cooley , Bonnie L. IVeeks^, and Anne L. Averill Department of Entomology In an earlier issue o£ FRUIT NOTES (Vol. 42, No. 1), we des- cribed how, after laying an egg, an apple maggot female drags its ovipositor on the fruit surface. In so doing, the female releases a substance (called a pheromone) which deters other females from attempting to lay an egg in that fruit. For the past three years, in cooperation with chemists from the USDA Lab in Gainesville, Florida and neurophysiologists from the Department of Zoology at the University of Massachusetts, we have been working on the chemical identity of this pheromone and on various physiological, behavioral, and ecological aspects of the pheromone deterrent system in the flies. Our eventual aim is to apply synthetic pheromone in sprays to prevent maggot fly egglaying. In the course of recent laboratory studies, we found that apple maggot fly egglaying is deterred not only by the pheromone but also by sodium chloride (table salt). As shown in Table 1, sodium chlor- ide at concentrations of 2 and 9 pounds per 100 gallons gave about the same moderately-strong levels of egglaying deterrence as 2 and 3 ovipositor dragging equivalents (ODE) of pheromone laid down by the flies (1 ODE = amount of pheromone deposited after laying 1 egg) . Apparently the flies do not like to lay eggs in fruit treated with table salt any more than they like to lay eggs in fruit treated with pheromone. Table 1. Percent arriving females attempting egglaying into hawthorn fruits treated with different concentrations of pheromone, sodium chloride, and calcium chloride (ODE = ovipositor dragging equivalent), Attempting Attempting Attempting egglaying Sodium egglaying Calcium egglaying Pheromone [%) chloride (%) chloride (%) Clean check 77 Clean check 79 Clean check 86 2 ODE 50* 2 lbs/100 gal 49* 3 lbs/100 gal 68 3 ODE 28* 9 lbs/100 gal 35* 7 lbs/100 gal 83 Significantly less than egglaying in clean check fruit Extension Entomologist 2 Extension Technicians 3 Graduate student. Entomology 10 These results suggestedthat calcium chloride sprays applied to apple trees in July and August (maggot fly season) to increase calcium in the fruit might possibly act like sodium chloride salt sprays, and deter egglaying of apple maggot flies. However, the data in Table 1 shows that at the recommended rates of 3 pounds per 100 gallons, and even at double that rate (7 pounds per 100 gallons) calcium chloride sprays have no discernible deterrent effect on maggot fly egglaying. Apparently the flies' contact chemical receptors (located on the bottom of their feet) respond differently to calcium compared with sodium salts. Thus, to their advantage, the flies are not put off by the type of salt we offer them in our orchards. ********** CAUSES OF DEFECTS ON MCINTOSH APPLES AT PACKING SHEDS AND THEIR EFFECTS ON RETURNS Henry M. Bahn Department of Food and Resource Economics and 2 Glenn Morin Department of Entomology Last year we summarized in FRUIT NOTES (Volume 44, No. 5) our evaluation of labor productivity in grading and packing Mcintosh apples grown under integrated pest management conditions in 1978. It was suggested that during the 1979-1980 storage season we in- spect Mcintosh apples at packing sheds in Massachusetts to deter- mine why they failed to meet grade requirements for US Fancy fruit and analyze the effect of defects on returns. The results of this study are presented below. Experimental Procedures Culled Mcintosh apples at 10 packing sheds were examined dur- ing the period from November, 1979 through January, 1980 to deter- mine the reasons for rejection. At least one-half day was spent at each packing shed which, with one exception, were all manual sorting, sizing, and packing operations. A total of 1431 bushels were packed and 315 bushels were culled. 1 Extension Specialist in Farm Management 2 Senior Pest Management Field Scout 11 The culls were inspected to determine the reason for re- jection. Only the first or most obvious defect observed was listed as the reason for culling. Thus, fruit with multiple defects were not double counted and the additional defects were not recorded. This procedure was used to duplicate as closely as possible the normal grading method. The packer/grader is interested primarily in removing defective fruit from the line rather than determining the specific type of defect. The first or most obvious defect is, therefore, the critical one. All culled apples were inspected by the same individual. During inspection of the culls, defects were noted and later categorized by type. Each category was expressed as a percentage of total culls and as a percentage of total apples graded . Results Defects on stored apples. The fruit sampled had a cull rate aver- aging 22.2 percent (Table 1). Cullage ranged from 3.3 percent to 53.4 percent. This large variation may be partly explained by the fact that the samples included first, second and strip pickings Table 1. Reasons why Mcintosh apples were below grade at grower packing sheds, 1979 Bushels Percentage of Percentage of total of culls showing apples culled because Grade defects culls this defect of this defect Misshapen 3.0 1.0 0.2 Insect damage 5.7 1.8 0.4 Disease damage 7.0 2.2 0.5 Russeting 18.5 5.7 1.3 Bruise 25.5 8.1 1.8 Mechanical^ 25.5 8.1 1.8 Stem puncture 31.2 9.9 2.2 Color (< US No.l) 53.0 16.9 3.7 Size (< 2-1/4") 145.0 46.0 10.3 Other 0.6 0.3 — Totals 315.0 100.0 22.2 Includes limb rub , cuts , and cracks 12. Size and color defects account for 46 and 16.9 percent, respectively, of all culls (10.3 and 3.7 percent of total fruit graded). Reducing size and color defects is no easy task. Fol- lowing proper cultural practices is imperative, with particular emphasis on pruning, thinning and proper fertilization. Beyond cultural practices, however, both of these categories are highly dependent on local growing and climatic conditions. They are, therefore, to some degree beyond the grower's control. Less than ideal growing periods during some portion of the 1979 grooving sea- son may have made the number of size and color defects dispro- portionately large in this study. An additional study should be undertaken to determine the "normal" distribution of defects. Physical damage (bruise, mechanical and stem puncture) re- present over 26 percent of the culled fruit and 5.8 percent of the total graded. Being a soft fleshed fruit, Mcintosh apples are more susceptible to damage during harvest, handling and pack- ing than most other varieties. For example, a Mcintosh apple dropped three inches onto a flat board surface will develop a bruise of about 7/8" diameter. This defect will downgrade apples to as low as U.S. Utility. Physical damage is an area in which cull rates could be re- duced and is thus worthy of the grower's attention. Using extra care when removing fruit from the tree, dumping picking buckets, during handling from the tree to the storage, and packing could reduce these injuries. It could be worthwhile to monitor closely the handling of fruit to determine when and how the damage occurs. One study showed that 17 percent of the apples harvested were severely bruised (bruises larger than 3/4" in diameter) by an experienced picker. Whereas only 4 to 6 percent of the fruits were severely bruised by other experienced pickers in the same harvest crew. Such a level of damage should be unacceptable to the grower. Pest and disease are two areas in which fruit growers use a variety of control measures. Defects in these categories account for only 4 percent of the culled fruit and less than 1 percent of all apples handled. These low damage levels are indicative of the importance growers place on controlling insects and disease in the orchard. The low levels are also a measure of the effectiveness of the research and development of preventive technology. Economic implications of defects. All damaged or defective fruit represents a loss of revenue to the grower. This loss can be expressed as the difference between the value of the fruit if un- damaged (Fancy or Extra Fancy) and the cull (cider) value. The information, presented in Table 2, was developed using an estimated yield of 600 bushels per acre, an average value of $10.50 per bushel for undamaged fruit and a value of $2.50 per bushel for culls. 13, The loss in revenue can be thought of as the "cost" of the defect. By being aware of this cost, the grower is in a position to assess the net value of taking some additional preventive action, Suppose, for example, most physical damage is found to occur when fruit is dumped from picking buckets into bulk bins. An estimate of the lost revenue due to the rough handling can be made. The grower can then determine if the cost of a little more time and effort to reduce handling damage is exceeded by the increase in returns . 2 gives an indication of those areas which cost the most in terms of lost revenue. Size and color defic- iencies together account for a loss in revenue of $672 per acre ($494 for size and $177.60 for color). Fruit culled because of Table grov/er the physical damage represents a loss of $287,40 per acre ($86.40 each for bruise and mechanical damage and $105.60 for stem, pu ture) . unc- Table 2. Revenue loss on cull Mcintosh apples at grower packing sheds, 1979. Grade defect Percent of total apples culled because of this defect Culls per acre with this defect Value of culls if not damaged'^ Cull value Loss of revenue due to this defect bushels $ $ $ Misshapen 0.2 1.2 12.60 3.00 9.60 Insect damage 0.4 2.4 25.20 6.00 19.20 Disease damage 0.5 3.0 31.50 7.50 24.00 Russeting 1.3 7.8 81.90 19.50 62.40 Bruise 1.8 10.8 113.40 27.00 86.40 Mechanical 1.8 10.8 113.40 27.00 86.40 Skin puncture 2.2 13.2 138.60 33.00 105.60 Color ( a < < UJ a: m a. to >«. Ui X a. >- z o o d z 2 < UJ Treatment A 10 EGGS NYMPHS ADULTS Treotment D / // -* — * — *- 100 r Treatment B I 10 0.1 \ / i i i i * * * * J Treatment E 1 1 r! A f \ ! \ 1 \ A / ^ / 1- 100 r Treatment 10 0.1 7 12 20 28 23 7 I I Aug. in e o c 0 E ^-J rt (D Si 4-> 0) T3 •H U •H 4-1 u o t^ c • H ■•-> . c Ol 0 r-- !-i CTi QJ t—l M-l <4-l •H • XI H U LO ^ (/, (D S-i 13 5-. LO i-H T3 t/) 03 U !h !-< rt O (U (U CC O -H >■. C- fH to o ■M ;/) • •H ^ o o3 O o ns rt 13 0) C 5. Adult populations in early spring were lowest on treatments which received oil (A, B, C and E) . Zwick and Westigard (1978) in Oregon reported a delay and a reduction in egg laying by overwinter- ing pear psylla adults attributable to the use o£ petroleum oils. We observed a similar delay in egg laying on oiled pear trees at Storrs in 1978. We did not note a delay or reduction in egg lay- ing in 1979 but we suspect that our oil treatments were applied too late to have gained that benefit. Hoyt , Westigard, and Burts (1978) have reported fenvalerate (Pydrin) to be highly toxic to predators of spider mites in pear orchards in the Pacific Northwest. In view of the current lack of effective insecticides for pear psylla control, fenvalerate (Pydrin) appears to be of considerable value, especially when used as pre- bloom treatments. Early season treatments might allow predators to recover in time to help manage summer spider mite populations. Connecticut is now in the process of applying for a special state registration to allow the use of fenvalerate (Pydrin) in 1981 for the control of pear psylla on pears. A summer treatment of amitraz (BAAM) applied to all plots was not highly effective in controlling pear psylla in our tests, and was associated with considerable leaf scorch. It could not be determined whether BAAM was directly responsible for this injury. A period of several days of high temperatures and humidity following the treatment may have contributed to the appearance of damage. Further tests are needed to evaluate more fully the role of BAAM for pear psylla control on pears in Connecticut. References Hoyt, S.C, P.H. Westigard, and E.C. Burts. 1978. Effects of two syn- thetic pyrethroids on the codling moth, pear psylla, and various mite species in northwest apple and pear orchards. J. Econ. Entomol. 71: 431-434. Zwick, R.W. and P.H. Westigard. 1978. Pre-bloom petroleum oil applications for delaying pear psylla (Homoptera: Psyllidae) oviDOsition. Can. Entomol. 110: 225-336. ORCHARD PRACTICES NECHSSARY FOR GOOD PEACH PRODUCTION lest G. Rutgeri Ernest G. Christ, Extension Poiiiologist "s University, New Jersey The peach industry is now and has been a stable segment of the agriculture in New Jersey. The industry dates back to the early 1600 's. Extensive orchards were planted by 1650 and the industry grew until 1890 when there were over 4 million trees in the state. Production per tree was low since there were only 775,000 bushels produced in 1890. Production improved as pest control became a more standard practice and in 1920 from about million trees the production was 2.1 million bushels. o The 1977 tree survey shows a total of all trees to be slightly over 1 million with about 200,000 in the 1-3 year age. Today the tree numbers are probably a bit above the 1977 survey figures based on observations of tree planting in 1979 and 1980. Production for the state in 1980 is estimated at about 2-1/2 million bushels. Production usually varies from 2 to 2-1/2 million bushels annually. The most recent above-average crop was in 1971 when it exceeded 3 million bushels on the trees, and the poorest crop in more than 40 years was in 1972 when only 500,000 bushels were recorded. Geographical location of New Jersey is especially suited to peach growing as evidenced by the fact that the most recent freeze- out of tlie entire crop and severe tree killing occurred in the 1934- 35 winter. Few if any other peach producing areas in the country have been as fortunate. Serious Problems and Solutions There are serious growing and production problems and there is constant change in growing, harvesting, handling and packing. Tlie short life of peach trees is being discussed in grower meet- ings and this is a problem in New Jersey as well as Georgia, South Carolina, Michigan and several other areas of peach growing. V/e have recommended and growers are following procedures for increasing the vigor, health and life of the tree. 1 Talk presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association, Inc., July 10, 1980. Much research has been conducted in an effort to increase the life of a peach tree and Dr. E.F. Savage of Georgia devoted many- years to this problem. As a result of his work and that of others, including those in New Jersey, our cultural recommendations have been updated and are as follows: 1. Soil fumigation is being practiced; both pre-plant and post- plant treatments are made to reduce nematode populations. This is an established practice in all peach growing areas since soil fumigation has improved tree vigor and extended tree life. Trees are less subject to cold damage and the virus disease "Stem Pitting" is reduced through fumigation. Fumigant type nematicides recommended for pre-plant treatment include DD* , Telone II*, EDB W-85*, Vorlex* and Telone 17*. Post-plant soil fumigants recommended are Nemagon 12.1* and Fumazone 12.1*. Non-fumigant nematicides include Furidan lOG* and 4F*, Nema- cur 15c;* and 3SC*, and Vydate L* as a foliage spray. 2. Calcium nutrition is important. Keep the soil pH between 6 and 6.5 using calcium lime. Apply 1/2 to 1 pound calcitic limestone mixed vvfith the soil around the roots at planting. Tiie late Professor M.A. Blake stressed the need for N-P-K fertilizer and liming to maintain a soil pil of 5.5 - 6.5 in the 1920's. 3. Painttree trunks with interior white latex (water base) paint in the fall to reduce cold damage. This is most essential on trees from 2 through 5 years of age. This reflects the sun's rays and the temperature of the trunk of the tree is more nearly the air temperature rather than 80 to 85 F as it can be on the south side of the tree in January and February. Research in this field was done in 1943-1944 by Dr. R. Eggert in New Hamp- shire. 4. Prune peach trees in late winter, after the coldest weather is past. March is a good time to start pruning if possible. If pruning must begin before March, prune the oldest trees first and the young last. It is better to prune young trees in bloom than to prune in January or February. 5. Cytospora (Valsa) canker can be a tree killer if ignored. On 1- and 2-year-old trees, prune off infected portions if possible. Cankers on the trunk that cannot be pruned out should be cut out, removing all diseased tissue until healthy, green bark shows. Paint the area with tree paint containing 2 tablespoons of Benlate per pound of tree wound paint or white latex paint or spray the trees with 1/2 pound Benlate 50WP* in 100 gallons within a day or two after pruning and cutting out cankers. A Trade name 6. Stem Pitting virus is less a problem today than it was 10 or 15 years ago but it is present in some orchards every year. It was a very serious problem in the late 1950's and was identi- fied as a virus in the early 1960 's through the efforts of Drs. J.C. Barrat, W. Virginia; S.H. Miretich and H.W. Fogel of the USDA and Drs. F.H. Lewis, R.F. Stouffer and F.N. Hewetson in PA. Nursery trees purchased today are far superior to those of 15 years ago from the standpoint of being free of the Stem Pitting virus. Nematodes transmit the disease and this is a major reason for fumigating the soil. Bud wood selection by the nursery is equally or more important. Other Practices Variety Selection. In New Jersey the two major requirements in the selection of peach varieties for planting are cold hardiness of buds and bacterial spot disease resistance. Observations during the last 10 years make it possible to recommend a scries of varieties that are superior in these two characteristics. Other desirable qualities include fruit firmness, color, flavor, and size, and tree vigor and growth characteristics. It isn't possible to find all of the best in any one variety, perhaps, but a few varieties have the 2 major requirements plus several other desirable qualities. A few of the best that we recommend in order of ripening include: Candor, Garnet Beauty, Harbelle, Redhaven, Harken, Harbrite, Summer- glo (NJ233) , Norman, Biscoe, Cresthaven, Jerseyglo (NJ244) and Emery. A few nectarines that show promise include: Harko and Sunglo (Red- haven season) , RedGold (Cresthaven season) and LateGold (Rio) . Loring, Blake, Jerseyqueen and Rio-Oso-Gem are major varieties in New Jersey and yet Loring, Jerseyqueen and Blake are not bud hardy; Blake, Jerseyqueen and Rio-Oso-Gem frequently have serious infections of bacterial spot and Rio is a poor tree. Blake is probably phasing out and Jerseyqueen also, but wholesale market demand is a factor in variety selection. Retail or pick-your-own selling can include some varieties not the best for shipping. Bulk Hauling. Bulk handling from the orchard to the packing house, into the storage and on to trucks is common practice in practically all orchards. Bulk hydrocooling has replaced packed box hydrocooling in many operations for more rapid cooling and efficiency, especially during heavy harvest. Fruit Thinning. Growers have tried and used all chemical thinners available as they appeared, and watched them disappear sometimes with regret. Dinitro first appeared in the 1940's, and then through the years NPA and CPA appeared, stayed for a while and then were removed. There is no chemical for use on peaches today but Ethephon will thin. Considerable research has been done regarding Ethephon as a peach thinner beginning in 1968. One of the problems has been leaf damage and heavy leaf drop but Dr. L. Edgerton in New York has included ProGibb* in the spray with ethephon and eliminated most of this damage. In the absence of a chemical thinner, some limb shakers, a few full tree shakers, clubs and whiffle bats are used to thin the fruit, plus much hand removal. Thinning is a most important cultural practice. Size is so very important in the wholesale market and frequently, 1/8" increase in peach size will return an additional $1.00 per 38 lb. box. Twice as many 2" peaches are required to equal weight of 2-1/2" peaches. Peaches gain 41 a day in volume as they approach harvest. Pruning for Low Profile Trees. flost trees in New Jersey orchards are being pruned to maintain a height of 7 to 8 feet. This makes possible the pruning, thinning and harvesting without ladders. Machine topping is extensive mainly with sickle bar mowers. Mowing is done in the dormant season on most acreage but more and more summer mowing is being done in orchards where tree and row spacing permits. Summer mowing is usually done between July 15 and August 1. There are several good reasons for summer mowing in addition to accomplishing some pruning: more sunlight enters the tree, fruit ripens more evenly and with less pickings, fruit color is improved and better fruiting wood develops in the center of the tree. Hand pruning is essential to complete any machine pruning to maintain good tree vigor and the best fruiting shoots throughout. Pneumatic pruners are used to some extent and custom pruning is done on a sizeable acreage. There is room for improvement in the pruning of much of the acreage but it's a time consuming, costly job and too few people are willing or able to do the job properly, so less than satisfactory pruning must be accepted. Irrigat ion. Most peach orchards are equipped with some kind of irrigation and during some time each year in late spring and summer the irrigation is usually needed. Tricke irrigation is established on perhaps 10 farms with capa- cities ranging from 50 to 100 acres per farm. There is no strong movement into trickle because of other equipment still in use and the cost of establishing trickle. Irrigation is a very necessary cultural requirement in peach growing. Chemical Weed Control. Some orchards are grown in an established sod, usually fescue, with chemical weed control in the tree row. More of the orchards, especially in southern New Jersey, are culti- vated with chemical weed control in the tree rows. Herbicides used for annual weeds include simazine, terbacil, diuron and a combination of diuron + terbacil. For established weeds, paraquat and dichlo- benil are recommended. "35 Trade name 10. In one and 2-year-old orchards some growers combine 1-1/2 gal. per acre of Furidan 4F* with the herbicide for nematode control plus weed control. Recent Innovations. Machine planting of peach trees is being done on substantial acreage in the southern area of the state and pro- bably will increase. There are only a few planters as of this date but they are shared since a grower needs the machine for only a a day or 2 to plant considerable acreage. The tree planter can not be used in all soils but in New Jersey it can be used in the areas where 901 of the peach trees are grown. Observations to date in- dicate no serious problems. Some orchards have completed 4 years and trees are growing well. Usually the trees are lined up in one direction only so cross cultivation or spraying is not easily done. Trees could be set on the square but this requires more time and effort and many growers feel this is not necessary. Subsoiling be- fore planting is recommended where old trees have been removed and limestone placement in the subsoil is also recommended. Hedgerow planting is being tried in one orchard rather extensively and a few other plantings have been made on a limited acreage. Trees are planted 10 feet in the row and the rows are 15 feet apart. Trees are summer mowed vertically and across the top at about 10 feet. The width of the trees is held about 5-4 feet. Some hand pruning is done in the dormant season to remove diseased and broken limbs and any strong growth growing into the row middle. As with trellised trees, there should be an open space for cross traffic at about 50 foot intervals. ****** NEW ENGLAND FRUIT MEETINGS AND TRADE SHOW The New England Fruit Meetings and Trade Show will be held at the New Hampshire Highway Hotel, Concord, Nev/ Hampshire. The meet- ings are scheduled for January 7 and 8, 1981. The hotel is accessible from all major highways. Routes 3 and 93, which lead to Concord, are accessible from anywhere in Massa- chusetts. Persons coming from Western Massachusetts and Southern Vermont may find the most convenient route to be Routes 9 or 10 to Keene, New Hampshire, and then Routes 9 and US 202, 89 and 93 to the Highway Hotel. a Trade name 11. INTEGRATED MANAGEMENT OF APPLE PESTS IN MASSACHUSETTS 1980 RESULTS: INSECTS^ W.M. Coli , G.E. Morin , N.D. Goodliue , M. Kuzontkoski , T. Green , 4 5 6 M.R. Paul , S. Marafino , and R.J. Prokopy Summary of Res ul ts . Intensive weekly scouting and grower advisement in 18 good-cooperator IPM blocks, resulted in a savings in insecticide, aphicide, and miticide spray use (dosage equivalents) of 40%, 97% and 56% respectively. Permanent type fruit injury was 8% lower in IPM than Check blocks. Cost benefit analysis indicated an average net savings from IPM of $93.37 per acre. Compared with previous years, 1980, the third year of operation for the Massachusetts apple IPM program, was char- acterized by significant changes in number o£ orchards scouted, grower financial support, grower participation in orchard scouting and sampling methodology ^. Program objectives continue to be: 1) to aid in the pro- duction of high yields of high quality fruit while reducing the amount of pesticide usage; and 2) to encourage the use of spray materials which allow for survival of beneficial predators and parasites . 1 Special thanks to Mr. David Chandler, Meadowbrook Orchards, Inc., Sterling Jet. for allowing us to room 2 scouts at his housing for harvest labor throughout the summer which allovved significant savings in travel time and gasoline. 2 Pest Management Specialist 3 Senior Field Scouts 4 Field Scouts 5 Lab Technician, Entomology Department 6 Extension Entomologist 7 Reduced spray programs on apples have been discussed in previous issues of Fruit Notes [41(1), 41(2), 41(3) and 43(3)1], and our 1978 and 1979 results were summarized in Fruit Notes 44(1) and 44(6).] 12. Number of orchard blocks scouted iiach week, field staff visited 25 IPM blocks in 16 commercial orchards throughout the major fruit growing regions in Massa- chusetts. IPM growers received a weekly written scouting report and were contacted either in person or via telephone by the IPM Specialist and advised as to the need for spraying, materials to use. and timing . In addition, we monitored Check blocks in 6 commerical orchards on a weekly basis when possible. Insect monitoring was identical to that in IPM blocks, although growers followed their own pesti- cide application program with no advice from us. Also, 4 orchards were Alternate Middle vs. Every Middle spray blocks. We will discuss the results of this aspect of the program in the next issue of Fruit Notes. Grower financial support The majority of funding for the IPM program continues to be the original 5 year USDA Grant which began in 1978. However, in- asmuch as USDA funds for scouts are scheduled to decrease each year and grower support for scouts is meant to increase, partici- pating IPM orchards were charged $300 for combined insect and dis- ease scouting and advice or $200 for insect scouting and advice alone. Growers paid a total of $4,500 into a special Extension Activity Fund, which was used exclusively for paying scout salaries. No fee was assessed Check or Alternate-Every Middle orchards. Grower participation in orchard scouting In response to substantial grower interest we offered a series of training sessions to acquaint growers or designated orchard personnel with insect identification and life histories, IPM monitoring techniques, and recommended control measures. These "grower scouts" were encouraged to participate in weekly scouting and data collection in their IPM blocks, and to scout additional blocks of their orchard on their own. Of the 16 IPM orchards, 11 utilized "grower scouts" on a weekly basis, 4 used them sporadically, and 1 not at all. Interest in the "grower scout" concept appears to be high, and may offer a means for growers to continue to im- plement IPM programs after September, 1982 when Federal funding is scheduled to end. Sampling methods Weekly, intensive orchard monitoring continues to provide the soundest basis for accurate pest management decision making and grower advisement. However, if IPM techniques are to be applied to large orchard acreages, more rapid methods of accurately esti- mating insect densities are desirable. For this reason in 1980 we utilized fewer trapping stations per block (1 per 2-3 acres) than in 1978 or 1979 (1 per 1-2 acres), although time spent at each station was similar to previous years. 13. Sampling stations were usually near the block periphery, 2 or 3 rows in from the border while one station for pheromone (sex odor) traps was positioned in the block center. Visual traps were used to monitor tarnished plant bug (TPB) , European apple saAvfly (EAS) , and apple maggot fly (AMF) adults. Pheromone traps were used to monitor Codling moth (CM), Oblique banded leafroller (OBLR) , redbanded leafroller (RBLR), San Jose' scale (SJS) , tufted apple budmoth (TARM) , and spotted tentiform leaf- miner (STLM) males. Mites and mite predators were monitored using leaf brushing techniques (Fruit Notes 43(4)) from mid June to harvest. Plum curculio (PC), green fruitworm (CFW), green apple aphids (GAA) , and their predators, woolly apple aphids (WAA) and STLM were monitored by examining ID fruiting spurs or foliar ter- minals in each of 3 tree areas (top, low inside and low outside) at each trapping station. Immediately prior to appropriate harvest dates for early, mid, and late season apple cultivars, insect injury levels were deter- mined in each IPM and Check block using on-tree surveys of 400- 1600 fruit per block (100 fruit per tree from each of 2 trees adjacent to trapping stations). In addition, we sampled at har- vest fruit injury from anotlier block in each IPM orchard of similar tree size and varietal composition. Injury in tliese blocks was determined by on-tree surveys of 1000 fruit per block (100 fruit per tree from trees randomly located within the block). Results Fruit injury At harvest, fruit injury was divided into categories: 1) in- jury to the skin or flesh (= permanent injury); and 2) injury confined to the skin surface (= temporary injury usually removable by washing, i.e., WAA in the stem cavity, sooty mold (SM) on aphid honeydew, or white apple leafroller (WAL) excrement). Drawing on the experience of IPM researchers in other states, we analyzed harvest injury levels (Table 1) and spray application totals (Table 2) taking into account the degree of adoption of IPM recommendations by participating growers. Specifically those growers who followed more than 60"o of spray recommendations were considered "good" cooperators , while those following less than 60-6 of these recommendations were considered "partial" cooperators. Overall, permanent fruit injury was only 2S% as great in good cooperator IPM blocks as in partial cooperator blocks, 501 as great as in same orchard non IPM blocks and 92% as great as Check blocks. These data indicate that partial cooperation with IPM recommendations can result in poorer quality fruit than if growers follow their own spray approach without IPM advisement. 14 Table 1. Average percent insect injury on fruit at harvest in good or partial cooperator IPM and in Check commercial orchards in Massachusetts, 1980. 1980 in; jury (%)^ Insects Good Partiaiy Same orchard^ CO operators cooperators non IPM Check (18 blocks) (5 blocks) (13 blocks) (9 blocks) Permanent injury SJS 0.72 11.8 4.26 1.43 TPB 1.44 2.0 2.09 1 .44 PC 1.19 1.28 1.00 0.87 EAS 0.24 0.46 0.22 0.11 AMF 0.10 0.04 0.09 0.14 CM 0.04 0.0 0.0 0.0 LR 0.02 0.04 0.05 0.03 GFW 0.01 0.02 0.0 0.07 Total per- 3.76 15.64 7.71 4.09 manent in- jury ("o) Temporary injury WAA 0.05 0.0 0.15 0.0 WAL 0.64 0.0 1.49 0.11 SM 0.03 0.0 0.33 0.08 Total tem- 0.72 0.0 1.97 0.19 porary in- jury i°i) Total Per- cent insect injury (per- manent and temporary) 4.48 15.64 9.68 4.28 z Based on on-tree survey of 600-1600 fruit per block at harvest (100 fruit per tree from each of 2 trees adjacent to trapping stations) . y Partial cooperators were those who followed less than 60% of advised spray recommendations. X Does not include "partial cooperator" blocks. Removable fruit injury was only 37% as great in IPM as in same orchard non-IPM blocks, but 74% more than in Check blocks, while no superficial type injury was found in partial cooperator blocks . 15. Specifically, TPB remained a highly damaging fruit pest in Massacliusetts commercial orchards (Table 1) , as was the case in 1978 and 1979. Tarnished plant bug injury in IPM and Check blocks was identical inspite of higher pest pressure in IPM blocks (7.4 TPB adults per trap in IPM vs. 6.0 adults per trap in Checks), Continuing our attempts to develop a TPB grading index, we found that bl% of TPB injured fruit would grade through as US Fancy, while 351 would grade US No. 1 and 6% would be culled. This high percentage of very minor TPB injury may relate to the rapid, early buildup in TPB populations before pink, when feeding results pri- marily in bud abscission rather than serious scars resulting in downgrading of fruit value. San Jose scale continues to be a serious pest of apples in Massachusetts, although injury in IPM blocks was only SC^ as great as in the Checks. The high average injury due to scale in partial cooperator blocks resulted from one grower's failure to treat for scale with prebloom oil, despite advice to do so. The result was scale injury on 55% of fruit sampled. Plum curculio injury was substantially higher in all blocks in 1980 than in 1979 even though some growers applied as many as 4 insecticide sprays to control this pest. Injury in IPM blocks was 271 greater than in Checks, due primarily to 9.4% PC injury in one block (the grower was unable to apply a recom- mended spray over the May 24-26 weekend, when PC activity was high, because beehives were still in the orchard). Trap captures of AMF adults were higher than in 1979, as was the injury from this pest in both IPM and Check blocks. In one IPM block, no AMF adults were captured until August 15, and CM captures were also low. As a result no insecticide sprays were applied between June 9 and August 15, and no AMF sprays were needed thereafter. Our harvest injury survey found no injury from either of these pests in this block, pointing out the poten- tial savings to growers that may result from use of sticky sphere and pheromone traps for AMF and CM, respectively. No spray applications were required in any IPM blocks for CM, LR, or GFW, and combined injury from these pests was slightly lower in IPM than Check blocks. Injury from WAA, WAL and SM was substantially higher in IPM than Check blocks, due principally to high (6.91) WAL injury in one IPM block. Inasmuch as speckling from WAL excrement is superficial and would probably be removed by normal post harvest handling, it is doubtful that this "injury" is of economic importance. Mite populations Populations of harmful plant feeding mites were virtually id- entical in IPM and Check blocks in 1980. European red mite and two spotted mite numbers generally peaked in late July and early August, in response to hot dry weather, and may have caused some fruit drop at populations lower than would normally be expected to cause drop. Perhaps mite feeding combined with the stress of 16 below average rainfall contributed to tliis phenomenon. Apple rust mites, which cause little damage except at very high popu- lation (about 300/leaf) but may serve as an alternate food source for Amblyseius fallacis, were found in substantially higher numbers in IPM than Check blocks. Table 2. Mean abundance at peak sampled population of pest and predaceous spider mites in relation to acaricide sprays, 1980. Acaracide dosage Number of mites per leaf Two- Apple equivalents European spotted rust Amblyseius Orchard type Oil Other red mite mite mite fallacis IPM 1.0 0.8 IPM partial cooperator? 0.7 1.4 Check 1.1 1.8 8.1 6.2 8.4 2.0 3.2 1.9 66. 5 50.4 22.4 0.07 0.02 0.03 „ . T ^ Actual pesticide rate/100 gal Dosage equivalent = -t — r '- 1 — r~- o^ — . . ^ — - ^ ^ Amt . recommended m Southern New England Apple Pest Control Guide Predator mite numbers were insufficient to achieve biological mite control because they never exceeded 0.5 per leaf in any block. We believe that the lack of snow cover during the 1979-80 winter may have resulted in substantial overwintering mortality to A. fallacis , as was the case in Michigan after a recent winter with similar conditions. Insecticide, aphicide and miticide use. IPM blocks received 26% fewer insecticide sprays (average 6.5, range 5-9) than the Checks (average 8.8, range 5-12} or same orchard non-IPM (average 8.8, range 5-10]°. These results appear to indicate that growers (same-orchard non-IPM and Check) are implementing some aspects of IPM on their own. Partially cooperating IPM growers applied 11°6 fewer sprays than good cooperators. However, any sav- ings in spray material and application costs were negated by sub- stantially higher fruit injury levels in these blocks. IPM growers applied 26% and 531 fewer miticide sprays compared to Check and partially cooperating 1PM growers, respectively (Table 3). Use of oil as an ovicide was nearly identical in IPM and Check blocks, but 36% lower in partial cooperator blocks. 8 Data incomplete 17. Table 3. Number of pesticide treatments and dosage equivalents of pesticide applied for insect and mite pest control in IPM and Check blocks, 1980. IPM as IPM partial % of Number of treatments IPM cooperators Check Check 1.0 110 8.8 74 2.0 70 0.5 20 Oil 1.1 0.7 Insecticide 6.5 5.8 Mit i cide 1.4 3.0 Aph icide 0.1 0.3 Number of dosage equivalents Oil 1.0 0.7 Insecticide 4.8 5.5 Mit icide 0.8 1.8 1.1 90 8.0 60 1.8 44 Aphicide 0.01 0.3 0.4 3 •7 . , ^ Actual rate/100 gal water Dosage equivalent = -^ 1 — -^ r — ^ ? tl — „ ^ ' Recommended rate m Southern New England Apple Pest Control Guide While there was a substantial reduction in spray application trips, there was an even greater reduction in number of dosage equivalents of insecticides, aphicides and miticides in IPM com- pared with Check blocks (60, 3 and 44^o as much used, respectively). (Table 3.) . Pesticide use 1977-80 Figure 1 shows t7ends of pesticide use in IPM and Check blocks in recent years. It is interesting to note in (Figure la and Figure Ic) that a general reduction in pesticide dosage equivalents has occurred. Although IPM orchards use substantially less pesticides. Check orcliards also appear to be utilizing some IPM information as well. In addition, the rapidly rising costs of pesticides (petro- chemical derivatives) probably accounts for some portion of this overall downward trend in spray material usage. As more sprays are IS c O > O "5 cr UJ a> o (n o Q 5, 2 a. Insecticide Usage IPM ■ — ■ CHECKd- -D -- ^ of Blocks ( ) 84- /9)S 4 b. Insect Injury to Fruit at Harvest 2.. d. Mean Abundance of Spider Mites at Peak Populatio Trends in pesticide use, injury to fruit, and spider mite populations. 1977-1979. required for STLM and SJS control, however, it is possible that this trend may be reserved in the future years. 19 Cost and benefit comparisons Table 4 summarizes our cost benefit analysis of IPM vs. Check blocks. IPM orchards realized substantial savings in spray mat- erials and application costs per acre compared to Checks. (Table 4). (All calculations were done using suggested retail prices, with no attempt made to account for grower liulk rate discounts, which vary considerably). Table 4. Cost benefit analysis of insect and mite results in 18 IPM and 9 Check commercial apple blocks in Massacliusetts , 1980 Parameter Orchard IPM Check (Avg. no. sprays/A) Oil Insecticides Aphicides Mit icides (Avg. no. of dosage equivalents for)^ Difference IPM vs . Check 1 6 0 1 (Avg. insect injur T ("OJ y (Avg. application cost / A)^ (Avg. cost/A spray materials) Oil Insecticides Aphicides Miticides 3. 7 7 $26.45 $18. 53 55.54 1.50 20.30 1.0 8.8 0.5 2.0 Oil 1.0 1.1 Insecticides 4.8 8.0 Aphicides 0.01 0.36 Miticides 0.8 1.8 4.09 $34. 27 $21 98 5 39 37 04 89 79 (Numerical) 0.32 $ -7.82 $ -2.84 -42.50 -4.30 -19.49 (%) + 0.1 + 10 -2.3 -27 -0.4 -80 -0.6 -30 0.1 -10 3.2 -40 0.35 -97 1.0 -56 (Avg. value/A of fruit loss due to insect injury)w $200.96 $217.38 (Avg. net benefit/A from IPM $-16.42 $+93.37 ' - , ^ Actual pesticide rate/100 gal Dosage equivalent = Recommended rate in Southern New England Apple Spray Cuide r Does not include injury from sooty mold, white apple leafhopper and woolly apple aphids which could be removed by washing fruit. Based on 15 min. time to spray 1 acre, $5.50/hr. labor cost and $2 . 20/acre/application for fuel and oil. Based on average values as of October 10: US Fancy Fruit $11.33/bu, US n fruit $7.00/bu., cull fruit $1.60/bu. and average yields of 550 bu./acre. w 20. Average value of fruit loss per acre was $16.42 lower in IPM blocks as well, resulting in an average net benefit per acre of $93.37 from IPM scouting and grower advisement. It should be noted that savings in spray materials and appli- cation costs seen in 1978, 1979 and 1980, are only the most immed- iate benefits of IPM. IPM has essential long-term benefits as well in reducing selection pressure for pesticide resistance and thus greatly delaying development of resistance, and prolonging tlie period of usefullness of currently available spray materials. FRUIT NOTES INDEX FOR 1980 (This index of major articles has been prepared for those who keep a file of Fruit Notes. The number in parenthesis indicates the pages on which the item appears.) January/ Feb urary Further Trials with Naphthalene Acetic Acid (NAAJ for Tree Training. (1-2) Winter Injury to Fruit Trees in 1978-79.(2-6) Winter Injury in New Hampshire - A Grower Survey (7-8) Progress Report: Height Containment on Spartan and Idared Trees (8-14) Alternate vs. Every Middle Spraying for Apple Pests in 1979(15-18) March/April Airblast Sprayers for Orchard Spraying (1- 6) Spotted Tentiform Leafminers : Biology, Monitoring, and Control (7 - 12) More About Nematodes and Fruit Trees (13-14) May/June The Way You Fertilize Your Fruit Trees Can Affect the Quality of the Fruit You Harvest (1-4) Suggestions for Use of Calcium Sprays in 1980(4-5) Suppressing Weed Growth Under Fruit Trees (5-6) Pomological Paragraph- Pruning at Planting (6-7) Influence of Pruning Peach Trees Late in the Spring(7-8) The Use of Promalin to Elongate Delicious Apples: Research Obser- vations and Suggestions for Use in 1980 (8-12) Soil Management of Peach Trees (12-15) Sampling Methods and Provisional Economic Threshold Levels for Major Apple Insect and Mite Pests in Massachusetts (15-18) Managing Mummy-Berry Disease of Blueberries in Massachusetts (19- 21) July/August Progress Report: Scion/Rootstock and Interstem Effects on Apple Tree Growth and Fruiting (1-2) Soil, Tree, and Fruit Response to Lime and Type of Nitrogenous Fertilizer Applied at Two Timings Under Sturdeepsur Delicious Trees (3-7) How Ethephon is Being Used to Advance the Maturity of Apples in Massachusetts (7-12) Excessive Apple Bud Abscission in 1980: Was It Caused by Tarnished Plant Bug Feeding or Cold Temperatures? (13-14) 21. TRUIT NOTIiS INDEX fcontinued) Sept ember /October Progress Report: Pruning Effects on Tree Growtli and Fruiting of Spartan Apple (1-8) Do Calcium Chloride Sprays Affect Apple Maggot Fly Egglaying? (9- 10) Causes of Defects on Mcintosh Apples at Packing Sheds and Their Effects on Returns. (10-14) Controlling Orchard Mice. (15-16) November /Dec ember Evaluation of Several Pear Psylla Control Programs in Connecti- cut (1-5) Orchard Practices Necessary For Good Peach Production (6-10) New England Fruit Meetings and Trade Show (10) Integrated Management of Apple Pests in Massachusetts 1980 Results: Insects (11-20) COOPERATIVE EXTENSION SERVICE U.S. DEPARTMENT OF AGRICULTURE UNIVERSITY OF MASSACHUSETTS AMHERST, MA 01003 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 46 No. 1 JANUARY/FEBRUARY 1981 TABLE OF CONTENTS Calyx-End Rot of Apples in Massachusetts Disease Results for the 1980 Integrated Pest Management Program for Apples in Massachusetts Research in Progress I. Scion/rootstock and interstem effects on growth and fruiting of apple trees. II. Effect of rootstocks and stempiece/ rootstock combinations on the tree performance and fruit quality of Mcintosh and Delicious strains III. Fruit variety evaluation at the Horticultural Research Center IV. Adaptability of apple tree rootstocks to representative orchard soils in Massachusetts V. Effect of soil water and depth to hardpan on rootstocks An Update on Fruit Trees Injured in 1978-79 Alternate vs. Every Middle Spraying for Apple Pests: 1980 Results for Arthropod Pests and 5-year Trends NOTICE The Massachusetts Cooperative Extension Service is faced with a crisis situation relative to funds. There- fore, in 1981 there will be only 4 issues of FRUIT NOTES a winter, spring, summer and fall issue. CALYX-END ROT 1 OF APPLES IN MASSACHUSETTS T.R. Bardinelli , C.W, Department of McCarthy , and W.J. Manning" Plant Pathology During the 1980 apple growing season, calyx-end rot disease caused greater than usual losses. Calyx-end rot is caused by the fungus Sclerotinia sclerotiorum. This organism has a wide host range, including many vegetable and ornamental plants. The first symptoms were observed as a dry tan-colored rot on the calyx end of young fruits during mid- July. Often the surrounding tissue ripened prematurely causing the epidermis in this area to turn red. The red areas make the diseased fruits highly visible. Severely affected fruits may drop prematurely. Other fungi can quickly invade the weakened fruit and furth( decay results if adequate moisture is available. ler The is not w and may periods fected f (1/4 - 1 the rest can rema small br proper e structur again oc life cycle ell unders extend int are probab ruits drop /2" diamet ing or ove in dormant own apothe nvironment es are pro cur. of S. sclerotiorum on app tood. Infections probably o June from windblown asco ly necessary for infection and decompose, small hard er) called sclerotia are p rwintering stage. On othe for up to 3 years, Scle cia during late spring or al conditions occur. Asco duced and windblown to the les in Massachusetts begin during bloom spores. Wetting After the in- black structures reduced. This is r crops , sclerotia rotia give rise to early summer if spores from these host where infections The average incidence of calyx-end rot in Massachusetts during 1980 was 2%. Severely affected orchards had losses of 4-8% in Red Delicious and Mcintosh blocks. The most susceptible varieties appeared to be Milton, Macoun, and Mcintosh. Red Delicious and Cortland fruit were also susceptible to calyx-end rot but to a lesser extent and Golden Delicious appeared to be the least susceptible. Extension Technician Extension Aide Associate Professor Two severely affected orchards were routinely surveyed for this disease in 1980 and the data in Table 1 show the percent of infected fruits for the period between mid-July and mid- September . Table 1. Percent calyx-end rot fruit infection in two severely affected orchards in Massachusetts, 1980. Orchard July Au gusi S( 3ptember 10 16 30 13 27 17 1 2 4.0 3.9 6.0 8.9 1.6 4.9 1.2 5.2 1.6 4.7 1.2 2.6 Average 3.95 7.45 3.25 3.20 3.15 1.90 The highest incidence of calyx-end rot was observed on July 16 with an average of 7.451. Many of the diseased fruit dropped prematurely and only 1.9% of the fruits on the trees September 17 were infected. Visual examinations of infected fruits on the trees at harvest showed a successful walling-off and healing of the previously rotted calyx-end. Calyx-end rot and other blossom end rots of apple fruits can easily be confused. The only reliable way to determine the cause of calyx-end rots is to culture tissues on media in the laboratory and identify the fungi that grow out. Many different fungi have been associated with calyx-end rots of apple, including Botrytis cinerea , Alternaria spp. , Physalospora obtusa, and Sclerotinia sclerotiorum. Isolations were made in mid-July from 200 fruit with early symptom expression and in early August from the same number of fruit with late symptom expression (Table 2) . Table 2. Occurrence of various fungi from calyx-end rot isolations, Early symptom isolations Late symptom isolations I Incidence % Pure culture 1 incidence % Pure culture Sclerotinia 60 36 18 0 57 21 0 20 1 0 13 6 sclerotiorum 98 Alternaria spp. 34 Botrytis cinerea 14 Other 0 Ninety-eight percent of the isolations from apples with early symptoms yielded S. sclerotiorum and 601 were pure culture. This, plus pathogenicity test results, indicated that S. sclerotiorum was the probable cause of calyx-end rot. Isolations from fruit with advanced symptoms showed a marked decrease in S. sclerotiorum and an increase in the isolation of other saprophytic and weakly pathogenic fungi. This illustrates the importance of early dia- gnosis in determining the cause of a calyx-end rot disease of apple. Our observations indicate that an adequate apple scab spray program may not prevent an outbreak of calyx-end rot, as both of the affected orchards surveyed had excellent management of all other apple diseases. ********** DISEASE RESULTS FOR THE 1980 INTEGRATED PEST MANAGEMENT PROGRAM FOR APPLES IN MASSACHUSETTS T.R. Bardinelli-^, C.W. McCarthy^, and W.J. Manning^ Department of Plant Pathology During the 1980 growing season, 11 commercial apple orchards cooperated in the disease management aspect of the Integrated Pest Management (IPM) Program. IPM and Check blocks were located in the same orchards. The disease management strategy for the IPM program was based on biological and environmental monitoring, such as apple scab asco- spore release data, tree growth stage, length of leaf wetting per- iods, and average temperature during these wetting periods. These factors were most important during the primary apple scab season, as determined by the period of ascospore release. Spray decisions were based on the Mill's Table which gives the approximate number of hours of leaf wetting required at various temperatures for the occurrence of a light apple scab infection. 1 Extension Technician 2 Extension Aide 3 Associate Professor Consideration was given to other diseases in addition to apple scab when choosing fungicides. Most sprays were applied after an apple scab infection had been determined. Intervals between sprays were at least 7 days and fungicides were incorpor- ated with insecticides whenever possible. Occasionally preventa- tive sprays were applied on a management decision basis, rather than a calendar basis. Only fungicides with an adequate kickback action were recommended. The end of the primary apple scab season was determined by the end of apple scab ascospore release. Fungicide applications recommended after this time was based on each orchards ' s specific disease problems. In certain orchards, only 1 or 2 fungicide applications, at approximately 1/4 to 1/2 dosage rate, were applied after the primary scab season. Fungicides were no longer applied after infection but rather incorporated with an insecticide or other type sprays. Results and Discussion The results of 1979 and 1980 IPM programs are compared in Table 1 to demonstrate trends associated with the program. Table 1. Cost benefit analysis for fungicide usage and fruit quality on IPM programs in 1979 and 1980. 1979 1980 IPM Check IPM Check Number of fungicide sprays 10.64 13.00 9.45 10.36 Dosage equivalents 9.77 11.11 8.11 8.80 Fungicide cost per acre ($) 74.06 88.68 85.26 94.58 Percent diseased fruits at harvest 0.99 0.93 0.88 0.90 Loss to disease per acre ($) 46.28 43.48 50.31 56.30 IPM net benefit per acre ($) 11.82 15.31 The reduction in the number of fungicide sprays in the IPM blocks in comparison to Check blocks was 18% and 9% in 1979 and 1980, respectively. The amount of fungicide used in the IPM blocks also was reduced by 12% in 1979 and by 8% in 1980. Since the in- cidences of diseased fruit in the IPM and Check blocks were very similar both years, the savings of $11.82 and $15.31 per acre in 1979 and 1980, respectively were mainly the result of reduced fungi- cide usage. Savings were greater in 1980 because of inflation even though the reduction in fungicide usage was less than in 1979. 5. We have noticed that growers tend to apply some information from IPM blocks in the remainder of their orchards. A more dramatic difference in fungicide usage can be noted in Table 2 where we also included non-IPM commercial orchards in our comparisons. Table 2. 1980 spray record comparisons in Massachusetts. Types of orchards IPM Check Commercial Number of fungicide sprays 9.45 10.36 12.00 Dosage equivalents 8.11 8.80 10.55 Cost of fungicide per acre ($) 85.26 94.58 120.56 IPM orchards had 21% fewer fungicide spray applications and used 23% less material than other commercial non-IPM orchards. This amounts to a $35.30 per acre savings. The results clearly show monetary savings for Integrated Pest Management and the use of environmental and biological monitoring for more efficient use of fungicides. It is realized, however, that it is difficult to spray large acreages on an after- infection or kickback program. New pesticides with extended kickback action (up to 92 hours) are presently being used on an experimental basis and might solve this problem in the future. We are also working on a spray prediction program based on fungicide residue sampling on apple foliage. This program may aid in the timing of fungicide applications and help reduce fungicide applications. ********** RESEARCH IN PROGRESS In January, 1981 the personnel who conduct pomological research at the University of Massachusetts reviewed their projects with members of the Massachusetts Fruit Growers' Association-University of Massachusetts Fruit Advisory Committee. Perhaps our readers also would like to know how the University of Massachusetts is attempting to serve the fruit industry in Massachusetts through research. Therefore, during the next several issues of FRUIT NOTES, we plan to have the leader of each project write a brief report that will state why the project was initiated and the major findings to date. The reports will appear under the heading of RESEARCH IN PROGRESS. I . Scion/rootstock and interstem effects on growth and fruiting of apple trees. William J. Lord New rootstocks and also virus-free clones of both rootstocks and varieties became available during the 1970's. A surge of interest also developed in interstem trees due to the high cost of providing support for trees on M9 , and an interest in high density plantings. Thus, our basic objective in this project is to evaluate tree size, yield, production efficiency and fruit quality of several varieties on various rootstocks and interstem/ rootstock combinations. Unfortunately, our oldest rootstock and interstem trials are only 5 years old, which is short when one considers the long life- span of apple trees. Nevertheless, our data and observations to date show that interstem trees, particularly with Empire as the variety, are more time consuming to train than are trees on more vigorous rootstocks such as M7 , It has been necessary to stake many interstem trees to support the leaders and to eliminate tree leaning. Suckering is profuse on interstem trees planted with the stem- piece/rootstock union 2 inches above ground level, whereas it can be minimized by deeper planting. The presence of burrknots on the M9 stempiece is readily apparent when the stempiece rootstock union of interstem trees is above ground. On many trees the burrknots are large and numerous and their presence has caused the stempiece to become twisted and distorted . In plantings established at the Horticultural Research Center in 1976, Empire trees on M9/MM111, M9/0ttawa 11, and M9/Antonovka are larger and have been more productive than Sturdeespur Delicious on similar interstem/rootstock combinations. Trees on M26, which in general are doing poorly in many commercial orchards, have per- formed well to date, Rogers Mcintosh has had higher production efficiency on M26 than on M7 or MM106. Rogers Mcintosh on M26, M7 or MM106 began fruiting in 1978 (in the 3rd leaf) whereas the first crop of Gardner Delicious on the same rootstocks was harvested in 1980. A planting of Empire on M26, M27, M9 , M9/MM106, M27/MM106, M9/^0^111 or M27/MM111 was established at the Atkins Orchards, Belchertown, MA in 1976. After 5 growing seasons differences in tree spread are still small, although the spread of trees on M9 and M27 is less than that of trees on M9/MM106, M27/MM106 and M26. 7. M27 is producing the smallest tree but has the highest produciton efficiency of the various rootstock and interstem combinations. A planting of Starkspur Supreme Delicious (Pagnelli strain) on M9, EMLA-'-g, EMLA27, EMLA7 , EMLA26, MAC^9, MAC24 , OAR^I, and Ottawa 3 was established in 1980 at the Horticultural Research Station. In 1981, a planting of Starkrimson Delicious (Bisbee) strain) on M27, C6/Antonovka , P2 Antonovka , and P22/Antonovka will be established. The effects of the rootstocks and interstem/rootstock com- binations on fruit maturation and quality in our plantings will be evaluated in the future. ********************* II . Effect of rootstocks and stempiece/rootstock combinations on the tree performance and fruit quality of Mcintosh and Delicious strains. F.W. Southwick In Spring, 1979, a randomized replicated Mcintosh rootstock trial was planted at the Horticultural Research Center. Both Rogers and Macspur strains are being tested on four rootstocks planted in rows 20 feet apart: M7A, M26, M9 , and M9/MM111. On M7A, Rogers and Macspur are planted 16 and 14 feet apart, respect- ively, in the row. On M26 and M9/MM111 they are planted 14 and 12 feet apart, respectively and on M9 they are planted 10 and 8 feet apart, respectively. All combinations are being trained as staked free-standing trees to a slender spindle system. In addi- tion, both Rogers and Macspur on M9 are also being trained as staked trees on a 4-wire trellis. Bisbee and Vance Delicious and Cortland serve as pollenizers. All blossoms were removed in 1979 and 1980. Training began in 1980, and cross-sectional areas of all trees were taken. In 1981 training and measurements will continue and fruiting may be allowed to begin. 1 EMLA(East-Malling and Long Ashton) : virus-free 2 Introduced by Michigan State University 3 Selected by Oregon Agricultural Experiment Station 8. In Spring, 1981, a similar randomized replicated Delicious rootstock trial will be planted. Both Gardner and Bisbee strains will be planted on M7A, M26, MMlll, M9/MM111, and M9/MM106 root- stocks. Gardner and Bisbee on M7A and MMlll will be planted 16 and 14 feet apart in the row, and they will be planted 14 and 12 feet apart, respectively, on M26, M9/MM111, and M9/MM106. All trees will be trained as staked free-standing trees to a slender spindle system. Rogers Mcintosh and Cortland will be the pollen- izers. Training and cross-sectional measurements will begin in 1981. As these plantings develop, it is intended that numerous eval uations will be made, including the following: a. annual yields per tree b. each tree's production efficiency c. tree survival d. prevalence of rootstock suckering e. nutritional status of each tree, and fruit susceptibility to bitter pit f. fruit maturation (firmness, red color develop- ment, watercore, etc.) g. postharvest storage life and susceptibility to physiological disorders following Ca and regular cold storage. ******************** III. Fruit variety evaluation at the Horticultural Research Center. James F. Anderson We are beginning a new phase in tree fruit evaluation at the Horticultural Research Center. This has been made possible by the removal of several of the original plantings made in 1964. Because of space limitations very few new varieties or selections were planted between 1965 and 1978. Most of the varieties and selections under test in these orig- inal plantings have been reported on at past meetings and in earlier reports. Two varieties that have not been reported earlier are Akana (TOHOKU #3) and Magnolia Gold. Akana looks promising for early September apple market and Magnolia Gold is an attractive, good quality Golden Delicious type apple, that has been completely russet free in our trials. Plantings of apple varieties in the past 2 years include a number of strains of Red Delicious, Mcintosh and Cortland. Addi- tional apple varieties will be set next spring. 9. The peach orchard set in 1980 has 15 peach and 6 nectarine varieties under evaluation. Five pear varieties have been added for evaluation in the past 2 years. Additional pear varieties will be set next spring. Small fruit varieties and selections are also evaluated at the Research Center. The emphasis has been on strawberry variety evaluation in recent years. This past summer, 9 numbered selections and about 10 varieties were evaluated. Scott a newly released var- iety from the U.S.D.A. was evaluated for 4 seasons and will be recommended for trial planting in Massachusetts. Several grape varieties that show promise are Alden, Lakemont and Steuben. ******* A ******:% A A*** IV. Adaptability of apple tree rootstocks to representative or- chard soils in Massachusetts. Peter L. Veneman Several new rootstocks have been introduced during the last few decades and claims pertaining to their adaptability to various environmental conditions sometimes have been contradicting and confusing. These claims as well as statements regarding the "old" rootstocks (M9, M7 , M26, MM106 and MMlll) often are not based on reliable field trials. Observations by pomologists and commercial fruit growers indicate that local differences in soil type pro- bably are largely responsible for variations in growth of apple trees on particular kinds of rootstocks. An evaluation of the effects of different environments on apple tree growth seemed justified and several studies were initiated to research this interaction. Following is a brief description of the various soil- rootstock research projects and a synopsis of this year's progress . Size-control rootstocks are, in general, more demanding than seedling rootstocks in respect to drainage, depth of soils and water holding capacity. When choosing which rootstock to use it is important to have a proper understanding of the particular rootstock-soil type interaction. The right match between rootstock and soil may be the difference between commercial success or fail- ure of the planting. A wide variety of different soil types is used in Massachusetts for growing apple trees. It is impossible to do an experimental planting on each different soil type but the most commonly used soils are closely related, which allows extra- polation of the results of a limited number of research sites to most Massachusetts and New England conditions. This project con- sists of two stages, one of which is concerned with the carefully monitored growth of selected rootstocks on 9 representative or- chard soils. The second stage involves the evaluation of the growth of the different size controlled rootstocks as related to 10. type of soil in a large number o£ orchards throughout Massa- chusetts . Ten research sites have been selected, each site being representative for a certain type of soil. The following soil series were chosen on the basis of importance for the New England fruit industry: Charlton, Colrain (2 sites), Paxton, Shelburne, Wethersf ield , Woodbridge, Ridgebury, and Cabot. The first two soil series do not have a hardpan and are well drained. The other soils have a hardpan within 3 ft. depth and are increasingly wetter; Paxton, Shelburne, and Wethersfield being well drained and Ridgebury and Cabot representing the poorly drained soils. The tree planting at each experimental site will consist of standard type 'Mcintosh' on either M7A, M26, M9/MM106, and M9/ MMlll rootstock. Spur 'Delicious' on M7A rootstock will be used as a pollinator. Each row will contain the four different root- stocks at random with the 'Delicious' in the middle. Spacing between trees in a row will be 14 ft. There will be 8 rows spaced 20 ft. apart. The planting will be established in the spring of 1982 . Most soils at the experimental sites have already been described, classified and sampled for physical and chemical laboratory analyses . During the second phase of this project a large number of orchards are visited. Production of selected rootstocks is ev- aluated, especially in relation to soil type. Rootstocks, in general, seem to grow and produce reasonably well on soils with a hardpan at depths greater than 20". This was substantiated by observations made in the fall of 1979 at the Horticultural Research Center in Belchertown. Trees planted in loamy soils with a hardpan within 20" did, in general, poorly or perished; while rootstocks in deeper, better drained soils did much better. During the dry 1980 season, M7 rootstocks were observed to suffer on shallow soils with a restrictive layer within 24" of the soil surface. Tree growth and especially anchorage was poor and several trees tipped over. Growth of MM106 on well drained Paxton soils (hardpan within 36") was judged excellent to good even during the dry 1980 summer. ******************** V. Effect of soil water and depth to hardpan on rootstocks. Peter L.M. Veneman More than 50% of the Massachusetts orchards are located on relatively shallow soils over bedrock or are at some depth under- lain by a hardpan. Both types of phenomena limit root penetration and ultimately restrict tree development. High seasonal or per- manent water tables may have the same detrimental effects on root- stock performance. This project is an attempt to accelerate the evaluation of the effects of soil moisture regime and depth of 11. growth restricting layers on the performance of apple trees on clonal rootstocks. This is accomplished by a newly developed testing procedure under controlled conditions in a greenhouse. The effect of a hardpan will be simulated by using growth containers with different heights. The bottoms of the containers will limit expansion of the root system and thus are limiting growth in the same fashion as actual hardpans. Massachusetts orchard soils often have growth restricting layers at 2-3 ft. and the growth containers in this trial are, therefore, either 2 or 3 ft. deep. The containers are equipped with a specially designed bottom which permits control of the soil moisture regime, Three moisture conditions are possible: dry, moist, or wet. Growth performance of each rootstock will be evaluated over a period of time until differences become evident. A greenhouse was erected in the fall of 1980 at the Horti- cultural Research Center in Belchertown. The necessary experi- mental equipment was assembled over the 1980 summer and the current set-up allows for the simultaneous evaluation of 8 differ- ent rootstocks. However, the greenhouse roof has yet to be installed because of adverse weather conditions, but it is hoped that an evaluation cycle can be started in January. That test- ing cycle will compare the growth of 'Mcintosh' apple trees on M7, M9, M26, MM106, MMlll and standard rootstocks. AAA******** AN UPDATE ON FRUIT TREES INJURED IN 1978-1979. William J. Lord Department of Plant and Soil Sciences Winter injury to fruit trees in 1978-1979 was predominantly damage to roots. The cause and factors influencing the injury, and symptoms of the injury were discussed in the JANUARY/ FEBRUARY 1980 issue of FRUIT NOTES. The majority of the weakened peach trees were removed during the summer of 1979, but not the apple trees. In late-summer we tagged individual limbs and whole apple trees at the Horticultural Research Center in Belchertown after rating the severity of winter injury. This was done to enable us to determine the degree of tree recovery in 1980. Lack of snow cover and relatively mild temperatures character- ized the winter of 1979-1980. No injured limbs or trees died dur- ing the winter. Bloom was heavy on many of the injured trees but fruit set was very light. Nevertheless, the fruits were removed chemically and by follow-up hand thinning. 12. Trees severely affected in 1979 showed no signs of recovery in 1980 and some died. Injury symptoms did not worsen on trees having only 1 or 2 affected limbs. However, the affected limbs produced little terminal growth in 1980. Our experiences with the winter injury of 1979-1980 lead us to conclude that damage to apple trees was most severe on poorly drained soils and that recovery from injury of severely injured trees may be slow. It appears that the best solution to the problem is tree removal. ********** ALTERNATE vs. EVERY MIDDLE SPRAYING FOR APPLE PESTS: 1980 RESULTS FOR ARTHROPOD PESTS AND 5-YEAR TRENDS W,M, Coli""-, G. Morin^, N.D. Goodhue^, M. Kuzontkoski"^ , T.A. Green^' M.R. Paul^, S. Marafino , and R.J. Prokopy Department of Entomology In previous issues of FRUIT NOTES, we have reported our findings on the relative effectiveness of alternate-middle vs. every middle spray programs for apple pests in 1976-1979 growing seasons. (See FRUIT NOTES 42(3), 43(3), 44(3), and 45(1). Here we present (a) our 1980 findings on alternate middle vs. every middle spraying for insects and mites, (b) a cost-benefit analysis with regard to insect and mite control in 1980 and (c) a summary of pest injuries and cost-benefit analysis for a multiple year period. Four test blocks in commercial orchards located in the major fruit-growing regions in Massachusetts were each divided into 2 plots of 2-6 acres. One plot received the alternate-middle pro- gram on each spray date throughout the season. The other received the every middle program. Each grower followed his normal spray schedule, using an air-blast sprayer and spray materials and con- centrations (Ix, 4x, etc.) of his own choosing. Except in one block, all trees were fully grown; some on M7 rootstock, others on seedling. Pruning was generally adequate to allow for good spray penetration into tree centers. 1 Pest Management Specialist 2 Senior Field Scouts 3 Field Scouts 4 Lab Technician, Entomology Department 5 Extension Entomologist 13. Monitoring of Pest Populations We monitored adult populations of tarnished plant bugs (TPB) , European apple sawflies (EAS) and apple maggot flies (AMF) using commercially available visual traps. In addition, pheromone (sex odor) traps were used to monitor redbanded leafroller (RBLR) , oblique-banded leafroller (OBLR) , codling moth (CM), San Jose scale (SJS) , tufted apple budmoth (TABM) and spotted tentiform leafminer (STLM) . Visual inspections of fruit and foliage in all portions of the tree canopy were used to monitor populations of plum curculio (PC), green apple aphids (GAA) . woolly apple aphids (WAA) and aphid predators and spotted tentiform leafminer (STLM) . Mites were monitored using leaf brushing techniques described previously . Sampling was weekly through petal fall and tri-weekly there- after. At harvest, an on-tree survey of 1200 fruit per treatment block was performed to determine injury levels to fruit. Insect Injury to Fruit at Harvest In 1980, total insect injury at harvest averaged 0.96% in alternate-middle blocks vs. 1.17% in every middle blocks. (Table 1) Table 1. Average percent of insect injury to fruit in 4 alternate- middle vs. every middle commercial orchard blocks in Massachusetts, 1980. Insect Every middle Alternate middle Tarnished plant bug 0.78 0.38 Plum curculio 0.25 0.15 San Jose Scale 0.00 0.20 Apple maggot fly 0.03 0.00 European apple sawfly 0.03 0.00 Green fruitworm 0.03 0.00 Codling moth 0.00 0.00 Leafrollers 0.05 0.08 Sooty mold 0.00 0.15 Other 0.00 0.00 Total % insect injury 1.17 0.96 % leaf terminals infested with apple aphids 10.2 5.5 Avg. number of mites/lf 2.0 0.7 In 1980, TPB was the most serious insect pest in both types of treatment blocks, although injury in each was substantially lower 14. than the statewide average percent TPB injury in IPM or Check blocks (1.44%). This variation in TPB injury probably relates simply to differences in pest pressure rather than any direct treatment effect. Injury to fruit from several of the major insect pests (PC, EAS, AMF, LR and GFW) was at acceptable levels, with no outstanding differences between treatment blocks (Table 1). However, SJS injury was higher in the alternate middle blocks in 1980, indicat- ing the need to thoroughly apply dilute rates of oil in an every middle treatment regime in 1981 to prevent further buildup of this pest . It is interesting to note that both the percent of leaves infested with aphids and the average number of plant- feeding mites per leaf were lower in alternate vs. every-middle blocks in spite of reductions in pesticide use in these blocks. Cost-Benefit Analysis In 1980, alternate-middle spraying resulted in a savings of $53.22 per acre for insecticide and miticide materials and $12.41 for application costs. In addition, fruit loss due to insect injury was $10.72 less per acre in alternate vs. every middle blocks (Table 2) . Table 2. Cost-benefit analysis of every middle vs. alternate middle treatments, 1980z. Dollor cost/acre Every middle Alternate middle Differences Avg. cost of insecticide and miticide materials $156.72 $103.50 -$53.22 Avg. application costs 32.22 19.82 - 12.41 Avg. value of fruit loss due to insect injury 61.36 50.64 - 10.72 Avg. net benefit from alternate-middle spraying for insects and mites +$76.35 - Based on suggested retail pesticide costs published by J. Williams, Regional Fruit Specialist: labor costs of $5.50 per hour, fuel costs of $2.20 per acre and average yields of 550 bu/acre. It is interesting to note that in 1980, alternate middle pro- gram costs were not exactly one half of those of every middle pro- gram costs. This is due to the fact that two growers applied oil 15. and miticide sprays on an every middle basis, which resulted in somewhat higher than expected material and application costs. ' Nevertheless growers utilizing alternate middle spraying realized an average net benefit of $76.35 per acre in 1980. Summary of 5-year trends in alternate vs. every middle blocks. Overall, during the period 1976-1980, average percent injury at harvest from insects was virtually identical in alternate vs. every middle treatment blocks (Table 3) . Table 3. Average percent of insect injury to fruit at harvest and percent infestation with aphids and mites in four alternate middle vs. every middle commercial orchard blocks, 1976-1980. Insect Every middle Alternate middle Tarnished plant bug 1.6 1.4 Plum curculio 0.2 0.1 San Jose scale 0.1 0.1 Apple maggot fly 0.1 0.1 European apple sawfly 0.2 0.2 Green fruitworm 0.1 0.1 Codling moth 0.1 0.0 Other 0.0 0. 1 Total percent insect injury 2.4 2.1 % leaves with aphids 7.8 8.6 % leaves with mites 8.8 (2.0)^ 11.2 (0.7)^ - 1980 data in ( ) = no. mites per leaf. Specifically, while it is evident that tarnished plant bug is the single most damaging pest in alternate and every middle blocks, all the major fruit damaging insect pests appear to be equally amenable to control using either alternate middle or every middle spray techniques. Table 3 also shows the average percent of leaves infested with aphids and mites in alternate vs. every middle blocks for the per- iod 1976-1980. During this period aphid populations were slightly higher in the alternate middle blocks. However, there was no sign- ificant fruit injury from aphid honeydew or sooty mold growth in either block, indicating that aphid infestations were below economic injury levels and would not justify the cost of additional spray applications (data not shown) . 16. Mite populations followed similar trends, with the exception that, in 1980, mite numbers (given in mites/lea£) were 65% lower in the alternate vs. every middle treatment blocks. Three year cost-benefit analysis While we are not able to perform cost benefit analyses on the 1976 and 1977 data owing to differences in sampling techniques and data collection methods, we believe that the composite of the 1978, 1979, and 1980 data indicates the potential benefits of alternate middle spraying over time. Table 4 indicates that for the latter 3 years, growers rea- lized a net benefit from alternate middle spraying of $41.40 to $85.38 per acre. Although it is difficult to make comparisons between years owing to variability in costs from year to year, alternate-middle spraying would appear to result in an average net benefit of about $67.00 per acre. Table 4. Cost benefit comparison of alternate vs. every middle spray treatments, 1978-1980^. Cost reduction/acre due to alternate-middle spraying 1978 1979 1980 Insecticide ^ Miti- cide spray materials -$29.61 -$48.05 -$53.22 Spray application costs - 8.87 - 14.22 - 12.41 Value of fruit loss due to insect injury - 2.92 - 23.11 - 10.72 Net benefit from alt. middle spraying +$41.40 +$85.38 +76.35 z Labor costs: 1978 - $3.50/hr; 1979 - $5.00/hr.; 1980 - $5.50/hr. Fuel costs: 1978 - $1.50/A; 1979 - $2.00/A; 1980 - $2.20/A Fruit value: Variable in each year based on current market quo- tations at harvest. Pesticide costs: Based on Coop. Extension Service suggested retail prices . _ The value of $67.00 average net benefit per acre compares to an average net benefit over the same period of about $105.00 per acre (exclusive of scouting costs) from the IPM scouting and grower 17. advisement program. Even allowing for scouting costs of $25.00 per acre (NY presently charges $17. 00/acre) , the IPM scouting and advisement program appears to yield a greater net benefit per acre than the alternate middle program. Perhaps the greatest po- tential rests in combining the IPM scouting and grower advisement program with the alternate middle program. We introduced this approach to orchard spraying on a limited basis in some of our IPM blocks in 1979 and 1980, with apparent success. We hope to continue on in this direction in 1981. Cooperative Extension Service U. S. Department of Agriculture University of Massachusetts Amherst, MA 01003 Official Business Penalty for Private Use, S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W, J. LORD AND W. J. BRAMLAGE Vol. 46 No. 2 SPRING ISSUE 1981 TABLE OF CONTENTS Nectarine Varieties Erratum in January.'February 1981 issue Root System Distribution of Highbush Blueberry Under a Sawdust Mulch Pomological Paragraph Considerations in Establishing Grower-Owned IPM Organinzations in Massachusetts Pomological Paragraph A Chemical Bird Repellent for Highbush Blueberries Research in Progress Fruit Research in Plant Pathology Control of Water Sprouts and Suckers with Tree-Hold" NECTARINE VARIETIES James F. Anderson Department of Plant and Soil Sciences There is an increasing interest in the production of necta- rines by Massachusetts growers who market their fruit through farm stores and pick-your-own operations. In the past the pro- duction of nectarines in this region \sias not very profitable. This was due in part, to the susceptibility of the fruit to brown rot and lack of fruit size. Breeding programs at Experi- ment Stations in Canada, New Hampshire, New Jersey, New York and Virginia and by the U.S.D.A. and several individuals have resulted in the introduction of many new varieties with improved size, flavor and hardiness. The development of improved pesti- cides and application equipment has allowed for better control of brown rot and the insects that contribute to its spread. We have had a very limited recent experience ivith nectarine varieties in our College orchards. We fruited Lexington, Cavalier, Nectaheart and Nectarose for 10 or more years at the Belchertoivrn facility, all performed satisfactorily but none of these are cur- rently offered by major nurseries. Nectarine varieties planted in our new orchard include Chero- kee, Harko, Stark Early Bird, Stark Crimson Gold, Stark Sweet Melody and 2 numbered selections, hopefully other varieties will be added this spring. As we have had no experience with the varieties currently offered, the comments that follow have been abstracted from several publications and nursery catalogs. This material is offered for informational purposes only and does not indicate a recommendation. The varieties are listed in order of ripening. Nectared 1: An introduction from the New Jersey Station. Intro- duced in 1962. Fruit is of medium size, oval in shape and is nearly completely covered with a dark red blush. The flesh is yellow, juicy, slightly coarse and moderately soft. The flavor is sweet and good. It is a clingstone. The flower buds are mod- erately hardy and it is productive. The New York Station considers this to be the best very early, yellow fleshed nectarine that they have tested. Ripens 12 to 14 days before Redhaven. Morton: Introduced by the New York Agricultural Experiment Station, Geneva in 1965. Fruit is attractive dark red but somewhat small in size. The fruit is white fleshed, juicy, slightly coarse and medium firm. The flavor of this semi-clingstone variety is very good. The tree is hardy and vigorous. Ripens about 5 days before Redhaven, Harko: Originated at Harrow, Canada. Introduced in 1974. Fruit is medium in size, roundish, with a solid red skin and a freestone. The flesh is yelloiv", medium in firmness with good texture and flavor. The trees are medium in size, spreading and productive. The trees are tolerant to bacterial spot and brown rot. Ripens 1 or 2 days after Redhaven. Independence: Originated in Fresno, California by the U.S.D.A. Introduced in 1965. Fruit is large, dark red over a yellow undercolor and slightly oval in shape. The flesh is yellow, firm, slightly coarse in texture and the flavor is good. The stone is free. Tree is vigor- ous, productive and about equal to Redhaven in bud hardiness. Ripens about 2 days after Redhaven. Hardired: Another 1974 introduction from Harrow. Fruit is of medium size vrith a brilliant almost solid red color. The flesh is yellow, medium- firm with good texture and flavor. The trees are vigorous, very hardy and very productive, requiring heavy thinning to maintain its medium fruit size. The trees are tolerant to bacterial spot and brown rot. Ripens 5 days after Redhaven. Flavortop: Originated in Fresno, California by the U.S.D.A. Intro- duced in 1969. Fruit is large, ovate mostly red and a freestone. The flesh is yellow, firm and smooth, the flavor is excellent. The tree is said to be vigorous and productive but tender to cold and sus- ceptible to bacterial spot. Ripens about a week after Redhaven. Mericrest: Nectared 4 An introduction from the New Hampshire Experiment Sta- tion. Fruit is medium in size, round v\rith a pronounced suture. The flesh is yellow, juicy and has excellent flavor. The trees are vigorous, highly productive and tolerant of bacterial spot and brown rot. Ripens 7 to 10 days after Redhaven. Fruit is medium in size, attractive with a dark red blush over a yellow undercolor. Flesh is yellow, med- ium firm and slightly fibrous in texture. The flavor is sweet and rich. A semi - freestone. The tree is moderately hardy and is productive, heavy thinning is required. Ripens 7 to 10 days after Redhaven. -4- ROOT SYSTEM DISTRIBUTION OF HIGHBUSH BLUEBERRY UNDER A SAWDUST MULCH R.E. Gough Department of Plant and Soil Sciences University of Rhode Island Kingston, RI Even though vegetative and reproductive growth of plants is very dependent on a functioning root system, relatively little attention has been given to root system development in fruit crops. This is certainly true of the highbush blueberry. Several studies show that the root system of mature plants is shallow and fibrous, but no one has studied its distribution in the soil. Therefore, in 1979, at the University of Rhode Island we undertook a study to determine the root distribution and general shape of the root system of young and mature bushes of cultivated highbush blue- berries. Six 13-year-old Coville and five 7-year-old Lateblue bushes were growing on a Bridgehampton fine sandy loam soil at a pH of 4.8. Bushes were spaced 6 feet x 10 feet and the entire area within and betxveen rows was maintained under at least 6 inches of sawdust mulch for the entire life of the bushes. The sawdust was a mixture of hardwood and softwood and was approximately 1-year- old prior to annual application. The water table was at least 5 feet below the soil surface. Bushes generally were not irrigated. Each bush received an annual application of 2 pounds of 5-10-10 fertilizer. Core samples containing roots were taken at different locations around each bush and a trench was excavated completely beneath the center and half way around 1 bush to determine the extent of vertical root penetration and the regularity and the relative density with which roots radiated from the crown. The dripline of all bushes was located approximately 2 feet from the crown. In all cases, the bush crown, considered to be that area from which new canes arose, was about 16 inches in dia- meter. Findings The root systems were primarly composed of fine, fibrous roots less than 0.1 inch in diameter. They were shalloiv and formed an inverted cone of from 11 to 33.5 cubic feet in volume. Roots tended to be primarily oriented parallel to the soil surface with very few noticeable vertical roots. In no case were roots found in the unde- composed layer of mulch. Fine, fibrous roots, intermingled with larger roots, first appeared in the upper layers of partially decomposed mulch. Stark SunGlo: Originated in LeGrand, California by F.W, Ander- son. Introduced in 1962. Fruit is large, symmetri- cal, globose with a yellow skin partly overspread with red. Flesh is yellow with some red around the pit, firm and the flavor is good. This freestone variety ripens evenly and has good keeping and ship- ping quality. The tree is large to medium, moderately vigorous and productive. Ripens 10 to 14 days after Redhaven. Fantasia: Originated in Fresno, California by the U.S.D.A. Introduced in 1969. Fruit is large, ovate, bright red with a yellow undercolor and a freestone. The flesh is yellow, firm, smooth and has good flavor. The trees are productive but susceptible to bacterial spot. Ripens about 2 weeks after Redhaven. Nectared 5: Fruit is of medium size, 75% to full red over yellow. Flesh is yellox\', slightly soft, juicy sweet and good in flavor. This freestone variety is vigorous, hardy and productive. Ripens 16 to 19 days after Redhaven. Nectacrest: Originated at the New Jersey Agricultural Experiment Station, New Brunswick. Introduced in 1947. Fruit is large, white fleshed and freestone. The flesh is fairly firm and has a fine nectarine flavor. The tree is vigorous and hardy. Ripens about 20 days after Redhaven. Stark Red Gold: Originated in LeGrand, California by F.W. Anderson. Introduced in 1962. Fruit is medium to large in size, skin is yellow overlaid with red. Flesh is yellow with red around the pit, firm and the flavor is very good. The tree is fair in hardiness, productive and is susceptible to bacterial spot and mildew. Ripens 4 weeks after Redhaven. There are other varieties that may be equal to or better than the above. ERRi\TUM IN JANUARY /FEBRUARY, 1981 ISSUE An error should be corrected on page 8 of the January/February 1981 issue of FRUIT NOTES. In the article entitled "FRUIT VARIETY EVALUATION AT THE HORTICULTURAL RESEARCH CENTER, James Anderson mentioned the apple variety Akana. The correct spelling of this variety is Akane. -5- The root system of 13-year-old 'Coville' plants extended in measurable amounts up to 4 feet firom the perimeter of the crown, and a few roots were noted regularly at distances of up to 6 feet. Roots were recorded at depths of 32 inches on most bushes. Overall, approximately 50^6 of the root system was located within 1 foot of the crown, while 84^ of the root system occurred within 2 feet of the crown, which was approximately the dripline of the bushes. The root system of a typical 7-year-old 'Lateblue' plant is usually located iv'ithin less than 2 feet from the crown perimeter. In only 1 instance were roots detected at a 2 foot distance and these were within 11 inches of the soil surface and comprised only 0.311 of the total root dry weight for that bush. Roots v\'ere occasionally found at depths of 32 inches within the first 1 foot from the crown perimeter. However, most or all of the root system (88-100%) of individual plants was located in the upper 14 inches of soil. Virtually 1001 of the root system of these plants was located within the dripline. Discussion Ihe shallo^^.' root system may be in part responsible for the blueberry's ability to survive in swampy locations. However, the general depth of the mature system coincides with those reported for other crops such as apple, peach, cherry, grape and olive. Depths can be expected to vary, however, depending upon soil type and aeration. For example, apple roots have been reported to penetrate to depths in excess of 32 feet in a well-aerated Nebraska soil, while the roots of similar trees growing in deep loam soils in California were found to penetrate to only half that depth. Presumably, the root system of the blueberry can also vary greatly as soil conditions are changed. Use of mulches certainly modified blueberry root distribution. Our finding of an absence of blueberry roots in the upper layers of mulch is similar to a report on apple root distribution. In a study of the effects of various m.ulches and fertilizers on yield and sur- vival of blueberry plants, Kramer et. al , in Maryland found remark- able differences in root distribution under peat mulch as compared to no mulch. They reported that the roots of 2-year-old 'Pioneer' and 'Concord' plants spread approximately 35 inches from the main stem but were limited totally to the upper 3 inches of mulch, while those of the control plant spread only 12 inches but penetrated to a depth of 9 inches. They reported similar but less dramatic results with other mulches, including pine needles, oak leaves, and straw. This experiment indicates that the cultivated highbush blue- berry plant posseses a shallow, fibrous root system that is primarily distributed within the area between the crown and the dripline of the bush. Fertilizer should therefore be placed beneath the dripline of the bush and cultivation, if practiced at all, must be very shallow in this area. -6- POMOLOGICAL PAMGRi\PH Insect larvae entering burrknots. Low light intensity at tree trunk level, caused by shading from the ground cover, low limbs and/or plastic mouse guards, favors the enlargement of the root initials on the M9 stempiece of interstem trees or on M26 rootstock. The clusters of root initials, called burrknots, are serving as entrance sites for insect larvae especially apple bark beetle larvae (apple bark beetles are close relatives of the peach tree borer) . Damage from these tree borers is occurring in Massachusetts and other fruit growing areas in Eastern United States. The use of mouse guards made from hardware cloth and deeper planting of interstem trees (setting the variety/M9 stempiece union 3 inches above ground at planting) should reduce burrknot formation and permit better spray coverage. 9! ft -H f! it * it 9: 9; it CONSIDERATIONS IN ESTABLISHING G ROW I: R- OWNED I PM ORGANIZATIONS IN MASSACHUSETTS William M. Coli Pest Management Specialist Entomology Department University of Massachusetts In November, 1980, Dr. David Ferro, Extension Vegetable Ent- omologist and I participated in the third annual National Exten- sion Workshop on organizing grower-owned 1PM organizations held at Kansas City, Missouri. Our purpose in attending this meeting was to familiarize ourselves with current model IPM organizations in other states. This ivould enable us to present Massachusetts growers with the numerous alternatives to implement IPM programs in the absence of federal government funding. At this writing, apple growers are the sole commodity group in Massachusetts participating in an IPM program. This program, sponsored by the Cooperative Extension Service, and funded by a 5 year USDA grant has resulted in increased interest in IPM. Growers have asked for aid in deciding how to continue to implement IPM when Federal funding ends in September, 1982. Thus the intent of this article is to present a discussion of a broad range of potential considerations and options available so that Massachusetts growers may decide which means of implementing IPM are best for their unique conditions. \i}\y IPM? Integrated Pest Management pilot programs are presently operating in nearly every state in the union in crops as diverse as fruit, cotton, soybeans, and alfalfa. Workshop participants agreed that there are important short and long-term benefits from IPM and that likely candidates for IPM are progressive farmers, farmers using a multi-spray, calendar-based spray schedule, and crops which have high pest control costs. -7- Who Should Perform IPM Scouting? If growers are to have peace of mind regarding pest pressures on their orchards, and if pesticide costs (especially for insecticides and miticides) are to be reduced, some form of field scouting is needed. This scouting may be per- formed by the grower, by a staff person, or by someone other than the grower or staff member. It was the general opinion of workshop speakers that scouting is probably best not left with growers since they are frequently busy with other management decisions. Some capable staff person would be acceptable provided they are free to scout when necessary rather than as other orchard jobs permit. Massachusetts IPM, with the institution of our "grower scout" training appears to be unique in this regard, as the majority of our "grower scouts" made observations with our field teams on a weekly (sometimes more often) basis. Several "grower scouts" scouted additional acreage in their orchards as well as indicated their interest in continuing the scouting procedures after IPM pilot program funds ended in September, 1982. However, most speakers at Kansas City agreed that some outside person, whose only respon- sibilities were scouting, is more likely to have the time and inter- est for training in pest identification, control measures (including alternatives) and economic threshold levels. What is Cooperative Extension's Role in IPM? Conference partici- pants generally stressed that Cooperative Extension's role in IPM is threefold. One important area is the implementation of research programs related to IPM, including an in depth look at pest bio- logies and life histories, development of effective monitoring techniques and the establishment of appropriate economic thres- hold levels (ETL) . A second role consists of creation and operation of effective commodity-based pilot programs to develop necessary base-line data and demonstrate, if possible, the potential environmental and econ- omic benefits that accrue to participating growers. Lastly, there was unanimous agreement that Extension should continue after pilot program funding ends to play a role with regard to education of growers, updating monitoring methods and ETL's, as well as training and supervision of field scouts. It would appear that the Extension Service is best equipped to utilize high technology (computers, weather forecasting networks, etc.) for information gathering and dispersal, to carry out needed research, and to coordinate an interdisciplinary approach to pest management once pilot programs have run their course. Several states offer scout training courses (up to 80 hrs. in some cases) through their Extension Service. Many have an exam -8- (open book in some cases) leading to state certification of field scouts, since some form of quality control is deemed desirable to prevent farmers from hiring minimally qualified scouts. Possible Alternative Forms of IPM Organizations After Pilot Program Funding Ends . ^ 1- IPM ceases to be implemented on any significant scale. Workshop participants uniformly believed that this is not likely to happen so long as growers realize potential advantages of IPM and so long as viable alternatives exist. 2. Some private commercial entity takes over. Such entities can be in the form of independent scouts making no recommendations, or private consultants who make recommendations (and perhaps serve as a supervisor of scouts hired by a group of growers for a large number of growers). If not enough qualified consultants or scouts are available to accomodate interested growers, pro- blems will ultimately result and IPM might fail. 3. Creation of a grower-owned entity [Cooperative). Where a cooper- ative is already in existence and providing services, there is the option to add 1PM services. It is important to keep sales of pesticides separate from IPM services in order to maintain credibility with growers and reduce potential for conflict-of- interest . Growers may choose to form a cooperative (one member-one vote, limited return to capital, and division of earning? in propor- tion to usage) independent of already existing supply or market- ing cooperative in order to provide IPM services, completely removed from pesticide sales. Such a cooperative could provide only IPM scouting, scouting plus purchasing supplies and/or services, or full agronomic services. A cooperative providing only IPM services, hoivever, will have problems due to the sea- sonal nature of the work, so the best option here is perliaps to offer other services (leaf 5 soil analysis for example). 4 . Creation of a non-profit grower-o^vned association (incorporated or unincorporated). Such an entity attempts to make no income over expenses. This type of organization typically supplies scouting services only, with no pesticide sales or application services and can serve as a data collecting agency for the Extension Service, receiving technical, educational and quality- control service in return. Once growers have the scouting in- formation, they can either make their own decision, ask the advice of a private consultant or ask the Extension Service. Alternatively, a non-profit groxver-owned organization can hire a scout supervisor who maintains extension liason, and makes recommendations to participating growers. -O. Alternatives in program scope and organization. Three principal topics were discussed. 1. Alternative geographic scopes : That is, should IPM programs be organized (a) on an individual grower basis with each con- tracting for IPM services independently, (b) on a county (or multi-county) basis, or (c) under a state wide umbrella. 2. Alternative program scopes: A first consideration is to decide whether to organize so as to cover single or multiple crops (e.g. vegetables, apples, or both, etc.) 3. Alternative services: Once program scope has been decided upon, it next remains to be decided whether to offer (a) scouting services only (this has minimal risks and minimal supervisory costs but requires a close alliance with the Extension Service for training and interpretation of scouting reports, (b) scout- ing plus other IPM services (spray material purchase, contracts with aerial applicators, predator releases, etc.) or (c) IPM services plus non-IPM services (soil testing, leaf analysis, etc.) . These latter two options typically require a full-time manager, substantial capitalization and some form of democratic organ- izational structure. Liability considerations. Conference participants agreed that tliis area was potentially one of the largest stumbling blocks to provid- ing IPM services after Extension-run pilot programs ended. Several aspects of this problem must be considered. 1. Protecting individual growers from liability (as in the case of an independent scout injured during orchard scouting). 2. Protecting scouts or private consultants from suits resulting from improper scouting or incorrect recommendations. 3. In the case of grower oxvned organizations (cooperative or non profit entity) , protecting this entity from suits brought by individual participating growers. There are numerous options in this area such as whether to limit liability by incorporation, best decided with advice of legal counsel when setting up IPM organizations. Scouts (or private consultants) can for example, be hired utilizing a service contract which specifies the job requirements. This contract would also specify that growers will not sue under any circumstances, whether by negligence or im- proper recommendations. Individual growers (or grower organizations) can then carry scouts or consultants under farm liability and work- men's compensation insurance. -10- Alternatively , individual scouts or consultants could purchase Errors and Omission insurance through private vendors. The diffi- culty here is that costs are so high, independents would probably find it impossible to carry adequate insurance and still make any money. It is apparent that there are numerous legal considerations and optional organizational forms for growers interested in implementing IPM practices on their farms. National Workshop participants con- tinually stressed the need for careful planning of IPM organizations utilizing skilled legal counsel, well in advance of anticipated need. ********** POMOLOGICAL PAR.'\GRAPH The Spread of San Jose Scale Revived Interest in Dwarf Apple Trees in the Late 1800's. The influx of San Jose scale in Massachusetts this past season brought to mind the fact that the rapid spread of this insect in New York State during the late 1800's was respon- sible for one of the periodic revivals of interest in dwarf apple trees. At that tim.e it was expected that San Jose scale would eventually spread throughout the fruit growing areas of the state and that the spread probably could be controlled only by fumigating trees under tents. Since it was thought that fum.igation of dwarf trees might be feasible, fruit growers asked the New York State Agricultural Experiment Station to determine if dwarf apple trees could be grown profitably in commercial orchards. U.P. Hedrick of the New York Agricultural Experiment Station said in 1915, "Had it not been for this apprehension of grievous disaster from San Jose scale it is doubtful if the fruit growers would have called for the investigation, or the Station have voluntarily undertaken it". Fortunately for commercial apple production but unfortunately for continued interest in dwarf trees, lime-sulfur and oil, which were introduced between 1907 and 1910, proved effective for the control of San Jose scale. Development of dwarf trees therefore had to wait until another crises threatened the industry many years later. ********** A CHEMICAL BIRD REPELLENT FOR HIGHBUSH BLUEBERRIES F. W. Southwick Department of Plant and Soil Sciences It is virtually impossible to produce a crop of highbush blue- berries in the Northeast without providing protection from birds. Consequently, successful producers of this crop have been forced to completely enclose plantings with netting to insure the harvest -11- of a major portion of the crop. Trapping, scare devices, noisemakers , distress calls of birds, electronic sounds, etc. are usually ineffect- ive or so objectionable that their use is impractical or prohibited. The use of netting is very satisfactory but its cost is excessive. The carbamate material methiocarb (Mesurol) originated as an insecticide by Farbenfabricken Bayer A.G. of Leverkusen, Germany. Since the early 1970's investigators associated with the U.S. Fish and Wildlife Service, have studied the bird repellent potential of this chemical sprayed on sprouting seeds, grain, cherries, grapes and blueberries, and in some cases these tests have been successful. At the present time methiocarb has been approved for use as a bird repellent on cherries, and in some states it has a "special needs" registration for use on blueberries. Since we were aware of the potential value of this bird repell- ent for highbush blueberries but lacked data comparing its effective- ness with protective netting, an experiment was conducted in 1980 at the Horticultural Research Center, Belchertown, MA., within a 100' X 150' area that contained about 40 varieties or numbered selections. Each variety or selection was in a plot consisting of 4 or 5 plants. Prior to treatment in early July, 16 plots were selected for uniform- ity of growth and yield potential , and then 4 plots were randomly selected for each treatment. Each plot represents a different variety or selection and, there- fore, time of fruiting ripening and harvesting ^^as variable, Neverthe less, the results show that methiocarb is an excellent bird repellent (Table 1). Table 1. The influence of bird repellents on highbush blueberry yields, 1980^. Treatments Dates applied Average plant yields (lbs.) J All for each replication^ r ep 1 i - I n ITI TV cations Check (uncovered) 11.94 0.42' 8,99 10,15 7.88 Methiocarb 7/11,7/31,7/27 15.16 7.00 12.02 23.63 13.95 1#/100 gals H2O Methiocarb 7/11,7/31,8/27 16.13 18.14 8.73 12,80 13.95 2V100 gals H2O Net covered 7/3 18.56 10.64 11.35 16.22 14.19 ^The harvesting period was from 7/22 to 9/8. ^Each randomized replication was a plot of 4 or 5 plants. Each plot contained a different variety. Check plot in replicate II ripened 7 to 10 days earlier than all the other plots and the crop was largely consumed by birds prior to the initial methiocarb applications. -12- The yield data show that 2 lbs. of 50% WP per 100 gallons of H^O applied 3 times at about 3 week intervals was as effective as the 4 lb. rate and as suitable as netting from July 3 to September 8, It also appears that yield of some of the check plots (replicate I, II and IV) which were adjacent to one or more sprayed plots was not greatly reduced by birds. This suggests that the presence of some treated plots in a field may tend to repel birds from unsrayed plants in the area. The poor yield (0.42 lbs. per plant) of the Replicate II check plot was related to its extreme earliness in ripening. This selection was fully ripe 7 to 10 days before the other plots and prior to the first methiocarb application on July II. Consequently, birds had an opportunity to devour the crop from this selection before coming in contact with methiocarb on any of the chemically treated plots. This chance situation provides addi- tional evidence of the effectiveness of methiocarb as a bird-repell- ent for highbush blueberries. Present recommendations of 2 to 3 lbs. of actual methiocarb per acre are suggested per application where clearance for use of this material has been obtained. A tolerance of 2S ppm on harvested fruit is allowable and a preharvest interval of 7 days will insure no harmful residues. No more than 3 applications per season are allowed. The effect of methiocarb on birds is reported to be temporary. Ingestion of small quantities of fruit treated x^'ith methiocarb is claimed to cause birds to become excited, slightly disoriented and unable to continue feeding. Affected birds give off distress calls and/or react in an agitated manner ichich conveys a warning signal to other birds. In a 1973 Fish and Wildlife Service study, blue- berries treated with 1 lb. actual methiocarb per 100 gallons of water were fed to robin, starling and grackle nestlings of differ- ent ages. Nestlings fed from 3 to 10 treated berries at one feeding survived without any incidence of ill effects. The data from this study indicate that feeding nestlings fruit treated with methiocarb at recommended bird repellent levels should not influence their long-term survival. RESEARCH IN PROGRESS Fruit Research in Plant Pathology William J. Manning University of Massachusetts, Amherst 1. Etiology of the Apple Replant Problem Apple replant is a problem of unknown origin tiiat can affect the growth and development of new apple trees in old orchards and . sometimes on newly-cleared sites. Some trees decline and die in the first season. Others survive, with varying degrees of stunt- ing and uneven growth. -13- We have investigated a number of instances of the apple replant problem in Massachusetts. At the present time we are determining which potential pathogens are involved and planning greenhouse work \\?ith rootstocks and seedlings to determine pathogenicity. Future work will involve screening major root- stocks and rootstock/scion combinations for reaction to the agent(s) of the replant problem. 2. Biomonitoring of Fungicide Residues on Apple Leaves As part of the Integrated Pest Management Program, we have been developing in the laboratory a method for determining bio- logically-active fungicide residues on apple leaves. This is done by plating leaf discs on agar plates seeded with spores of Gloeosporium or Saccharomyces . Zones of spore germination inhibition indicate the relative concentrations of biologically- active fungicide residues on the leaves. This information can be used to predict fungicide spray timing. Limited field results were obtained last year and more extensive data will be obtained from field tests this year. 3. Disease Resistant Fruit Trees Apple cultivars that are immune to scab, and varying in their resistance to powdery mildew, rust and fireblight, have been planted at the Horticultural Research Center in Belchertown. These include 4 trees each of: NY613452, Liberty, Priscilla, Sir Prize, Mac Free, Nova Easygro and Prima. Imperial Mcintosh trees are used as disease-susceptible comparison trees. Pear Cultivars that are resistant or tolerant to fireblight have also been planted. Four trees each of HW602, HW603, and Highland have been planted. Bartlett trees are used for compari- son. We plan to evaluate these trees under our conditions and to begin looking at possible differences in leaf surface microflora between resistant and susceptible trees, as a prelude to biolog- ical management of apple scab and other diseases. 4. New Disease Investigations Block A new block has been established to do research on integrated chemical and biological management of apple diseases: 15 trees each of Cortland, Empire, Roger's Mcintosh, Double Red Delicious, and Yellow Delicious were planted in 1978 for a total of 75 trees. Trees are in randomized units of three, \\'ith 5 replications. -14- CONTROL OF WATER SPROUTS AND SUCKERS WITH TREE-HOLD* William J. Lord and Joseph Sincuk Department of Plant and Soil Sciences Water sprouts, which generally are removed to maintain tree form and prevent shading, are particularly troublesome on standard- type Delicious and follo\Nring heavy pruning. Unfortunately, their removal becomes more time consuming in succeeding seasons' because of the proliferation from the stubs created by pruning. Sucker groKth from the trunks and roots of mature seedling trees and in plantings of M.7, M.7A and interstem trees is a serious problem in Massachusetts. Suckers are costly to remove, increase in number annually, provide mouse cover, and are a haven for insects and diseases. Recently, Union Carbide Agricultural Products Company received a Federal conditional registration for TRE-HOLD Sprout Inhibitor A112 for control of sprout growth on bearing apples, pears and olives and on ornamental olives, pears and crabapples. TRE-HOLD Sprout Inhibitor A112 contains 13.2% 1-Naphthalene- acetic acid equivalent, as the ethylester. This formulation must be diluted before use, with either water or white interior latex paint. Tree-Hold diluted in a combination of water and water-base, interior-grade, white latex paint has given good control of water sprouts at our Horticultural Research Station in Belchertown and in grower orchards. However, the results with our trials using Tree- Hold to control suckers under mature Cortland and Early Mcintosh trees on .M7 rootstocks have been disappointing. Tree-Flold was applied under the trees on June 19, 1978, June 8, 1979 and June 4, 1980. Sucker counts have not been made this spring but counts made in the spring of 1980 indicated that the spray applied in 1978 and again in 1979 failed to reduce the number of suckers. The failure of Tree- Hold to effectively control the suckers is indeed a disappointment and we believe further trials are needed. Perhaps the Tree-Hold should have been applied earlier when the suckers were smaller. Or perhaps Tree-Hold is more effective for sucker control under younger trees than with which we have been working. We certainly hope that growers will conduct some trials with Tree-Hold for sucker control because grower experiences will add to the information currently being obtained. Mixing for Water Sprout and Sucker Control For the control of water sprouts use 10 fluid ounces (2/3 pt) of Tree-Hold and make up to a volume of 1 gallon with a combination of water and interior- grade latexpaint. The latex paint "marks" the treated areas and makes the mixture more viscous, thus restricting the IIAA to the treated area. It has been our experience that at least 4 pints of latex paint should be used in each gallon of treating solution. Be sure to use an interior-grade latex paint and one that does not contain a mildcwcide. Trade Name -15- For spraying suckers on a trial basis, mix 10 fluid ounces of Tree-Hold with sufficient water to make 1 gallon of spray mixture. Eight gallons of Tree-Hold are required for 100 gallons of spray. Control of Water Sprouts Prune water sprouts and then apply Tree- Hold mixture thoroughly over the cut surfaces. It can be applied ivith a paint brush or a small compressed air sprayer. We found that a 1-1/2 gallon compressed air sprayer with a 12-foot hose worked well, and that attaching a sponge to the nozzle was useful for swabbing the mixture on pruning cuts. The treatment can be applied anytime weather permits before growth starts in the spring. Areas where pruning cuts have been made should be covered thoroughly but drip on to other parts of the tree should be avoided. The Tree- Hold mixture can kill buds. Be sure to follow the label. Control of Suckers Prune the suckers during the dormant season. The Tree-Hold mixture can be sprayed on the stubs during the dormant sea- son or when the new shoots from the suckers are 6 tol2 inches in height. However, the most effective timing is when the suckers are actively growing. Since the Tree-Hold mixture contains 10,000 NAA, the label restricts its use from bud swell through 4 weeks after petal fall to eliminate the possibility of fruit thinning and leaf damage. Therefore, the Tree-Hold mixture should be sprayed the 3rd or 4th week in June when the suckers are 6 to 12 inches in height. Coverage should be thorough. The Tree-Hold mixture is too expensive to apply as a band appli- cation under the trees. Since the population of suckers is generally more dense near the trunk and very troublesome inside wire mouse guards, the spray may be limited to these areas using a compressed air sprayer, a weed sprayer with an air gun, or a weed sprayer and boom with a trunk-directed nozzle. Cooperative Extension Service U. S. D«f>ar^m^iil ai AgriCitHm^ University of Massachusetts Amherst, MA 01 003 Official Business Penalty for Private Use. S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGaiCULTURE (AGR 101) BULK THIRD CLASS MAIL PERMH FRUITpr NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 46 No. 3 SUMMER ISSUE 1981 TABLE OF CONTENTS U.S. Apple Exports Mark 'Coming of Age' as Volume Registers 41 -year High Laboratory Repellency of Orchard Pesticides to the Mite Predator Awblyseius Fallacis Summary of Apple Growing Questionnaire Grade Defects of Mcintosh Apples: Strip vs. Selective Pickings ♦ U.S. APPLE EXPORTS MARK •COMING OF AGE' , AS VOLUME REGISTERS 41-YEAR HIGH Gilbert E. Sindelar Director of Horticultural and Tropical Products Division, FAS. It was the year of the American apple in Taiwan as sales there led a world-wide surge in U.S. exports, with the 1979/80 volume hitting the highest level in 41 years. Taiwan became the leading foreign market for U.S. apples, taking the top spot long held by Canada. Outlook for the 1980/81 season points to another banner year . The 1979/80 season was the third straight strong showing for U.S. exports and marks a "coming of age" for U.S. apples in foreign markets . Today, apple exports are beginning to be a factor in the market- ing equation, with one out of 10 cartons for the fresh market moving into export. Thirty years ago, when controlled atmosphere storage was in its infancy, apple export markets were virtually nonexistant- except for Canada. The importance of export markets for U.S. apple producers has been aptly demonstrated the past three seasons. Both 1977 and 1978 were excellent export years, with 7.9 million cartons (42 lbs. each) moving abroad in 1977 and 7.5 million in 1978. But the 1979 season- that ended on June 30, 1980-was even better as the equivalent of 12.4 million cartons of U.S. apples moved into export, with impress- ive gains in all major markets being topped off by the tremendous success in Taiwan. The 1979/80 volume to all destinations was the largest since the 1938 season when 13.8 million cartons were exported The final tally of the 1979/80 season revealed a gain of almost 5 million cartons-or 65 percent-over the very good showing of the preceding season. Exports earnings totaled $125 million versus $67 million in 1978/79 as the derived unit value of export sales averaged $10.06 per equivalent carton, compared with $8.87 the season earlier. As the 1980/81 export season begins to shift into high gear, it is still difficult to project export totals, especially for the two leading markets of Canada and Taiwan, because of the volatility of the marketplace. Although early estimates indicate a dropoff in these two markets, gains elsewhere are expected to nearly offset these losses. As a result, U.S. apple exports in the 1980/81 market- ing year are forecast at 12.3 million cartons, just under last year's 1 Reprinted from February, 1981 issue of Foreign Agriculture level. However, because of the higher- than-expected U.S. crop this season, particularly in the Pacific Northwest, exports could exceed this projection. Recently, USDA estimated total U.S. sales of fresh apples- domestic and export-at 102,4 million units (42 lb) in 1979/80. Exports alone represented 12.1 percent of these-a sharp contrast to the early 1970 's when exports amounted to less than 3 percent of the total U.S. marketings of fresh apples. Export gains this past season were widespread, with advances of 19 percent in Western Europe, 48 percent in Central America, 35 percent in both South America and the Caribbean, and 12 per- cent in the Middle East. In the Far East, U.S. apple exports to Hong Kong, a key market of long standing, rose 7 percent while those to Singapore, another market of growing importance, expanded 61 percent. Further brightening the picture as the all-time high of 3.2 million cartons to Canada-an increase of 600,000 from the year earlier. While these gains were remarkable, they were overshadowed by the sensational performance in Taiwan. On August 1, 1979 Taiwan liberalized its import policy for apples. U.S. exporters, mostly in the Pacific Northwest, responded quickly, moving 3.4 million cartons to Taiwan. Value of these sales totaled $41.6 million or $12.26 per equivalent 42-pound carton. In the preceding five seasons, U.S. apple exports to this market averaged a mere 134,000 cartons . A sizable increase was expected following Taiwan's decision to liberalize its import policy, but the final U.S. export volume exceeded expectations. Prior to liberalization, Taiwan's limited import volume drew fantastically high retail prices-sometimes as much as U.S. $1.75 or U.S. $2 per apple. With liberalization, many importers sensed an opportunity for large profits. As a result, many newcomers entered the importing business . In addition, some established importers of hard goods with no experience in handling perishables got into the market. The result: skyrocketing imports. Can the U.S. export performance in Taiwan be repeated in the 1980/81 season? This is perhaps the major factor in projecting the quantity of U.S. apple exports for 1980/81. A region-by- region survey follows. Far East The big export question is this area centers on Taiwan. Because of the market turbulence last season, those traders who experienced unprofitable ventures are likely to drop by the wayside this season. As a result, a degree of stability should return to the market, and shipments of U.S. apples should take a more orderly flow. While the 1980/81 projection remains conditional at this point, U.S. apple exports to Taiwan should be down from 3.4 million cartons in 1979/80. Other markets in the Far East and the Pacific should show a slight gain from the 1.6 million cartons in 1979/80. Canada The large increase in the export volume to Canada last season still defies pinpoint measurement. Costs may have had a bearing on the record flow of U.S. apples to our northern neighbor, but the most plausible reason probably rests on the fact that Canada's per capita consumption of fresh produce is rising rapidly. The so-called "fresh approach" seems to be catching fire there as in many other countries around the world. But the export projection for U.S. apples to Canada this season is guided only by the distribution of the Canadian crop. In view of the anticipated crop increases in Ontario and to a lesser extent in Quebec, movement of U.S. apples will probably be somewhat less than last season's. Western Europe The apple crop in this area is down very slightly to 13.4 million metric tons in 1980/81, with most of the drop occur- ing in the southern European countries, especially Spain and Greece. The combined crops in the three key exporting countries-France, Italy, and the Netherlands-are almost on par with last year's pro- duction of 4.3 million tons. Turning to the key market countries, apple production in the United Kingdom is expected to be about 358,000 tons, about 1 percent below the 1979/80 outturn. Market prices in the United Kingdom were exceptionally low this past season. As a result, the National Farmers' Union has been waging a vigorous campaign, claiming that the very survival of the English apple is at stake. Charges of unfair competition against French goldens have been denied in France. In 1980/81, U.K. growers hope the low prices of last season will not be repeated because of an agreement with French exporters to limit shipments of French goldens to only the higher grades, with bulk shipments excluded. In 1979/80, French apples represented a staggering 87 percent of the total U.K. imports during the v/inter months. In Norway, the apple crop this season is expected to top last season's total, so the opening of the import market was delayed. However, importers remain confident that the import level will remain high-possibly around 200,000 cartons. A small plus for U.S. apples lies in Sweden where the commercial crop is estimated at 33 percent below last season's output. In total, U.S. shipments of apples to Western Europe are expected to be the same as the 1.1 million cartons moved in 1979/80, with the major markets being Sweden, Norway, Finland, and the United Kingdom. Mexico and Central America Mexico's crop loss from a severe frost last spring has been estimated at 20-25 percent by Conafrut, a national fruit organization. Although increased imports may result from this shortfall, Government efforts to provide relief to growers through higher prices could mean a lower- than-expected import level. How much goes across the border is the most important factor in projecting U.S. apple exports to this region. Though still small, markets of the Central American bloc have shown a modest growth over the past few years in purchasing apples from the United States. The 1980/81 outlook calls for U.S. apple exports to exceed last season's level of 744,000 cartons. Caribbean Collectively, the islands in the Caribbean have been showing rather steady growth since 1973 in their takings of U.S. apples. The generally increasing tempo of tourist traffic in this area is largely responsible for this increase, especially in the Netherlands Antilles and Trinidad. The trend should continue in 1980/81 with U.S. apple exports topping the season-earlier ship- ments of 343,000 cartons. South America Colombia has been the shining import star in this area. Since its import liberalization of 1976, there has been a buildup every year in U.S. apples to this market, reaching a high of 289,000 cartons last season. Elsewhere in South America, the outlook is not as bright. Brazil remains-and is expected to stay-a small market for U.S. apple exporter while Venezuela continues as an erratic market. U.S. apple exports to South America are almost certain to rise substantially above the previous season's figure of 676,000 cartons. Middle East For three straight seasons, moderate gains in U.S. exports to Middle Eastern markets have been posted, and the overall volume is fairly high. Last season, 1.3 million cartons of U.S. apples were shipped to the region, with Saudi Arabia taking about 1 million and the United Arab Emirates most of the balance. The recent trend should continue in 1980/81. Africa This region represents only a small slice of total U.S. apple exports. U.S. exports to this area should approximate last season's performance of about 64,000 cartons. -5- LABORATORY REPELLENCY OF ORCHARD PESTICIDES TO THE MITE PREDATOR AMBLYSEIUS FALLACIS 1 2 2 Robert Hislop , Peter Auditore , Bonnie Weeks 3 and Ronald Prokopy For the past four years, we have been evaluating the impact o£ orchard pesticides on the survival of Amblyseius f allacis , the most important spider mite predator in Massachusetts apple orchards (FRUIT NOTES 43(4): 5-8; 43(5): 14-18; 44(5): 6-8). In our laboratory and field trials, we found that A. fallacis could readily survive exposure to field rates of several key orchard pesticides, including phosmet, azinphosmethyl , endosulfan, and captan. However, in certain commercial orchards sprayed with these materials, we observed occasional buildup of red or two- spotted spider mites. We theorized that application of such pesticides at a time when spider mites were building could actu- ally enhance buildup by repelling A. fallacis from treated areas. Recently, we explored this possibility of pesticide repellency to A. fallacis in laboratory tests, and we present here our find- ings. Our tests were conducted in the following manner. First, we sprayed one half of a 2- inch-diameter bean leaf disc with pesticide and allowed the residue to dry. Next we placed 15 two- spotted mite eggs (previously sprayed with the same pesticide) on the sprayed half of the disc, and placed 15 unsprayed eggs on the unsprayed half. After two hours, we placed one adult female A. fallacis on each disc, incubating all discs for 14 days. Each Jay during the incubation period, we recorded three types of information: (a) the number of two-spotted mite eggs consumed by A. fallacis (consumed eggs were replaced daily) ; (b) the location of each A. fallacis female every two hours from 8:00 AM to 6:00 PM; and (c) the number and location of all eggs laid by A. fallacis . We replicated each test 14 times. Our results are presented in Table 1. Compared with the un- sprayed halves of bean leaf discs, the presence of residues of phosmet, azinphosmethyl, captan, or Dikar on the sprayed halves resulted in substantially lower consumption of spider mite eggs by A. fallacis females. Residues of endosulfan, dodine, inert carrier powder, or distilled water had little or no such effect. In addition, residues of phosmet, azinphosmethyl, captan, and Dikar resulted in substantially less oviposition and substantially reduced presence of A. fallacis on treated sites. To a lesser extent, this was truF ot endosulfan and inert carrier powder residues as well. 1 Presently Research Technician, Department of Entomology, University of California at Berkeley 2 Work Study Student, Department of Entomology 3 Extension Entomologist Together, these results show that residues of commercially- formulated wettable powder applications at orchard rates of phosmet, azinphosmethyl , captan, and Dikar have substantial repell- ent effects on A. fallacis females. This could have negative implications for integrated pest management programs involving biological control of spider mites by A. fallacis . For example, summer application of any of these four materials at a time after A. fallacis has entered the trees could affect the food supply available to A. fallacis by rendering spider mite eggs less pala- table, thus reducing the rate of increase in the A. fallacis popu- lation. In addition, pesticide repellency could Torce A. fallacis into less well sprayed parts of the tree or out of the tree al- together, thereby allov>?ing more rapid buildup of pesticide resistant spider mites in the well sprayed parts. Further research under field conditions is needed to determine the true impact of pesti- cide repellency on A. fallacis . Table 1. Influence of pesticide residues on prey egg consumption, oviposition, and location of Amblyseius fallacis on bean leaf discs. Pesticide Disc half % prey eggs consumed % A. fallacis eggs laid % A. fallacis observed locations Phosmet 50 WP Sprayed Unsprayed 38.3 61.7 24.5 75.5 31.4 68.6 Azinphosmethyl . 50 WP Sprayed Unsprayed 31.2 68.8 25.7 74.3 29.6 70.4 Endosulfan 50 WP Sprayed Unsprayed 47.1 52.9 38.0 62.0 34.3 65.7 Captan 50 WP Sprayed Unsprayed 37.3 62.7 12.4 87.6 22.4 77.6 Dodine 65 WP Sprayed Unsprayed 51.1 48.9 55.3 44.7 55.4 44.6 Dikar 80 WP Sprayed Unsprayed 31.3 68.7 4.7 95.3 22.3 77.7 Inert carrier powd er Sprayed Unsprayed 47.7 52.3 33.8 66.2 41.7 58.3 Distilled water Sprayed Unsprayed 50.1 49.9 44.7 55.3 46.4 53.6 -7- SU^ttlARY OF APPLE GROWING QUESTIONNAIRE William J. Lord Department o£ Plant and Soil Sciences We frequently are asked questions by pomologists and fruit growers from other areas about apple growing practices in Massa- chusetts. In most instances we think we know what growers are doing but, this may not be true. Thus, we asked growers this past January to complete a short questionnaire. We were pleased that 55% of the apple grower members of the Massachusetts Fruit Growers' Association answered the questionnaire and wish to share the results with our readers. We have listed the questions below and under each have summarized the response to the question and added some comments of our own. 1. What do you consider the ideal height of apple trees on M7a or MM106? The tree height considered "ideal" by growers averaged 12,4 feet with 68% of the answers falling between 10 to 14.8 feet. At our Horticultural Research Center in Belchertown, average height of mature Delicious trees on M7 is 11.5 feet in one block and 13 feet in another, although we believe that spur- type trees of the same cultivar on this rootstock could be easily maintained at 9 feet (height of central leaders) . In contrast, tree height of 9 feet is too low for the natural vigor of non-spur Delicious on MM106 at our Research Center and watersprouts have been troublesome. However, we are main- taining Idared and Spartan trees on M.7 at 8.2 feet and 9 feet, respectively, without difficulty. 2. Do you use chemical thinners (yes or no)? If the answer is yes, which chemical thinner do you use on Mcintosh ', on Delicious ? Ninety-six percent of the growers stated that they use a chemical thinner on Mcintosh. Of those using a chemical thinner: 54% used carbaryl (Sevin) ; 15% used naphthaleneacetamide (NAAm) ; 13% used naphthaleneacetic acid (NAA) ; and 18% used carbaryl and/or NAAm, carbaryl and/or NAA, or NAAm or NAA. It is obvious that the growers prefer carbaryl for thinning Mcintosh trees, possibly because of convenience (Delicious and Mcintosh are usually in the same block of trees and carbaryl is the only thinner suggested for Delicious) or because of less risk of overthinning than when using an application of NAAm or NAA. Nevertheless, NAAm and NAA do have some direct flower- promoting capabilities, an attribute not shared by carbaryl, and will thin later in the season than carbaryl. A surprising 90^ o£ the growers used a chemical thinner on Delicious. This certainly would indicate that at least in some years, lack o£ fruitfulness is not a problem as frequently mentioned with Delicious in many fruit growing areas of the United States. Of the growers using chemical thinners on Delicious: 85% used carbaryl, 9% used NAA, and 61 used carbaryl or NAA , or carbaryl or NAAm. We do not recommend the use of NAA or NAAm on Deli- cious because following their use many small seedless fruits may persist on the tree. 3. Do you apply a growth regulator to prevent pre-harvest drop (yes or no?) If the answer is yes, what material do you use on Mcintosh, on Delicious? As expected most growers (981) used a growth regulator to pre- vent pre-harvest drop of Mcintosh. Of them, 93% used Alar-85* and 7% used NAA. Only 51% of the growers used a growth regulator to prevent pre-harvest drop of Delicious, and of these, 93% used Alar-85*, 3% used 2 , 4 , 5- trichlorophenoxypropionic acid (2,4,5-TP), and 3% used either Alar-85* or 2,4,5-TP. We caution growers to avoid rates in excess of 1.5 lbs. of Alar-85* per acre (assuming 300 gallons/A of dilute spray) on Delicious because of possible fruit size suppression and fruit flattening. On trees where fruit size may be small, 2,4,5-TP is suggested rather than Alar-85*. At 20 ppm, 2,4,5-TP will reduce rate of drop for about 4 weeks. This growth regulator is generally applied in early October before frost injures the leaves . 4. Have you used Promalin* within the last 2 years to elongate Delicious (yes or no)? Do you plan to use Promalin* next spring (yes or no) ? Forty percent of the growers indicated that they had used Promalin* on Delicious. Of the growers that have used Promalin* 64% stated that they plan to use this growth regulator again. Nine percent of the growers who have not used Promalin* plan to use it, weather permitting. The author considers the results of Promalin* to be very unpre- dictable under Massachusetts conditions. It can increase the typiness of Delicious but frequently the fruit response is slight and this growth regulator has fruit thinning capabilities if misused. Trade Name 5. What kind of fertilizer do you use in bearing apple orchards (a complete fertilizer, ammonium nitrate or \\rhat)? Fifty-six percent of the growers applied a complete fertilizer and 301 of the growers used calcium nitrate (CaCNO,)-^. Perhaps some growers like the convenience of obtaining and applying a complete fertilizer rather than purchasing a "bulk" mix containing nitrogen, potassium and minor elements such as boron. However, cost could be reduced by using fertilizer con- taining no phosphorous (P) since there is no evidence that our apple trees need this element beyond what is present in the soil . P deficiency can reduce tree growth and yield and in several parts of the world it has been shown to be associated with fruit breakdown in storage. Nevertheless, there has been very little evidence of P deficiency in fruit. In fact, Drake and Bramlage of our Department of Plant and Soil Sciences recently found that high levels of P in apples, especially in combination with low levels of calcium, greatly increased breakdown of apples during storage. Soil applications of Ca(NO,)-, are being used to enhance the Ca levels in fruit. Nevertheless, we have no evidence that Ca(NO^)-;> in comparison with ammonium nitrate (NH^NO^) or pot- assium nitrate will increase fruit Ca levels. Ca(NO^)^ unlike NH.NO, will not acidify the soil but NH.NO^ is a more economical source of nitrogen (N) . We believe that tne cost and the amount of N applied to apple trees is more important than the source except under unusual situations. 6. Do you apply calcium chloride sprays to improve the calcium level in your trees and fruit (yes or no)? Changes in cultural practices frequently are slow, thus it was a pleasant surprise to note that 11% of the growers are using calcium chloride sprays. 7. Do you have early maturing apples (yes or no)? If the answer is yes, have you applied ethephon (Ethrel*) within the last 2 years to advance the maturity of your early maturing apples (yes or no)? Of the growers having early maturing varieties, 471 used ethephon to advance their maturity. 8. Have you used within the last 2 years ethephon (Ethrel*) to advance the maturity of Mcintosh apples (yes or no)? What % of your Mcintosh crop was treated? The author was surprised to find that more growers (641) were applying ethephon to Mcintosh than to early maturing varieties. 10- The response also indicated a rapid acceptance of this relatively new growth regulator as a marketing tool for Mcintosh, An average of 81 of the Mcintosh crop is being sprayed with ethephon by the growers . 9. Have you planted Mcintosh (non-spur) apple trees on M7 or M7a within the last 10 years (yes or no)? What tree spacing or spacings did you use? If you were planting the same trees would you used wider or closer spacings? The tree spacing used by growers averaged 18 feet apart in the row with 681 of the answers by the growers falling between 14.4 feet and 21.6 feet. Between row spacing averaged 25.1 feet with 681 of the answers falling between 20.4 feet and 29.8 feet. The percentage of growers stating that they now would plant the trees closer was about comparable to the percentage favoring wider spacings, and 41''6 were satisfied with present planting distances. Thus, it is obvious that there is no trend for close spacing of trees on M.7 rootstock. We have a heavy soil at our Horticultural Research Center and tree spread of our mature non-spur trees averages from 16 to 19 feet depending upon the variety and block. 10. Do you have trees on M26 rootstock (yes or no)? What varieties? Are you sufficiently satisfied with the trees and plan to plant more? Forty percent of the growers had trees on M26 rootstock and of those that had trees on this rootstock only 39% were sufficiently satisfied with the trees and plan to plant more. There are probably several reasons why so many growers are not satisfied with tree growth and fruitfulness on M26. This rootstock reacts more to unfavorable growing conditions than those on more vigorous clonal rootstocks. Trees within a block may be extremely variable in vigor, with some of them weak and difficult to train. Spur-type trees appear weak when planted on light soils, as do Cortland and Empire on this rootstock. Trees on M26 require good deep soils with good drainage and waterholding capacity and even on these soils they may require temporary support or permanent support on some sites. A Comparison Among States The questionnaire also was sent to Maine and Connecticut growers by the Extension Fruit Specialists in these states. The comparisons among Massachusetts, Maine and Connecticut growers regarding the answers on the questionnaire are of interest, and the differences J regarding the practices are probably due to climatic conditions and " -11- and emphasis given by Extension and Research personnel in these states. The growers from the 3 states virtually agreed on the answer to the question concerning the "ideal" height of apple trees on M7a or MM106. The tree height considered ideal by Connecticut, Maine and Massachusetts growers averaged 12.6, 12.1 and 12.4 respectively. Sevin was more frequently used in Maine than in Massachusetts for chemical thinning of Mcintosh, but the reverse was true regarding the use of NAAm. A higher percentage of Massachusetts and Maine growers thinned Delicious than did growers in Connecticut. The pre-harvest drop control practices were similar among the growers in the 3 states except that none of the Maine growers used 2,4,5-TP for drop control on Delicious. Only 16-0 of the Maine growers had used Promalin* within the last 2 years to elongate Delicious in comparison to approximately 401 of the Massachusetts and Connecticut growers. The fertilizer formulations used varied strikingly among the 3 states. An orchard mix (6-0-16 formulation) was used by 84% of the Maine growers and none mentioned the use of calcium nitrate (CaNO,)^. Fifty-six percent of the Massachusetts growers applied a complete fertilizer and 30% of the growers mentioned using CaNO,. Eighty-four percent of the Connecticut growers used a complete fertilizer but only 51 mentioned the use of CaNO,. Calcium chloride sprays to improve the calcium level in apple fruits were used by only 11% of the Maine growers and 28% of the Connecticut growers in comparison to 71% of the Massachusetts growers. A higher percentage of Maine growers (75%) used ethephon to advance the maturity of early maturing varieties than did growers of Massachusetts (47%). Only 26% of the Connecticut growers used ethephon to advance fruit maturity on early maturing varieties. About 64% of the Maine and Massachusetts growers and 42% of the Connecticut growers used ethephon to advance the maturity of Mcintosh. The tree spacing for non-spur Mcintosh apple trees on M7 or M7a used by Connecticut, Maine and Massachusetts growers averaged 16.2 feet x 23 feet, 15.7 feet x 20.4 feet, and 18 feet x 25.1 feet, res- pectively. Some of the Maine growers indicated that they had planted Mcintosh on M7 too closely with spacings of 9 feet x 14 feet, 10 feet x 16 feet, 12 feet x 18 feet, 10 feet x 18 feet, and so forth. There- fore, the average planting distance used in Maine for Mcintosh on M7 was considerably lower than that used in Massachusetts. Slightly more growers in Maine (52%) and Connecticut (53%) had trees on M26 rootstock than did Massachusetts growers (40%) . The percentage of growers stating that they were sufficiently satisfied with their trees on M26 and plan more was relatively small (averaging 30 to 39% among the states) because of dissatisfaction with tree per- formance, or because the plantings are too young to be adequately evaluated. 12- GRADE DEFECTS ON MCINTOSH APPLES: STRIP VERSUS SELECTIVE PICKINGS 1 2 "^ Henry M. Bahn , Janice O'Kelley and Glenn Morin In a previous study o£ causes of defects on Mcintosh apples (FRUIT NOTES, Volume 45, No. 5) we noted a large variation in packout rates ranging from 96.7 percent to 46.6 percent. We felt this variation was due at least in part to the fact that the 1979- 1980 samples included both strip picked and selectively picked (picked for color) fruit. In repeating the study this past year we separated the fruit into 2 categories: strip picked and selectively picked apples. Sampling Procedure We used the same general sampling format as was employed in the previous study. A total of 16 packing sheds were visited between January and March 1981 and the amount of fruit packed, cullage and the reason for culling were noted. A total of 3,930 bushels were packed and 885 bushels were culled for an overall packout rate of 77.5 percent. The culls were inspected in the same manner as in 1979-80 although the volume of culls in 1981 did not allow the inspector to check each apole. Depending on the volume of culls and the length of the sampling period, the inspector checked from 15 to 100°o of the culls to determine the reason for rejection. An average of 69% of the culls were phy- sically inspected. The same individual insnected the culls in 1980 and 1981. Resul ts Composition of defects. The cull rate and reasons for culling were similar for 1979-80 and 1981 (Table 1). The largest differ- ences between the years were in color and size, russeting and "other". The large difference in the "other" category can be traced to hail damage and to soot due to malfunctioning refriger- ation equipment at one packing shed in 1981, Insect and disease damage totaled 0.9% of total fruit packed in 1979-80 and 1.0% in 1981. This indicates the importance growers place on controlling pests and disease and of the effectiveness of preventative measures. 1 Extension Farm Management Specialist, Food and Resource Economics. 2 Agricultural Business Management, Stockbridge School of Agriculture 3 Senior Pest Management Scout, Department of Entomology. 13- Table 1. Composition of defects on Mcintosh apnles at grower packing sheds in 1979-80 and 1981. Culls showing Total fruit culled this defect because of this defect Defect 1979-80 1981 1979-80 1981 i'o) il) (%) (%) Insect damage 1.8 2.9 0.4 Disease 1 damage 2.2 1.5 0.5 Color ( US No. 1) 16.9 22.5 3.7 Size ( 2-1/4' ') 46.0 34.5 10.3 Bruise 8.1 9.9 1.8 Stem puncture 9.9 5.5 2.2 Mechanical 8.1 8.3 1.8 Russeting 5.7 1.9 1.3 Other^ 1.3 13.0 .2 Totals 100.0 100.0 22.2 0.6 0.4 5.3 7.5 2.6 1.2 1.7 0. 5 2.5 22.3 z Includes limb rub, cuts and cracks. y Includes misshapen, bitter pit, sun scald, hail damage, rodent damage, storage freeze and soot. Physical damage (bruise, mechanical and stem puncture) ac- counted for 23.71, of culled fruit (5.5% of total fruit packed) in 1981. This is just slightly better than in the 1979-80 study. We feel this is an area where damage could be reduced by closer monitoring of picking, handling and grading practices. Strip picked vs. selectively picked--some economic comparisons. Separating the samples into strip picked and selectively picked (picked for color) categories did not, as we had hoped, account for the variation in packout rates. Although selectively picked apples did have a higher packout rate than the strip picked (82.8% vs. 72.6%) the variance for selectively picked fruit was greater. Packout rates for selectively picked fruit ranged from 96.6% to 42.2% while the range for strip picked was 88.9% to 54.4%. The large variation on the packout of selectively picked fruit was due to one sample with considerable handling damage and another with hail damage far in excess of what might be considered normal. An examination of Tables 2 and 3 reveals a substantial differ ence in lost revenue due to the cullage of apples. Selectively picking fruit (Table 2) resulted in an additional $451.20 per acre -14- from undamaged fruit. As might be expected, selectively picked apples had a lower incidence o£ culling for color, 15.11 of the culled fruit compared with 29.3-0 for strip picked fruit. Note that this does not necessarily mean that selectively picked orchards had less color-rejected fruit; the pickers simply left it on the trees while strip picked rejects were picked, stored, graded and culled. In order to assess the economics of strip versus selective picking, growers must consider several points including the skill and wage rates of pickers, storage capacity and costs, and skill and wage rates of grader /packers . The grower must consider the cost of picking, storing and grading the additional substandard fruit against the costs of selectively picking. By comparing Tables 2 and 3 the reader can note a similarity in cullage rates for most defects other than color and size. (Presumably selective pickers leaves more undersized apples on the trees than do strip pickers.) In nearly every category the selectively picked fruit has slightly fewer culls and correspond- ingly less lost revenue due to defects. In the area of physical damage (bruise, stem puncture and mechanical) strip picked fruit had 241 more of total fruit culled than the selectively picked and the additional revenue lost was $57.60 per acre. Strip pickers may hurry a bit m.ore than selective pickers and may thus do more physical damage. Although most growers feel they can effectively control their pickers, they may need to monitor them closer to reduce damage. The similarities between strip and selectively picked fruit damage for other categories including insect and disease damage, russeting and "other" (misshapen, bitter pit, sun scald, hail, rodent and refrigeration damage) are as expected since these defects are not affected by picking and handling procedures. Conclusion We feel that growers have the potential to increase packout rates, and thus net revenue, by carefully evaluating causes of defects, determining which defects may be reduced and taking the necessary action at the proper time to insure that less defective fruit is picked, stored, and graded. After color and size, both of which are difficult for the grower to control, physical damage is the most often occurring and most expensive defect. Close scrutiny of picking, handling and grading operations and an under- standing of the additional costs of handling and storing defective fruit may enable growers to increase returns by raising their packout rates. -15- n o M C 3 3 4> 3 H- 3 C CO n o i 3 Ln (a) O c ra o c > en i fti en ON O o cr c 01 n (D (tl H O W :^ tyj W Vi n O M O rt c h) rt i-( H- o H- 3 rt 3" en o ft) c N h-" W U) CD fD tn rr =1 H- fl) o fU rt> 1— ' f-i (D w cn ri w n rt 3 -a ID cn rt H- H> c O 3 O n (J- OQ CU n rr C fD CD (D a (D n o o ^ ^J U) 00 4> O Ln O 00 ho o 00 o K3 O ro o> u) ON O N) o o o 00 Ul o i_o b 00 OS Ul O ON ON O 00 OS o o o K3 OS M 00 hO M 00 00 Ul K5 4> O O O O o o o 00 o o o ON o N3 o o o n c cn cn s^ cl cn -^ fD 3^ i-h O fD K n H- rt 3 H O (X rt C CU (D I— ' O I-! C Q. 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M C ■cr> C M ^-^ fD M r' D- O C cn ft) rt -r ft) SO r( H cr t-' (D < 3 c fD O cn cn O 3 n c n o cn 3" ft) T3 ■a M tD cn I cn rr ri ■a ■a n ?r (t) a- o o 3" ft) rl a cn c» Cooperative Extension Service U. S. Department of Agriculture University of Massachusetts Amherst. MA 01003 Official Business Penalty for Private Use, S300 POSTAGE AND FEES PAID U. S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT I FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 46 No. 4 FALL ISSUE, 1981 TABLE OF CONTENTS Pomological Paragraph Origin of Some Old and New Apple Varieties Orchard Mouse Bait and The Weather The Mediterranean Fruit Fly in Massachusetts: Can It Happen? What 's Happening in CA Storage Research Tree Fruit Physiology Trials Underway at the C.D.A. Farm of Frelighsburg, Quebec Notes Concerning the Harsh Winter of 1980-81 FRUIT NOTES INDEX FOR 1981 POMOLOGICAL PARAGRAPH Publications available Proceedings of the New England Small Fruit Meetings wliich was held at Concord, New Hampshire in January, 1981 may be obtained by making a check payable to the University of New Hampshire and send it to Prof. W. G. Lord, Department of Plant Sciences, University of New Hampshire, Durham, NH 03824. The Strawberry: Cultivars to Marketing. Edited by Norman F. Childers. This publication resulted from the 1980 National Strawberry Conference held in St. Louis, Missouri. The book includes over 40 papers presented by outstanding breeders, researchers and growers. This book is an invaluable reference and should be included in the library of anyone interested in the strawberry. It is obtainable from Horticultural Publications, 3906 N.W. 31st Place, Gainesville, FL 32601. The cost of $21.90 includes postage and handling. AAA******* ORIGIN OF SOME OLD AND NEW APPLE VARIETIES William J. Lord and James F. Anderson Department of Plant and Soil Sciences There is a continuing request for information as to the origin of both old and new apple varieties. Most of these re- quests come from operators of farm markets who are frequently asked such questions by their customers. Most of the apple varieties planted in this country origin- ated here, but the history of many is obscure and except for varieties more recently introduced, few came into existence as as the product of the plant breeder. Most of the varieties originated as chance seedlings and were discovered and introduced into cultivation by some observer or admirer of the fruit. Mcintosh, Delicious, Wealthy, Northern Spy and Baldwin are examples of commercial varieties that originated as such chance seedlings. The following is a list of some of the apple varieties being sold in Massachusetts and their origin. Where varieties have resulted from a controlled cross between two other varieties, the origin of such varieties is expressed by placing the letter "X" between the parent varieties. For example, the Milton variety is a cross between Yellow Transparent and Mcintosh. Akane Jonathan X Worcester Pearmain. Introduced by the Fruit Tree Research Station, Aomovi , Japan in 1970. Also listed as TohoKu #3, Primerouge and Prince Red. Baldwin A chance seedling discovered about 1740 on a farm in Wilmington, Massachusetts. It was widely planted in Eastern Massachusetts as early as 1784. Cortland Ben Davis X Mcintosh. This cross was made in 1898, selected in 1911 and introduced (named) in 1915 by the New York State Agricultural Experiment Station, (N.Y.S.A.E.S.) , Geneva Delicious A chance seedling discovered in 1881 in Peru, Iowa. It was named and introduced by the Stark Brothers Nurseries in 1895. Early Yellow Transparent X Mcintosh. The cross was made Mcintosh in 1909, selected in 1921 and introduced in 1923 by the N.Y.S.A.E.S., Geneva. Empire Mcintosh X Delicious. An open-pollinated cross made in 1945. It was selected for trial in 1954 and introduced in 1966 by the N.Y.S.A.E.S., Geneva. Golden Originated as a chance seedling in Clay County, West Delicious Virginia about 1895. It was named and introduced by the Stark Brothers Nurseries in 1916. Idared Jonathan X Wagener. Was selected in 1935 and intro- duced in 1942 by the Idaho Agricultural Experiment Station, Moscow. Jerseymac New Jersey 24 X Julyred. The cross was made in 1956 and introduced in 1971 by the New Jersey Agricultural Experiment Station, (N. J .A.E. S . ) , New Brunswick Jonagold Golden Delicious X Jonathan. The cross was made in 1943, selected in 1953 and named in 1968 by the N.Y. S .A.E. S . , Geneva. Lodi Montgomery X Yellow Transparent. The cross was made in 1911, selected in 1922 and named in 1924 by the N.Y.S.A.E.S., Geneva. Julyred N.J. 8 X [Melba X (Williams X Starr)]. Selected in 1955 and introduced in 1962 by the N.J.A.E.S., New Brunswick. Macoun Mcintosh X Jersey Black. The cross was made in 1909, selected in 1922 and introduced in 1923 by the N.Y. S. A.E .S. , Geneva. -3- Melba An open pollinated seedling of Mcintosh selected in 1909 and introduced in 1924 by the Canada Dept . Agricultural Experiment Station, Ottawa. Mc Intosh Originated as a chance seedling in Dundas County, Ontario, Canada. Propagation of this variety began in about 1870. Milton Yellow Transparent X Mcintosh. The cross was made in 1909, selected in 1920 and introduced in 1923 by the N . Y . S . A. E .S . , Geneva. Mollie ' s (Golden Delicious X Edgewood) X (Red Gravenstein X Del icious Close). The cross was made in 1948, selected in 1956 and introduced in 1966 by the N.J.A.E.S., New Brunswick . Mutsu Golden Delicious X Indo. The cross was made in 1930 and the cultivar was introduced by the Fruit Experi- ment Station, Aomori, Japan in 1948. It was intro- duced into the United States in 1948. Called Crispin in England. Northern Originated as a chance seedling in East Bloomfield, Spy Ontario County, New York about 1800. Paulared Originated as a chance seedling. Discovered in an orchard in Sparta, Michigan in 1960 and introduced in 1967. Puritan Mcintosh X Red Astrachan. The cross was made in 1929 and the cultivar was introduced in 1953. Quinte Crimson Beauty X Red Melba. A selection of the Canada Department of Agriculture Research Station, Ottawa. Introduced in 1964. Red This is a Russian variety imported by the Massachusetts Astrachan Horticultural Society in 1935. Rhode Island Originated as a chance seedling probably in the Greening vicinity of Newport, Rhode Island in about 1750. Rome Originated as a chance seedling in Lawrence County, Beauty Ohio before 1848. Spartan Mcintosh X Yellow Newtown. The cross was made in 1926 and introduced in 1936 by the Canada Dept. Agr . Res. Sta., Summerland, British Columbia. Spencer Mcintosh X Golden Delicious. The cross was made in 1926, selected in 1938 and introduced in 1959 by the CD. A. R.S., Summerland, British Columbia. Vista N.J. 77349 X Julyred. The cross was made in 1956, Bella selected in 1962 and introduced in 1974 by the N.J.A.E.S., New Brunswick. Wealthy Originated in Excelsior, Minnesota from a seed of the Cherry Crab planted about 1860. Winter Originated as a chance seedling on a farm in Cass Banana County, Indiana about 1876. It was introduced in 1890. Wisconsin N.J. 148842 X PRI 187--^. The cross was made in 1956, Viking selected in 1963 and introduced in 1969 by the Wis- consin Agr . Exp. Sta., Sturgeon Bay. Yellow This variety was imported from Russia by the United Transparent States Department of Agriculture in 1890. A********* ORCHARD MOUSE BAIT AND THE WEATHER Edward R. Ladd Fish and Wildlife Service 4 Whalley Street, Hadley, MA 01035 One of the more common rodenticides used today for the control of orchard mice is zinc phosphide (Zn,P-,). It is a dull gray crystaline material insoluble in water and alcohol, slightly soluble in alkalis and oil and readily degraded under various acid conditions. Because zinc phosphide is more stable under certain conditions than others, the question arose concerning how long it remains effective under various field conditions. There are several research findings on zinc phosphide which tends to clarify the question on field stability. 1. Zinc phosphide kept in a sealed, dry condition should remain stable for 3 or more years. Grain treated baits stored under the same dry conditions should have a similar shelf life. 2. Grain baits placed out-of-doors under protected conditions can remain toxic for several months. 3. The use of oils or waxing materials in bait preparations or as an overcoating will extend the field life span of baits. 4. The major cause of loss in effectiveness of field applied baits is the physical removal of zinc phosphide by rainfall. One inch of rain can remove up to 601 of the toxicant. -5- 5. Zinc phosphide eroded from the bait material decomposes quite rapidly in soils. Wetter the sodl the faster the breakdown. 6. Under moist, humid conditions carrier grains and other mater- ials used to present zinc phosphide tend to mold and disinte- grate becoming unacceptable to mice. With all of these conditions in mind plus the knowledge that microtus are most active on warm, sunny days the following recommen- dations are given: 1. Pick a series of warm, sunny days to apply orchard mouse con- trol materials. This is particularly true if material is applied by a broadcast method. 2. Consider placing at least part of the baits under some type of protective cover .... i . e. , a square of roofing, a board, or 1/2 a tire to protect bait. 3. Keep a small amount of your orchard mouse bait in a dry con- tainer. If a rain of any consequence does fall, run a visual check on bait from several locations in the orchard. Compare the two ; if the field applied material shows a loss of 15-20% of its zinc phosphide coating consider re-application where necessary. THE MEDITERRANEAN FRUIT FLY IN MASSACHUSETTS: CAN IT HAPPEN? Ronald J. Prokopy Department of Entomology University of Massachusetts Whither the Mediterranean fruit fly? This insect, pictur- esque to behold and s o enticing to an entomologist studying its behavior and ecology, has for decades proven to be a devastating pest of fruit wherever it has become established. Will it event- ually reach Massachusetts, and if so, might it establish itself here as a pest of our own locally growm fruits? Drawing upon the extensive literature published on this insect (in particular the fine article by Hagen, Allen, and Tassan in the March-April 1981 issue of California Agriculture), and upon my own research experience with the behavior of Medflies in apricot groves in Greece and coffee plantations in Hawaii and Guatemala, I will attempt here to briefly describe the biology of the Medfly and to 6- predict its future in Massachusetts. The Medfly is a close relative of the apple maggot fly. Both are members of the same subfamily, and both have similar behavior. The main differences are twofold: (1) the Medfly attacks 253 different species of fruits, nuts, and vegetables, while the apple maggot fly attacks only six, and (2) the Medfly cannot readily survive cold conditions while the apple maggot fly can easily overwinter in very cold regions or as pupae in the soil. What are the principal fruits grown in Massachusetts which are potential favorable hosts for the Medfly? The most favored one would probably be peaches, followed (but not necessarily in order) by nectarines, apricots, plums, cherries, apples, and pears. Occasional host fruits include grapes, peppers, and tomatoes. Where did the Medfly come from? It originated in tropical West Africa, spread to north and south Africa, and then in the 1800's moved into Spain, France, Italy, Greece, and the Middle East. It arrived in South America in 1901, Hawaii in 1907, Costa Rica in 1955, and northern Guatemala in 1977. It has remained firmly established in all of these countries ever since. The first record of Medfly infestation in the USA occurred in 1929 in Florida. Since then, it has re-entered Florida thrice more (1956, 1962, and 1963), Texas in 1966, the Los Angeles area in 1975 and again in 1980, and finally, in June of 1980, the Santa Clara County area of Central California. Biochemical genetic analysis studies suggest that the flies which entered Santa Clara County probably came from Central or South America. Except for this last infestation, the Medfly in the USA has in each case been successfully eradicated through ground or aerial application of insecticide bait sprays, aided by fruit stripping. In the present central California outbreak, an attempt was made to achieve eradication through a combination of sterile male releases to render female eggs infertile (more than 100 million sterile flies per week were released for several months), stripping of susceptible fruits from plants, and ground applications of malathion bait sprays. Because these combined techniques did not prove successful, state and federal agencies have been recently obliged to resort to the only proven method of eradicating Medflies from substantial pockets of infestation in the USA: aerial appli- cation of malathion bait sprays. This article is not aimed at debating the merits of aerial application of pesticide for Medfly eradication vs. the possible injury that may result to those few individuals which may be highly susceptible to deleterious effects of malathion (as with bee stings, we can expect purely on the basis of probability that a small per- centage of people in every population are inordinately susceptible to the effects of potentially harmful materials entering their system). Suffice it to say that if the Medfly cannot be contained within its present bounds, the amount of pesticide application then necessary to prevent fruit injury in California and possibly other states and the amount necessary to fumigate fruit picked from infested areas would vastly exceed the amount presently contemplated for use in aerial bait sprays. Why has the infestation spread so rapidly since last June to now cover more than 1000 square miles in 3 California counties? There may be 2 principal reasons. First, the Medfly in California has probably undergone 4- 5 , generations of reproduction and multi- plication since last June. Under ideal conditions, each female can lay as many as 1000 eggs, but under normal field conditions, each probably lays only 400 eggs or so. Thus, even though half of the eggs were to yield males, a single fertile female by the fifth generation could conceivably give rise to more than 300 billion other females. Of course, given natural mortality, only a small percentage of this possible number is actually realized. Still, it has been enough to result in a major outbreak. A second factor contributing to the rapid spread is the dispersal characteristics of the Medfly. Several research studies have shown that Medflies infrequently fly more than 1 mile or so. However, many years of observing fruit fly behavior in nature in several countries have emphatically illustrated to me that under certain weather conditions, the distance of dispersal can be great, exceeding several miles. These conditions are hot, dry days with strong winds. On such days, I have observed large numbers of fruit flies leaving favor- able host trees and dispersing with the wind. If some of the dispersers were to be carried into upper air currents, they could go for a very long distance. It turns out that such weather con- ditions have been frequent in the infested California areas this spring and summer. Thus, there is real danger of flies being carried over the mountains which presently form a barrier between the great agricultural Central Valley of California and the present areas of Medfly infestation. Will the Medfly eventually reach Massachusetts? If the current infestation in California cannot be eradicated, the chances are good that at some time in the future, a shipment of California produce, or more likely an individual travelling from California to Massachusetts carrying a sack of infested fruit from a backyard tree, will result in introduction of the fly to our state. Al- though since 1955 the fly has spread by natural dispersal from Costa Rica to northern Guatemala, the chances of its spreading by natural dispersal from California or other states into Massachusetts is extremely remote. Can the Medfly survive in Massachusetts? To answer this question, we must examine the temperature range tolerance o£ the Medfly. At a constant 30°F, the adults die within 100 hours, and few survive more than 12 days at 45°F. The eggs cannot develop unless the temperature is above 52°F. The larvae are incapable of growing at temperatures below 50°F. The pupa is the most cold resistant stage. But if Medfly pupae are subjected to 32 F for 4 consecutive days, or to 42 F for 10 consecutive days, few, if any, can survive. Thus, under normal winter con- ditions in Massachusetts, no Medflies can be expected to survive, just as they cannot normally survive in central Europe. However, should a very mild winter occur, a few individuals might possibly survive in the most temperature parts of the state, that is, areas near the ocean. Even if this were to happen, however, chances are the infestation would be wiped out by colder temperature the next winter. To conclude, it is conceivable that should Medfly larvae in infested fruit accidentally.be introduced into Massachusetts in May or June, then the adults which they produce could lay eggs in locally-grown fruits, especially stone fruits, and establish a population for one or two generations before winter sets in. This population would probably be restricted to a small area around the site of introduction. Unless there were to be a dramatic shift in climate toward very warm winters, however, it is extremely unlikely that the Medfly could become firmly established in any part of our state. Postscript: Would it be a fair exchange if California were to send us the Medfly in return for our sending them the apple maggot fly? In fact, the apple maggot fly, for the first time ever west of the Rockies, was discovered in Oregon in 1979 and now sits just a few miles north of the California border. It could become a real threat to California apples, and numerous red sphere traps and baited yellow rectangle traps are currently in use in apple growing regions of northern California to detect any possible apple maggot flies. If there had to be an exchange between these two pests, I think we would get the better of the deal, given our cold winters. WHAT'S HAPPENING IN CA STORAGE RESEARCH? William J. Bramlage Department of Plant and Soil Sciences To answer this question, the Third National Controlled Atmosphere Research Conference was held July 22-24, 1981 at Oregon State University, Corvallis, Oregon. Approximately 100 people participated in this Conference, including numerous researchers from the U.S. and Canada, researchers from a number of other countries, and representatives o£ business with interests in CA storage. Here is a summary o£ the information from this Conference that I think would be of interest to Northeastern fruit growers. A major development of CA storage of apples is the demon- stration that apples can be successfully stored at about 1% 0^, with considerably better retention of quality than at the normally recommended 0^ concentrations. Research in a number of places, most notably England, Nova Scotia, and Michigan, has produced very successful results, especially on soft varieties like Mcintosh. However, as Dr. E.C. Lougheed of the University of Guelph, Ontario put it: "Low oxygen storage is not for everyone. The user must be prepared to take risks." And he might have added, the user must be prepared to take a number of extra precautions and to be extra careful in storage management. The primary risk is that storing near 1% Oy offers extremely little margin for error. We have long known that 3% 0^ is a con- servative recommendation, but it allows for some error. With low-0^ storage, precision is essential. For example, a tiny leak in the CA sample line could cause loss of an entire room of fruit due to fermentation. Either a new sampling system must be employed or else very careful and frequent cross-checking of atmospheric composition must be made. In England, Cox's Orange Pippin rooms need to be read every hour, so they have developed automatic con- trol systems for low-0^ storages. However, in North America once- a-day readings appear to be satisfactory if done with sufficient precision. Different speakers emphasized different limitations of low- 0-, storage of apples. Dr. Perry Lidster, in Nova Scotia, empha- sized that only less mature apples (judged by a starch test) could be stored in low 0^; more mature ones developed a form of internal browning. He also found temperature to be critical for Mcintosh, and recommends 35-36 F. Several speakers emphasized that CO2 had to be very close to 01 with low-0^ to avoid low-0^ injury. The benefit from low-0-^ storage is a much slower ripening of the fruit in CA. Dr. Lidster estimates that Mcintosh can be kept 18 months in low-0^ CA, and ones kept 6-10 months are much firmer and less ripe than ones in normal CA for the same length of time. Certainly, low-0-, storage is something that will receive much attention in the next few years. We have no experience with it in Massachusetts, but are very wary of its use in most of our storages. It is clear that it can work, but it is also clear that substantial new risks are involved and only a storage operator who has an excell- ent storage system and who is willing to invest great care and signi- ficant risk should consider employing it at this time. 10 A closely related subject is that of ethylene scrubbing in CA storages. Ethylene gas is the hormone that causes apples to begin ripening and it has long been debated whether or not ethylene levels in CA storages were important. The debate exists largely because there has been no way of preventing ethylene build- up, or of scrubbing it down to a very low concentration that is not biologically active. Recently, Dr. Frank Liu and Dr. David Blanpied at Cornell University have had impressive results in main- taining Mcintosh firmness during storage when they have succeeded in preventing ethylene buildup, although they have not always been successful in preventing buildup. They presently think that a commercial ethylene adsorbant plus special harvest and storage management may be commercially successful, but the cost of the ad- sorbant is high. They continue to test this approach. Meanwhile, at Michigan State University Dr. David Dilley is using catalytic burners to remove ethylene from storage atmospheres. His equip- ment is still in the experimental stage, but his results are encouraging. Perhaps "ethylene scrubbing" is approaching reality, and if so a new dimension may be added to CA storage. In the early 1970 's, a high CO^ treatment was developed for Golden Delicious apples in Washington State. The apples are treated with a high CO^ environment for a few weeks at the begin- ning of CA and they remain firmer much longer during CA. In neighboring British Columbia, Golden Delicious were severely injured by the treatment. Later tests in a number of areas showed that Mcintosh were also too susceptible to injury from the treat- ment. Dr. George Mattus has now found that Virginia Golden Deli- cious can be successfully treated with high CO^ , so the - treatment is now being used for the first time outside of Washington State. In British Columbia, Dr. O.L. Lau has found that "rapid CA" is as effective as high-CO« treatment in retaining firmness during storage. "Rapid CA" simply means reaching CA conditions within a day or 2 after loading the room, and doing so produced fruit that were 2 lbs. firmer at removal from storage than ones that had slow pull-down. However, we believe that it is essential to thoroughly cool the fruit before sealing a room and pulling it down. "Rapid CA" would require very high cooling capacity or else a system for pre-cooling. Rapid pull-down makes good sense but not at the expense of thorough cooling. It should also be noted that in conventional CA, the CO2 level is important to retention of firmness. Dr. D.H. Dewey at Michigan State showed that putting dry lime into the CA room produces softer apples by keeping CO^ too low in the room. Humidity in the storage is something that has been given little attention, although it has long been recognized that too high a humidity causes excess rotting and increases breakdown, while too low humidity causes excess weight loss and can cause shrivelling. 11 Dr. Blanpied surveyed humidity in 40 sealed Northeastern CA rooms this past year. He found that in rooms with wet coils the relative humidity averaged 89%, and in rooms with dry coils it averaged 931. This is a substantial difference and indicates that excess weight loss is occurring in the wet coil rooms. He also found that fruit lose less water when the refrigeration coil is operated at a higher temperature, even though the system is operating over longer periods of time. Fan speeds did not affect the humidity level in storages. Humidities were about the same in 36-38 rooms as in 32° rooms, but it should be pointed out that more water will be lost from fruit at 36-38 than at 32 , even though the relative humidity is the same. Mr. D.L. Hunter of Food Plant Engineering Co., Yakima, Washington, pointed out that use of ammonia rather than Freon as the refrigerant allows operation of the coil at a higher temperature, and therefore reduces moisture loss from the fruit. CA continues to be a storage method used almost exclusively for apples and pears. Much research continues to be done to try to find ways of using it on other commodities, but benefits are limited. Some sweet cherries are CA stored, but only for short times. A small amount of avocados are also CA stored, and studies suggest that CA storage of kiwi fruit may be successful. Peaches and nectarines can be stored successfully in CA, but it requires intermittent warming of the fruit and has not been adopted commercially. With vegetables, cabbage is successfully stored in CA. Many other vegetables are shipped in modified atmospheric con- ditions although their long-term storage is not attempted. Some vegetables such as tomatoes can be CA stored for moderate lengths of time but their quality, while better than for air-stored vegetables, is not as good as that of freshly harvested produce. Research with flowers is continuing, but benefits are quite limited in most cases. This Conference provided an excellent opportunity to re- examine the best uses of CA storage. We in the Northeast have a rather stable CA situation, but changes are always being con- sidered and it is essential to keep abreast of current develop- ments so that we neither get left behind nor mistakenly apply new techniques without understanding them. ********** -12' TREE FRUIT PHYSIOLOGY TRIALS UNDERWAY AT THE CD. A. FARM OF FRELIGHSBURG , QUEBEC"^ Raymond L. Granger C.D.A. REsearch Station St-Jean-sur -Richeleiu Quebec, Canada J3B 6Z8 Response of apple trees to mycorrhizal fungus: In vitro propagated apple trees of the clones Mailing Merton 111 (MMlll) and Mailing 7 (M7) were planted in pots containing sterile chips of baked Montmorillonite clay and placed in a greenhouse. At planting time they were inoculated with vesicular-arbuscular (VA) mycorrhizal fungus (Glomus epigaeus), fed weekly for 15 weeks with a Long Ashton solution and watered with distilled water as needed. Tree height was measured once a week. At the end of the experiment both the total leaf area and the volume of the root system of every tree were also measured. Root samples of every tree were then stained with red Fuschin for microscopic examination. The weekly measurements showed the heights of the M7 mycorrhizae- treated trees to be 1.7 times greater than those of the control group (Table 1) . Table 1. Mean effect of Glomus epigaeus on the growth of two apple rootstocks (St-Jean, Quebec, 1981J. Rootstock Root volume (cm3) Leaf area (cm2) Plant height (cm) M7 treated untreated Mill treated untreated 16.06a^ 11.89a 12.72a 15.83a 479.56a 257.05b 392.29a 363.58b 38.67a 24.28b 37.17a 36.56a z Numbers in a column followed by a different letter are signi- ficantly different at odds of 19 to 1. Similarly, after 15 weeks the total leaf area and the root volume of the former were 1.9 and 1.4 times greater than the latter, growth differences having appeared three weeks after inoculation. At the end of the experiment microscopic examination revealed that the roots of both clones of inoculated M7 trees were colonized by the fungus (Table 2). However, no growth differences were observed on the trees of the MMlll clone (Table 1) 1 Talk presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association, Inc., July 15, 1981 -13- Table 2. Mean percentage of root penetration by Glomus epigaeus in two clonal apple rootstocks (St-Jean, Quebec, 1981)^. Tree No. MMlll rootstock M7 rootstock 1 17y 70 2 23 32 3 31 47 4 30 67 5 48 23 6 61 31 7 16 93 8 62 39 9 0.7 47 X 33 50 z No mycorrhizal colonization was observed on the control trees. y Each mean represents 90 systematic microscope scannings. These findings indicate that apple clones do not respond uni- formly to a given species of mycorrhizae. This phenomenon may reflect the different phosphorus requirements of each clone since mycorrhizae increase availability of P to roots. In vitro pro- pagation apple trees might benefit greatly from mycorrhizal treat- ments provided their genetic make-up allows for the mycorrhizal symbiosis along with the appropriate mineral nutrition regime. Training and density studies on compact apple trees: The Spartan and Mcintosh cultivars, grafted on M9, M7 , Ott . 3 and M26, were planted at 296, 592, and 984 trees/acre and trained as slender bell, oblique palmette, Van Roechoudt palmette and free standing trees. 1980 was the fourth cropping year for the trees of this trial. The highest yields came from the Spartan/Ott . 3 trees planted at a density of 984/acre and trained as slender bell. With a net profit of $1379/acre this combination almost reached the break-even point in 1980 and yielded 20,455 lbs/acre. The second most profit- able combination was that of Spartan/M9 planted at 484 trees/acre and trained intheslender bell system. It yielded 18,567 lbs/acre. The McIntosh/M9 trained in the Van Roechoudt palmette system was the poorest combination, producing only 506 lbs/acre. The free -14- standing trees o£ Spartan gave an overall mean of 12, 273 lbs/acre. Nutrition trial in a close planting of compact apple trees: Upon reaching their fourth leaf stage 'slender bell' shaped appl e trees, planted at 500 trees/acre had their third cropping year in 1980. Twelve fertilizer treatments were applied at zero, low and high levels of N, P, K, Ca, Mg to the cultivar Morspur Mcintosh grafted on M9, M7, Ott. 3 and M26. The best yields of 25 lbs. per tree were obtained from the trees submitted to low N and high amounts of the other elements. The analyses revealed that the amount of elements kept increasing in the soil, as did the pH in the Ca treated plots. Mg deficiency was the prime cause of low yields and poor tree vigor. Trees on Ottawa 3 were particularly sensitive to this deficiency while those on M26 proved to be affected mostly by lack of P. A low Ca regime aggravated preharvest fruit drop. Data on fruit and leaf mineral content are not yet available. ********** NOTES CONCERNING THE HARSH WINTER OF 1980 -SI-*- Raymond L. Granger CD. A. Research Station St -Jean- sur- Richelieu Quebec, Canada J3B 6Z8 The winter of 1980-81 was the second most severe of this century in the province of Quebec. It was preceded by drought in June and July, 1980 and then the fruit trees received an abundance of rain in early and late fall. Thus, the trees lacked maturity at the first cold period on September 28, 1980. Unhar- vested fruits were frozen on the trees. On Christmas Eve thermographs recorded -33 C for 2 hours at the CD. A. farm at Frelighsburg . This was followed by some bark splitting. From February 16 to the 24th in 1981 we had unusually warm weather. At this time some of our apple trees grafted on M. robusta 5 started to break their dormancy with bud swelling. In March we had some sun scald injury. April was more or less normal but in May a freeze was experienced at bloom and growers used burners and irrigation systems to protect their apple crop. Regardless of the fact that there were long periods without snow cover the frost penetration in the ground was not abnormal and no particular injury to the root system of fruit was noticed. I Talk presented at the Annual Summer Meeting of the Massachusetts Fruit Growers' Association, Inc., July 15, 1981. -15- It was the scion cultivars which were hit by cold and not the rootstocks. However, many apple trees on M. robusta 5 rootstock died this year with those 10 to 15 years of age parti- cularly affected. Trees over 20 years of age on M. robusta 5 were not damaged. It looks as if the young M. robusta trees which started to come into bearing were more susceptible to low temper- atures in late winter or early spring. The most affected areas in the province were those located along the U.S. Border and the Two Mountains region. The Rouville region proved to be somewhat less vulnerable to winter injury. The Lower St-Lawrence region (below Quebec City) suffered the least from the 1980-81 winter. The presence of a large body of water, the more abundant snow precipitation and the late blooming season of that location are certainly the prevailing factors which may explain the better performance of the fruit trees (apple, plum, pear, cherry) in this area. The cultivar Lobo sustained the least winter injury in all regions of the province. Along with Lobo some other cultivars such as Melba, Jersey Mac, Wealthy, Jonamac, Melred, Yellow Trans- parent, Vista Bella and Paulared proved to be cold resistant. However, cultivars such as Mutsu, Red Delicious, Golden Delicious, Northern Spy, Rhode Island Greening and Golden Russet were classed as those most sensitive to winter injury. Cultivars such as Mcintosh, Cortland, Idared, Empire, Spencer, Spartan and Red Haralson fell into the medium class of resistance to cold injury. Needless to mention, having experienced such a severe winter this year's apple crop is greatly reduced. Our average production for the past 5 years has been 5.3 million bushels. This year's crop will most likely fall between 2 or 3.5 million bushels. Because of the late spring frosts there also will be a larger percentage of culls (misshapen fruit) this year. Since the trees are weaker than normal there also is a fairly large quantity of apples that were attacked by diseases and insects. Special attention had to be given to the cold injured trees during the summer of 1981. Dead limbs were removed to prevent the development of cankers. Painting large pruning wounds or tree crevasses with Bordeau paint appears to have proven very effective. This paint consists of a mixture of 2 pounds of monohydrated copper sulfate or fixed copper (c.o.c.s., etc.), 4 pounds of hydrated lime and two parts of boiled linseed oil. It is important to mix the two powders first and then add the oil. Otherwise the mixture will not be uniform. Moreover the Bordeau paint dries very rapidly. It will harden within 6 hours if exposed to air. Since it is a paste- like mixture it could be easily applied with a brush. Other coat- ings such as interior white latex paint plus mercuric bichloride or plus a fungicide such as sulphur or Thiram have been used and seem to have served the purpose. In several cases a special tree •16- nutrition program was followed to help the tree to recover. A few growers who used soil injections with root feeding solutions claimed that it did help a great deal. In many cases irrigation has also helped tremendously. The winter of 1980-81 did more harm to pear, plum and cherry trees than it did to apple trees. The pear cultivars or selections which suffered most from cold injury were Bartlett, Beurre Bosc, Highland, 0-361, H-68- 31-1- 12 , HW-603, Baierschmidth , Larwick, Sierra, HW-601 and Magness. On the other hand the cultivars Flemish Beauty, Clapp's Favorite, Guyot, Enie, Caspar #5, Krol Sobiensky, Pioneer, Phileson, Soothworth and Luscious were quite resistant to cold injury. Najou, Aurora, Kieffer and Patten were of medium cold hardiness. Of 30 cultivars of plums evaluated only a few seem to be cold resistant. These are Mont Royal, Stanley, Grenville, Kahinta, Damas and Reine Claude. Among the sour cherry cultivars Meteor, Suda Hardy and English Morello seem to be more cold hardy than North Star and Montmorency. In general the trees which bore a bumper crop of fruits in 1980 proved to be quite tender to cold injury during the winter of 1980-81. The trees which were weak and the ones located in frost pockets or the ones growing in poorly drained areas behaved the same way. Many Mcintosh trees that were girdled (scored) 10 days after full bloom in 1980 died during the winter of 1980-81. Almost all the trees which had been pruned in November, December and January died. Severe summer pruning during June and July of 1980 created a weak resistance to cold stress. Deer damaged trees in many instances appeared as severely injured by the winter injury as those that were summer pruned. In many cases excessive herbicide applications caused the death of fruit trees. Thus factors that interfered with tree maturity during the summer and fall of 1980 had an important bearing on cold tolerance during this last test winter . White plastic mouse guards protected the bottom of many trees as well as did a heavy coat of snow. The trees pruned with the new TTS (Tip top shape) pruning method were less injured by cold than others. ********** 17- FRUIT NOTES INDEX FOR 1981 (This index of major articles has been prepared for those who keep a file of FRUIT NOTES. The number in parenthesis indicates the pages on which the item appears.) January/February Vol. 46, Vo . 1 Calyx-End Rot of Apples in Massachusetts (1-3) Disease Results for The 1980 Integrated Pest Management Program for Apples in Massachusetts (3-5) Research in Progress (5-11) An Update on Fruit Trees Injured in 1978-79 (11-12) Alternate vs. Every Middle Spraying for Apple Pests: 1980 Results For Arthropod Pests and 5-year Trends (12-17) SPRING ISSUE - Vol. 46, No. 2 Nectarine Varieties (1-3) Root System Distribution of Highbush Blueberry Under a Sawdust Mulch (4-5) Pomological Paragraph - Insect Larvae Entering Burrknots (6) Considerations in Establishing Grower-Owned IPM Organizations in Massachusetts (6-10) Pomological Paragraph - The Spread of San Jose Scale Revived Interest in Dwarf Apple Trees in the Late 1800's. (10) A Chemical Bird Repellent For Highbush Blueberries (10-12) Research in Progress (12-13) Control of Water Sprouts and Suckers With Tree-Hold* (14-15) SUMMER ISSUE - Vol. 46, No. 3 U.S. Apple Exports Mark 'Coming of Age' as Volume Registers 41-year High (1-4) Laboratory Repellency of Orchard Pesticides to The Mite Predator Amblyseius fallacis (5-6) Summary of Apple Growing Questionnaire (7-11) Grade Defects on Mcintosh Apples: Strip vs. Selective Pickings (12-16) . FALL ISSUE - Vol. 46, No. 4 Pomological Paragraph - Publications Available (1) Origin of Some Old and New Apple Varieties (1-4) Orchard Mouse Bait and The Weather (4-5) The Mediterranean Fruit Fly in Massachusetts: Can It Happen? (5-8) What's Happening in CA Storage Research? (8-11) Tree Fruit Physiology Trials Underway at the CD. A. Farm of Frelighsburg, Quebec (12-14) Notes Concerning the Harsh Winter of 1980-81 (14-16) Cooperative Extension Service U. S. Department of Agriculture University of Massachusetts Amherst. MA 01003 Official Business Penalty for Private Use, S300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE (AGR 101) BULK THIRD CLASS MAIL PERMIT DR. WILLIAM LOPD PLANT & SOIL SCIENCE FRENCH HALL DD 01003 I FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 47 No. 1 WINTER ISSUE, 1982 Table of Contents A Comparison of Tree Size, Productivity and Fruit Quality of Delicious Strains Pomological Paragraph A Visit to Yakima and Wentachee CA Storages Observations of the New York Fruit Industry Defoliation by Gypsy Moths Predisposes Young Apple Trees to Canker and Dieback Integrated Management of Apple Pests in Massachusetts 1981 Results: Insects Frost Heaving: Causes and Effects A COMPARISON OF TREE SIZE, PRODUCTIVITY AND FRUIT QUALITY OF DELICIOUS STRAINS W.J. Lord, F.W. Southwick, R.A. Damon, Jr., and J.F. Anderson The performance o£ Delicious strains at the Horticultural Research Center was discussed in a previous issue of FRUIT NOTES (Vol. 44, No. 6). Information reported here includes 1979 findings and data previously not presented. Experimental Design A planting was established in 1964 at the Horticultural Research Center, Belchertown, MA to evaluate the following Delicious strains on M7 rootstock: Richared, Turner Red, Jardine Red, Royal Red, Gardiner Red, Red Prince, Rogers Red, Sturdeespur (Miller Strain), and Starkrimson (Bisbee Strain), the last two being spurs. The experi ment was a randomized block design with 6 single-tree replicates. The trees were planted at 20 feet by 30 feet spacing. Summarized below are our findings to date. Tree Size The trunk cross-sectional areas of the trees with the standard- type growth habit were similar and about twice as large as those of the spur strains (Table 1) . Table 1. Mean size of the 7 standard and 2 spur strains of Delicious, 1979. Growth Trunk cross- 2 Tree Tree habit sectional area (cm ) height (ft) spread (ft) Standard 342 13 19 Spur 173 12 14 The difference in tree height was not large because commencing in 1977 we restricted height on the standard strains. Of particular interest to note is that we could have allowed 5 feet less spacing in-the-row and between- the-row for the spur trees than the standard trees without encountering tree crowding. No limb spreaders were used when the trees were young. This practice, which has recently been adapted almost universally, may have altered tree spread and productivity. Branches of spur strains are more upright growing than those on standard strains, but our differences are much less striking than what have been illustrated in some publications and what we have observed in some other orchards. 2- Nevertheless , limb spreading probably would have altered tree structure and spread more on the spur than on the standard strains. Other researchers have reported that the need of spreading is greater on spur than on non-spur Delicious trees and that the practice will increase fruitfulness . In an earlier study at the Horticultural Research Center we increased bloom but not fruit set on young Deli- cious trees by limb spreading. Nutrition Leaf analysis in 1972, 1973, 1977, 1978 and 1979 showed that within a year nitrogen, potassium, calcium, and magnesium levels varied among the 8 strains. In 1973 and 1979 the spur strains were higher in calcium than the standard strains. Nevertheless, no strain was consistently different from another in regards to nitrogen, pot- assium, calcium or magnesium levels in the leaves. Differences in leaf N and Ca among Delicious strains have been reported but it has not been shown that these differences persist among the same trees in successive years. It is of particular interest to note that the elements did not vary consistently between the standard and spur strains even though equivalent amounts of fertilizer were applied annually to both types of trees and the spur trees were smaller (Table 1). Our data suggest that it may not be necessary to fertilize spur and standard 'Deli- cious' strains differently. Production Why Delicious is unproductive in the eastern United States was the subject of a conference hosted by the USDA in 1977. Researchers in attendance stated that strains differ in fruitfulness but there was a lack of supportive data. It was reported that spur-type strains perform somewhat better than standard-type strains and that Red Prince, Richared, and Royal Red in some apple growing areas are less productiv( than other strains. We lost 2 of our Red Prince trees in 1972, but by statistical techniques it was possible to obtain an estimate of yields. Thus, the productivity of Red Prince in comparison to other strains in the test is reported. Early production: Yield data was first recorded in 1970 when the trees were in their 7th year, and at this time the strains averagec at least a bushel per tree. In 1970 production per tree was similar among strains. Gardiner Red Produced more fruit per tree than either spur strain in 1971. In 1972, Turner Red was more productive than the spur strains. Although yield per tree favored the more productive standard-type strains in 1971 and 1972, higher tree numbers per acre are possible -3- with spur trees. Actual spacing trials provide the most reliable estimate o£ yield per acre. In absence of these, we arrived at theoretical tree spacings for the strains by using tree spread in 1979. Theoretical yields per acre were determined by multiplying average yield per tree by trees per acre. The theoretical yields showed that Sturdeespur was more productive in 1970 and that there was no difference in productivity between standard- type and spur- type trees in 1971. In 1972, Turner Red was as productive as Stur- deespur and Starkr imson. Thus, in this study yields per acre in the early fruiting years favored neither the standard nor spur-type strains . Yields from 1970 through 1979. The mean cumulative yield per tree, except for Red Prince, was higher on the standard trees than on the spur trees. Theoretical cumulative yields per acre of Sturdee- spur and Turner Red were similar but Sturdeespur was more productive than the 7 other strains. Sturdeespur had the highest production efficiency (production per area occupied) of all strains. The theoretical cumulative yields of Starkrimson, Red Prince, Rogers Red, Richared, Royal Red, GardinerRed and Jardine Red were similar. Thus, the results of our strain comparisons differ from those re- ported from other areas which indicate that Red Prince, Royal Red, and Richared are less fruitful strains of Delicious. The mean yield of the 36 Mcintosh pollinator trees in compari- son to that of the Delicious strains are of interest because the trees were interplanted in the same block. This frequently is not true when yields of Delicious have been compared to other cultivars. The Mcintosh pollinators averaged 11.2 bushels per tree in comparison to a mean of 1.1 bushels for all Delicious strains in the frost year of 1977 (Table 2). However, except for 1977, the standard strains of Delicious and Mcintosh were equally productive. Our study shows that consistent high yields of Delicious can be obtained if the trees are planted on a relatively frost-free site and provision is made for adequate cross-pollination. Table 2. Comparative yields of Mcintosh and Delicious strains with standard growth habit. Cultivar Yield (bushels per tree) in: 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 Mcintosh 2.0 3.7 2.4 8.3 5.6 14.2 9.5 11.2 15.1 14.1 Delicious 1.3 3.6 2.8 9.6 4.1 9.2 11.0 1.1 13.2 15.1 Fruit color: With the exception of Rogers Red, which is a tree sport found in Massachusetts, the color characteristics of the strains have been described by others since our study was initiated. Most fruits of Red Prince were striped whereas descriptions from other areas vary from prominently striped, to slightly red striped during early period of coloration, to solid red. Rogers Red has blush-type fruits with color intensity similar to Royal Red in most years. Red color on Turner Red lacks some- what in uniformity and is less intense than on Starkrimson, Royal Red, Sturdeespur, and Rogers Red. J.E. Swales, Summerland, B.C. stated (personal communication) that Turner Red has proven very stable in Okanagan Valley of British Columbia and no lack of uni- formity of color has been observed where the fruit is well exposed to sunlight. Like ourselves. Dr. Marshall Ritter in Pennsylvania reported that color of Turner Red was quite variable. The fruits of Jardine Red are blush with some striping but lack intensity of red to meet present standards for color. Sturdee- spur, Starkrimson, Royal Red, and Rogers Red have consistently been rated high for color by our orchard personnel and pomology students because of their intense red color. In good coloring years, however, some individuals considered these strains too dark and preferred the bright red blushed fruit of Gardiner Red and Richared. Fruit Weight and Shape We measured fruit weight and fruit shape in 1978, 1979 and 1980 because some early evaluators of Delicious sports reported some mutants produced longer fruits. Starkrimson fruits were smaller than Royal Red, Richared and Rogers Red in 1978 but there were no differences among strains in 1979 and 1980. The fruits of Starkrimson (spur strain) and Gardiner Red (standard strain) were longer than those of Jardine Red in each of the 3 years, otherwise there was no consistent difference among strains in fruit length. Thus, our data on fruit length appear to differ somewhat from those of researchers in Washington and British Columbia. Ketchie and Olsen in Washington found no specific trend in fruit circumference, weight or shape. These workers concluded that there may be more variability in fruit size and shape among years and locations than differences among strains themselves. Meheriuk et al. in British Columbia showed that the fruits of spur strains were longer than those from standard strains but in our study Sturdeespur was not longer than the standard strains. Watercore Fewer Starkrimson fruits had watercore in 3 of the 4 data years but many fruits were as severely affected with the disorder as some other strains. The severity of watercore at harvest is of more concern than the presence of the disorder. Watercore will disappear 5- from a high percentage o£ fruits during storage but internal break- down may develop in severely affected fruits. In contrast, an earlier 3-year study by the senior author showed that watercore was more severe in Richared than Starking Delicious, Overmaturity is a common problem with Delicious in new England because the fruits are not harvested until Mcintosh and other earlier-maturing cultivars have been picked. Watercore is of annual concern and a reliable index of overmaturity under our con- ditions. Based on watercore development, it appears that strains of Delicious mature at different times but the present study and those of others indicate that maturity differences may be small; however, these differences might be accentuated by local conditions. Spur Flowering and Fruiting of Three Strains During the 1979-80 and 1980-81 periods the amount of flowering and fruiting on previously fruiting or non-fruiting spurs was determined for Red Prince, Richared and Starkrimson (spur-type) strains of Delicious. The relationship of seed number to subsequent flowering of previously fruiting spurs was studied as well. Table 3. Flowering and fruiting of three Delicious strains, 1979-80 Strains % Spurs flowering in 1980 Avg seed number, 1979 fruiting spurs Fruiting Non-fruiting Flowering Non-flowering in 1979 in 1979 in 1980 in 1980 Red Prince Richared Starkrimson 13 57 2 64 89 60 4.7 4.4 3.0 6.5 5.9 6.3 Table 4. Flowering and fruiting of three Delicious strains, 1980-81 % Spurs flowering in 1981 % 1980 fruiting % 1980 non-fruiting Fruiting Non-fruiting spurs spurs in 1980 in 1980 fruiting in 1981 fruiting in 1981 Red Prince 11 Richared 12 Starkrimson 2 93 76 78 4 7 2 38 29 36 It is apparent (Table 3) that spurs which failed to bear fruit in the previous year are much more apt to flower the following year than those which fruited the year before. The Richared strain was more likely to produce spurs which bear fruit one year and flower the next year than the other t\\?o strains. However, the spur- type Starkrimson strain is clearly inferior in this regard to either Red Prince or Richared. The data also show that spurs bearing fruit with low seed num- bers were more likely to produce a "repeat" bloom. The data obtained in 1980-81 (Table 4) show that the 1980 fruit- ing spurs which flowered in 1981 set very few fruits in 1981 in com- parison to the spurs that did not fruit in 1980. This v\?as most noticeable for the Starkrimson strain where only 1% of the 1981 "repeat" bloom set fruit whereas 361 of the 1980 non-fruiting spurs possessed apples in 1981. These data indicate that a sizeable proportion of non-fruiting spurs are essential on bearing trees if substantial annual production is to be maintained. Summary A planting was established in 1964 and 1965 to evaluate the following Delicious strains: Red Prince, Jardine Red, Royal Red, Turner Red, Richared, Rogers Red, Gardiner Red, Sturdeespur, and Starkrimson the last 2 being spur types. The strains have been evaluated through 1980. Leaf N, K, Ca and Mg levels varied among the strains but none was consistently different from another. The cumulative yield per tree from 1970 to 1979 was higher for all stand- ard strains except Red Prince than for the spur strains. Theoretical cumulative yield per acre was highest for Sturdeespur and signifi- cantly higher than all other cultivars with the exception of Turner Red. Sturdeespur had the highest production efficiency. Watercore severity at harvest was inconsistent among the strains, but in 3 of 4 years fewer Starkrimson fruits were affected. A sizeable num- ber of non-fruiting spurs are essential each year on bearing trees if substantial annual production is to be maintained. ********** POMOLOGICAL PARAGRAPH Publication available. A book entitled "Tree Fruit Growth Regulators" edited by Ronald B. Tukey, Washington State University and Max W. Williams, USDA-SEA-AR, is available for $12 from Growth Regulators, Conference Office, Room 323, AG. Sciences II, Washington State Univer- sity, Pullman, WA 99164. Checks should be made out to Washington State University. This book is a compilation of papers presented at a shortcourse held in February, 1981 on the subject of growth regulators and chemical thinning of deciduous fruit trees. Among the topics dis- cussed are: growth and development of fruit trees, pollination and fruit set, growth regulator and cultural techniques to promote early fruiting of apples, physiological aspects of pruning and training, chemical thinning of apples, and growth regulator uses of tree fruits. This book should be valuable to growers desiring to increase their understanding of fruit trees and of the use and action of plant growth regulators . -7- A VISIT TO YAKIMA AND WENATCHEE CA STORAGES Dr. G. David Blanpied Department of Pomology Cornell University A group of 6 eastern CA storage specialists spent July 27 in Yakima with D. Loyd Hunter (Food Plant Engineering, Inc., Yakima) and July 28 in Wenatchee with Dick Bartram (Coop. Exten- sion Agent, Chelan County). In this report I will share with you some observations from these visits. CA construction in Washington is booming. Approximately 4 million boxes of new CA capacity will be added in 1981 to their present total of about 26 million. Their construction techniques are very different from ours. Perimeter walls are almost exclu- sively tilt-up concrete panels, which are poured at the construc- tion site. Polystyrene insulation (less expensive than urethane) is frequently set into the wet concrete before erection. The gas seal for the inside of the perimeter walls, a thin layer of sprayed urethane, is applied to the polystyrene after the panels are erected. Urethane in storage rooms is covered with a fire barrier (Zonolite- 3300) . Partition walls and ceilings are 3/8 to 1/2 inch plywood (waterproof glue) nailed to 2 inch x 6 inch wall studs or to ceiling joists, leaving 1/16 inch spaces on all sides. Seams between the plywood sheets are then filled and taped. Wall-wall, wall-ceiling, and wall-floor joists are flashed. The partition walls and ceiling are then spray coated twice with an acrylic rubber coating. Ceilings and warm interior walls are insulated with fiberglass; walls common to 2 storage rooms are not insulated. The plywood-acrylic rubber gas seal is used for the partition walls and ceilings to cut costs. Under Eastern U.S. conditions of outside high relative humidity, the plywood-acrylic rubber gas seal should be considered only for ceilings, and then only when attic spaces are well ventilated to keep the insulation dry. Built-up roofs are installed and built with a slight pitch above aluminum, laminated-wood trusses, which are not available in the east. Although roofing felt between 2 concrete slabs is sometimes used to seal floors, a single concrete slab treated with a floor sealer and hardner is frequently used. A metal-clad, sliding door is usually sealed with rubber gaskets between the door and the jam or with duct tapes applied inside the room after the room has been filled. What's the turn-key cost, including electricity and refriger- ation? About $3 per box for a one million box plant, and $3.75 if only 100,000 box capacity is built. In the east we pay in excess of $5 per box. Are they tight? Most storage operators require a pressure drop of 1 inch to no less than 0.75 inches water gauge in 1 hour. They get it. Many of our CA rooms could meet that requirement, but many are not that tight. CA equipment in most establishments is similar to ours. I believe all rooms are equipped with a Tectrol-Samif i or a COB oxygen burner. After the rapid O2 pulldown, CO^ scrubbing is usually done with lime and/or a molecular sieve"scrubber . The latter draws many kilowatts, which cost only l.lfilliam J. Manning Department of Plant Pathology Canker and dieback diseases were unusually prevalent on apple trees of all ages in Massachusetts in 1981. The fungi that causes these diseases are weak pathogens that usually infect and cause disease only on trees weakened by various stress factors, such as drought, winter injury, etc. Cold temperature injury from the previous winter seemed to have weakened a number of young trees. Sunken cankers were noted at the origin of young branches on trunks (see Figure 1). The young branches were often girdled and dieback resulted by late June or early July. In other cases, dark sunken lesions developed near branch tips, resulting in dieback of new shoots. The canker- causing fungus Nectr ia isfas usually associated with these dieback problems. mc 1 bloc Cent comp Deli a re tree dieb 1 is have on t from in c this Cyto An dence k at er in letel cious suit s dev ack . an e been hese gyps anker case spora intere occur the Ho Belch y def o , Mu t s of the eloped The c X ample some trees, y moth and d , caus sting cas red in ou rticl tura ertown . 1 iated so u and Rom defol iat cankers anker sho While cold temp it appea dcfoli at ieback th ed by the e of canker r own new 1 Research Gypsy moths me young Red e trees. As ion, these and branch wn in Figure these may erature stress rs that stress ion resulted at was , in fungus 1 Apple Pest Management Technician Fig. 1. Cytospora canker on 3-year-old Red Delicious following severe defoliation ^y gypsy motli caterpillars. Professor of Plant Pathology 15 Defoliation by gypsy moths alone will not kill a young apple tree. This defoliation, alone or combined with other stress factors, may result in predisposition to cankers and extensive branch die- back of young apple trees. A********* INTEGRATED MANAGEMENT OF APPLE PESTS IN MASSACHUSETTS ,1 1981 RESULTS: INSECTS" . 3 3 •m , L.J. Mancino , D. C. Sienkiewicz^ , R. Spitko4, and R.J. Prokopy 5 W.M. Coli^, G.E. Morin^, L.J. Mancino"^, D. Gordon"^, T. Green^ Summary of Results - Intensive weekly scouting and grower advise- ment in 19 orchard blocks that had been on an IPM program for one or more years resulted in a savings in insecticide and miticide use (dosage equivalents) of 21% and 60% respectively compared to the checks. Fruit injury in such IPM blocks averaged 2.51 versus 2.0% in the checks. In spite of this slightly higher injury level, IPM blocks experienced a benefit of $40.18/A from IPM (exclusive of scouting costs) . Number of Orchard Blocks Scouted - In 1981, each week (April 1 through October 1) field staff visited 41 IPM blocks (about 450 acres) in 22 commercial orchards throughout the major fruit-growing regions in the state. Growers received a written scouting report and were contacted either in person or via telephone by the IPM Specialist and advised as to the need for spraying, materials to use and timing. 1 Special thanks to Mr. David Chandler, Meadowbrook Orchard, Inc. , Sterling Junction, for allowing us to room 3 scouts at his housing for harvest labor, throughout the summer. 2 Pest Management Specialist 3 Senior field scouts 4 Field scouts 5 Extension Entomologist 6 Reduced spray programs on apples have been discussed in previous issues of Fruit Notes: 41(1), 41(2), 41(3) and 43(3), and our 1978, 1979 and 1980 results were summarized in Fruit Notes 44(1), 44(6) and 45(6) . -16- In addition, 7 commercial check orchards were monitored for presence o£ aphids and mites and their predators 2-3 times during the season. An on-tree survey of insect and disease injury was performed in these check orchards as well as an analysis of spray usage. Grower Financial Support and Cooperation with IPM Specialist Advise- ment - Participating IPM growers paid $16-20/A (depending on total acreage scouted) for insect scouting and advisement in 1981. The charge for disease scouting and advisement was $100 per orchard. Total grower contribution to the IPM program was $8,500 (up from $4,500 inl980) . This was used to pay scout salaries. The degree of grower cooperation with IPM specialist recommen- dations was quite high in 1981, averaging 89% cooperation (range 651 - 100%) compared to 78% cooperation in 1980. This indicates increasing willingness of IPM growers to (a) rely on predators when possible, (b) to better synchronize sprays with vulnerable stages in pest cycles, (c) to use reduced rates of pesticides, and (d) to withhold sprays entirely should pest numbers be below economic threshold levels. Sampling Methods - We have discussed our monitoring techniques in previous issues of Fruit Notes: 44(1), 44(6) and 45(6). With few changes, we employed these same methods in 1981 with the principal changes being: more extensive use of San Jose Scale (SJS) pheromone traps than in 1980, field testing of a visual trap for monitoring Spotted Tentiform Leafminer (STLM) , and mite brushing of leaf samples taken proximal to "hot spots" rather than at random locations in blocks . Results New or Unusual Outbreaks - The Gypsy Moth (GM) was a problem at numerous sites in 1981. Early instar larvae "ballooning in" were controlled well by pink sprays of endosulfan (Thiodan) or azinphos- methyl (Guthion) . In cases where insecticides were not applied at pink, petal fall sprays provided excellent control, but in some cases not before foliage and fruit were fed on extensively. Later instars were also troublesome, as the large larvae migrated from defoliated hardwood stands into adjacent orchards in search of food. In some cases, repeated border sprays were required to prevent extensive damage from these GM larvae. Pesticide resistant Spotted Tentiform Leafminer (STLM) advanced into central and eastern parts of the state. First generation STLM counts averaging only 0.1 mine per leaf (10 mines per 100 observed leaves) resulted in second generation counts averaging 0.8 mines per leaf, and third generation counts averaging 2.8 per leaf. No IPM blocks experienced pre-harvest drop that could be char- acterized as severe and clearly related to STLM injury. In most -17- cases, drop severity appeared more related to factors such as calcium chloride application, stop-drop use, tree vigor, or crop size. 1981 data collected with the cooperation of IPM grower Elmer Fitzgerald, Jr. of Ashby, MA., indicated that while STLM injury undoubtedly predis- posed apple trees to a certain amount of pre-harvest drop, moderate to severe phytotoxicity from calcium chloride sprays in one block where third generation STLM was controlled (only 0.8 mines per leaf), resulted in substantial drop (19-0 compared to an adjacent block (11% drop) where second generation and third generation mines reached l.S and 4.5 mines per leaf, respectively. Fruit Injury - As mentioned above, degree of grower cooperation with IPM special ist advice was generally excellent . Consequently, compari- son of good cooperator blocks (18) with the few partial cooperator blocks (5) as in 1980 was not feasible. For the following reasons, we chose for purposes of analysis to group IPM blocks as either First Year IPM or previous year IPM (those blocks which have been on the IPM program for one or more years previous to 1981) : (a) First Year IPM blocks typically present numerous residual pest problems (1st year growers frequently assign field staff to monitor "problem" blocks) , (b) there may be less likelihood of bio-control agents being present in First Year blocks in substantial numbers due to previous spray practices, (c) program field staff are hampered by a lack of knowledge as to which pests can be expected to exert the most serious pressure on First Year blocks. Overall, fruit injury in Previous Year IPM, First Year IPM, and check blocks was 2.5, 3.7 and 2.0"^ respectively (Table 1). All these were within acceptable injury limits for Massachusetts commer- cial orchards. As in previous years, injury from Tarnished Plant Bug (TPB) , represented the largest single source of fruit injury from insects in Massachusett 's commercial orchards. It is questionable whether or not this injury is economically important, however, since a relative- ly small proportion (4%) of such injury results in downgrading of fruit quality during packout. White rectangular TPB traps indicated that several IPM blocks could safely eliminate pre-bloom insecticide sprays directed at TPB. Due to substantial pressure from Gypsy Moth and Spotted Tentiform Leafminer, however, only three such blocks were actually able to do without pre-bloom insecticide sprays in 1981. San Jose Scale (SJS) injury ranks third in importance in Pre- vious Year IPM (0.271) or check blocks (0.23%) but second in im- portance in First Year IPM blocks (0.94%). The relatively high average injury from SJS in First Year blocks resulted primarily from assess- ment by 2 growers that SJS was not a serious enough problem to require the recommended spray treatments. We feel that a year of experience in IPM blocks allows us to develop a management program for SJS that leads to effective control. For example, a partial cooperator IPM block that in 1980 had 55% injury to fruit from SJS sustained only -18- 1.81 injury from SJS in 1981 after a concerted effort by field staff and the growers to accurately time sprays with regard to observed stages of SJS development. Plum curculio injury was substantially lower than in 1980, amounting to 0.61, 0.74 and 0.47% injury in Previous Year IPM, First Year IPM and check blocks respectively. PC injury in most injury Injury from European Apple Sawfly (EAS) , Apple Maggot Fly (AMF) , Codling Moth (CM), White Apple Leafhopper (WAL) , Green Fruitworm (GFW) and Leafrollers (LR) was relatively low in all blocks. Total injury from these pests averaged 0.28, 0.35, and 0.75% in Previous Year IPM, First Year IPM and check blocks respectively. One block of 5 year old "spur-type" Cortlands on M7 experienced substantial injury from first generation European Corn Borer (ECB) . This was observed during the course of grower hand- thinning of fruit, although no injury from ECB was found at harvest. This is perhaps because hand thinning removed the protected feeding sites within fruit clusters on spurs, and aided in spray penetration and control. It is also possible that sprays against apple maggot killed second generation ECB adults or that mowing of tall grasses and weeds near the trees deprived ECB adults of egglaying sites. Mite Populations - 1981 marked a partial resurgence of popu- lations of Amblyseius fallacis, our major predatory mite. It was found in relatively high numbers (> 0.4/leaf) in 8 IPM blocks in 1981, while no A. fallacis were found in check blocks (Table 2). This compares to 1980, when predator numbers were extremely low throughout the state, perhaps due to high overwintering mortality resulting from lack of snow cover. With a few exceptions, spider mites were more easily controlled in 1981 than in other years, although some blocks, especially those with normally troublesome cultivars such as 'Puritan' and 'Delicious' required repeated treatments. Other blocks, several of which had required miticides in the past, needed little if any miticide. Heavy oil use directed at San Jose Scale may have contributed to this latter phenomenon. In addition, heavy rain showers in May, June and July may have contributed to the fewer than usual mite pro- blems in 1981. Insecticide, Aphicide and Miticide Use. Previous Year IPM blocks (averaging 7.95 sprays, range 3 to 11) and First Year IPM blocks (averaging 7.57 sprays, range 5 to 10) received 23% and 26% fewer insecticide applications, respectively, than check blocks (average 10.28 sprays, range 8-13) (Table 3). -19- Uneven performance of repeated, early season endosulfan sprays for STLM adult control, as well as an earlier than normal third generation of STLM in some blocks, required unanticipated added use of methomyl or oxamyl in IPM blocks. Insecticide use in IPM blocks would likely have been lower had growers been advised to rely more heavily on early season use of the latter two materials. Residual San Jose Scale problems in several blocks necessitated frequent sprays aimed at this pest. Fortunately use of Penncap M against scale also provided excellent apple maggot control. Previous Year IPM growers applied 34% fewer miticide sprays compared to the check, while First Year IPM growers applied 10% more such sprays. Difficulties with First Year grower sprayer calibration, poor penetration of concentrate sprays into overly thick tree canopies, and the reluctance of some of these growers to utilize spot treatments for mites, probably account for this differ- ence . No aphicides were used in check or IPM orchards in 1981, and syrphid fly and cecidomyiid midge predators of aphids were abundant in most blocks (Table 2). Predator numbers, combined with numerous hard rainshowers in June and July, helped to keep fruit from accumu- lating aphid honeydew. Endosulfan used for STLM control may have resulted in a highly favorable prey/predator ratio, with an enhanced likelihood of biological control. Dosage equivalents (DE) of insecticide and miticide use reflect- ing pesticide application rates, showed patterns similar to those for number of spray application trips. DE of insecticide used in Previous Year and First Year IPM blocks were 11% and 26% less than the check. DE of miticide used were 60% lower in Previous Year IPM blocks compared to the checks, while First Year IPM blocks used 10% fewer miticide dosage equivalents than the checks. Cost and Benefit Comparison - Table 4 summarizes our cost benefit analysis of IPM vs. check blocks in 1981. Both Previous Year and First Year IPM blocks realized substantial savings in insecticide and miticide materials costs, as well as spray application costs, compared to the checks. Due to somewhat higher fruit injury levels, however, value of fruit loss due to insect injury was $25.26 and $87.54/A higher than the checks in Previous Year and First Year IPM blocks respectively. As a result, while Previous Year IPM blocks experienced a net benefit from IPM of $40.18/A, First Year IPM blocks experienced a net loss of $29.84/A. It should be emphasized that this analysis is intended to show relative not absolute numerical or percentage differences, and that the values therein are average ones. As such, they do not reflect grower wholesale prices for spray materials, per acre yields higher (or lower) than 550 bu/A. , nor fruit prices that may differ substan- tially from those used in this analysis. -20- This latter analytical component likely introduces substan- tial error in 1981, a crop year when growers throughout the state are reporting better than normal packout percentages (i.e., relative- ly few fruit being culled for insect or disease injury, poor color or poor size). Recent work of Bahn, et al . (Fruit Notes 46:3) shows that only about a third of insect injured fruit observed in on-tree harvest surveys actually ends up in the cull bin. As a consequence, we believe that the "avg. value/A of fruit loss due to insect injury' parameter should not be weighed as heavily as it is here, and that the cost benefit analysis should principally reflect differences in spray application and pesticide material costs. Pesticide Use and Insect Injury, 1977-1981. Figure la details trends in Insecticide use in IPM and check blocks since the onset of the Massachusetts' Apple IPM program. These data indicate that while check insecticide use has remained relatively constant at or near 1977 levels, IPM growers (all 1980 IPM data from 18 good cooperator blocks) have substantially reduced the number of dosage equivalents of insecticide used in their orchards, averaging about 30% fewer such sprays during the four year period noted. A similar pattern is evident in Figure lb, with IPM orchards registering about 601 fewer dosage equivalents of miticide used in comparison to the checks. Check blocks nonetheless showed a slight downward trend in miticide usage over this period as well. Such savings were not made at the expense of fruit quality, however. Figure Ic indicates about 201 less permanent type fruit injury in IPM blocks vs. the check overall, with IPM blocks sustain- ing less average injury than the check in 3 out of the 4 years. Fruit injury resulting from aphids has been relatively unimport- ant during the period cited (Figure Id) with a steady downward trend evident in IPM and check blocks alike. -21- Table 1. Average percent insect injury on fruit at harvest in Previous Year IPM, First Year IPM , and check commercial orchards in Massachusetts, 1981. 1981 Injury (%)^ Check (7 blocks) 1.20 0.47 0.23 0.02 0.04 0.01 0.01 0 0.03 0 Previous Ye y ar-' First Year Insects IPM (20 bio cks) IPM (21 blocks) TPB 1.25 1.57 PC 0.61 0.74 SJS 0.27 0.94 EAS 0.16 0.11 GM 0,11 0.14 AMF 0.05 0.12 LR 0.05 0.03 WAL 0.02 0.07 GFW 0 0.01 CM 0 0.01 Total Insect Injury 2.52 3.73 2.01 ^Based on on-tree survey of 600-2400 fruit per block at harvest (100 fruit per tree from each of 2 trees adjacent to each trapping station) . ^Orchards which have been on an IPM program one or more years. 22- n Tl ►D o H 3" H- >-! <-t C3 ro 11 (B n a* n CO < 3* M 7^ rt o B3 (D Kj c a to n> CO p rt i-t k! v; (D ^a T) S M PJ (D M fD '-O i-l (D 03 s M (ti C n abundan daceous s M ^ C» CL t-i •z •a o • • • O c H- ft) -O -P- 00 3 "O s CL H- (D cr (B 03 rt IB fD t^ rt ro 3 o Ml g "o H- (B rt 03 H fB 7^ s: g CD o H- » CO o o o g rt 03 • • • H- CD n M g Ol vO ^J rt T) (D O CO rt ■d M fB rt ft) • ex. m n 0^ (B 03 o C t-t) CD r i-h 1— 1 03 o O o M cf rt • • M M H- h-" M D3 ^ O > s: CU rs3 K3 T3 H- CD ON ■^ CJN 3" rt CO CO s: 03 I rt ■< H- ^9 ti M c» a^ t^ rt T3 3- rt -o 3^ m ti H- n fB CL g CL CO 3 &3 CD 03 rt O ti CO n s (D H- 03 O rt 3 H' Ui ON H- 3- D- O 3 a. CO O 13 fB CD (-t D- 23- Table 3. Number of pesticide treatments and dosage equivalents^ of pesticide applied for insect and mite pest control in IPM and Check blocks, 1981. Treatment Previous Year'' IPM blocks First Year IPM blocks Check blocks Oil 1. ,1 Insecticide 8. ,0 Miticide 0. .9 Aphicide 0 Dosage equivalents Oil 1, .0 Insecticide 6, .2 Miticide 0, ,4 Aphicide 0 0.9 7.6 1.4 0 1.0 10.3 1.3 0 0.8 6.3 0.9 0 1.1 8.5 1.0 0 Blocks which have been on an IPM program for one or more years Vy. • T ^ Actual pesticide rate/100 gal •^Dosage equivalent = -r 7—^ 3— -3 — ■■ — ^-o — t^ — ^ ^ Amount recommended in Southern New England Apple Pest Control Guide 24- Table 4. Cost benefit comparison of insect and mite results in 20 Previous Year IPM, 21 First Year IPM and 7 Check commercial apple blocks in Massachusetts, 1981. Parameter Orchard Previous Year IPM First Year IPM Check Difference (%) vs. check Previous Year IPM First Year IPM (Avg. no. sprays/A) Oil Insecticide Aphicide Miticide 1.1 0.9 1.0 +5 -9 8.0 7.6 10.3 -23 -26 0 0 0 0 0 0.9 1.4 1.3 -34 +10 (Avg. no. of dosage equivalents /A) Oil Insecticide Aphicide Miticide 1.0 0.8 1.1 -10 -28 6.2 6.3 8.5 -27 -26 0 0 0 0 0 0.4 0.9 1.0 -60 -10 (Avg. cost /A spray materials) Oil Insecticide Aphicide Miticide $26.16 $87.86 0 $11.74 $20.93 $95.53 0 $19.11 $28.78 $124.87 0 $28.59 -$2.62 -$37.01 0 -$16.85 -$7.85 -$29.34 0 -$9.48 (Avg. application cost/A)^ (Avg. % Insect injury) $35.37 2.5 $33.30 3.7 $44.33 2.0 -$8.96 +25 -$11.03 +85 (Avg. value/A of fruit loss due to insect injury)' (Avg. net benefit or loss from IPM)" $126.46 $188.74 $101.20 +$25.26 +$40.18 +$87.54 -$29.84 Based on 15 mins time to spray one acre, $6.05/hr labor cost and $2.42/acre per spray date for fuel and oil. ^Based on average values as of Nov. 15: U.S. Fancy Fruit @ $12.50/bu, U.S. //I fruit (a $8.50/bu, cull fruit @ $3.30/bu and average yields of 550 bu/A. w. Does not Include cost of scouting, traps, travel or administration in IPM blocks (estimated at $45.00 per acre per year). 25- Figure 1. Trends in Pesticide Usage and Insect Injury to Fruit, 1977-1981. OJ W) p /^-^ U3 Q) XJ T3 C •H 0) O 1—; •H (C U > O •H (U D m cr c W M (U H-l 00 o CO CO 4J o e P 3 ^—' •77 Insecticide Usage IPM« — — « // of blocks ( ) X= 8.98 b. Miticide Usage IPK« • '78 '79 '80 @ 30% reduction '81 '78 '79 '80 '81 @ 60% reduction c 0) u u w Pu Total Insect Injury to Fruit at Harvest 3.91 w •H a < E O 1-1 D •I—) C M ,2 -■ ,16 .12 .08 .OA ,. '78^ Aphid Injury to Fruit at Fiarvest IPM( CHECK© O '79 '80 26- FROST HEAVING: CAUSES AND EFFECTS Peter L.M. Veneman Department of Plant and Soil Sciences Soil structure is generally improved by the annual cycle of freezing and thawing. These processes result in better aeration, increased water holding capacities, smaller clods, and smoother seedbeds. Considering these beneficial effects most agronomists and soil scientists will recommend fall plowing to farmers espec- ially in areas where fine textured soils are predominant and if soil erosion during the following winter and spring is not of great concern. While freezing and thawing cycles may be advan- tageous for the production of annual crops, their detrimental effects on perennials such as alfalfa have been demonstrated in those parts of the country where the soils are periodically frozen. Like alfalfa, the fruit tree has its feeder roots in the upper 18 inches of the soil profile, which is also the part mostly affected by annual frost action. In the spring and early summer of 1979 we observed that many trees throughout Massachusetts experienced root injury the preceding winter especially on sites with soil drainage problems. Injury initially was limited to the tree roots but later in the year it resulted in the loss of some branches and in the most severe cases the trees died. Some of the partially damaged trees are still weak and need to be replaced. Most of the winter injury problems are related to the formation of ice lenses in the soil profile as a result of excess soil water. Since the cold season is with us once again, it seems appropriate to discuss this matter in greater detail in this winter issue of Fruit Notes and to indicate possible ways to prevent such damage to fruit trees in the future. Frost heaving occurs mostly on moist to wet soils, although it sometimes can be found in well drained, fine textured soils with shallow water tables. Researchers (2) studying the susceptibility of alfalfa to frost heaving in southern Illinois found that poorly drained soils with high ground water tables exhibited the most heave and greatest winter-kill of alfalfa seedlings. Well drained soils had some heave but this did not result in significant injury to the plants. These experiments showed that the greatest amount of heave occurred when the night temperatures were a few degrees below freez- ing and the day temperatures were above 32 F. Water in freezing soils is transformed into ice crystals. This ice functions as a center for further crystallization of moisture when additional water is allowed to flow towards the frozen part of the soil, which can happen when the initial soil was wet or has a water table close to the soil surface. As long as water can move -27- through the soil, the ice will continue to grow, until most pores are filled with ice and the formation of ice lenses begins. The overlying soil is pushed up while the ice lens is expanding. Most injury to the plants occurs at this time. The roots are locked in the frozen soil clods and when an ice lens is forming between the clods, it pushes the aggregates apart with a force much greater than the strength of the roots, resulting in breakage of especially the smaller roots. The tree loses part of its anchorage and is pushed up with the overlying soil by the growing ice lens, or more likely, a combination of several such lenses. When the weather warms the following spring, some of the surrounding soil may fill the cavity left by the ice lens while the tree remains uplifted, thereby exposing the roots. This may result in drying-out of the roots or injury by subsequent cold temperatures. The immediate cause of frost heaving is excess moisture, but a soil does not always have to be excessively wet to be prone to heaving. Dirksen and Miller (1) in a series of laboratory experi- ments found that water lost from the unfrozen soil enters the frozen soil and causes its ice content to increase. This transport of water occurs even when the soil is frozen, through thin liquid water films associated with the ice surfaces. These researchers (1) concluded that when ever the soil was about 901 saturated, ice wedge formation and thus heaving could be expected. The practical implication for the fruit grower is to provide adequate soil drainage. When the soil is kept sufficiently dry the movement of water in the soil is reduced and ice lens formation and subsequent frost heaving can be prevented. Sometimes, such as during the 1978-79 winter, the weather conditions may be so adverse (e.g., rainstorms during short, warmer periods in the winter) that significant wetting of the profile occurs and frost heaving results. If the grower suspects that such root injury occurred, measures such as extra pruning should be taken to balance the above-ground vegetative parts with the reduced root system. This will be especially important when the growing season following the winter injury has lower than average rainfall and thus puts an extra demand on the already strained root system. The extent of the root injury also depends on the soil texture. Sandy soils drain quickly, have a lesser capability to utilize water and are therefore less susceptible to winter injury. The finer textured soils are generally more prone to frost heave damage. Fortunately, the winters in Massachusetts are rather cold with- out too many warming cycles in January and February and significant root injury due to frost heaving most likely will remain the excep- tion rather than the rule. References 1. Dirksen, C. and R.D. Miller. 1966. Closed-system freezing of unsaturated soil. Soil Sci. Soc. Amer. Proc. 30:168-173. 2. Russell, W.E., F.J.D. Smith, E.T. Bingham, and R.M. Soberalske. 1978. Frost heaving in alfalfa establishment on soils with different drainage char- acteristics. Agron. J. 70:869-872. Cooperative Extension Service U.S. Department of Agriculture University of Massachusetts Amherst, Massachusetts 01003 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 POSTAGE AND FEES PAID U.S. DEPARTIVIENT OF AGRICULTURE AGR 101 BULK THIRD CLASS MAIL PERI I FRUITpf NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. W. J. EDITORS LORD AND W. J. BRAMLAGE Vol. 47 No. 2 SPRING ISSUE, 1982 Table of Contents Chemical Control of Water Sprouts and Root Suckers of Apples Varieties of Plums for Massachusetts Boron For Peach Trees Evaluation of Dilute vs. Concentrate Sprayer Performance Varieties of Apples For Massachusetts Apple Disease Management in Massachusetts: 1981 Results and a Four Year Summary Orchard Nutrition Issued by the Cooperative Extension Service, Daniel I. Padberg, Director, in furtherance of the Acts of May Band June 30, 1 91 4; United States Department of Agriculture and County Extension Services cooperating. The Cooperative Extension Service offers equal opportunity in programs and employment. CHEMICAL CONTROL OF WATER SPROUTS AND ROOT SUCKERS OF APPLES-'^ William J. Lord, Joseph Sincuk and Maureen Tumenas Department of Plant and Soil Sciences Water sprouts are particularly troublesome on standard- type Delicious and following heavy pruning. Generally they are re- moved to maintain tree form and prevent shading. Unfortunately, their removal becomes more time consuming in succeeding seasons because of the proliferation from the stubs created by pruning. Sucker growth from roots of mature seedling trees and in plantings of M.7, M.7A and interstem trees is a serious problem, and diffi- cult to control in Massachusetts. Suckers are costly to remove, increase in number annually, provide mouse cover, and are a haven for insects and diseases. Water sprouts and suckers can be controlled with a special formulation of naphthalene acetic acid (NAA) . This formulation is available as Tre-Hold Sprout Inhibitor A112* and is registered for use on bearing apple trees. Mixing Directions For the control of water sprouts use 10 fluid ounces (2/3 pint) of Tre-Hold and make up to a volume of 1 gallon with a combination of water and interior-grade latex paint. The latex paint "marks" the treated areas and makes the mixture more viscous, thus restricting the NAA to the treated area. It has been our experience that at least 4 pints of latex paint should be used in each gallon of treating solution. Be sure to use an interior- grade latex paint and one that does not contain a mildewcide. Do not use oil base or exterior grade latex paint, since they can cause injury. For spraying suckers, mix 10 fluid ounces of Tre-Hold with sufficient water to make 1 gallon of spray mixture. Eight gallons of Tre-Hold are required for 100 gallons of spray. The addition of a surfactant or spreader- sticker to the Tre-Hold mixture may increase its effectiveness. Application for Control of Water Sprouts Prune water sprouts and then apply the Tre-Hold mixture thor- oughly over the cut surfaces. It can be applied with a paint brush or a small compressed air sprayer. We found that a 1-1/2 gallon compressed air sprayer with a 12-foot hose worked well, and that attaching a sponge to the nozzle was useful for swabbing the mixtu on pruning cuts. The treatment can be applied anytime weather permits but before growth starts in the spring. Areas where prun- ing cuts have been made should be covered thoroughly but dripping onto other parts of the tree should be avoided. The Tre-Hold mixture can kill buds. Be sure to follow the label. re 1 Water sprouts are vigorous shootis arising from any part of the tree above the ground. Suckers are shoots which arise from the roots. Trade name Application for Control of Root Suckers Root suckers are more difficult to control than water sprouts because they originate from roots below the soil surface and their source is not treated directly. Sucker control is achieved by killing the suckers sprayed and by the translocation of the NAA in the Tre-Hold downward through the suckers. Clumps of suckers, with their height varying within the clump, proliferate from stubs created by~ pruning. iheretore , good coverage of Tre-Hold on all suckers within each cTump appears necessary for their control. Spray coverage also is facilitated by the control of weeds with herbicides. We found that spraying the grass, weeds and suckers with paraquat 2 weeks prior to the application of Tre-Hold effective for increasing sucker control. This treatment killed the grass and weeds and "injured" the leaves on suckers. The injury of the leaves made good spray penetration into clumps of suckers easier and yet allowed enough leaf surface to remain for effective absorption. Adequate spray coverage of dense sucker populations is likely to be difficult when using a tractor-mounted weed sprayer and boom since the sprayer should be used at low pressure (10-20 psi) to avoid fruit thinning or ripening from spray drift. Better spray coverage can be obtained with hand-carried or back-pack sprayers because the nozzle of the sprayer can be thrusted into clumps of suckers. Merely directing the spray at the suckers fails to pro- vide adequate coverage and sucker control. Even following the procedure for increasing spray penetration within clumps of suckers may not eliminate the need of repeat annual applications of the Tre-Hold to achieve complete sucker control. Avoid spraying Tre-Hold on windy days to reduce drift of fine spjay particles. Do not apply Tre-Hold when the temperature exceeds 85 F. because volatilization of the NAA can cause leaf damage or fruit ripening on early maturing varieties. The Tre-Hold mixture is very expensive and to reduce the expense of application apply on suckers beyond the reach of the mower. The sucker population is generally most dense near the tree trunks and most troublesome inside the wire mouse guards. Therefore, in gen- eral, the spray should be limited to these areas. The most effective timing of the Tre-Hold application is when the suckers are actively growing. The suckers should have been pruned during the dormant season prior to treatment to shorten their height and to force succulent growth. Since the Tre-Hold mixture contains 10,000 ppm NAA the application should be delayed until about 4 weeks after petal fall to eliminate the possibility of fruit thinning and leaf injury. VARIETIES OF PLUMS FOR MASSACHUSETTS James F. Anderson Department of Plant and Soil Sciences Variety Recommended for Harvesting season Formosa (J) Shiro (J) Santa Rosa (J) Ozark Premier (J) Redheart (J) Bradshaw (E) Mohawk [E) Seneca (E) Iroquois (E) Elephant Heart (J) Imperial Epineuse (E) Stanley (E) Bavay (E) Oneida (E) c ^ H c § H c T H c H T T T H c H H c H T H Early August Early to mid-August Mid-August Late August Late August Late August Early September Early September Early to mid-September Early to mid-September Early to mid-September Mid-September Late September Late September (J) (E) T H Japanese Species European Species Trial Home Commercial Varieties so marked are not equally adapted to all sections of the state . Note: To insure successful pollination and fruit set, it is advisable to interplant two or more varieties of each species. Suggested pollenizers for the Japanese varieties are listed following each variety description. Variety Notes Formosa - The tree is large, vigorous and moderately productive. The fruit is large, attractive, and the yellow color tends to become completely overlaid with red as the fruit ripens. The flavor is very good and the fruit holds well in storage. (Elephant Heart, Redheart) Shiro - The tree is medium in size and vigor. Shiro tends to overset and thinning may be necessary to maintain good fruit size and annual production. The fruit has a very attractive, bright yellow color, is of medium-small size and good flavor. (Ozark Premier, Redheart) • Santa Rosa - A large reddish purple Japanese plum of good quality. The tree is large and vigorous. Santa Rosa ripens about a week later than Formosa. The fruit keeps and ships well. Though usually a productive variety, Santa Rosa has been a poor producer in our University orchards. (Elephant Heart, Redheart) Redheart A very good producer of medium- sized , heart-shaped, red-fleshed plums. The fruit has not developed satis- factory flavor in our orchards. Redheart ripens in the third week of August. This variety is said to be a very good pollenizer for other Japanese plums and may prove valuable for that purpose alone . (Elephant Heart) Bradshaw - The tree is medium to large in size and productive. The fruit is above medium size, blue and of good quality. Bradshaw is recommended for those who desire a succession of varieties in the home garden. Seneca - A large reddish-blue plum of very high quality. The fruit ripens in early September. The tree was a good producer in our Amherst orchards. Mohawk - Mohawk is an attractive blue prune, ripening in late August. The size is medium to large, and the quality is very good. Production has been moderate. Mohawk is said to be self -unfruitful . Iroquois - An attractive blue prune that ripens in early September about a week before Stanley. The fruit is of medium size, longer than Stanley and of good quality. The tree is productive. There was some splitting of the fruit when the trees first came into bearing. Iroquois is said to be self - fruitful . Elephant Heart - The tree is large and vigorous. The fruit is very large, dark red and heart-shaped. The flesh is blood- red in color and good in quality. Elephant Heart is a desirable variety where high yields can be maintained. (Redheart) Imperial Epineuse - The tree is large, upright-spreading and pro- ductive. The fruits are reddish-purple in color, medium to large in size and of excellent flavor. This rather unattractive prune is recommended for the home orchard v/here high quality is desired. This variety is highly susceptible to brov/n rot. 5 - Stanley - The tree is medium in size, vigorous and productive. This attractive blue prune is medium to large in size and very good in quality. Stanley is a desirable var- iety for canning. Bavay - The tree is large, upright, vigorous and moderately productive. This green gage type plum is of medium to small size, unattractive, but of high quality. Bavay is recommended for the home garden. Oneida - The tree is medium in size, vigorous and productive. The fruit is large, reddish-black, prune-shaped and very good. Oneida keeps well in storage and appears to be worthy of trial where a late ripening plum is desired- A**** A A* ********* ft** BORON FOR PEACH TREES William J. Lord Department of Plant and Soil Sciences Analyses of peach leaves from commercial orchards in 1981 showed that in some instances boron (B) was less than 30 ppm. Since 30-50 ppm is considered optimum for peaches, the question of whether or not to apply this element arose. Peach trees are more sensitive to excessive applications of B than apple trees, thus this element should be applied only in small amounts if needed. Peach tree symptoms of excessive B are characterized by withering and dying-back of terminal shoots during the growing season, the development of cankers and gumming along the shoots, rough bark, prominent lenticels, and excessive develop- ment of lateral shoots. To avoid B toxicity, Ernest G. Christ, Extension Specialist of Pomology at Rutgers University in New Jersey is very cautious about recommending the use of this element when fertilizing peach trees. He states that ... "fertilizer with 5 pounds of bora:x per ton is usually OK for peaches. No additional B is ever needed or added. Also, keep pH of soil 6-6.5". We suggest that peach growers in Massachusetts follow the recommendations of Ernest Christ concerning use of B. EVALUATION OF DILUTE vs. CONCENTRATE SPRAYER PERFORMANCE 12 3 Frank Drummond , James T. Williams , and Ronald J. Prokopy There has been debate during the past decade as to the effi- cacy of low-volume spraying in comparison to dilute spraying in orchard crop protection practices. The advocates of low-volume spraying in orchards cite several advantages for this practice, the most important of these being water conservation and greater spray droplet deposition on the foliage (Brann 1964, Lewis et al. 1969, and Hall et al . 1981). Steiner (1976) reported that approx- imately 701 of pesticide- active ingredients are deposited upon target surfaces with low-volume spraying whereas only 55% is de- posited with dilute spraying. However, growers as well as researchers (Hall et al., 1975) have found that low-volume sprays are not always deposited efficiently in all parts of the apple tree canopy. Our objective in this study was to evaluate the deposition of dye applied by 2 types of orchard sprayers on Cort- land and Delicious trees 17 feet and 8 feet in height, respectively. The experimental design incorporated an early season trial on May 4 (trees were in the pink stage of bud development) and a mid- season trial on July 28. On May 4th the sky was overcast and the temperature was in the mid 60's. The wind velocity averaged 15 mph from the northeast, with gusts up to 25 mph . On July 28, the sky was clear, the temperature was approximately 74 F and the wind velocity ranged 0-5 mph from the east. Both spray trials were conducted at Marshall Farms in Fitchburg, Massachusetts. The treatments were applied with a Hardie sprayer at 4X and 125 psi gauge pressure, and a Kinkelder sprayer at 25X and 25 psi gauge pressure. The Kinkelder was used both with and without the operation of an electrostatic charger. Each experi- mental block consisted of a row of trees running north to south from which subsamples of leaves were collected. The sprayers were driven on each side of the treatment row. There were 2 buffer rows between each treatment row to minimize the effects of drift. Spray deposition was measured by a method similar to that used by Jubb (1980). A fluorescent dye. Dayglo* fire orange (AX-14-N) was applied at the rate of 1 lb. /acre. Surfactants were used to aid in incorporating the dye into water (1/2 pt./lOO gal. Ajax* liquid soap for the first trial and 1 pt./lOO gal. Triton-B* spreader sticker for the second trial) . The distribution and 1 Technical Assistant, Department of Entomology, University of Mass. 2 Regional Extension Fruit Specialist, Middlesex County. 3 Extension Entomologist, Department of Entomology, University of Mass Trade name amount of dye per leaf was estimated by a single index rating made visually under a 15 watt ultra-violet lamp (Table 1) . Table 1. Rating system for evaluating deposition of fluorescent dye on apple leaves. Amount of dye Value assigned Typical appearance None Trace Light Medium Heavy Very heavy 0 3 4 LeaA'^es from 6 positions in the tree canopy (top center, bottom center, north, south, east, and west peripheries) were rated separately for initial analysis of droplet distribution and were later pooled into four positions (top center, bottom center, alley periphery, and within row periphery) for subsequent analysis Results The dye deposition on the sprayers was similar ex where the low-volume spraye did not provide as heavy a However, differences in dye the tall Cortland trees. L of these trees after being dye deposits when the elect than when not used (Table 2 a more evenly distributed c either of the low-volume me May 4 in the small Delicio cept in the top center of r without the electrostati coverage as the dilute spr distribution were more di eaves from top center and sprayed with the Kinkelder rostatic charger unit was ) . The dilute sprayer app overage throughout the tal thods . us trees by the trees c charger ayer (Table 2) scernible in bottom center had heavier in operation eared to apply 1 trees than The results of the July 28th trial indicate no discernible differences in dye deposition on small trees due to sprayer type. Such was not the case, however, in the Cortland trees. Here, the dilute sprayer proved far superior to the low-volume sprayer in -8- delivering impinging droplets to the top center o£ the trees. Analysis of droplet deposition in the bottom center of the trees suggests that the electrostatic charger played a positive role in dye deposition at this site. Table 2. Due deposition on leaves sampled from different sections of the tree. Low-volume spray Dilute spray electrostatic with without May 4 Dye deposit rating (0 = no coverage; 5 = heavy coverage Delicious, height 8 ft. Top center 3.0ab^ 2.3a 3.3b Bottom center 3.1a 2.8a 2.4a Within row 2.9a 3.2a 3.0a Alley 2.9a 2.7a 2.9a Cortland, height 17 ft. Top center 3.2b 1.4a 2.8b Bottom center 3.1b 1.5a 3.3b Within row 2.2a 3. lab 3.4b Alley 2.8a 2.2a 3.1a July 2 8 Delicious, height 8 ft. Top center 3.0a 2.8a 3.0a Bottom center 2.8a 2.4a 3.1a Within row 3.9a 2.9a 3.8a Alley 4.1a 3.6a 4.2a Cortland, height 17 ft. Top center 2.5a 2.6a 4.4b Bottom center 3.0b 1.8a 3.2b Within row 2.8a 2.9a 3.3a Alley 3.9a 3.6a 3.9a z Within a row ( — * ) ratings followed by a different letter are signi- ficantly different at odds of 10 to 1 (Lehman-Hodges test) . Discussion One should be careful in formulating general conclusions from a study such as this. One problem is that an interaction between sprayer performance, tree phenology, and weather conditions exists. As a result, it is difficult to evaluate the impact of these factors when formulating general guidelines for selection of appropriate sprayer type. Nevertheless, it has been shown by this study that under windy conditions in the spring, and calm conditions during mid- season the low-volume Kinkelder sprayer with or without electro- static cliarger in operation performed with nearly equal efficiency as the dilute sprayer when used to spray small trees. The positive influence of the electrostatic charger was more easily discernible when used in spraying tall trees (17 feet in height) in the spring. Here the Kinkelder (25X) with electrostatic charger in operation performed about as efficiently as did the Hardi dilute (4X) sprayer, both being superior to the Kinkelder without the use of the electrostatic charger. The dilute sprayer appeared to apply more evenly distributed dye coverage throughout the tall trees both on May 4 and July 28 than either of the low-volume methods. It may not be possible to translate our findings on spray coverage to actual pesticide efficacy. One might assume that the best coverage will yield the best pesticide effectiveness. However, this relationship may not always hold true. In a recently published work. Dr. Franklin Hall of the Ohio Agricultural Research Center (1981) found that no direct correlation could be made between spray de- position (amount and droplet size) of Permethrin and mortality of two spotted spider mites (Tetranychus urticae Koch) . Until more research is conducted, comparison of sprayer efficiency will have to be based on a relative method such as the one utilized in this study. Literature Cited 1. Brann, J.L., Jr. 1964. Factors affecting the use of airblast sprayers. Amer. Soc. Agric. Eng. 1964:63-103. 2. Hall, R.F., H.Y. Forsythe, Jr., B.M. Jones, D.L. Reichard, and R.D. Fox. 1975. Comparison of orchard sprayers for insect and disease control on apples, 1966-69. Ohio Agric. Res. Dev. Cent. Res. Bull. 1078. 22 pp. 3. Hall, R.F., D.L. Reichard, and H.R. Krueger . 1981. Effects of spray volume and nozzle pressure on orchard deposits. J. Econ. Ent. 74(4): 461-465. 4. Jubb, G.L. 1980. Orchard sprayers. Unpublished manuscript. Penn. State University. 5. Lewis, F.H., D. Asquith, E.R. Krestenson, and K.D. Hickey. 1969. Calibration of airblast sprayers for use on deciduous fruits. Penn. State Univ. Agric. Exp. Sta. Prog. Rept. 294. 16 pp. 6. Stiener, P. 1976. Factors affecting the efficient use of orchard airblast sprayers. Proc. 111. Hort. Soc. 110:57-64. -10- VARIETIES OF APPLES FOR MASSACHUSETTS James F. Anderson Department of Plant and Soil Sciences Variety Recommended for Harvesting season Vista Bella C Late July to early August Jerseymac T Mid to late August Tydeman's Early C Late August to early Sept. Paulared C Late August to early Sept. Akane T Early September Mcintosh C Mid Septem.ber Macoun C 5 H Late September Spartan C § H Late September Empire C ^ H Late September Cortland C e, H Early October Delicious C 5 H Early to mid October Golden Delicious C § H Mid October Idared C § H Mid October Spencer C § H Mid October Mutsu C Mid October T = Trial; H = Home garden; C = Commercial - Varieties so marked are not necessarily equally adapted to all parts of the state. Variety Notes Vista Bella: The fruits are of medium size, firm, and have a bright smooth finish and medium red color. The fruits are very good quality for an apple of this season. The tree is large, vigorous, and productive. Jerseymac: An attractive Mcintosh type. Fruit color is attractive (801 red), size is above medium, texture is medium- firm, but fruits show bruises easily. Eating quality is good. The trees are annual and productive. Tydeman's Early: Often labeled Tydeman's Red. A Mcintosh type, ripen- ing in late August. Fruit has green undercolor overlaid with a medium-red blush. May average larger than Mcintosh in size. Similar to Rome in habit of growth. Paulared: Ripens with or slightly later than Tydem^an's Early. The fruits are medium to large in size, roundish-oblate in shape and have excellent color and finish. The fruits color very early. The fruit has tended to cluster on our young tree. Production appears to be good. 11- Akane: The fruits are o£ medium size, attractive with a bright red color but show some russet. The flavor and keeping qualities are very good. The trees in our plantings have been less than medium in production. Mcintosh: Fruit is attractive and has excellent quality but bruises easily. Tree is vigorous, hardy, annual and productive. A good red strain such as Rogers, Summer- land, Imperial or Marshall is preferred. Spur types are available. Macoun: Fruit of excellent quality, attractive dark red color. Tree has poor structure, is biennial and requires thinning to maintain good fruit size. Spartan: Fruit has good color and quality but has a tendency to small size. Tree is vigorous and of good structure, annual, will pollinate Mcintosh. Empire: A very attractive apple with full red color, medium size, and very good dessert quality. Empire is annual, and productive and a good keeper. Cortland: Fruit is attractive, good quality, excellent for salads as flesh does not discolor, very susceptible to storage scald. Tree is hardy, productive, and annual. An excellent pollenizer for Mcintosh. Delicious: Fruit of excellent quality but susceptible to watercore and internal breakdown. Tree is of medium vigor, often biennial and may require thinning. A good pollenizer. Among the non-spur red strains Royal Red, Rogers Red and Gardiner Red have looked good in our plantings. Starkrimson (Bisbee) and (Miller) Sturdeespur are recommended where spur types are desired. Golden Delicious: Fruit of excellent quality and attractive where well-grown. Fruit is subject to russeting. Tree is of medium vigor, biennial and requires thinning to obtain satisfactory size, color and quality. Russet- free and spur type strains are now available. Idared: Attractive, bright red, winter apple of good quality and size. Suitable for both dessert and cooking. Tree is productive and annual, Spencer: Fruit is attractive, bright red and has very good quality, Suitable for dessert and pie. Tree is hardy, productive and annual. Mutsu: A Golden Delicious type that is less susceptible to fruit russeting and storage shrivel. Tree is vigorous and productive. Mutsu pollen is triploid and not viable. Fruit size may be too large and a susceptibility to blister spot has been noted. -12- APPLE DISEASE MANAGEMENT IN MASSACHUSETTS: 1981 RESULTS AND A FOUR YEAR SUMMARY 1 2 Christopher M. Becker , Kristin G. Pategas , and William J. Manning^ Department of Plant Pathology The Massachusetts Apple Integrated Pest Management (IPM) program has been in operation for 4 years. As the IPM program enters its final year, we present the disease management results for 1981 and a 4-year summary of the disease management program. 1981 Season During the 1981 season, 17 commercial apple orchards were involved in the disease management part of the IPM program. Eleven of the orchards were scouted and visited on a regular basis and participated in apple disease management. Modified hygrothermographs were placed in each orchard so that fungicide sprays for apple scab could be applied on an after- infection or "kickback" basis. The other six orchards were not in the IPM program and served as controls. The 1981 growing season was most unusual. Usually the apple tree buds and the spores of the apple scab fungus (Venturia inaequalis) develop at about the same rate and growers begin spray- ing when green tissue shows. However, in 1981, green tissue developed prior to the discharge of scab spores, but it was diffi- cult to convince growers not to spray and some growers applied 1-2 unnecessary sprays. Also, many wetting periods were encountered and it was difficult in the early growing season to reduce fungi- cide sprays and manage apple scab. The wetting periods for primary scab development at the Horticultural Research Center in Belchertown, Massachusetts are shown in Table 1. The ascospores did not begin to mature until near the end of April, whereas green tissue was present on April 14. The first 2 significant apple scab infection periods at the Horticultural Research Center (Table 1) occurred when 81 mature scab spores were released during two severe infection periods at tight cluster and pink. Despite the low percentage of spores, the relatively long wetting periods (50 and 27 hours) were most important in designating them as significant and severe infection 1 IPM technician 2 IPM scout 3 Professor of Plant Pathology 13- periods. Another severe infection period was recorded at petal fall, when 38°6 of all potential scab spores were discharged dur- ing a 34 hour wetting period, A moderate infection period on June 20 and 21 ended the primary scab season. Table 1. Apple scab season at the Horticultural Research Center, Belchertown, Massachusetts, 1981. Apple growth stage Date Wetting Mean Cumulative % potential period temp Rainfall scab spores scab infection (hrs) op (mm) discharged -*- severity^ Green tip 1/2" green Tight cluster Pink Bloom Petal fall 1/2" fruit 4/14 4/17 4/23-25 4/29-30 5/11-12 5/12-13 11 12 50 27 16 5/15-16 34 5/29 9 6/6 7 1" fruit 6/9 11 6/10-11 12 6/12-13 12 6/20-21 13 45 56 50 59 62 55 61 70 66 69 57 59 67 Trace 0.3 0.6 1.0 0.5 0.4 36.8 29.5 8.9 20.3 Trace Trace 12 END OF PRIMARY SEASON 1 0 60 68 72 86 90 94 99 No infection Light 2 Severe 8 Severe 20 Moderate 22 No infection Severe Light No infection Light Light Light Moderate Collected weekly. Infection severity was determined by the Mill's Table for primary scab infection. 14- Fungicide usage and the incidence of fruit diseases at harvest in the IPM orchards are summarized in Table 2, and similar information for control orchards is found in Table 3. The IPM orchards averaged 2 less fungicide sprays than the non-IPM orchards, and received about 3 less dosage equivalents. In contrast, a slightly higher percentage of diseased fruits were harvested from the IPM orchards (Table 2) than from the control orchards (Table 3) . Neverthless, $7.79 per acre was saved in the IPM orchards, because the savings from reduced fungicide usage more than offset the higher loss due to downgrading of fruit because of diseases (Table 4) . Table 2. Cost benefit analysis of fungicide usage and fruit quality for IPM orchards in 1981. Orchard Number IPM orchards of I diseased Fungicide $ loss to fungicide Dosage fruits at cost per disease sprays Equiv. harvest acre per acre 1 14 8.83 0.1-Scab 100.14 18.26 0.3-Other 2 11 10.43 0.5-Scab 125.57 31.95 0. 2-Other 3 11 11.68 0.1-End rot 93.61 4.65 4 8 8.27 0.2-Scab 132.05 31.95 0.5-Other 5 11 9.36 0.5-Scab 97.17 73.04 1.1-Other 6 11 7.95 0.5-End rot Pt 92.37 22.82 Black rot di Bitter rot 7 13 10.53 0.1-Scab 93.73 50.21 1.0-Other 8 9 7.96 0.2-Scab 123.88 9.13 9 11 10.62 0.1-Scab 101.31 31.95 0.6-Other 10 12 9.88 0.1-Scab 96.10 54.78 1.1-Other 11 10 10.48 0.1-Scab 117.96 59.34 1.2-Other Averages 11 9.63 0.17-Scab 106.72 35.28 Q.60-Other 0. 77-Total z n „„ • 1 ^ amount of fungicide applied Dosage equivalent = ^ ^ ■■ ■■ ^v^ r^ average recommended rate for that funpicide -15- Number of fungicide sprays varied from 8 to 14 among the IPM orchards, witli dosage equivalents ranging from 7,95 to 11.68 (Table 2). The lower number of fungicide sprays and dosage equivalents were due to efficient timing of fungicide applications aimed especially at apple scab. (Fungicides were Table .3. Cost benefit analysis of fungicide usage and fruit quality for control orchards in the IPM program in 1981. Orchard Number Dosage Control orchards of Equiv. % diseased Fungicide $ loss to fungicide- fruits at cost per disease sprays harvest acre per acre 1 13 10.20 0.1- 0.1- -Scab -Other 113.48 9.30 2 13 9.77 0.2- 0.8- -Scab -Other 130.36 46.50 3 14 13.54 0 147.45 0 4 13 14.01 0 157.95 0 5 14 14.33 0 140.17 0 6 11 10.43 0 135.57 0 Averages 13 12.04 0.2 140.00 9.79 applied as protective sprays just prior to predicted long wetting periods while sprays were withheld prior to predicted shorter wet- ting periods, applying kickback sprays only when wetting periods and temperature suggested infection periods--as measured by hygro- thermographs .) Increased number of fungicide applications', without Table 4. Cost benefit analysis of fungicide usage and fruit quality for IPM programs 1978 through 1981. 1978 1979 1980 1981 IPH' Control IPM Control IPM' Control IPM Control No. /fungicide sprays 11.80 12.5 10.64 13.00 9.45 10.36 11.00 13.00 Dosage equiv. 12.04 12.18 9.77 11.11 8.11 8.80 9.63 12.04 Fungicide cost/ acre ($) -^ - 74. 06 88.68 85.26 94.58 106.72 140.00 % diseased fruits at harvest 3.45 1.32 0.99 0.93 0.85 0.40 0.77 0.20 Loss to disease/ acre ($) - - 46.28 43.48 50.31 56.30 35.28 9.79 IPM benefits per acre ($) 11.82 15.31 7.79 — — . . _, _ _ Data not taken. 16- increased dosage equivalents, in several of the IPM orchards were attributed to the growers' addition o£ low rates of fungicides when applying insecticides or growth regulators. Increased dosage equivalents were mostly due to applications of a high rate of fungicide (esp. Cyprex*) aimed at "burning out" establislied scab lesions . 4 -year Summary The average number of fungicide sprays has traditionally been correlated with weather patterns, especially rain. Increased numbers of spring and summer rains usually has necessitated increased fungicide applications and dosage equivalents. Long per- iods of rain in 1978 and 1979 and weekly wetting periods early in 1981 made kickback spraying difficult in IPM orchards. Therefore, protective sprays were necessary prior to predicted long rainfalls, with at least one extra fungicide application to "burn out" esta- blished scab infections and inhibit secondary infections. 1980 was a m.uch drier growing season; therefore, fewer numbers of fungi- cide applications were required (Figure 1), with fewer dosage equivalents (Figure 2) . Fungicide applications were greatest in control blocks in 1979, but there were fewer dosage equivalents than the other wet years of 1978 and 1981. This is explained by growers adding low rates of fungicides with insecticides in spring. Regardless of weather, IPM disease management has consistently reduced num.ber of fungicide applications and dosage equivalents in IPM vs. control blocks. While the first year of the IPM disease management program reduced fungicide applications onlv by 5.6% and dosage equivalents by 1.21 (Table 5), during the wet years of 1979 and 1981, IPM blocks experienced 18.2 and 15.41 reductions in fungicide sprays and a 12.1 and 20.1% reduction in dosage equivalents. The drier year, 1979, had an 8.8% reduction in fungicide sprays, with 7.9% fewer dosage equivalents. Percent fruit disease at harvest (Figure 3) has consistently showed IPM blocks to have disease percentages lower or comparable to control blocks. In Table 4, dollar amounts are given for fungicide applications and losses due to fruit diseases IPM benefits per acre for 1979, 1980, and 1981 were ,Ul.82, $15.31, and $7. 79. Table 5. Fungicide usage in IPM orchards in comparison to control orchards; 1978 through 1981. Year No. fungici de sprays % diff. // dosage equivalents % diff. IPM control fungicide IPM control fungicide orchards orchards usage IPM ( vs. control Drchards orchards usage IPM vs. control 1978 11.80 12.50 5.6 12.04 11.18 1.2 1979 10.64 13.00 18.2 9.77 11.11 12.1 1980 9.45 10.36 8.8 8.11 8.80 7.9 1981 11.00 13.00 15.4 9.63 12.04 20.1 Trade name 17- In connection with the li^^' Apple Program, several workshops on disease and insect control are conducted. In addition, non- IPM growers used information gathered by IPM scouts. Thus, it is possible that fungicide usage also has been reduced in many non-IPM blocks, as a result of this information. The IPM Program has another season to go before being terminated, Nevertheless, it is evident that disease management practices can reduce fungicide usage without lowering pack-out and saves money for the grov/er. Control (Non IPM) blocks ■ I IPM blocks 13 12 CO < Cm CO w n C5 s =N: 11 - 10 1978 T 1979 ' 1980 198] Figiire 1. Trends in the average number of fungicide sprays applied to IPM and non-IPM blocks: 1978-1981. 18 Control (Non IPM) "blocks ,, IPM blocks 13 CO Eh w < > M :=> w < CQ O O 12 11 10 1978 1979 1980 1981 Figure 2. Trends In the average number of dosage equivalents used in IPM and non- IPM blocks: 1978-1981. -19- Control (Non IPM) blocks IPM blocks ^•••••••., I I I I 1978 1979 1980 1981 Figure 3. Average per cent fruit disease at harvest in IPM and non- IPM blocks: 1978-1981. -20- ORCHARD NUTRITION Warren C. Stiles Department of Pomology Cornell University, Ithaca, NY Orchard nutrition is often a major factor influencing orchard productivity and fruit quality. More intensive planting systems, higher yields, and changes in production management systems require re- evaluation of orchard nutrition needs. Orchard nutrition management starts with an evaluation of conditions that exist in the soil and in the trees. Limited soil depth and imperfect internal drainage limit root development and the volume of soil from which the tree can obtain nutrients and water. Likewise, coarse- textured soils may have limited exchange capacity as well as limited water holding capacity. Any factor that limits root development or water supply will influence tree nutrition. Soil pH , cation exchange capacity, inherent nutrient supplying power as determined by parent materials and organic matter content must also be considered in developing fertilizer programs . Soil Testing Soil testing is one means of m.easuring chemical soil factors. Soil testing to determine pH , lime requirement, calcium (Ca) , potassium (K) , magnesium C^g) a^id phosphorus (P) levels gives some information on nutrient status and possible causes of pro- blems. Samples of both topsoil (o to 8") and subsoil (12 to 24") should be examined. When preparing a new site or in renovating an old orchard site, soil tests are the only feasible means of determining the amounts of lime, type of lime, and amounts of other nutrients that must be added before the trees are planted. After trees have been established, soil testing is useful in moni- toring soil pH and may help to explain abnormalities detected in leaf sample analyses. Soil pH and Lime Requirements Adjustment of soil pH and incorporation of lime is easier and more effective during site preparation than after trees have been planted, particularly if large corrections are required. The amount of lime required to raise the plow depth to a pH of 6.2 to 6.5 varies with soil texture and initial pH approximately as follows : 1 Associate Professor of Pomology Tons P er acre 4.5-4.7 3.0 5.5 9.0 4.8-5.1 2.5 5.0 7.0 5.2-5.5 1.5 3.0 4.0 5.6-5.9 0.5 1.0 1.5 6.0-6.3 0.25 0.5 0.75 -21- Table 1. Soil pH and lime requirements (approximate values) Initial Soil texture soil pH Sands Sandy loams Loams ^^ silty loams Silty clay loam 12.0 10.0 5.0 2.5 1.0 Actual quantity of lime needed varies with the equivalent neu- tralizing value of the limestone used. High-magnesium (Mg) lime- stones usually have greater neutralizing value than low-Mg limestones. Applications of over 2 to 3 tons per acre should be m.ade as split applications to established orchards. During preplant soil prepar- ation, part of the lime can be applied and worked in before plowing the soil and applying and working in the remainder. Soil test results for potassium (K) , calcium [Ca) , and magnesium (Mg) are helpful in identifying potential problems especially during site preparation. The amounts of these elements tliat should be applied varies with soil texture, exchange capacity and initial quantities present. In general, these should be built up to high or very-high levels before the orchard is planted. In most Eastern New York orchard soils this means 200 lbs . or more of K (over 150 lbs. in some of the heavier clayey soils); and 200 lbs. or more of Mg per acre. Ca levels should approximate 2500 lbs. per acre. Since not all soils have the exchange capacity to hold these quan- tities it is best to start with a soil test. P is often overapplied in apple orchards. An initial application of 100 to 120 lbs. of PtOt per acre during soil preparation, combined with correction of soil pH , should be sufficient to provide adequate amounts of P for a number of years. P requirements of apple trees are relatively low (approximately 8 to 10 pounds removed per year in the fruit). No clear-cut beneficial effect of increased P levels has been shown on tree growth, flesh quality or keeping quality of the fruit as long as leaf samples contain at least 0.08 to 0.16% P. On the other hand, excessive rates of P application may pre- cipitate zinc (Zn) or copper (Cu) as insoluble phosphates and pro- duce deficiencies. It is suggested that the initial broadcast application of P in preplant soil preparation may be supplemented with a high P starter solution applied to the newly set tree to possibly help tree root development and that further application of phosphates be eliminated unless leaf samples of P fall below 0.08%. -22- This is not likely to occur if soil pH is properly maintained. Leaf Analysis Leaf analysis, with all of its faults, still represents the best tool available for monitoring the nutritional status of established trees. Some basic considerations must be kept in mind : 1. Method and time of sample collection should be uniform if samples are to be compared. Specifying the sampling time, i.e., 60 to 70 days after bloom, and location of leaves to be sampled is helpful in comparing results to standards. 2. The leaf sample analysis indicates the amounts of various elements in the sample as submitted. Leaf analysis does not distinguish the amount of an element that is physio- logically active from the amount that may be present as contamination from various sources such as spray materials. 3. Varieties, rootstocks, growth status and cropping levels, as v/ell as soil variability and weather conditions during the growing season, influence leaf contents of elements in various ways and must be considered in interpreting leaf analysis results. When growth is severely limited by deficiency of some elements, the concentrations of all elements including the deficient one(s) may appear to be normal. In such cases diagnosis of the actual cause of the problem may require much additional information, or even field trials of suspected elements. Some of these types of relationships will be illustrated as individual elements are considered. 4. Leaf analysis can be used for various purposes such as diagnosing possible causes of a problem, or, preferably, to monitor nutrient status so that corrections can be made before a problem becomes serious. In practice, both approaches are usually involved. Leaf Analysis Standards for Apples 1. N. Optimum N varies with variety and purpose for which it is grown. Usually the optimum values fall within an over- all range from 1.8 to 2.4%. Values below 1.81 N are usually associated with reduced growth, smaller fruit size, and greater tendency toward biennial bearing. Annual removal of N by fruit is in the range of 30 to 40 lbs. per acre. An additional 30 to 60 pounds may be required for tree growth, to build reserves, and to support grass growth -23- under the trees. Eliminating grass competition by herbi- cides reduces the rate o£ N applications required by approximately 30 to 40 pounds per acre per year. Ex- cessive tree vigor resulting from excessive N applications can be partially compensated for by late summer pruning. This has two main effects: it improves fruit color by improving light distribution, and tends to limit root growth. Fruit size may also be reduced by summer pruning. P. Leaf concentrations of P may range from 0.08 to over 0.301. Mcintosh tends to accumulate less P than Delicious. High levels of P in leaf samples indicate the possibility that tree growth has been stunted by lack of N, drought, competition from grass, root and/or trunk injuries, or because of other nutrient deficiencies. K. Optimum K levels usually fall between 1.2 and LSI. Varieties such as Delicious appear to be more efficient in taking up K than others such as Mcintosh. K levels should be considered in relation to N levels, with N/K ratios of 1.25 to 1.50 indicating reasonable balance. Levels below 1.2% indicate possible need for additional application of K; those below 0.8% indicate deficiency. The form of K applied should be related to Mg levels. If both K and Mg are needed, sulpomag should be applied, v\fhile if Mg is adequate the use of muriate of potash or other forms may be appropriate. Ca . Ca levels below approximately 1.24% should be con- sidered as low, those below 1.00% as deficient. Low levels of Ca may indicate insufficient soil levels of Ca (parti- cularly as indicated by the subsoil), and/or low pH , but may be the result of shortages of other elements such as N or boron (B) or of other factors that limit the ability of the tree to absorb and translocate Ca. Leaf Ca levels normally show a direct positive relationship with leaf N concentrations. Liming and correcting soil pH should be the first step in dealing with low Ca levels. If additional corrective treatments are required these might include soil applications of calcium sulfate (gypsum) if pK is too high, and/or foliar applications of calcium chloride. Fruit content of Ca has been related to keeping quality. Large fruit usually contains lower concentrations of calcium. Foliar sprays and/or post-harvest application of CaCl2 may be needed on such fruit. Mg. Optimum levels of Mg fall in the range of 0.30 to 0.45%. ^Rapidly growing young trees and trees bearing heavy crops of fruit are most susceptible to Mg deficiency. Low Mg supply in the soil is the major limiting factor. High-Mg dolomitic lime and applications of Mg salts such as kieserite or langbeinite (sulpomag) are usually required to overcome -24- this problem. Raising soil pH with calcitic lime may give a partial and temporary improvement in Mg availability but does not correct the basic Mg shortage. Response to soil applications o£ Mg salts may be slow. Inclusion of Epsom salts in the petal fall, first and second cover spray is usually necessary until soil Mg levels are corrected. Epsom salts should be applied at a rate of 45 lbs. per acre in each of these 3 sprays if Mg levels in leaf samples are less than 0.5%. B^. Optimum leaf concentrations of B are in the range of 35 to 50 ppm. B sprays are effective in meeting fruit requirements and avoiding cork formations and early drop associated with B deficiency. However, B is also nec- essary for root development. Annual applications of B in the fertilizer or applied separately plus foliar sprays may be required to meet the needs of high-producing orchards on size-controlling rootstocks. Using annual soil applications of 1-1/4 to 2 lbs. actual B per acre (equivalent to 6-1/4 to 10 lbs. of a 20% fertilizer grade borate) approximate annual needs but may require 1 or 2 foliar sprays of Solubor (total of 2 to 6 lbs. depending on tree size and planting density) to fully meet the boron requirements. Zn. Optimum Zn leaf levels are similar to those of B, i.e., '6b to 50 ppm. Leaf concentrations below 15 ppm should be considered deficient. Varieties that accumulate higher levels of P appear to have higher Zn requirements than those that accumulate less P. Annual requirements for Zn are approximately 2 lbs. per acre if applied as inor- ganic salts in dormant sprays or approximately 0.2 to 0.3 lbs. of actual Zn applied as foliar sprays of EDTA chelates (3 to 5 lbs. /acre). Amounts of Zn required to correct severe deficiencies may be 4 to 5 times these amounts. Zn-containing fungicides provide some benefit but are not adequate to supply the total need. Leaf samples from trees sprayed with Zn-containing fungicides may contain 150 ppm to 500 ppm Zn but most of this is not active. In such cases, P contents of the samples and tree growth and fruiting are usually more indicative of the Zn status. Mn. The optimum levels of Mn range from 35 to 50 ppm. Mn deficiency may be associated with high pH conditions, K deficiency, or in some cases may be associated with long- term effects of certain herbicide programs. It is easily supplied by using Mn-containing fungicides in the petal fall, first and second cover sprays, or by applying Man- ganese sulfate (2 to 4 lbs. per 100 gallons dilute rate equivalent) at first cover. Leaf samples from trees -25- sprayed with these materials may contain high levels of Mn, but much o£ this represents inactive contamin- ation. 9. Cu_. Optimum levels o£ Cu are in the range of 7.5 to 12 ppm. Leaf concentrations below approximately 3.5 ppm are deficient. High soil pH and/or high P levels may aggravate Cu deficiency. Cu can be added to the fertilizer but this is usually less effective and more expensive than a spray of a fixed-copper fungicide applied between green-tip and 1/4-inch green. Delaying this spray to 1/2-inch green may result in fruit russeting. 10. IrGn(Fe).Fe is not usually a problem and leaf concentrations vary considerably depending on several factors. Levels of 50 ppm appear to be adequate under most circumstances. High levels of Fe in relation to Mn may be used as an indicator of Mn deficiency, i.e. if Fe/Mn ratios approach or exceed 2.0. 11. Sulfur is not included in most leaf analyses but require- ments are believed to fall in a range between those for P and those for Mg , i.e. approximately 0.2-0 + leaf con- tent. Responses obtained from soil applications of gypsum, or sulfate of potash magnesia, or foliar sprays of Epsom salts suggest that at least a part of the response to such treatm.ents may be related to sulfur. Until more definite information, pro or con, about sulfur requirements is developed, it would appear appropriate to rely on sulfate forms of other nutrients to supply this element. Combinations of Deficiencies It is common to find two or more elements involved in a parti- cular orchard nutrition problem. These combination problems may involve low K plus low Mg , low B plus low Zn ; low Mg plus low Zn; high P plus low Zn qr_ low Cu among others. In a few such cases, the cause of the problem may be a matter of imbalance, but in most instances the amounts of each of the elements available to the trees can be considered independently. For example, if both K and Mg are in short supply, application of both will be required. The apparent aggravation of a Mg short- age by increased application of K indicates a need for increasing the supply of Mg rather than limiting the supply of K. Another common problem involves B and/or Zn shortages. Young trees that are flowering heavily for the first time or that bore their frst heavy crop during the previous season may show varying degrees of shoot dieback resembling winter injury. Examination of these trees usually shows that the cambium has not been damaged by cold. -26- Prompt application o£ B and Zn sprays usually enables such trees to recover before dieback occurs. Left untreated, however, the same trees may lose a high percentage of terminal shoots and leaders, with the damage extending considerable distances back into older wood. As is the case with deficiencies of most micro-nutrients, this type of injury may be evident only on some branches and not as a general condition throughout the tree. Summary The nutritional status of an orchard should be evaluated by thoroughly analyzing soil test results, leaf sample analysis and observations of tree performance on a block to block basis. Varietal, cultural, soil and weather factors must be considered. After this has been done, a preventive fertilizer program can be developed and applied. This approach should minimize the adverse effects of nutrient shortages and optimize the production of high-quality fruit. Cooperative Extension Service US- Department of Agriculture University of Massachusetts Amherst, Massachusetts 01003 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. $300 POSTAGE AIMD FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 Bulk Third Class Mail Permit FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 47 (3) SUMMER ISSUE, 1982 Table of Contents Effects of Summer Pruning on Growth and Yield of Apple Trees and on Fruit Quality Nutrient Sprays for Tree Fruits Grower Responses to the Apple IPM Program Brown Rot of Peaches: An Update on Managing the Disease Disease Diagnosis'- Information for Growers Suggestions for Use of Calcium Sprays in 1982 Recommendations for Use of Growth Regulators Is it Worthwhile to Refrigerate Blueberries? ssued by the Cooperative Extension Service, Daniel I. Padberg, Director, in furtherance 3f the Acts of May 8 and June 30, 1 914; United States Department of Agriculture and bounty Extension Services cooperating. The Cooperative Extension Service offers equal opportunity in programs and employment. EFFECTS OF SUMMER PRUNING ON GROWTH AND YIELD OF APPLE TREES AND ON FRUIT QUALITY William J. Lord and Duane W. Greene Department of Plant and Soil Sciences Recent results from England, South Africa, Europe, and the United States indicated that late summer pruning can restrict growth, increase red color on fruit, increase leaf Ca, reduce the incidence of bitter pit, increase fruit flesh Ca, and reduce internal breakdown in storage. In England Preston pruned by the established spur method. Tliis involved the removal of strong laterals not needed for new branches and shortening of weak ones to 3 inches to induce spur formation. Laterals of medium vigor, mainly on the tree periphery, were not pruned. Subsequently, these were shortened to a spur, or removed when crowding occurred or they became too large. Laterals from spur systems or induced spurs were shortened to 1 inch. In the United States, the trees were summer pruned by removing all current season's shoots. Terblanche et al. in South Africa removed all current season's growth of the bearing units as well as excessive shoot growth. Only sufficient shoots were left to serve as future bearing units. Utermark in West Germany drastically reduced leaf area by remov- ing growth beyond the outermost fruiting spur on each branch. The summer pruning techniques that enhanced fruit quality seem severe and time consuming, and contradictory findings have been reported. Thus, this experiment was designed to compare effects of summer pruning with winter pruning and to evaluate methods that fruit growers might adapt. Studies With Red Prince Delicious These trees planted at 14 foot x 21 foot spacing, were badly crowded by the end of their 8th growing season in 1977. Stubbing cuts (cuts made in 2 or 3 year-old-wood to reduce the length of limb) were necessary for passage of equipment prior to harvest in 1977. Pruning treatments were initiated in 1978 and consisted of 1) light dormant pruning (to simulate current pruning practices of growers), 2) corrective dormant pruning, and 3) corrective dormant pruning-plus- summer pruning in early- August . Corrective dormant pruning was initiated in March, 1978 and consisted of removal of 1-2 large limbs per tree that caused crowd- ing and/or competed with the leader. Removal of very few large limbs was necessary during the 1978-79 dormant pruning season and none were removed in 1979-80 season. Tree height was lowered by about 2 feet and a limb renewal program was initiated in the top third of the tree. The limb renewal program consisted of rem.oving some of the stronger branches or their length was shortened by cutting to a weak lateral branch. All water sprouts were removed -2- except those that were in a favorable location for limb replace- ment. These were retained and spread. Thus, we developed a branch rotation program which consisted of removing large branches in the top third of the tree and leaving weak branches wliich in turn are removed when they became large. These pruning procedures have helped to contain tree height and to maintain a conical tree shape (Christmas tree shape) . Equally important procedures of corrective dormant pruning were stubbing into older wood to stiffen branches that drooped because of fruiting and shortening branches causing in-ro\\? and between-row crowding . Summer pruning procedures followed were: (1) removal of limbs or portions of limbs of 1 inch diameter or less if too vigorous or causing shading, (2) removal of water sprouts and vigorous upright growth, and (3) branches stubbed to weak lateral when additional stiffening was required. Table 1. Effect of summer pruning on growth, fruiting and quality of Red Prince Delicious apples. Parameter 1978 Responses 1979 1980 Growth Trunk circ. incr. Terminal growth No effect Decrease No effect No effect No effect Fruiting Flovjer bud formation Fruit set Yield No effect No effect No effect No effect No effect No effect Fruit quality at harvest Fruit size No effect Flesh firmness No effect Soluble solids No effect Bitter pit No effect Flesh calcium No effect No effect No effect No effect No effect No effect Increase No effect No effect No effect No effect Fruit quality after storage Flesh firmness No effect Breakdown Increase Bitter pit & cork spot No effect No effect No effect No effect No effect No effect Increased The pruning treatments have had virtually no effect on growth, fruiting, fruit quality, and storage (Table 1). Nevertheless, the corrective pruning procedures have enabled the grower to keep the Red Prince Delicious trees within their allotted space. J)- Studies with Cortland This study was initiated on 6-year-old on Mailing 7 root- stock planted at 14 foot x 21 foot spacing. These vigorously growing trees were not croAvding when the treatments were started, but if some growth restriction was not used a crowding situation would have soon developed. The summer pruning treatments in this experiment were as follows: 1) control (dormant pruning), 2} dor- mant pruning-plus- summer pruning in early July, and 3) dormant pruning-plus- summer pruning in early-August. The summer pruning procedures consisted of cutting shoots back to the first fruit (the terminal apple on 1 -year-old- wood) and/or a lateral branch originating from 1- or 2-year-old wood. Some upright growing shoots also were removed. Dormant pruning-plus - summer pruning in early August in com- parison to dormant pruning restricted trunk circumference increase consistently and terminal growth the year after pruning was greater (Table 2). Otherwise, there were either no effects of summer pruning, the responses were not consistent from year to year, or they were undesirable. Examples of undesirable responses are smaller fruit, lower soluble solids (sugar content), more scald, bitter pit and cork spot (Table 2) . Table 2. Effects of sumnier pruning on growth of Cortland apples. fruiting and quality Parameter 1978 Responses 1979 1980 Growth Trunk circ. incr. Terminal growth Decrease (J&A)' Decrease (A) Increase (A) Decrease (J&A) Increase (J&A) Fruiting Flower bud formation Fruit set No effect No effect No effect No effect Fruit quality at harvest-' Fruit size Flesh firmness Soluble solids Red color Bitter pit Flesh calcium Decrease (J&A) No effect Decrease (J&A) Increase (A) No effect No effect No effect No effect Decrease (J&Aj No effect No effect No effect No effect No effect Decrease (J&A) No effect No effect No effect Fruit quality after storage Flesh firmness Breakdown Scald Bitter pit & cork spot Decrease (J&A) No effect (J&A) No effect No effect No effect No effect Increase (J&A) Increase (J&A) No effect No effect No effect No effect July and August pruning treatments. To determine the effects of summer pruning on fruit quality, the fruits were sampled near the pruning cuts. Studies with Mcintosh This study ivas initiated on 8-year-old Mcintosh trees on seedling roots planted at the Horticultural Research Center in Belchertown. The pruning treatments were: 1) check (no piun- ing) , 2) dormant type pruning in early August, 3) mechanical hedging (simulated) in early August, 4) cutting terminal branches back to the first fruit in early August, 5) removing in early August water sprouts and removing or stubbing limbs in the upper third of the tree that shaded the lower two-thirds of the tree, 6) cutting all current season's shoots to 4-6 buds in early July and 7) cutting all current season's shoots to 4-6 buds in early August . All pruning treatments consistently increased red color with the exception of treatments 6 and 7, otherwise there has been little response to summer pruning (Table 3). Table 3. Effects of summer pruning on growth, and quality of Mcintosh apples. Parameter 1978 Responses 1979 1980 Growth Trunk circ. incr. No effect Decreased No effect Fruit quality at harvest* Fruit size Flesh firmness Soluble solids Red color Flesh calcium No effect No effect No effect Increase No effect No effect No effect No effect Increase No effect No effect No effect No effect Increase No effect Fruit quality after storage Flesh firmness Breakdown Brown core Internal browning No effect No effect No effect No effect No effect No effect No effect No effect No effect No effect No effect No effect Summary and Discussion The corrective winter pruning or corrective winter pruning- plus-summer pruning procedures reduced the problem of tree crowd- ing in the block of Red Prince Delicious trees. Hov,fever , corrective winter pruning-plus- summer pruning in comparison to corrective winter pruning had little or no effect on growth or fruit quality (Table 1) . To determine the effects of summer pruning on fruit quality, the fruits were sampled near the pruning cuts . Summer pruning has been suggested as a technique for devital- izing trees in crowded plantings. The overall growth of the Cortland trees, as indicated by trunk circumference increase, was reduced by summer pruning (Table 2). Nevertheless, terminal growth the year following summer pruning was greater than on the dormant- pruned trees (Table 2) . The Red Prince Delicious trees also were not devitalized by summer pruning (Table 1} . The only consistent beneficial effect of summer pruning was improved red color of Mcintosh apples from trees receiving the dormant- type , mechanical hedging, or the cutting to the first fruiting spur summer pruning treatments (Table 3). When large branches were thinned or stubbed in the top of the Mcintosh trees in early August (Treatments 2 and 5) they caused bruising and drop of some fruit on lower branches as they fell. This could have been avoided by stubbing or thinning large branches during dormant pruning. Otherwise, the dormant-type pruning treat- ment on Mcintosh, the treatment of restricting growth in the upper third of Mcintosh and the summer pruning procedures on Red Prince Delicious were not particularly troublesome or time consuming. These procedures could provide work for employees experienced in pruning during the slo\v season, in some orchards, prior to harvest. Cutting all current season's shoots on Mcintosh and the summer pruning methods on the Cortland trees were most time-consuming of the summer pruning practices. Hov;ever, tliese procedures could be performed by labor inexperienced in pruning. Hedging performed by a mechanical device would be the least time consuming of the summer procedures followed. Emerson and Hayden in Indiana reported that in comparison to normal winter pruning, summer hedging every year plus dormant pruning every third or fourth year, reduced prun- ing costs, increased fruit color, and maintained good yields. Other researchers besides the authors have reported that summer pruning failed to suppress terminal growth. Nevertheless, it is difficult to explain why cutting to the first fruit on the Mcintosh and Cortland trees failed to increase fruit calcium (Ca) . In an earlier study at the Horticultural Research Center in Belchertown, MA, Drake and Bramlage reported that the removal of all current-year shoots improved fruit Ca levels and fruit quality. However, it does seem reasonable to assume that the magnitude of responses to summer pruning depends on tree vigor and the amount of leaf surface removed. The responses may develop more quickly with precocious varieties on the more dwarfing rootstocks. It is possible that Drake and Bramlage and others who have reported an improvement in fruit quality following summer pruning removed a much higher proportion of the total leaf surface than in present study. Also the effects may be cumulative, thus the responses to summer pruning of trees on seedling roots or vigorous size-control- ling rootstocks may be slow to develop except in situations where a larger percentage of the leaf area is removed. -6- Conclusions Majority of trees in Massachusetts are on vigorous- size controlling rootstocks and the responses to summer pruning, with the exception of improved red color, may be slow to develop. Summer pruning can reduce the amount of pruning necessary during the winter months and possibly improve work efficiency during the summer. However, it is doubtful that summer pruning will become a common practice except in a few situations of severe tree crowding. Summer pruning will be mainly practiced for tree train- ing in non-bearing blocks and has the potential for improving fruit color in crowded bearing trees. *********** NUTRIENT SPRAYS FOR TREE FRUITS Warren C. Stiles'^ Department of Pomology Cornell University, Ithaca, NY Foliar application of nutrients can supply essential elements directly to foliage and fruit at times when rapid responses may be desired. This method of application, with few exceptions, should be considered as a temporary measure that supplements soil appli- cations. Conditions such as cold weather during the period of bloom, or cold soils in the spring may require the foliar application of certain elements to avoid short stress periods. At other times, such as the grand period of growth, particularly in young trees, rapid expansion of foliage may demand more of certain elements than can be supplied by normal root absorption and transport processes. Nutrient sprays, then, can be looked at as a fine-tuning tech- nique. In addition, such sprays can be used to confirm a deficiency diagnosis and provide guidance in adjusting fertilizer programs for future seasons. Foliar nutrient sprays have been tested more on apples than on the other tree fruits. Therefore, the majority of this discussion will concentrate on apples, with suggestions for trial treatments with other crops where feasible. Nitrogen (N) . Foliar sprays of urea have been used on apples for over 20 years. Formulations of urea that are low in biuret content are suggested for this purpose. Reasons for using urea sprays include temporary adjustment of nitrogen level to favor 1 Associate Professor of Pomology m fertilization of ovules to increase fruit set, and to supplement, or replace a part of soil applications of nitrogen. Low N status of the flower buds and/or low temperatures during the pollination and fertilization period lead to more rapid degeneration of the ovules. Conversely, high temperatures and/or high N status can delay this degeneration and allow a longer period of time for fertilization to be completed. To acheive this situation, urea sprays can be applied at the rate of 3 lbs/100 gallons dilute rate in the pink spray and/or 5 lbs/100 gallons dilute rate in the petal fall spray. This approach should be considered whenever the preceding season's leaf samples indicate a leaf N content of less than 2.2 percent. Used in this manner, the amount of actual N applied per acre will range from approximately 3 lbs on close trellis plantings to 16 lbs on large standard trees. The foliar sprays of urea are not suggested for use on pear, peach, or cherry trees because they do not absorb and utilize urea as efficiently as apple trees. Magnesium (^1g) . Foliar sprays of Mg sulfate (Epsom salts, tech- nical grade) have been used to overcome temporary deficiency of Mg in a number of fruits. These sprays are most effective if applied soon after bloom while foliage is capable of absorbing the material. With apples, the usual suggestion is to apply 15 lbs. of Epsom salts per 100 gallons (dilute rate) in the petal fall, first and second cover sprays. Epsom salts is compatible with most pesticides up to 15X concentrate (225 lbs. per 100 gallons of tank mix) . Young rapidly growing trees may require additional applications to provide adequate amounts of Mg . Mg chelates (EDTA) are available in liquid or powdered formulations Because of greater efficiency in correcting deficiencies, the chelates are used at lower rates (i.e. 1 lb . or 1 qt. per 100 gallons) and may be more amenable to use in concentrate appli- cations . Corrective treatments for Mg deficiency must be considered in terms of both soil and foliar applications. In a preventive pro- gram, suggested combinations might include the following: Leaf Mg (% dry wt.) Magnesium treatment 0.30 to 0.45 Continue present program. (Satisfactory) 0.20 to 0.30 Apply dolomitic lime if pH is below 6.5, plus (Low) 600 lbs. of Sulpomag per acre if K level is not excessive, plus three sprays of Epsom salts or below 0.20 equivalent Mg treatment. (Deficient) For fruits other than apples there is less information avail- able on foliar applications of Mg . Epsom salts (10 to 15 lbs. per 100 gallons dilute rate) have been suggested for use on pears and peaches, and, at lower rates (2 lbs, per 100 gallons plus a casein spreader) on plums, prunes and apricots. Manufacturer's suggested rates should be followed in trials with magnesium chelates. Boron (B) sprays are commonly used on apple orchards. Rates suggested are usually in the range of one-half pound to one pound of Solubor or Polybor per 100 gallons of dilute spray equivalent in one or two post-bloom sprays. Spray timings most often suggested are first and second cover sprays. Applications at the one-half pound rate at tight- cluster or pink have been found to increase pollen germination in some tests and might be suggested where leaf samples collected the previous year indicate boron to be low. B sprays may be used in conjunction with soil applications as follows: Leaf B (ppm dry wt . ) Boron treatment 35 to 50 Continue present program (Satisfactory) 25 to 35 Ground application of 201 fertilizer grade borate (approximately 10 to 15 lbs/acre) or apply 1 or 2 sprays of Solubor or Polybor (2 to 3^ lbs per spray) during the period from petal fall through second cover. below 25 Ground application of 201 fertilizer grade borate (10 to 15 lbs per acre) plus Solubor or Polybor at tight cluster or pink (one-half pound per 100 gallons) plus Solubor or Polybor at first to second cover (one lb/100 gallons dilute rate). With pears, a post-harvest application of Solubor or Polybor (one to two lbs. per 100 gallons dilute rate) has been reported to be more effective than early spring applications in avoiding a temporary boron deficiency during bloom. Additional trials are needed to determine the value of this treatment under our conditions. Foliar sprays of B are not recommended for peaches because of their sensi- tivity to this element. Zinc (Zn) is best supplied to tree fruits in dormant or foliar sprays. Dormant sprays of Zn sulfate (35''o zinc sulfate monohydrate) at rates oT^lO to 20 lbs per 100 gallons as a dilute spray (do not concentrate above 2X) have been generally recommended for all decid- uous tree fruits. Dormant sprays (before green tissue appears) have resulted in injury to buds and spurs of apple trees if frost occurs within 24 to 48 hours of the application or if oil sprays are used. ■9- Zn-containing fungicides contribute a certain amount of zinc to the tree, but are not adequate to correct deficiencies. Zn chelates (EDTA) offer the most satisfactory control. These are compatible with many of the commonly used pesticides. Rates as suggested by the manufacturer would be adequate under most circum- stances. In relation to leaf analysis results, the following may be suggested: Leaf Zn (ppm dry wt . ) Zinc treatment 55 to 50 Continue present program. If zinc fungicides were used add 1 spray of ZnEDTA (1 lb. per 100 gallons dilute rate) at first cover. 20 to 35 One spray of ZnEDTA (1 lb. per 100 gallons dilute rate) at first cover. below 20 Two sprays of ZnEDTA (1 lb. per 100 gallons dilute rate) at tight cluster plus first cover. Correction of Zn deficiency is often difficult. Contributing factors include cold soil temperatures during the spring, high soil organic matter content, and high levels of P in the soil. The ratio of P/Zn sometimes indicates the Zn status more accurately than Zn alone. Ratios over 150:1 generally are associated with Zn deficiency, while ratios below 100:1 indicate adequate Zn availability. Var- ieties such as Delicious and Golden Delicious usually accumulate higher levels of P and are more sensitive to Zn deficiency than varieties like Mcintosh. Severe pruning results in temporary relief from Zn deficiency. One difficulty in diagnosing Zn deficiency from leaf analysis results from the lack of normal dilution because growth is limited. Similar treatments are suggested for other tree fruit crops. Manganese (Mn) shortages are most likely to occur under high pH conditioiTs~(generally above 6.3). Coarse soils, especially those of glacial-till origin, may be inherently low in manganese. Trees on these soils may show Mn deficiency at lower pH levels. Mn-containing fungicides applied in 2 or 3 cover sprays, or a single spray of Mn sulfate (2 to 4 lbs. per 100 gallons dilute rate) applied 1 to 2 weeks after bloom are usually adequate to over- come Mn deficiencies in tree fruits. In a preventive program., these applications might be suggested where leaf samples are found to contain less than 35 ppm Mn, or where symptoms are evident. -10- Mn deficiency may be associated with low or deficient levels of K under orchard conditions. In addition, the use of herbicides has been shown to reduce manganese levels, possibly because of increased soil temperatures. Copper (Cu) deficiency in the Fast is usually associated with high soil pH (6.3+) and/or soils that are inherently low in Cu , i.e. coarse glacial tills and sands or gravels. Fixed Cu fungi- cides such as Tribasic Copper Sulfate or C.O.C.S. applied at green-tip to 1/4-inch green at rates of 2 to 4 lbs. per 100 gallons dilute rate are effective in supplying Cu to apple trees. These sprays are suggested for trial on apples and pears when leaf samples contain less than 5 ppm of Cu. The higher rate is usually required to overcome Cu deficiency (leaf samples containing 3.5 ppm or less copper) . DO NOT apply Cu sprays after flower buds are exposed. The foliage of peaches is highly sensitive to copper sprays. Low rates of Cu sulfate (1/2 lb. per 100 gallons dilute rate) have been reported to be effective in supplying Cu to prunes and plums and to be somewhat effective in reducing cracking in sweet cherries when applied as foliar sprays. Further work is needed to determine safe corrective treatments for use on stone fruits. Summary Nutrient sprays represent a means for immediate applications'-- of an element to the foliage and fruiting surfaces of fruit trees. In most cases, these sprays should be considered as supplemental treatments for adjusting nutrient status rather than as the sole means of supplying the element in question. Zn sprays, however, represent the most efficient and effective means of supplying this element because of numerous problems involved in obtaining adequate response to soil applications of Zn. Frequently, multi-element imbalances are encountered that present difficulties in correctly identifying the critical problem. In cases involving reduced growth, lack of normal dilution may interfere with identification of nutrient deficiencies. Visual evaluations of factors such as vigor of shoot growth, leaf size, crop level, and fruit development should be used to supplement leaf analysis in diagnosing the need for additional amounts of a particular element or elements. -11- GROWER RESPONSES TO THE APPLE IPM PROGRAM* William M. Coli and Ronald J. Prokopy Department of Entomology In December, 1981, the IPM sub-Project Steering Committee discussed the future prospects of the IPM Program for apples in Massachusetts. Many at the meeting agreed that an integrated approach to pest management v;as desirable for growers. However, no agreement was reached on whether or not growers were prepared to continue some form of IPM once USDA pilot program funds end in September, 1982. It was suggested that a questionnaire be mailed to fruit growers to gauge the interest in IPM, indicate the feasibility of private scout/consultants providing IPM services in Massa- chusetts, and determine the need to continue staffing of an Extension Pest Management Specialist. This article summarizes the responses to the questionnaire and adds comments where pertinent. In all, 87 questionnaires were returned out of 850 that were sent. Tliirty five were from individuals with less than 20 acres of bearing trees, 43 respondents had more than 20 acres, and 9 did not indicate their acreage. The total acreage listed by the respondents v;as 3,605, or just about half of the total apple orchard acreage in the state. The questions and responses are as follows: 1. Do you feel that you have received any direct or indirect benefit from the Apple IPM program during its pilot program phase (1978-present) ? 81 Yes 6 No 2. If yes , please indicate all of the ways listed below in which the program has been a benefit. 64 Educational/training sessions 49 Has enabled me to reduce pesticide usage and costs. 60 Improved pest messages received through Regional Agent newsletters and "code-a-phones" . 18 Direct participation in pilot program. 62 FRUIT NOTES articles summarizing program results and related research . 27 IPM information passed on from other growers. 10 Other * We would like to express our sincere thanks to those individuals who took the time to answer and return the questionnaire on which this review is based. I A substantial percentage (56?.) indicated savings in pesticide " costs and application costs, suggesting that growers other than those directly participating in the pilot program have been able 3. If it were possible to expand the pilot program into your area, would you wish to receive IPM scouting and grower advisement for a fee of $20-25/acre? 45 Yes 36 No Personnel and logistical considerations have limited the number of pilot program participants. However, such a positive response to this question may indicate a strong potential for private scout/consultants to offer IPM services in the future. Sixty percent of those with less than 20 acres responded with a "yes" answer to Question #3. In spite of this interest, it may be difficult for private scout/consultants to accommodate these smaller growers unless a substantial number of orchards located reasonably close to one another can be contracted. 4. Po you feel that grower education, training, and informational needs would be adequately met once IPM pilot program funding ends, utilizing levels of Plant Pathology, Entomology, and County Extension staff input as before the initiation of the apple IPM program? 16 Yes 61. No Seventy percent of respondents acknowledged the difficulty of adequately meeting grower needs in a fast- changing agricultural environment with staff input levels that existed before the apple IPM pilot program. As noted in the cover letter that accompanied the questionnaire, federal funds which have for the period 1978- 1982 been earmarked for apple IPM, will in 1983 be mandated for im.plementing IPM in other commodities. It is possible, therefore, that many of the benefits noted by growers (Question #2) resulting from the IPM pilot program will be difficult to maintain. Prokopy and Groden indicated plans to continue with an ongoing format of IPM information transfer via monthly IPM training sessions in grower orchards in spring and summer after 1982. Inasmuch as Prokopy and Manning have substantial research and teaching respon- sibilities, they may not be able to adequately respond to the high volume of day-to-day questions from growers regarding pest manage- ment decisions presently being handled by IPM program specialists Coli (insects and mites) and Becker (diseases). Also, building a The Annual March Entomology Message to Massachusetts Fruit Growers, 1982. -13- framework within which growers or private scouts can do their scouting with regular advice from extension pest managers, as well as providing for a rapid, computerized system of delivering accurate timely pest messages, may be difficult. 5. If not, should an IPM specialist continue to be located at the University to serve as a resource person for growers interested in practicing IPM and/or to assist with private sector implementation of IPM? 66^ Yes 6 No This question was similar in intent to Question #4 and while 17^ of those returning questionnaires chose not to answer this, 761 felt that an IPM specialist position should continue to be located at the University. 6. If an IPM specialist continued to be located at the University, should this person have responsibility for: (3) 111 Only insect and mite IPM. Only disease IPM Both diseases and insect/mite IPM Weed IPM Vertebrate IPM (rodents, deer, etc.) All the above Options ranked by growers with a (1) were given 4 points; those ranked (2) were given 2 points; and those with a (3) were given 1 point. Options marked (4), (5) and (6) received no points. The numbers appearing in this summary next to the option are the total number of points awarded that option, and the number in parentheses indicates its rank with respect to the other options. This ranking was also used for Questions #7, #8, and #9. It is not surprising that the first choice of respondents to Question #6 was "all of the above", since IPM is a blend of many disciplines. While it is unlikely that any one person has substan- tial expertise in all of these areas, this response indicates areas where growers feel further effort is required. The close second choice also points out the need for a specialist with multi -discip- linary skills and responsibilities. 7. Due to cutbacks at both State and Federal levels, it is not certain whether funds for an IPM specialist position would be available from these sources. Were such a specialist to be retained at the University, should: (2) 15 7 Individual growers contribute to the partial financial support of such a position (remaining support to come from available state and/or federal funds) . (4) S5 (2) 220 (5) 44 (6) 40 CD 226 -14- (3) 142 The Massachusetts Fruit Growers Association, Inc. be asked to contribute to the partial financial support of such a position (remaining funding to come from available State and/or Federal sources) . (1) 205 The Massachusetts Cooperative Extension Service and/or the Federal governm.ent be asked to fully fund such a position. In designing this questionnaire, we felt it important to present growers with several options regardless of their feasibility. The only realistic option here is for individual growers to contribute to the partial funding of an IPM Specialist, with remaining funds to come from Federal/State sources. It should be apparent by now that one of the tenets of President Reagan's "New Federalism" is more self reliance on the part of the states as well as commod- ity groups and less reliance on steadily declining Federal support. As noted in the Annual March Entomology Message To Massachusetts Fruit Growers, 1982 by Prokopy and Groden , an Apple IPM Specialist position can only be continued if fruit growers are willing to match a certain level of Federal/State support v/ith yearly support of their own. While most growers with more than 20 acres indicated an interest in full funding from Federal/State sources, most growers with less than 20 acres preferred that individual growers partially fund such a position. 8. When pilot funding ends in September, 1982, I would like to see: (6) ^8 IPM cease to exist, and growers return to a standard preventative spray schedule. (5) "hl^ Private IPM scouts offer services presently offered by the pilot program., with no University contact. (3) 138 Private IPM scouts offer services presently offered by the pilot program, with scout training and peri- odic orchard visits provided by a University IPM Extension Specialist. (4) 36^ The grower or some member of orchard staff perform IPM scouting with no University contact. (1) 217 The grower or some member of orchard staff perform IPM scouting, with training and periodic orchard visits provided by a University Specialist. (2) 204 IPM related training and information provided by the Regional Fruit Agents. It seems clear that respondents prefer to continue grower or private scout contact with University IPM specialists after the pilot program ends. In many other states, extension personnel con- tinue in a resource capacity to make available updated IPM techniques and assist with training and occasional supervision of growers and private scouts. Cooperative Extension administration as well as USDA IPM program leaders have expressed support of this relationship, believing that it makes little sense to spend 5 years developing a -15- system of pest management and information transfer, and then fail to provide growers and scouts with continued extension staff support . Questionnaire respondents' second choice here was to have IPM related training and information provided by the Regional Fruit Agents. Thus, it would seem desirable to intensify efforts to better utilize Regional Agent skills, grower contacts, and field observations as part of the overall statewide IPM effort. How- ever, the uncertainties associated with county funding for Extension may limit the extent to which this can be accomplished. 9. Should private IPM scouts be available for a reasonable cost, say $20-25/acre, I would: (5) 5^ Not choose to hire one for scouting my orchard. (4) 80^ Hire one to scout my acreage only. (2) 179^ Hire one in cooperation with some other grower(s3 . (3) 9_3 Rely on chemical company fieldmen for assistance in daily or weekly spray decision making, (1) 191 Rely on County Extension staff for assistance in daily or weekly spray decision making. Due to budget uncertainties mentioned above, it is questionable whether the respondents' first choice is realistic. Of course, it would be the least costly to the grower. A substantial number of growers appear willing to hire private IPM scouts either alone or in cooperation with other growers. Numerous growers, however, would continue to rely on the traditional sources of advice con- cerning spray decisions, such as fieldmen from chemical companies. Summary It appears that substantial numbers of growers believe they have benefited from the apple IPM program. A majority of respon- dents also felt that the level of extension input prior to the IPM Apple Program may not be adequate for present needs and that an IPM specialist with multi-disciplinary responsibilities should be continued at the University. This person would supplement the activities of present extension faculty and serve as a resource and liason person between practicing IPM growers, private scouts, and University extension personnel. Finally, while respondents would prefer funding for such a position to come from Federal sources, a substantial number feel costs for a specialist position and for private scouting should be borne partially by the growers. -16- BROWN ROT OF PEACHES: AN UPDATE ON MANAGING THE DISEASE Daniel R. Cooley , Christopher M. Becker 2 William J. Manning Department o£ Plant Pathology Where peaches, plums and cherries are still grown in Massa- chusetts, brown rot remains the most serious disease problem on these fruits. It attacks blossoms, spurs, twigs, stems and fruit. Throughout the season, and after harvest, brown rot is a problem. The Life Cycle of The Fungus Brown rot is caused by a fungus, Monilinia fructicola. This fungus survives the winter in cankers, on twigs and branches, or in mummified fruit. In spring, when the first green tissue appears on fruit trees, the fungus also starts to grow. It produces a grayish fuzzy mold, which contains a huge number of spores called conidia. These conidia will produce new infections when they are carried to new, growing tree tissue. Conidia are not the only type of spore produced by the fungus. Ascospores are also released in the spring. Tiny cup-like "mush- rooms" grow from mummified fruit on the ground, and ascospores are released as visible clouds from these structures when conditions are right. Air currents carry ascospores and conidia to new tissue. Flowers are particularly susceptible. It takes only a few hours for these spores to germinate and cause infection. If unchecked, the fungus grows in two ways. It quickly produces new tufts of conidia on blossoms which are then released. It also grows down the blossom petiole to the fruit spur and twig. In the twig, a reddish-brown, sunken canker develops. The twig is often girdled by the fungus and soon dies. The surface of lesions soon grows greyish tufts of conidia. These conidia will infect fruit later in the season. Brown rot does not infect leaves and/or bark directly, but grows in from blossom and fruit infections. Ascospores and conidia do not live long. The apothecia which produce ascospores also disinte- grate in late spring. Therefore, when fruit ripens, the ascospores have disappeared. When ripening fruit become infected, the infec- tion is caused by conidia from twig cankers. As fruit matures, it 1 Extension Technician 2 Extension Plant Pathologist -17- becomes more susceptible to infection. Wounds made by insects, wind or hail increase infections, but even without wounds the fungus often invades the ripe fruit. As the fungus grows in the fruit, it produces more conidia, which can spread the rot to more fruit. Infected fruit can also dry on the tree to form a shriveled mummy, which, after falling, can last in the ground for two or more years. These mummies will produce apothecia and asco- spores in the spring. The life cycle of the brown rot fungus is outlined in Figure 1. Management To satisfactorily manage brown rot, it is important to pay attention to the life cycle of the pathogen. In particular, the following facts should be kept in mind. 1. Spores which cause primary infections come from twig cankers, stem cankers, and mummified fruit. Getting rid of cankers and rotten or mummified fruit prior to growth in the spring will reduce the number of spores in an orchard, and thus reduce the chance of early infections. 2. Reducing early infections reduces the number of later infec- tions. Fewer spores are available to cause infection through- out the rest of the season. 3. When spores are available, they cause infection during wet weather. At 45 F the infection is established in 6 to 7 hours; at 70°F infection occur in 3 hours. To get protection fungi- cides must be applied before a rain or before the time for establishing an infection has gone by. 4. There are two times when brown rot control is particularly important; (a) during blossoming to protect from blossom blight, spur blight and later twig blight; (b) during ripening and harvest to protect against fruit rot. (a) Brown rot blossom blight: As mentioned, preventing infec- tion at this time greatly aids in preventing fruit rots later in the season. The number of fungicide applications needed depends on rain and the fungicide used. All fungi- cides should be applied around pink blossom, providing the rain necessary for infection is occurring or expected. Thereafter, applications may be necessary at as little as 3 day intervals if rain is heavy and tree growth is rapid. These intervals may be extended as the rain allows. One exception is the fungicide triforine 18.2% EC (Funginex) . Start at pink, make a second application after 50% bloom and a final after petal fall. In dilute sprays, use 12 to 16 fluid ounces per 100 gallons of water. For low volume -18- use 36 to 48 fluid ounces in 50 to 200 gallons o£ water per acre. No more than 3 applications of Funginex should be made. Often, this is enough to cover bloom even during warm, wet weather. Other fungicides may be used as needed. These include dichlone 50 WP 1/2 lbs. (1-1/2 lbs/acre low vol.); dichlone 50 F 6.4 oz. (19.2 oz/acre low vol.); captan 50 WP 2 lbs (6 lbs/acre low vol.); thiram 65 WP 2 lbs (6 lbs/acre low vol.); benomyl 50 WP plus captan 50 WP, 4 ounces plus 2 lbs, (12 ounces plus 6 lbs/acre low vol.); thiophanate-methyl (Topsin) 70 WP 8 ounces (24 ounces/acre low vol.); DCNA(Botran) 75 WP 1-1/3 lbs (4 lbs/acre low vol.). Captan may cause leaf injury such as "shot-holing" on some varieties. Thiram is a good alternative if such injury occurs. Dichlone should not be used after petal fall. Dichlone is effective up to 12 hours after rain starts; benomyl applied dilute is effective up to 15 hours after rain starts. Always check label recommendations and precautions. (b) Fruit rot: Immature fruit will not generally rot unless there is a great deal of wet weather. Fruit becomes increasingly susceptible as it starts to ripen. There can be considerable fruit rot in trees if weatlier is rainy unless the fruit is well-protected with fungicide. Rot will continue through harvest and marketing. Fungicides should be applied starting about 3 weeks before harvest and be repeated as needed until fruit is harvested. Re- peat sprays may be made at 7 days (possibly longer) if there is little or no rain. Captan or benomyl plus captan used at the above rates may be used up to harvest; Botran and Topsin may be used up to 1 day before harvest; thiram may be used up to 7 days before harvest. Postharvest brown rot. Brown rot and another disease, Rhizopus rot, may be reduced on harvested fruit by postharvest dips or sprays. Captan 50 WP (2 lbs) plus Botran 75 WP (1 lb) in 100 gallons of water is recommended. In addition, rotting fruit should be culled rapidly. Hands which touch a fruit with brown rot transfer spores to healthy fruit causing new infections. Likewise, containers which are used repeated- ly carry infections to healthy fruit, so use new or disinfected containers . I I 19 — -T) TJ ^> — , ■3- ^ " O rt f O X --. '-'"' - . n n rn "Id ^ rr o -^ OQ g • c 2 --• n ^ 3 2 S rD si. o -J I c (t> u — • o < fi> (D in a. a. -20- DISEASE DIAGNOSIS: INFORMATION FOR GROWERS Daniel R. Cooley , Christopher M. Becker William J. Manning^ Department of Plant Pathology The Plant Pathology Department has a number of facilities in the state devoted to plant disease diagnosis. The department at Fernald Hall, the Shade Tree Laboratories, the Field Stations at Waltham and Wareham, and specialists in different regions of the state all offer assistance in identifying plant disease problems. In addition, private consultants, usually working for agrichemical companies, offer assistance. This system allows basically three options to fruit growers. First, most problems are identified by growers themselves. V/hen a problem is outside the realm of a grower's experience, a regional specialist or chemical company representative can be consulted. If the problem is not resolved at that level, a fruit grower or the regional specialist will then go to the University. Hence, generally it is the most difficult diagnosis problems which find their way to the University. Sometimes these problems can be resolved in a matter of hours, by examining the sample microscopically and consulting reference books or other specialists. However, disease problems often take longer to identify. Samples must be submitted for culturing and then the organisms in these cultures have to be identified. This may take weeks. Virus diseases are particularly difficult to ident- ify, and may require months or even years to diagnose, as artificial growth media which speed identification of other pathogens do not \\fork for viruses . The policy at the University is to give growers an informed opinion as soon as possible. If culturing tests or other information contradicts the initial diagnosis, then the revised diagnosis is relayed to the grower. The amount of effort involved in a diagnosis will also reflect the options available in managing a problem. For example, if the same fungicide plus pruning program are recommended for managing several different canker diseases, it is not vital that the specific canker problem be identified, as long as it is one which can be managed by the program. To most growers, economical disease control is the goal of diagnosis. The goal of the Plant Pathology Department is to fit diagnosis to the growers needs. We encourage growers to consult with us on any problem. We would appreciate suggestions as to how we might improve our diagnostic services 1 Extension Technician 2 Extension Plant Pathologist SUGGESTIONS FOR USE OF CALCIUM SPRAYS IN 1982 Mack Drake and William J, Bramlage Department o£ Plant and Soil Sciences Calcium chloride (CaCl2) foliar sprays are recommended in Massachusetts for all apple growers to increase the flesh cal- cium (Ca) content. Higher flesh Ca can markedly reduce bitter pit, cork spot and fruit breakdown during storage. Apply foliar sprays of CaCl^, beginning 3 weeks after petal fall and repeat at 2 week intervals totaling 6 to 8 applications. Apply & pounds CaCl-, per acre per spray until mid-July. After mid-July apply S-lO^pounds per acre per spray. Continue foliar CaCl2 until fruit are ready for harvest. Use a technical grade of CaCl2 such as Allied Chemical Dow Flake, 77-801 CaCl2. Other brands may be equally suitable. Experience in Massachusetts has shown that CaCl^ can be combined with pesticide sprays. However, some growers have observed that the combination of Cantan or Guthion [azinphos methyl) 50 WP and CaCl^ may increase foliar burn. DO NOT MIX CaCl2 AND SOLUBOR SPRAYS I ALWAYS DISSOLVE CaCl2 IN A PAIL OF WATER and add this last, when the spray tank is nearly full, to insure that the CaCl^ is completely dissolved before spray- ing begins. Foliar CaCl^ sprays may be applied dilute (300 gallons/acre) or up to lOX concentration (30 gallons/acre). In our research, apple flesh Ca was increased more by concentrated than by dilute sprays. In 1977, 6X and lOX foliar CaCl2 sprays were equally effective in increasing Mcintosh flesh Ca. CaCl^ sprays can cause burn of leaf margins. Foliar injury has been more serious on Mcintosh than on Delicious or Cortland. Apple leaves are less susceptible to CaCl2 burn after mid-July. Mcintosh growing on M7 may be more susceptible to foliar burn than those on standard rootstock. Weak or injured trees may be more susceptible to CaCl^ burn than heathy trees. To reduce the chance of leaf burn, DO NOT REPEAT A FOLIAR CaCl^ SPRAY UNLESS 1 INCH OF RAIN HAS FALLEN SINCE THE LAST APPLICATION. In 1981, 3 different materials were used to supply foliar Ca at the University of Massachusetts Horticultural Research Center. Rate of application was that recommended by the manu- facturer. Control, CaCl2, Carrier 1, and Carrier 2 supplied a total of 0, 86, 64 and 16 grams Ca per tree in 8 applications. -22- Fruit Ca was 109, 155, 142 and 118 parts per million in dry flesh, respectively. Breakdown was 33, 4, 10 and 17%, res- pectij^ely, for fruit air stored at 32 F for 5 months and then at 72 F for 7 days. These results agree with those of previous years and show the positive effect of increased fruit Ca to reduce storage breakdown of Massachusetts-grown Mcintosh apples. We do not recommend long-term storing of Mcintosh apples with less than 150 ppm flesh Ca. Questions have been asked about possible accumulations of chloride (CI) in the soil. Chloride salts are highly soluble. Research in the Netherlands showed that there was no annual buildup or accumulation of chloride where annual rainfall exceeded 30 inches per year. Rainfall in all areas of Massachusetts exceeds 30 inches per year. Annual rates of application of potassium chloride fertilizer for corn silage, vegetable crops and alfalfa in Massachusetts usually exceed 200 pounds per acre, supplying about 100 pounds of chloride per acre. Our recommendation of foliar CaCl^ amounts to 75 pounds CaCl2 annually. This contains about 35 pounds of chloride per acre. Also it is important to note that this 35 pounds of chloride is applied in 6 to 8 increments of 4 to 6 pounds per acre per foliar application as compared to the 100 pounds of chloride in one application for corn, vegetables and alfalfa. ********** RECOMMENDATIONS FOR USE OF GROWTH REGULATORS Readers of FRUIT NOTES from outside New England have in the past requested our recommendations for use of growth regulators. Our recommendations for growth regulator use on apple trees, start- ing this year, now are included in the New England Apple Pest Con- trol Guide which is revised annually. -23- IS IT WORTHWIILE TO REFRIGERATE BLUEBERRIES? William J. Bramlage Department o£ Plant and Soil Sciences Blueberries are not stored for prolonged periods of time because their relatively short postharvest life, even at low temperatures, does not make this practical. In fact, many are not stored at all, being sold directly to the consumer at harvest. Yet, some do pass through marketing channels and their short postharvest life can lead to substantial losses, usually due to berry rotting. As with all plant materials, blueberry postharvest life can be extended considerably by refrigeration. Most plant materials change as much in 1 day at 85°F as they do in about 2 weeks at 32of. Still, many blueberries are sent to the mar- ket without refrigeration, and it is reasonable to ask whether or not it would be worthwhile to refrigerate them first. Two recent reports from New Jersey are enlightening. One by Cappellini, Ceponis , and Koslow (HortScience 17: In press) of Rutgers University assessed the extent of defects in blue- berries on the counter in New York City supermarkets. They found that an average of IS-o of the berries were defective, with rots accounting for two-thirds of these defects. Shriveling, mechanical damage, and overrjpeness accounted for the other one- third of the defects. As would be expected, the percent of fruit that were defective was higher for late harvests than for early harvests (about 20% vs. 10^). These results show clearly that thereis a problem with quality of blueberries in the supermarkets. The second report, by Hudson and Tietjen (HortScience 16: 656-7) of the USDA Lab in New Brunswick, N J , shows the impact that refrigeration can have on blueberry losses. They obtained commercial Bluetta and Bluecrop berries, which at the packing- house had temperatures ranging from 72 to 850F. In 1 test, some of these berries were cooled to 35^F in 2 hours while others were cooled to only 50°F over the course of 24 hours . Both batches of berries were then put in a 50 F room for 3 days, after which they were put at 70°F for 1 or 2 days. This test examined the value of rapid cooling to a low temperature before marketing with limited refrigeration. After the 3 days at 50°F, all of the samples had 2-3% rotted berries. However, after an additional day without refrigeration (as is often the case in the market) the berries that were rap- idly cooled to 350F still had about 3% rot while those not cooled 24- to 35°F had 7 to 9% rot. After a second day without refrigeration the rapidly cooled berries now had about 151 rot and those not cooled to 35°F before marketing had 301 rot. In a second test some of these berries were cooled to 35°F in 2 hours, and others were cooled to 35°F over the course of either 24 or 48 hours. They were all kept at 350F for 10 days and then placed at 70OF for 1 or 2 more days. This test there- fore examined the importance of the speed of cooling. Right out of storage, the berries cooled over the course of 1 or 2 days had about 4% rot while those cooled quickly had about 21 rot. After 1 day without refrigeration the amount of rot had doubled, and after an additional day without refrigeration the amount of decay tripled again, so that 2 days after removal from storage over 201 of the slowly cooled berries were rotting while about 10% of the quickly cooled berries were rotting. These tests showed that rapid and continual refrigeration can control rotting of blueberries during the normal transit and marketing periods. The best temperature for blueberries is about 320F. One cause for concern about refrigerating berries is the moisture that condenses on their surface when they are removed from the cold. Condensation might cause loss of bloom, and many shippers and receivers believe that condensed moisture will increase the amount of rotting. While it is true that moisture on berries can help mold spores germinate and grow, there is no clear evidence that it actually increases rot because the cooled berries are in better condition and can resist infection better than berries of the same age that were not properly cooled. Hudson and Tietjen concluded that by rapidly cooling blue- berries to near 320F and keeping them at this temperature, they should be suitable for shipment by boat to Europe. If they can withstand this kind of transport, it should certainly be worth- while to refrigerate blueberries thoroughly before they enter the normal marketing channels. Cooperative Extension Service U.S. Department of Agriculture University of Massachusetts Amherst, Massachusetts 01003 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 Bulk Third Class Mail Permit FRUIT NOTES PREPARED BY DEPARTMENT OF PLANT AND SOIL SCIENCES COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF MASSACHUSETTS, UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTY EXTENSION SERVICES COOPERATING. EDITORS W. J. LORD AND W. J. BRAMLAGE Vol. 47 No. 4 FALL ISSUE, 1982 Table of Contents A Glimpse at the Tree Fruit Industry in the Pacific Northwest Controlled Atmosphere Generators - Their Function and Malfunction Apple Maggot Trap Efficacy and Optimal Positioning Orchard Mouse Baiting and Vegetation Preventing Explosions in CA Storages When Atmosphere Generators are Employed Issued by the Cooperative Extension Service, Daniel I. Padberg, Director, in furtherance of the Acts of May 8 and June 30, 1914; United States Department of Agriculture and County Extension Services cooperating. The Cooperative Extension Service offers equal opportunity in programs and employment. A GLIMPSE AT THE TREE FRUIT INDUSTRY IN THE PACIFIC NORTHWEST"^ ' ^ William J. Lord Department of Plant and Soil Sciences In late October and early November, 1981 the author visited orchards in Oregon, Washington and for the longest period of time in British Columbia (BC) . It would take months to adequately assess the fruit industry in the Pacific Northwest. Nevertheless for the benefit of the reader who have never had the opportunity to visit this area I have included below some general and specific comments on fruit growing, mainly apple, in Oregon, Washington and BC. General Comments In contrast to those in Massachusetts, apple trees in the Pacific Northwest are irrigated, closely spaced, heavily spurred, more uniform in size within a block, and more vigorous growing. High light intensity in the Pacific Northwest and long days dur- ing the growing season make high tree density possible and enhances spur development and other growth. I suspect that soil variability in orchards is less than in Massachusetts. This fact and the ability to supply water by irrigation when it is needed are responsible, in part, for fruit tree size uniform.ity in the Pacific Northwest. M26 is gaining popularity and seems to be performing more satisfactorily than in Massachusetts, although leader support is being provided in some instances. This rootstock is being used because it induces early bearing and produces smaller less vigor- ous trees than more vigorous size- controlling rootstocks. It appears promising as a rootstock for the extremely vigorous Granny Smith. 1 The writer is indebted to Dr. Robert Stebbins, Extension Horti- culture Specialist, Oregon State University; Dave Burkhart, Extension Agent, Hood River, OR; Tom Darnell, Extension Agent, Milton-Freewater , OR; Dr. Tom Toyama, Research and Extension Center, Prosser, WA; James Ballard, Horticulturist for Carlton Nursery, Selah, WA; Dr. Max William, Horticulturist, USDA-SEA-AR, Wenatchee, WA; J.E, Swales, Horticulturist, Okanagan Similkameen Cooperative Growers' Assoc, Oliver, British Columbia, and numer- ous fruit growers for showing him the fruit industry in the Pacific Northwest . 2 A more detailed account of the author's comments on the fruit industry in the Pacific Northwest can be found in the Proceedings of the Massachusetts Fruit Growers' Association, Volume 88, 1982. -2- Disease problems in the Pacific Northwest are less than in Massachusetts, because of the arid climate. Nevertheless, apple powdery mildew is much more troublesome than in Massa- chusetts. On Golden Delicious this disease causes fruit russet- ing. Powdery mildew damages leaves and russets fruit on Newtown and Rome Beauty trees and the Granny Smith trees are highly susceptible to leaf damage. Mites, San Jose scale, and codling moth are perennial pests of apples. The apple maggot now poses a threat to the fruit industry in the Pacific Northwest and Spotted Tentiform Leaf- miner can be found in isolated areas with the potential to spread. Bulk bins are constructed from plywood with no air spaces in the sides of the bins. I question whether similarly con- structed bins would permit adequate cooling in many of our older storages which frequently have less refrigeration and insulation than newer storages . High light intensity and long days during the growing season enable growers with well-managed orchards and with newer varieties and strains to obtain higher yields of Extra Fancy apples than in Massachusetts. It was suggested that New England growers can survive on lower fruit quality because of their nearness to market and more profitable market outlets for lower quality fruit. This may be partly true but no apple grower can do well financially without a high pack-out of Extra Fancy apples. Pruning was a popular topic of discussion among the growers, fruit specialists and the author. The central leader tree has been the basic tree form in Massachusetts for many years and is now common in the Pacific Northwest. There were few points of disagreement among us concerning the training of central leader trees, however, heading cuts on 1-year-old wood to contain growth and induce lateral branching were common. Under Massachusetts conditions, I believe that the main value of heading cuts is for stiffening the scaffold limbs or the central leader. Heading cuts under our conditions are relatively ineffective for inducing lateral branching and delay production on young trees. We certainly are indebted on Don Heinicke, now a grower in Orondo, WA, for making growers conscious of the benefits of limb spreading. It was interesting to note that "tie downs" are gaining favor among growers in the Pacific Northwest for limb spreading (polypropyene twine attached to the limb and a "w" clip fhop clip)) pressed into the soil. Also, some growers delay spreading limbs on spur Delicious until the trees are 3 or 4 years old. Early spreading reduces growth which frequently is -3- undesirable and regardless, longer wooden spreaders are required when the trees becomes older. One grower advocated using no spreaders shorter than 12 inches in length. This length of spreader is unsuitable for 1-to 3-year-old trees. Summer pruning is gaining favor as a method of controlling excessive vigor and "compacting" young trees and for controlling size and vigor of bearing trees. An application of Alar-85* and Ethrel* is also being used to control growth on young trees large enough to bear. Alar-85 alone is used on bearing trees to restrict growth and increase fruit fulness . Specific Comments on Oregon Of most interest in Willamette Valley were 2 trellised hedge- row plantings on M9 or M26 with tree height comparable to the 12 feet or 15 feet alley width. In Massachusetts trellised trees on M9 rootstock are short and can be harvested by a picker stand- ing on the ground. Thus, the tall hedgerows in the Willamette Valley should produce higher per acre yields than the trellised trees in Massachusetts and also allows the removal of low limbs that have to be harvested by bending or kneeling less costly from the standpoint of reduced yields. The trees in the trellised hedgerow planting of Dr. Eugene Petroff in Salem are on M9 and M26 rootstocks. The trees are attached to a 4-wire trellis by staples. However, when the leaders are too small for stapling, they are tied to the wires. The trees are trained like free-standing trees with pyramid (Christmas tree) shape; the only function of the wire is to pro- vide leader support. Gravensteins on M9 planted in 1975 are spaced 8 feet by 15 feet with 1 tree in 9 being a Jerseymac pollenizer. The Gravenstein trees produced 12.7 tons per acre in 1980. The planting also contains Delicious and Golden Deli- cious on M26 rootstock planted in 1975 and spaced 6 feet by 15 feet and 6 feet by 14 feet, respectively. The Delicious and Golden Delicious produced 6 tons and 32 tons, respectively, in 1980 but the Goldens had a light crop in 1981. An adaption of Tatura Trellis, developed in Australia for mechanization of peach harvest, was being tried in the Petroff orchard. Each peach tree will have 2 limbs attached to wire so each can be trained at an angle of 60-70° from the horizontal towards limbs in the next row. The final canopy of the trees will be "v" shape. The goal is to maximize yield rather than attempt mechanization of harvest. It is the author's opinion that the h ligh cost of wire and posts for any trellis preclude their use except in a few instances such as high land values, for maximi zing yields on small holdings , or when the g( oai is earlv, heavy yie Ids. The multitude of train- ing systems b^ eing experimented with throu ighout the tree fruit *Trade name growing world shows that the fruit trees are remarkably toler- ant to the manipulation of their natural configuration by man. In the Milton-Freewater area I first learned that Promalin* was being used to increase the typiness of Delicious in the Pacific Northwest and that drip irrigation appeared to be improving crotch angles on spur Delicious. The Red King Oregon Spur strain of Delicious was found in the orchard of Wayne Trumball in Milton-Freewater. This strain is popular in the Pacific Northwest because it produced better crotch angles than Starkrimson and the tree is more vigorous. Nevertheless, some limb and tree reversion has been encountered on older trees. These reversions produce fruit similar to the Standard Delicious. The Red King Oregon Spur now is being planted in Massachusetts. Specific Comments on Washington Acreage and Production The apple industry continues to expand rapidly in Washington with thousands of acres being planted annually. Nevertheless, the average orchard size is only about 50 acres with few plantings in excess of 1000 acres. In one of the large holdings being developed it was impressive to see 1-year-old trees in orchard rows approximately 6600 feet long. In 1980 Washington produced about 72 million bushels of apples. One reliable source predicted that unless something unforeseen happens, future crops could exceed 100,000,000 bushels annually. Thus, over-production of apples in the United States seems possible because modest production increases also are predicted in other areas. Unfortunately, some orchardists will fail financially if the predicted production increases become a reality. But I was reminded that orchards with a sizeable percentage of the total acreage planted to well-managed young trees of newer varieties and strains should continue to be profitable. Rootstocks Most apple orchards are now planted with 200 to 300 trees per acre. Seedling trees are the most common rootstock but many successful orchards are on M7a, MM106 and MMlll. Granny Smith This variety continues to create much excitement in the apple industry. It produces long willowy growth, particularly on igorous rootstocks, and some fruit is borne terminally. Thus, there is much interest in vigor control with M26 rootstock, summer pruning, limb spreading and growth regulators. At least one grower TT- Trade name V summer prunes twice annually and supports the leaders of trees on M26 vv'ith a wire to which the leader is attached by string to prevent tree swaying. This same grower has double rows with densities of 950 to 1900 trees per acre. The trees have responded well to his system of heavy fertilization, pruning and training. Whether these double rows of Granny Smiths can be maintained at such high density remains to be seen. Currently, they are pro- ducing exceptionally heavy yields, which was the goal of the grower when the planting was established. If tree removal becomes necessary, I expect that the extra trees will have made money for the grower because of the high prices for Granny Smith apples. It is commonly stated that Granny Smith requires 180 days to mature but soil, slope and climate are factors that influence this requirement. In one orchard, a grower stated that his Granny Smiths would mature in 165 days. Immature Granny Smiths are highly susceptible to scald but on the other hand, the market wants dark green skin color. Un- fortunately, a red blush may develop on mature fruit or those exposed to bright sunlight. Perhaps a cheek with a tinge of red could be the trademark for Granny Smiths from some orchards. Granny Smith fruit are highly susceptible to bitter pit, and calcium sprays may be required in some instances to reduce the severity of this disorder. Also, it was of interest to note that fruiting spurs develop no abscission layer, thus the har- vested fruit has a sheared stem or it is stemless. The Granny Smith apple is partially self sterile, thus cross pollination is necessary. Pollenizers being used for Granny Smith are Delicious, Rome Beauty, Golden Delicious and Winter Banana. There is interest in spur type trees of Granny Smith, namely Greenspur and Granspur, but questions remain concerning productivity, in comparison to trees with standard growth habit, and fruit quality. Mutations in fruit color also have been found. The production potential of Granny Smith based on present acreage, is a guess however, one guess is 10,000,000 bushels. It also is believed that the full market potential for Granny Smith has not been reached and that demand can be increased by advertis- ing. Specific Comments on British Columbia The Industry Orchards in this beautiful province of Canada were visited with J.E. (Ted) Swales, Horticulturist for the Okanagan Similkameen Cooperative. The cooperative has 600 grower members who on 5,000 acres produce apples, pears, cherries, peaches, apricots and prunes. It is obvious that many members have small acreages since the orchard holding per member averages about 8 acres. (The British Columbia Fruit Growers' Association classifies growers with more than 1 acre as being commercial. The opinion was expressed that 25-30 acres were necessary to support a family.) According to Swales, 951 of the 30,000 acres in tree fruit are planted in the Okanagan and Similkameen Valleys with approx- imately 70'o of this acreage in apples. Apple growers produced 10.6 million bushels in 1980 and the 1981 crop also will exceed 10 million bushels. The leading apple varieties are Delicious (501), Mcintosh (25%) and Spartan (10%). Approximately 2000 acreage of peaches are grown in Okanagan and Similkameen Valleys. Varieties grown include Redhaven, Triogem, T.H. Hale, Valient, Fortuna A., Veteran and Vedette. Apple Orchards MM106 and MMlll rootstocks are not recommended in BC because of collar rot. Whereas, M4 , which is more vigorous than M7a, M2 and M26 are currently the most popular size- controlling rootstocks. Trees are being planted at 250 trees or more per acre even when on vigorous- size controlling rootstocks. Many of the spur-type strains of Mcintosh originated in BC. A discussion by Ted Swales of these strains can be found in the Proceedings of the Massachusetts Fruit Growers' Association, Volume 87, pages 90-98, 1981. As in Massachusetts, BC growers have encountered trees with standard- type growth habit in plantings of Macspur and the varia- bility is between trees rather than within a tree. The problem also occurs in plantings of Morspur Mcintosh and whether it will occur in the recently introduced Starkspur Ultra Mac (Dewar strain) , remains to be determined. The Dewar strain, a whole tree mutation of Summerland Red, was discovered in the Dewar orchard in Oyama, BC and the propagating rights were purchased by Stark Brothers Nur- series in 1977. Trees on Antonvoka rootstock were seen in one orchard. (There is considerable nursery interest in this rootstock because of its winter hardiness.) The Antonvoka rootstock in this planting and at our Horticultural Research Center in Belchertown is producing numerous root suckers. At the Horticultural Research Center, Antonvoka is being used as the understock on interstem trees. Peach Orchards Most striking in orchards visited were high tree vigor and the absence of Fusicoccum and/or Valsa Canker. Perhaps the absence of the devitalizing effects of these cankers helps explain the good tree vigor and ivhy even older blocks had no missing trees. -7- During the 2-day tour of peach growers, I observed a variety of tree spacings and training systems. Tree spacings varied from double rows with trees 8 feet x 8 feet and a 12 foot alley, 7 feet X 14 feet, (432 trees/acre), 10 feet x 18 feet, 12 feet x 16 feet, 10 feet x 20 feet, 16 feet x 18 feet to 20 feet x 20 feet. The trees were being trained on wire using the 2-arm oblique cordon system, by the open-center method, by the modified central leader system, or as central leader trees. Yields as high as 30,000 lbs. per acre were reported. The major problem being encountered in older plantings of closely- spaced trees was that of containing tree height. In these plantings the majority of the current season's growth (3-5 ft. in length) was beyond the reach of a person standing on the ground. It also was interesting to note that summer pruning was being practiced to restrict tree size in some plantings. Orchard Value The most frequent question asked of the writer was about the value of orchards in Massachusetts. With orchards in the Okanagan Valley valued from $15,000 to !^25,000 per acre, the BC growers were amazed at the comparatively modest value of our orchards. Certainly high land values and concern about fruit tree loss from periodic winter freezes helped explain the high trees densities in BC in relation to tree densities in Massachusetts. Tree fruit growers in BC could make more money by selling their land than by selling apples because the scarcity of suitable land and the need for water limits acreage available for tree fruit production, residences and businesses. Unfortunately the freeze on sub-division of agricultural land has not deterred buying sizeable acreages for real estate. It is, however, a deterrant for most people wanting to become fruit growers or for growers wanting to expand their acreages. Labor Force It was estimated that 60 to 701 of the orchard labor were transients from Quebec who receive "starting" salaries of approx- imately six dollars per hour. Harvest help is paid on a piece work basis, nevertheless, attempts are being made by the Canadian Farmworkers Union to organize the transient labor force. Summary In retrospect the most striking difference between orchards of the Pacific Northwest and Massachusetts is tree density. Den- sities of 250 to 300 trees per acre even with seedling rootstock are common whereas in Massachusetts growers are planting trees on M7a or M>U06 rootstocks at 72 to 140 trees per acre. The question is, why the difference? We are not blessed with the long hours of high light density as in the Pacific Northwest. Our land values -8- are less. There is no strain of Mcintosh that will produce 1001 red color like many Delicious strains. To obtain a high packout of Extra Fancy Mcintosh fruit we need well pruned, well managed, and non-crowded trees and long-term storage potential of fruit. Many Massachusetts growers store , grade, and sell themselves at least part of their crop which means less time is available for the orchard. This generally is not true in the Pacific North- west. Lastly and perhaps the most important reason for our lower tree densities is Yankee conservatism. ********** CONTROLLED ATMOSPHERE GENERATORS - THEIR FUNCTION AND MALFUNCTION David R. Dilley Horticulture Department Michigan State University* The process of controlled atmosphere (CA) storage consists of storing fruit in a virtually air tight and well insulated refrig- erated room at high humidity in 2 to 31 oxygen plus 1 to 51 carbon dioxide with the balance of the atmosphere being mostly nitrogen. Room size varies from 10,000 to 100,000 cubic feet. Various means are employed to adjust the gas atmosphere initially and to sub- sequently control it for storage duration of up to 10 months. The disastrous explosion of a controlled atmosphere storage room and resulting personal tragedy at Peabody Orchards, Inc. near Fenton, Michigan in November (See GLFGN Nov. 1981) caused great concern among storage operators and suppliers. This accident occurred as an Arcat CA generator was being employed to lower the oxygen level for the CA storage of apples. Propane gas used in the CA generator was theorized to have accumulated to an explosive con- centration in the sealed room. Several kinds of CA generators are used in Michigan and elsewhere that are fueled by natural gas or propane. The purpose of this article is to describe CA generators and to answer many questions that have risen since the storage dis- aster. Hopefully, this will direct the attention and action of owners, operators and suppliers of this equipment to ensure that all possible precautions are taken to prevent such accidents in the future. More knowledge about CA generators may also be import- ant to arrest unwarranted fear in the use of this important equip- ment and technology for fruit storage. * Printed with permission of the author. Article originally prepared for the Great Lakes Fruit Growers News. An explosion hazard results v\rhen propane or natural gas passes through the generator uncombusted due to a malfunction and accumulates to an explosive ratio with oxygen in the storage room. What are the facts about explosive levels of propane and natural gas? For pro- pane the lower explosive limit (LEL) is 1.1% in air and the upper explosive limit (UEL) is 9.5^. This means that at any concentration between 2.2 and 9.5% propane in air an explosion can occur if touched off by a spark or flame. At less than 2.21 there is insufficient propane to cause an explosion and at more than 9.5% propane there is insufficient oxygen in the air to cause an explosion. Air con- tains 1\% oxygen. A minimum of \\% oxygen is required to cause an explosion with propane. In the case of Peabody CA storage explo- sion this means that at least 1.1% propane was present while the oxygen was greater than 11°. For methane, the primary component of natural gas, the LEL and UEL are 5.31 and 14.0%, respectively, and a minimum of 12.1% oxygen is required for an explosion. Incomplete combustion of propane also produces carbon monoxide and ethylene which are also combustible. Moreover, carbon monoxide may accumu- late in work areas and this poses a health hazard as a poison. There will be more about this later but let's return to some begin- ning questions about CA generators. What are they? Why are they used and how do they work? The term CA generator means a mechanical device that lowers the oxygen concentration of the atmosphere by causing a net increase in the percentage of nitrogen in a storage room. CA generators were introduced in the early 1960 's and currently most of the controlled atmosphere facilities in North America are equipped with some type of generator. They are used to rapidly establish the desired low oxygen level of 2 to 3% within 2 to 5 days after hermetically seal- ing the refrigerated storage room of fruit. Without using such a device it generally takes several weeks to lower the oxygen content of the storage room to the same level as the fruit consume oxygen in the process of respiration. There are numerous reasons and beneficial effects of rapidly establishing the CA condition that need not be elaborated here. Some CA generators adjust the level of both carbon dioxide and oxygen while others adjust only oxygen and a separate device is used for scrubbing carbon dioxide. Since carbon dioxide is produced by the fruit by respiration some means is necessary to limit carbon dioxide accumulation in both conventional or generated CA storages. The CA generator provides a means to adjust the oxygen level in the room independently of the fruit. There are several types of CA generators used commercially and differ widely in basic principles. They include: nitrogen purge systems using liquid or gaseous nitrogen; inert gas generating systems which produce the low oxygen atmosphere external to the -10- storage and recirculatory systems which utilize the storage at- mosphere as part of the system. The basis for the nitrogen purge and inert gas generating systems is to dilute the initial storage oxygen by displacing it with the nitrogen-rich atmosphere. The recirculatory system removes oxygen directly by converting it to carbon dioxide. Each system will be described. Nitrogen Purge System Liquid or gaseous nitrogen is bled into the storage room where it displaces an equal volume of storage atmosphere. It is basic- ally inefficient because at the start each cubic foot of pure nitrogen introduced pushes out 1 cubic foot of air which contains 19% nitrogen and 21?; oxygen. As the oxygen level is reduced the inefficiency becomes more pronounced. Some improvement can be made by connecting several rooms in series. No one in Michigan employs this system. Inert Gas Generators There are three basic types. Tectrol System: This was intro- duced in the early 1960 's which combusts propane or natural gas with fresh air in a flame and uses a catalytic burner to ensure clean combustion. The storage room is purged with this low oxygen atmosphere (about 2% oxygen) at a flow rate of 700 to 1200 cubic feet per hour until the storage room has been lowered to the desired low level, e.g., 2 to 3% oxygen. A minimum of 11% oxygen is required to support a flame with propane so this type of generator can not be used in a recirculatory system. The carbon dioxide produced is removed with an activated carbon adsorber. This is now known as the Gen-o-Fresh system of the Samifi Transfresh Corporation. When operating properly with propane with an effective catalyst the atmosphere introduced into the storage room contains about 2% oxygen and 971 nitrogen with less than 1 ppm of carbon monoxide, ethylene and other hydrocarbons. If the catalyst is functioning poorly the effluent from the burner can contain several hundred ppm of carbon monoxide and ethylene and if the air fuel mixture is not adjusted properly, several thousand ppm of carbon monoxide and ethylene along with other hydrocarbons. One thousand ppm equals 0.1%. It is important to supply fresh make-up air to this type of generator. If the make-up air becomes contaminated with the refrigerant freon, the catalyst can become poisoned by hydrofluoric and hydrochloric acids formed as freon is decomposed on the hot catalyst. This is the reason that these units should not be located near the refriger- ation compressors. The catalyst can also be damaged by over heating which causes it to agglomerate and fuse which reduces the effective calalytic surface area. This is one reason the catalyst on these units has a cooling jacket. Open Flame Burner This is known variously as the Eaves, Australian, Anderson and Wilde system. Propane or natural gas in combusted with fresh air in a flame. And, as with Tectrol, a minimum of 11% oxygen is -11- required to support a flame so a recirculatory system can not be used safely. No catalyst is employed to ensure removal of incom- pletely combusted fuel so proper adjustment of the air/fuel mix- ture is essential. The storage room is purged with the low oxygen effluent from the burner and the carbon dioxide produced is gener- ally removed by dry lime in the storage room or by adsorbers or absorbers. It is not uncommon for these systems to introduce at- mospheres into the storage room containing several thousand ppm of carbon monoxide and ethylene I And, carbon monoxide can permeate the storage room walls and enter work areas where it is a hazard to workers. Ammonia Cracking This system is known as the Smit Oxydrain process and converts ammonia to nitrogen and water vapor at high temperature and the room is purged as with the other inert generators. We have no experience with this system in Michigan. It is being used to a limited extent in the U.S. but more widely in Europe where it was developed. Since no hydrocarbon fuel is used only the carbon dioxide produced by the fruit needs to be scrubbed from the room. There seems to be no danger of ammonia leaking into the CA room and damaging the fruit, Recirculatory Systems These include the Arcat and COB units already widely in use and the Acotec unit under development by Atmosphere Control Tech- nology, Inc. of Grand Rapids. Unlike the inert gas generators such as Tectrol, Gen-o-Fresh or Wilde which rely on flame combustion to convert oxygen to carbon dioxide, the recirculatory system oxi- dizes the fuel on a catalyst surface without a flame. Catalytic oxidation of the fuel will occur, without flame down to as low as 0.51 oxygen. It is necessary to maintain the proper balance of fuel and oxygen to ensure there is sufficient oxygen to combine with all the fuel introduced. As the oxygen supply becomes limit- ing with propane as fuel, the propane is 'cracked' to carbon mon- oxide and ethylene. The recirculatory systems consist of an air blower, pre-heater, catalyst and cooler. Air from the storage room is heated to a temperature of about 450° to 600°F to initiate the catalytic oxi- dation of fuel. Propane is then introduced and as it undergoes catalytic oxidation the heat of combustion increases the operating temperature of the catalyst to 1000 to 1200 F. This high temper- ature will be maintained as long as the fuel and air flow remain at the proper setting and the catalyst remains functional. The catalyst allows the fuel to be completely oxidized to carbon dio- xide and water at temperature as low as 900 F which is about half the temperature of a flame. The oxidation of propane becomes prggress ively poorer as the catalyst temperature decreases below 900 F. If a minimum operating temperature of 900° can not be achieved at the recommended fuel and air flow rate the catalyst many need renewal. Over-heating and freon from a leak in the refrigeration system in the storage room -12- can damage the catalyst as mentioned earlier. With each pass of the storage room atmosphere through the catalyst of the recirculatory system, a reduction of 3 to 41 oxygen is obtained. When the oxygen level of the CA storage room reaches 51, the fuel flow must be reduced to about one-half the initial rate as recommended by the manufacturer. With insufficient oxygen, propane is 'cracked' to carbon monoxide and ethylene. Moreover, as oxygen becomes limiting this reduces the amount of propane oxidized so the temperature of the catalyst will decrease. When the catalyst temperature decreases to the low temperature thermo- stat setting this turns the fuel supply and the equipment off. If there is any question of propane or other combustible gases in the storage room when using a recirculatory system, simply turn off the fuel supply but continue to recirculate the CA room atmosphere through the generator. This will remove the combustible gases from the storage room and the catalyst will remain hot until the gases have been reduced to safe levels. Several users of Arcat and COB units routinely do this to scrub out the combustible gases after an oxygen pull-down. A survey of CA storage room atmospheres was conducted in Michigan after the Peabody storage explosion. It revealed that the amount of combustible gases such as carbon monoxide, ethylene, and propane in storage rooms varied widely even between rooms at a single storage location depending on the type of CA generator used and how it operated. Since the explosion, no instances have been found where propane or other combustible gases approached explosive levels. Propane levels of 0.1 to 0.51 are commonly found where Arcat units have been employed. In one storage 1.71 propane was found and this was lowered by recirculating the atmosphere through the CA generator. Similar experiences of significant levels of combustible gases in CA storage rooms have been observed in New York and Washing- ton with Arcat, COB, Wilde and Tectrol units. These experiences point out the need to more carefully monitor the operation of CA generators to see that they are operating properly to ensure com- plete oxidation of the fuel being used. Safety devices such as thermostats for high and low temperature cut-off should be tested. Air pressure switches, fuel regulators and solenoid valves should be checked. An additional safety device such as a combustible gas sensor could be installed in the exhaust of the CA generator to shut-off the equipment and fuel supply to prevent a significant amount of fuel or products of incomplete combustion from entering the storage room. The Acotec oxygen/ethylene scrubber now under test at Chase Fruit Storage in Sparta, Michigan has a combustible gas sensor as a component of the safety controls. The Acotec unit is designed to -13- initially reduce the oxygen level in a CA storage by catalytic oxidation similar to an Arcat or COB unit and subsequently scrub ethylene from the storage atmosphere for the first several months of the storage season. Portable gas analyzers are available from numerous manufacturers to determine combustion efficiency of CA generators, to adjust fuel/air ratios, and determine the effectiveness of catalysts in oxidizing the fuels. In summary, CA generators of various types can all serve a very useful purpose in the storage and marketing of apples and pears in all major fruit areas. Operating a CA generator that utilizes a combustible or toxic fuel can pose a risk but safety precautions can and are being employed that minimize these risks. To ensure proper maintenance and operation of a CA generator it is essential that operators understand the theory of operation and be thoroughly familiar with the functioning of the equipment. Much has been learned since CA generators were first introduced and since the Michigan storage disaster and instrumentation is now available to ensure the safe operation of CA generators at all times. Understanding how generators function and what might make them malfunction should help arrest unwarranted fear in the minds of those who use and depend on this equipment. ********** APPLE MAGGOT TRAP EFFICACY AND OPTIMAL POSITIONING Frank Drummond, Eleanor Groden, and Ronald J. Prokopy Department of Entomology University of Massachusetts Presently, several different traps for monitoring apple maggot flies (AMF) are used in commercial apple orchards in the USA and Canada. These traps are essentially variations of 2 basic types. One type, a sticky-coated red sphere, mimics the fruit, and con- stitutes an oviposition- type stimulus (see FRUIT NOTES, Vol. 41 (6), 1976). The other, a baited sticky-coated yellow rectangle, mimics honeydew-coated foliage and constitutes a feeding-type stimulus (see FRUIT NOTES, Vol. 41(5), 1976). Researchers in different apple growing regions have arrived at disparate conclusions regarding the comparative efficiency of these 2 basic trap types. All AMF traps have one attribute in common, a visual component acting as a stimu- lant to the flies. On this account, one may expect a trap's position within a tree to have a strong effect on trap visibility and hence effectiveness . -14- In 1981, we investigated (1) the comparative efficacy of different AMF traps and (2) the effect of within-tree trap positioning (relative to surrounding fruit and foliage) on AMF captures on red sphere traps. The study was conducted in 4 commercial apple orchards located in Middlesex, Worcester, and Hampden Counties in Massachusetts. Efficacy of Different Traps We compared 5 different AMF traps: (1) unbaited wooden spheres, 8.5 centimeters (cm) in diameter, painted red (Tartar Red Dark enamel- Sherwin Williams Corp., Cleveland, Ohio); (2 § 3) baited and unbaited Pherocon ICYTM yellow rectangular traps (Zoecon Corp., Palo Alto, Calif.); (4 ^ 5) baited and unbaited Pherocon ICYTM yellow rectangular traps with a red disc, 8.5 cm in diameter, painted at the center of each side of the trap. All traps received an initial coating of Tangle Trap (The Tanglefoot Co., Grand Rapids, MI). A 0.5 gram mixture of equal parts of ammonium acetate and enzymatic yeast hydro- lysate was added to the Tangle trap for each side of the baited traps tested. All traps were hung 25-50 cm from the nearest foliage or fruit. They were emplaced during the first week of July (when the earliest flies were found entering commercial orchards) and remained there for 8 weeks. TABLE 1 ry r Mean number captured AMF per trap ^^ First sample date Combined sample dates ^^^P (July 21) Red sphere 1.2 14.8 Baited yellow rectangle 0.3 1.8 (with red disc) Unbaited yellow rectangle 0.5 1.2 (with red disc) Baited yellow rectangle 0.2 1.4 (plain) Unbaited yellow rectangle 0.0 1.4 (plain) z 15 replicates per treatment. Table 1 shows that early in the season as well as throughout, red sphere traps were far more effective in capturing AMF than any of the yellow rectangle traps. In fact, by the first sample date, 81^ of the sphere traps had captured at least one AMF, compared with values of 0-31% for the rectangle traps. Previous studies in commer- cial apple orchards have shown the red sphere trap to range from being -15- equally effective (compared with baited yellow rectangle traps) at detecting early season AMF to being consistently more effec- tive in capturing the first AMF. This result pattern is contrary to that obtained in unsprayed, abandoned orchards where first cap- tures usually occur on baited yellow rectangles. The difference may be due to the fact that first- captured AMF in unsprayed orchards are likely to be newly emerged and probably more apt to respond to feeding stimuli. Hence, they are attracted to yellow rectangles mimicking the reflectance of leaves (the feeding site). First- captured AMF in commercial orchards are usually sexually mature (immigrating to commercial orchards from abandoned trees or orchards) They respond somewhat to feeding stimuli, but even more so to egg laying stimuli, thus being attracted to fruit -mimicking red spheres. Trap Positioning We conducted 2 experiments aimed at defining an effective, within-tree position for the red sphere trap. In the first, we evaluated the influence of spatial distribution of fruit within a 1 meter radius around a sphere. The 3 treatments were: fruits solely above a sphere; fruits solely below a sphere; and fruits both above and below a sphere. In the second experiment, we eval- uated the influence of distance of sphere from nearest surrounding fruit alone and from nearest surrounding fruit and foliage combined. The treatments were: spheres cleared of all foliage to a standard distance of 25 cm, with surrounding fruit cleared to a distance of 0 cm, 25 cm, 50 cm, or 100 cm (1 meter); and spheres cleared of surrounding fruit as well as foliage to these same distances. For all treatments, spheres were hung about 2 meters above ground, toward the outside of the tree canopy. TABLE 2. Within-tree position Mean number captured of red sphere trap AMF per sphere Location of fruit relative to sphere Above 11.4 Below 16.0 Above and below 14.6 Distance of sphere from nearest surrounding fruit 0 cm 6.9 25 cm 16.1 50 cm 17.1 100 cm 8.5 Distance of sphere from nearest fruit and foliage 0 cm 2.7 25 cm 14.2 50 cm • 19.5 100 cm 1-3 15 replicates per treatment -16- Data in Table 2 suggests that the effectiveness of spheres in capturing AMF is greatest when there is substantial fruit below the sphere, and when the sphere is 25-50 cm from "the nearest surrounding fruit and foliage, but no further away than this. Our behavioral observations indicate that more AMF flights to fruit originate from below fruit than from above, affirming the value of placing a sphere in a position with substantial fruit below. While our results suggest that clearing foliage and fruit increases sphere visibility to AMF, too great a distance between a sphere and surround- ing fruit or foliage may exceed the average distance of within-tree movements or visual capabilities of AMF, making it difficult for an AMF to detect a sphere. Conclusions Research conducted by Dr. W.H. Reissig of Geneva, NY on AMF trap height and direction within a tree, combined with that presented here, suggest that the most effective currently-available trap for monitoring AMF in commercial apple orchards is a red sphere positioned about 2 meters above ground toward the outside of the tree canopy, with 25-50 cm of distance maintained between the trap and the near- est foliage and fruit, but not further than 50 cm from abundant (though not excessive) foliage and fruit. ********** ORCHARD MOUSE BAITING AND VEGETATION Edward R. Ladd U.S. D.I. Fish and Wildlife Service To be effective orchard mouse control materials have to be placed so that mice can find them. With hand or machine bait placements this is no problem. When baits are broadcast however, the condition of grasses and other vegetation in the orchard can be very important. The question when to mow the orchard now has to be considered. The best answer is to bait first and mow later. Mowed vegetation particularly if it is tall and thick will fall in a mat and prevent the broadcast bait from getting down to soil level where they are most effective. This same matting effect under trees will be present shortly after picking. In this case it will be caused by harvesting crews working around and under the trees. For the broadcast baits to reach -17^ the soil level a week or two should be allowed after harvest for the vegetation to recover and for the mice to re-establish their travel systems. After the bait is applied mowing can then work to the growers advantage by providing protective cover for the bait and giving the mice the secluded feeding cover they require. Reminder: A permit is required from Massachusetts Division of Fisheries and Wildlife to applying orchard mouse bait. Apply early and beat the last minute rush. AAA******* PREVENTING EXPLOSIONS IN CA STORAGES WHEN ATMOSPHERE GENERATORS ARE EMPLOYED F. W. Southwick Department of Plant and Soil Sciences Many Controlled Atmosphere (CA) storage operators have atmos- phere generators available to hasten the rate of oxygen (0^) decline to around 5%. These generators often use propane as the fuel source but some may use natural gas. Incomplete combustion or leakage past the generator burner may result in the accumu- lation of propane (where propane is the fuel source) or methane (where natural gas is the fuel source) above their lower explos- ive limit (L.E.L.) in the CA room. Propane and methane detectors are available to warn CA operators before these gases reach explosive levels so that the generator can be shut down before any hazard exists. The safety of personnel and property is so important that we believe all CA operators utilizing atmosphere generators should have a suitable gas detector available whenever a generator is being used. In addition, CA operators can greatly reduce the explosive haz- ard associated with the use of an atmosphere generator by not using a generator until the 0^ level in CA rooms is below 10%. Theoret- ically, neither propane nor methane is explosive at O2 levels below 10%. Also, annual tightening of CA rooms against atmosphere leaks can greatly reduce or completely eliminate the need for an atmos- phere generator. Apples in CA rooms which are very gas tight are capable of reducing the 0^ level to the desired point (by their normal respiration) within the time span allowed by our CA laws without any assistance from an atmosphere generator. Cooperative Extension Service U.S Department of Agriculture University of Massachusetts Amherst, Massachusetts 01003 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 POSTAGE AND FEES PAID U.S. DEPARTMENT OF AGRICULTURE AGR 101 DJ? fRENCH HALL ^^-^ENCE Bulk Third Class Mail Permit DD 01003 O