stn . ^i*Ii. " Mxrarp •IBS THY P*]C~HLETS SILVICULTURE voi.znn Artificial Reproduction Trees, Shrubs & ?1 nts .Tor Farm & Home Planting By C.P.Ealligan. Michigan Agricultural College Bulletin #281. February, 1918. j Tested Forest Trees for Planting in Idaho. By I1. G. Miller. University of Idaho Agr. Exper. Sta. Circular #5. Jan., 1918. A Shade Tree Guide. By Alfred Gaskill. Dept. of Conservation & Development , State of Hew Jersey. 1918. t> Steam Sterilization of Seed Beds for Tobacco and Other Crops. By E.G.Beinhart. U.S.D.A. Farmers1 Bulletin #996. July, 1918. Rodent Pests of the Farm. By D.E.Lsntz. U.S.D.A. Farmers1 Bulletin #932. 1918. The Spotted Garden Slug. By Wm. H. White. U.S.D.A. Farmers1 Bulletin #959. Preventing Fruit Tree Injury by tfield Mice. Article by ?/.C.Dutton. Dusting & Spraying Experiments of 1918 & 1919. Michigan Agr. College, Special Bulletin #102. Trees & Shrubs on the tfarm. By O.B.Whipple & C.C. starring. University of Montana. Circular #78, March, 1918. Tree Planting Along Highways. Article from Michigan Agr. Sxp. Sta. of Feb., 1920. Broad-Leaved Evergreens for Ohio Planters. Article by W.E.±jontrager. V Rodent Protection for Fruit Trees. Treatment for Injured Trees; How to Make Grafting Wax. Article from Ohio Exp. Sta. Bulletin. Frost & the invention of Damage "by it. U.S.D.A. Farmers1 Bulletin f!096. .. -~* v HP FORESTRY PAMPHLETS SILVICULTURE Vol. XIII (Gont'd) Artificial Reproduction. Hlhe Monthly Bulletin of the Ohio Agricultural Sxperinent Station. Vol.V, #2. Feb. ,1920. /s - Planting the Rural School Grounds. By C.P. Ealligan. Michigan Agr. College Experiment Station Circular #36. February, 1919. tch-Budding Large Limbs & Trunks of Pecan Trees. By J.1. Evans. Texas Agr. Exper. Station. Circular #20. February, 1920. i ^Spraying Lawns with Iron Sulfate to Eradicate Dandelions. By M.T.Munn. N.Y. Agricultural Experiment station, Geneva, N.Y. Bulletin #466 in two parts - Sept. ,1919 and Dec. ,1919. Tree Planting in Texas Towns & Cities. By L.Wyman. Bulletin #11 - State Forester, Texas. Nursery & Orchard Insect Pests. By L. Easeman. University of Missouri Agr. Exper. Sta. Bulletin #176. October, 1920. An Investigation of the Dipping & Fumigation of Nursery Stock. By 1C. C.Sullivan. University of Missouri Agr. Exper. Station Bulletin #177. December, 1920. lant Inspection in Missouri. By K.C.Sullivan. University of Missouri Agr. Exper. Station Circular #101. December, 1920. Forest Planting in Southern Michigan. By L.J. Young. Reprinted from Journal of Forestry, Feb. ,1921. 3. if Hypertrophied Lenticels on the Roots of Conifers & Their Relation to Moisture & Aeration. By G.G.Hahn, C. Hartley & A.S.Rhoads. Reprinted fror? Journal of Agricultural Research A Chlorosis of Conifers Corrected by Spraying with Ferrous Sulphate. -By C .F.KorstJan, C. Hartley, L.F. Watts & G.G.Hahn. Reprinted from Journal of Agricultural Research, May 2, 1921. -Growing & Planting Hardwood Seedlings on the F^rm I By C.H.Tillotson. U.S.D.A. Farm. Bull .#11 23.' FORESTRY PAMPHLETS SILVICULTURE Vol. XIII (Cont'd) Artificial Reprodaction Beautifying the rarmstead. By F.L.Mulford. U.S.D.A. Farmers1 -Bulletin #1087. Dan ping-Off in Forest Nur series* By C. Hartley. U.o.D.A. Bulletin #934. ^Reforestation in Massachusetts. I3y J.'-l. Simmons. Under the direction of the ^tate Forester. ie.- Forestry. Main Library BULLETIN NO. 281 FEBRUARY, 1918 MICHIGAN AGRICULTURAL COLLEGE EXPERIMENT STATION HORTICULTURAL SECTION TREES, SHRUBS AND PLANTS :FOR FARM AND HOME PLANTING'-,' »,,' BY C. P. HALLIGAN EAST LANSING, MICHIGAN 1918 The Bulletins of this Station are sent free to all newspapers in the State and to such individuals interested in farming as may reqvest them. Address all applica- tions to the Director, East Lansing, Michigan. MICHIGAN AGRICULTURAL EXPERIMENT STATION Postoffice and Telegraph address, .......................................... East Lansing, Mich. Railroad and Express address, ............................................. Lansing, Mich. A DEPARTMENT OP THE STATE AGRICULTURAL COLLEGE, AND, WITH IT, CONTROLLED BY THE INCORPORATED STATE BOARD OF AGRICULTURE HON. ROBERT D. GRAHAM, Grand.Rapids, Chairman of the Board .................. Term expires 1920 HON. ALFRED J. DOHERTY, Clare .............................................. Term expires 1920 HON. I. R. WATERBURY, Detroit, ............................................... Term expires 1922 HON. WILLIAM H. WALLACE, Bay Port .......................................... Term expires 1922 HON. JASON WOODMAN, Paw Paw ............................. ...... . ........... Term expires 1924 HON. JOHN W. BEAUMONT, Detroit, .......................... .................. Term expires 1924 FRANK S. KEDZIE, D. Sc., President of the College, ....................................... Ex officio HON. FRED L. KEELER, Lansing, ........................................................ Ex officio ADDISON M. BROWN, A. B., Secretary. STATION COUNCIL F. S. KEDZIE, D. Sc., ............... Pres. Ex officio M. M. McCooL, Ph. D., ............. Soil Physicist ROBERT S. SHAW, B. S. A., ............... Director J. F. Cox, B. S. A., ................... Farm Crops H. J. EUSTACE, B. S., Vice Dir. and Horticulturist (Assoc. in charge) R. H. PETTIT, B. S. A., .............. Entomologist G. A. BROWN, B. S., ........... Animal Husbandry A. J. PATTEN, B. S ....................... Chemist (Assoc. in charge) A. C. ANDERSON, B. S., .......... Dairy Husbandry H. H. MUSSELMAN, M. S., ........ Farm Mechanics E. A. BESSEY, Ph. D ..................... Botanist (Assoc. in charge) W. GILTNER, D. V. M., M. S., ....... Bacteriologist C. H. BURGESS, A. B ........... Poultry Husbandry A. K. CHITTENDEN, M. F., ............... Forestry (Assoc. in charge) A. M. BROWN, A. B ............... Sec. and Treas. ADVISORY AND ASSISTANT STAFF C. P. HALLIGAN, B. S., ........ Assoc. Horticulturist H. J. STAFSETH, B. S., ............ Research Asst. in G. H. COONS, Ph. D ............... Assoc. Botanist Bacteriology ZAE NORTHRUP, M. H E ....... Asst. Bacteriologist J. H. MUNCIE, M. A., ............ Research Asst. in C. S. ROBINSON, Ph. D., ........ Research Assoc. in Plant Pathology Chemistry ................... , ........... Research Asst. in G. J. BOUYOUCOS, Ph. D., ....... Research Assoc. in Horticulture Soils W. A. LAUDEMAN, B. S., .......... Research Asst. in F. A. SPRAGG, M. S ............. Research Assoc. in Soils Crops Breeding EUGENIA McDANlEL, B. S ...... Asst. in Entomology L. H. COOLEDGE, M. S., ......... Research Assoc. in W. C. DUTTON, B. S., ......... Asst. in Horticulture Bacteriology F. T. RIDDELL, B. S., ............ Asst. in Dairying J. F. MORGAN, M. A., ........... Research. Assoc. in EUGENE DOWN, B. S ........... Asst. in Farm Crops Bacteriology' . ' . ' . • ' S. J. BROWNELL, B. S., ........... Asst. in Dairying R. P. HIBBARD; PV p.,. ... '. . . . 1 P^^atch- Assoc. in A. C. LYTLE, B. S., .............. Asst. in Dairying Plant Physioldgy' E. J. MILLER, M. S ............ Asst. in Chemistry .......... j. . ._,. , . •., . ,,. ... ...,.,. .Research Assoc. in E. F. BERGER, B. S., ............ Asst. in Chemistry Entomology^ - T. E. FRIEDEMANN, B. S., ....... Asst. in Chemistry C. W. BR, •'•'. '-, ••. •' ..... Posva/eh A"st. in P. O'MEARA, B. S., ............. Asst. in Chemistry Bacteriology R. W. PETERSON, B. S., ....... Asst. in Horticulture 0. B. WINTER, B. S., ............. Research Asst. in P. B. WILTBERGER, M. Sc, . . . . Asst. in Entomology Chemistry EZRA LEVIN, B. S., ........ Asst. in Plant Pathology 1. F. HUDDLESON, B. S., .......... Research Asst. in C. F. BARNUM, B. S.,. Inspector Fertilizers & Feeds Bacteriology F. F. HEBARD, B. S.,... Inspector Fertilizers & Feeds C. G. NOBLES, B. S., ............. Research Asst. in S. S. BOYCE, ................. Fibre Investigations Bacteriology MRS. L. E. LANDON, .................... Librarian SUB-STATIONS Chatham, Alger County, 760 acres deeded. B. W. Householder, Supt. Grayling, Crawford County, 80 acres deeded. South Haven, Van Buren County, 10 acres rented; 5 acres deeded. TREES SHRUBS AND PLANTS FOR FARM AND HOME PLA3tfT:i:NG BY C. P. Halligan INTRODUCTION Why One Should Plant. (a) Because of a desire to make the farm home a better place in which to live. The rural ideal today of making the country a better place in which to live begins with the improvement of the interior conveniences of the house and the exterior surroundings of the home. The attachments that are formed for the home are frequently associated with the trees, shrubs and flowers that surround it. A farm house standing out in its nakedness to the severest storms of winter and the torrid heat of summer with no trees to shelter it or shrubs to clothe it, is hardly conducive to the formation of loving thoughts and tender memories. From such farms the young folks migrate to the cities and the old folks to the towns. If the farm is worth farming, then the grounds about the house are worth developing into a pleasing home grounds. (b) Because it is one's duty to plant. Every man owes it to his family, his neighbors and his community to develop his property and maintain it in as neat and attractive a manner as his means will permit. The environment of children to a large degree measures their ideals. Noble characters and lofty ideals are not formed amid unclean and un- kempt surroundings. Healthy children with wholesome thoughts demand an environment that is healthful, clean and inspiring. The value of property for living purposes depends considerably upon the general appearance of the surrounding property. It no longer remains a personal privilege for one to neglect the appearance of his grounds as such neglect detracts from the value of the property of his neighbors as well as from his own. A community that is characterized by pleasing homes that are neat and trim in appearance constitutes an inviting location for desirable people seeking new farm sites. The value of such farm properties is measured upon this factor as well as upon the general productive value of the land. It is a public duty, therefore, of all who are fortunate enough to possess a bit of land surrounding the house, to make the place as pleasing, interesting and livable as a home grounds should be that its attractiveness may enhance the beauty of the street and community of which it is a part. (c) Because it is a good financial investment. A few dollars and a little labor spent in developing and improving the home grounds, in properly planting a few trees and in arranging shrubs around the grounds, will, in a few years, often increase the financial value of the property more than a similar amount spent in any other manner. oC94G TREES, SHRUBS AND PLANTS A log cabin; the farm home of the pioneer, typical of the first stages in the agricultural development of Michigan In fact, the value of a stately huge elm, majestically overspreading the house and lawn, can hardly be reckoned in dollars. Such well developed trees and plantings that have been judiciously placed are simply the basis of all that is desirable about them. If farmers would invest more of the profits of the farm in improve- ments on the place, rather than in outside investments that they know less about, making the farm home annually a better place in which to live, many of them would be far more comfortable today both financially and physically. Invest at least a part of the profits of the farm each year in making the place a more pleasing and comfortable one in which to live and one will feel less disposed to give it up and retire to the town. Make the farm grounds themselves worth retiring upon. Make this, a well improved farm, the heritage of your children and more of the younger generation will not only stay on the farm but a farm for them worth remaining on will be the result. SELECTION OF BUILDING SITES In the selection of a site for any building, there are three determinant requisites. The first of these requisites is soil drainage. A poorly drained site for a building is unhealthful, disagreeable and frequently a very costly site to maintain. A well soil-drained site is of first importance. Air drainage is of equal importance. A damp or stagnant air is as objectionable to the health as poor soil drainage. The site for buildings, therefore, should be such as to possess a good natural circulation of air. Beware of hollows or pockets on hill sides where the cold damp atmosphere FOR FARM AND HOME PLANTING The farm home as desired today, made pleasing by good architecture and proper landscape plantings collects and has no channels through which it may drain away. Gener- ally, where we find good soil drainage, we also find it well air drained but there are many exceptions to this rule. The third requisite is sunshine. Sunshine makes a dwelling bright, cheerful and attractive as well as exercising a great beneficial influence in maintaining its healthfulness. Direct exposure to sunlight kills most germs. Germs thrive best in a dark, moist atmosphere. A dwelling or barn then, with plenty of windows exposed to the direct rays of the sun, is a great help in maintaining pleasant and healthful surroundings. That a site for a building should possess these three requisites, namely, soil drainage, air drainage and sunlight is of first importance. Selecting the House Site. The future value and pleasantness of the farm home will depend also upon a proper consideration of the aesthetic qualities of the site for the house. The house should be situated some little distance back from the main road. It is a common error to find the average farm house entirely too near the public road to give that privacy and air of dignity and refinement which may be obtained by a proper treatment of a farm grounds, possess- ing an ample front lawn. Today, with the increased traffic on the country TREES, SHRUBS AND PLANTS Before Planting. Is planting worth while? A house with no trees to shelter it or shrubs to clothe it. See the following picture. roads, the dust nuisance becomes a very serious problem, the principal solution of which consists in keeping the house well back from the road and sometimes planting heavily along the roadside. In selecting the site for the house, advantage should be taken of any vistas that are especially pleasing. If the house is placed so as to obtain a beautiful view over a lake, along a river or across a valley, it will enhance the value of the property without increasing its cost. Today, with the ever increasing demand for country homes, these vistas prove very desir- able assets. It is well also, in selecting a site, to consider the exposure. A site that is more or less protected from the north and west with an open exposure to the south and east, is ideal. On many farms, a site sheltered by a woods, hill or other natural condition, may be found which would prove a great protection during the winter months. Whether or not these condi- tions are available, there is always room enough on the farm to place the buildings in such a way as to receive the greatest amount of sunlight, especially during the winter. Whereas it seems to be the prevalent opin- ion that a building should run directly north and south or east and west, it is these problems of sunshine and exposure that should determine its direction. Any topographical feature of the land might also largely determine the location of a building. The position of a group of large trees or a rugged boulder might prove the chief determinant. FOR FARM AND HOME PLANTING After Planting. Same place as preceding picture but about three years later. Was planting worth while? A slight knoll generally makes an ideal site for a building. If the land is level and such a spot is not available, a building should be set rather high on its foundation and the soil from the excavation with a little addi- tional filling, will tend to obtain at least a portion of these advantages. On farms that are hilly and rough, ideal sites may be found,— sites, too, that would prove of very little value for farming purposes. THE PLANTING PLAN In the development of the home grounds, there is need of a precon- ceived plan. This plan should be conceived in a general way when the building sites are being selected but the details may best be worked out after the buildings have been constructed and the drives and walks have been laid out. While the need for a plan is real and its existence essential, there is no necessity of carrying it out all at once. The execution of the plan may be gradual; the most important parts of it may be developed first and the remaining parts as circumstances permit. In fact, this gradual development is often desirable as the experience gained the first year or so often suggests desirable changes for future work. Under such conditions, a plan drawn to a definite scale, furnishing a definite record for future reference, is very essential as it insures the progressive develop- ment of the scheme that otherwise might be forgotten. TREES. SHRUBS AND PLANTS Masses of hardy shrubs about the foundation of the house tend to harmonize it with its site. GENERAL DIVISIONS An ideal landscape development of the home grounds involves a study of the general arrangement of the various divisions of the grounds to make them as serviceable and livable as possible. For example, there should be a service division for performing the necessary but often un- sightly functions of a dwelling; a place for the ingress and storing of supplies and the egress of wastes; a lawn for the drying of clothes, a vegetable garden and places for any other such desirable purposes as the amount of available space will permit. This division should be designed to perform these functions most conveniently and to be maintained in a most tidy manner. It has been said that the typical American style of development about the home grounds consists in maintaining a "Queen Anne front and a Mary Ann back/' This typical unsightly appearance of many back yards is largely due to an arrangement of the service division that does not conveniently and thoroughly serve these necessary functions. The entrance division of the property usually includes the front lawn and entrance walks and generally is that portion of the property by which the public receives its impression of the entire place. The walks should be apparently direct and convenient while the appearance of the division, as a whole, should be trim and tidy, simple, dignified, hospitable and har- monious. Often there may well be other divisions, as a living division where the family may enjoy the privacy of family life out-of-doors without An improperly planned home grounds showing the walks and drive ill-arranged and the plantings cluttering the lawns. (See Page 11) 10 TREES, SHRUBS AND PLANTS being in full view of the neighbors and every passerby. A study of the general arrangement and coordination of these divisions is the first step in the development of the home grounds. It simply answers the question of what purposes the home grounds are to serve and what general arrange- ment of the grounds will serve such purposes in the most convenient and pleasing manner. SOME DETAIL PROBLEMS Grading. After this general arrangement of the grounds has been determined, the more detailed problems of improvement may be under- taken. Usually there is more or less grading that should be done and this work may prove very expensive without giving very gratifying results unless a careful study is made to adapt the new grades to the existing ones. Ideal grades should produce a proper setting for the house, making it appear somewhat higher than the surrounding property; provide surface drainage away from the buildings and for all portions of the lawn and smooth off all the small irregularities over the surface of the lawn. A building will possess an ideal setting as far as grades are concerned when it appears to be located on the summit of a slight knoll with the land Explanation of Planting Plan on Page Eleven This design shows a desirable location for a house and barn on a small suburban lot in reference to the exposure and distances from the sides and front of the lot. The drive is so designed and planted as to screen the view of the barn and its service yard from the road. Tne plantings consist largely of masses of hardy shrubs disposed around the foundation of the house, the boundaries and corners of the lot, leaving an unbroken lawn in front and a well screened and protected back lawn. A few trees are so disposed as to frame the view of the house from the road, to aid in screening the barn and to produce some shade over the back lawn. Hardy perennials and annuals are massed in the fore- ground of the shrubbery plantings about the back lawn and along the stepping-stone walk leading to the garden and back of the lot. The first number in the mass plantings indicates the number of plants to be used, the dots showing the location of each, while the number after the dash is the index number of the kind to be used. Index, number Common name of plant Latin name I Japanese Barberry II Bridal Wreath Spirea III Tartarian Honeysuckle IV Japanese Rose V Lilac VI Paeony VII German Iris VIII Hardy Phlox IX Lemoines Deutzia X Deciduous Tree XI Evergreen o Vine Berberis Thunbergii Spiraea Vanhouttei Lonicera Tartarica var. grand. rosea Rosa Rugosa Syringa (In Variety) Paeon i a (In Variety Iris Germanica (In Variety) Phlox decussata (In Variety) Deutzia Lemoinei VEGETHBLL CFfRDEN A properly planned home grounds, 11 12 TREES, SHRUBS AND PLANTS A typically ill-arranged home grounds. The front lawn cluttered by meaningless plantings. A good opportunity wasted. sloping gradually away from it on all sides. On small lawns, the grades may be straight but as the extent of the lawn increases, they should assume the more graceful effect of a slightly rolling or waving surface. The use of terraces should usually be avoided as they are expensive to construct and to maintain and are conducive to a very formal effect. A properly arranged home grounds. A simple, harmoniously designed farm house, situated well back from the road on a slight knoll, with a wide, unbroken front lawn framed along the back and boundaries with trees. FOR FARM AND HOME PLANTING 13 WALKS Walks. On the small place, the designing and laying out of the walks and drive is a simple problem. They should be as direct and as convenient as conditions will permit; but on the larger place where the house is situated some distance back from the road, their design is often a more perplexing problem. Besides being convenient and direct, they should be graceful and pleasing in their lines, making them harmonious with the natural landscape effect of the grounds. Frequently, they may enter the property near the front corners and in simple sweeping curves approach the building, leaving a broad unbroken front lawn effect. Such an effect adds to the apparent extent of the grounds and produces an ideal setting for the buildings and plantings. It is desirable, therefore, in arranging the walks and drives to keep them well to the sides and boundaries when- ever conditions permit. LAWNS A good lawn is the most important feature of a well developed home grounds. It is often referred to as the canvass upon which the picture is painted. It should possess openness and extent and be framed with plantings of trees and shrubs about its borders. Never should it be cluttered with meaningless plantings of individual shrubs and trees as is most commonly done. Being such an essential and permanent source of beauty, its construction and maintenance deserves the most careful con- sideration. Construction. The soil for a lawn should be of good texture containing plenty of plant food and enough humus to retain moisture. A strong clay loam or a sandy loam with a clay subsoil most nearly approaches these conditions. When a lawn is to be constructed upon light sandy soil, a top dressing of about two inches of clay with a heavy application of well rotted manure should be mixed with the first three or four inches of sand. Frequently, in building a house, the soil excavated from the cellar is spread about covering the good top soil with a poor sub-soil. This sub- soil is of poor texture, contains little available plant food and is an extreme- ly poor soil for lawns. Where it is necessary to use this sub-soil for filling, the top soil should be first removed to be later replaced on the surface . In the grading of a lawn, first endeavor to obtain good surface drainage; see that there is a slight slope away from the buildings; that there are no low pockets where water may stand during the winter and spring, and that the area as a whole, is either naturally or artificially well drained. Except in some very special cases, a level lawn should not be con- structed. It lacks naturalness and decreases the apparent extent of the lawn. In grading, endeavor to preserve the slight natural slopes and curves of the land, remembering that nature never produces perfectly level surfaces. This part of the grading should be carefully studied and considered before starting the work. The way in which it is done will determine whether a graceful, pleasing, natural lawn is secured or a stiff, restrained, unsatisfactory one is the result. After the general slopes have been established, the land may be har- rowed if necessary and any small uneven places smoothed off. A simple planting design of a small corner lot, showing the arrangement of the plantings, drive and garage with the service lawn screened by plantings from the road. 14 FOR FARM AND HOME PLANTING 15 If the land has been allowed to remain over winter in a rough condi- tion, the soil will have become well settled by spring and will be ready for the final work before seeding. Pick off all the stones which have come to the surface during the winter and then go over the land with a shallow harrowing or raking. If it can then be rolled, the small uneven spots will become very apparent and they can then be leveled off with a hand rake. By re-rolling and re-raking the land in this way, the surface can be made as smooth and even as desired. Fertilizers. Well decomposed stable manure is the best general purpose fertilizer for lawns. It contains all the chemical elements essential for plant growth and adds humus to the soil, thus making it more retentive of moisture and also improving its texture. If this can be used, a heavy dressing should be applied. A ton to two thousand square feet would not be too heavy. Chemical fertilizers may be used to advantage after the grass is well started but should never be applied at the seeding time as they may kill the young roots which come in contact with them during germination. It must be remembered also, in using commercial fertilizers that they never improve the physical condition of the soil. There is no humus added to the soil by their use and hence the soil texture is not improved. It is simply an addition of the essential food elements and should always be regarded as such. They are easily applied, contain no weed seeds and may be readily obtained. Some of the most desirable forms of chemical fertilizers for lawns are fine ground bone, wood ashes, and the high grade forms of complete fertilizers. Ground bone is a very good form of fertilizer for lawns and although it contains principally phosphoric acid, it furnishes some nitrogen and lime. Unleached hardwood ashes are used as a source of potash and if applied each spring soon after growth begins, will generally prove very beneficial. Complete high grade fertilizers for lawns may be obtained from almost any fertilizer dealer and, while more expensive than the other forms, they are often quite efficient in maintaining the lawn. Although the amount of fertilizer advisable to apply will depend much upon the condition of the soil as well as upon the form and strength of the fertilizer to be used, a dressing of about 2.5 pounds per hundred square feet would be a moderate application under average conditions. Varieties of Grass for Lawns. The best variety of grass for lawns, under general conditions in Michigan, is Kentucky Bluegrass (Poa prat- ensis). While it is rather slow in starting, it produces a permanent lawn of fine texture and of a rich green color. The crown of the plant sets very close to the ground thus permitting close clipping and the plant, after becoming established, spreads rapidly by underground roots. Although a permanent bluegrass lawn may be desired, it is often advis- able to sow other varieties with the bluegrass seed. Of the rapid growing grasses that may be used for this purpose, the English rye grass (Lolium perenne var. tenue) is one of the best. It is an annual grass and a little coarse in leaf, but starts rapidly, produces a very early effect and covers the ground which might otherwise be occupied by weeds. Do not use oats, rye or timothy for this purpose. 16 TREES, SHRUBS AND PLANTS A row of cottages before planting. Note how bare and bleak they appear. See the picture on the following page. Redtop (Agrostis alba) is a thick growing grass which produces a good lawn effect the first season. It is of a finer texture than rye grass but does not grow quite as rapidly on the start. It grows better under adverse soil and moisture conditions than most other grasses. White clover (Trifolium alba) is frequently used on lawns as many people desire the appearance of the white clover blossoms in the summer. Others object to its tendency of giving the lawn a spotted effect. On a very sandy soil the Rhode Island Bent grass (Agrostis conina) does well, while in very shady places the Woodland Meadow grass (Poa nemoralis) may be used. Where the lawn is on high, dry situations or slopes the Sheeps Fescue (Festuca ovina) will be found desirable, while on low wet places the Various-leaved fescue (Festuca heterophylla) will thrive. For the average lawn, a good mixture is one-fourth Fancy Red Top, one-fourth English Rye grass and one-half Kentucky blue grass. If the area to be sown is small and the conditions of soil or exposure somewhat variable, it is advisable to buy a high grade prepared lawn mixture from a reliable seedsman. This mixture will generally contain- seed adapted to various conditions and will prove more convenient and frequently better than the homemade mixture on such a small scale. Frequently grass seed contains a great many weed seeds, often of a kind that may prove a serious nuisance and expense to get out of the lawn if they once become established. It is best to buy only the best seeds from the most reliable seedsmen. If a large quantity is to be procured, it would be advisable to send a sample to the Division of Botany of the State Experiment Station where it will be examined for purity free of charge. FOR FARM AND HOME PLANTING 17 The same cottages as in previous picture three years after planting. The simpler the architectural features the greater is the importance of plantings. Sowing the Seed. In starting a lawn use plenty of seed, one and one fourth pounds to about 1000 square feet or fifty pounds to the acre (43560 sq. ft.) being none too much* Thick seeding chokes out weeds and assists in producing a quick effect. Select a day when there is no wind to sow the seed. Early in the morning or about sun down is a very good time, and if just before a rain, so much the better. By sowing the seed in the following way, an even stand is quite assured : taking one half of the amount of the seed to be sown and beginning at one end of the lawn, sow in parallel strips until the entire lawn is covered; then take the remaining one half of the seed and sow in strips in the other direction. If this is properly done, there should be no streaks or vacant spots in the future lawn. After sowing the seed, unless directly followed by rain, the soil should be rolled. Raking or harrowing after sowing is apt to bury the seed unevenly. Maintenance. After the grass has grown to a height of from four to six inches, it should be given the first clipping, being careful not to cut very close. A scythe is better for this cutting than a lawn mower as it will not pull out the young plants or cut as close as the mower. The future cuttings should be performed frequently enough to permit the clippings to remain on the lawn without being unsightly. These clippings if allowed to remain, will form a dense mulch around the base of the plants and protect the soil from drying out during the summer months. Cut frequently then but not too close. Additional seed should be applied. to all lawns at least every spring and often another sowing would prove beneficial the latter part of June or in September. The most effective method of controlling weeds in lawns is by securing good drainage to the soil, keeping the lawn well supplied with plant food and the soil well filled with pure seed. Make the conditions for plant growth most favorable and there will be little chance for weeds to gain a foothold and develop. 18 TREES, SHRUBS AND PLANTS PLANTING Very ordinary looking buildings can be made attractive and homelike if the planting is properly done. It may be said that the less prominent the architectural features of a place, the greater the relative importance of the plantings. Hence it is very important that considerable attention be given to the planting of the ordinary farm house. Functions of Planting. Before any successful attempt may be made in this line, one must first inquire as to the functions or purposes of the plantings to be made. In planting farm grounds, let it be realized that it is the endeavor to create a picture. That in this picture there are given as its elements, a farm house and other buildings, — roads, walks, lawns and other more or less separated elements. To unite these several disconnected parts into the production of one harmonious composition is the leading function of the plantings. To arrange the plantings about Farm buildings may be made to harmonize with the home grounds by appropriate planting, the house that the building may seem a natural outgrowth of the spot; to so arrange the plantings on the grounds that each and every planting may seem dependent upon the presence of every other planting or other element in the design, is the purpose of the planting. When it can be realized that these plantings are made not primarily for the sake of their own individual beauty but more because of their relationship to the design as a whole, to the picture about to be created, the first principle to guide one in planting has been mastered. FOR FARM AND HOME PLANTING 19 The planting of each and every grounds is a new problem, differing in certain respects from every other one. There are no definite rules then that can be given to guide one in the work; no ideal plan which may be drawn to serve all places; but there are a few general principles which may be suggested as a guide when solving many of these problems. Before any planting design is made, the grounds should be studied in reference to the general arrangement that is most serviceable. The style of architecture of the house, the position and character of any large trees already on the grounds, the slope and general character of the land, and any other natural condition should be studied to "see what kinds of beauty, Plantings used to screen an unsightly view of neighboring barns. what general character of pleasing appearance these conditions most readily suggest." Each and every home grounds is more or less suggestive of a certain type of beauty which may be brought forth and emphasized with the least difficulty. After perceiving this type of beauty, one must then proceed to make the necessary details of arrangement, emphasize and enhance the charac- ter thus selected. One will first find certain elements which detract from the beauty of the grounds, which are defects in the picture, and should be screened by the use of plantings. Views within the grounds, such as of the henhouse, barnyard, a boundary fence or service drive and other unsightly spots; views beyond the grounds, as of a neighbor's shed, the back of a neighbor's barn and other views hardly pleasing and accept- 20 TREES, SHRUBS AND PLANTS able to the sight, — all these should be entirely hidden from view by the use of plantings, or at least partially broken up to minimize their unsight- liness. A mass planting of hardy shrubs about the base of the porch tends to harmonize it with the lawn. There are other elements in the design which should be just as care- fully preserved and enhanced by plantings. The most pleasing lines and portions of the house, for example, may be emphasized and carefully Preserved to the view. A wide sweep of open lawn, with a border and ackground of trees and shrubbery, is always a pleasing and acceptable sight. Vistas without the grounds, as of a distant woods, a winding river or a neighboring farm house and even the travel upon a public road, are often welcome sights which add to the pleasure and value of the grounds. It is especially important that these vistas be carefully pre- served from the living rooms of the house, not always from the parlor but from those rooms where the family spend the major portion of their time. The plantings then serve a very important function by concealing the defects in these places and by enhancing those parts that are most pleasing. Thus, it may be seen how beautiful and attractive some of the ordinary looking farms of today may become by the proper use of plantings. How much more important this landscape use of plantings becomes on a common, ordinary looking farm where there are generally so many unpleasant sights which detract from the looks and very often from the value of the farm. Plantings, when improperly used, may detract from the value and looks of the farm as well. The effect of a well-designed farm house is very frequently ruined by poorj plantings. Trees planted too thickly FOR FARM AND HOME PLANTING 21 Mass plantings of trees and shrubs should be disposed about the boundaries of the lawn. or too closely in front of the house; a lack of harmony in the design of the grounds to that of the house; plantings so placed as to hide the house from its most pleasing point of view— these are a few of the many causes which often spoil the effect of a well designed house by improper plantings. Let it be remembered then that plantings are to enhance rather than to detract from the expression already given by the design of the house and to harmonize it with its site. There are three general rules of guidance tn arranging the plantings-. First,— avoid straight lines in planting. The general effect of all lines in planting should be graceful and naturalistic rather than stiff, formal or artificial. Plantings should seem to be a natural outgrowth of the spot rather than a crude piece of man's handiwork. Second, — arrange the plants in groups and masses, selecting few kinds and many of each rather than many kinds and few of each. Avoid planting meaningless, isolated specimens over the lawn. Natural- istic masses and groups of plants are necessary to give structural charac- ter to the design and each group or mass should consist of many specimens 22 TREES, SHRUBS AND PLANTS Plantings properly arranged to enhance the architecture of the house of but a few kinds, rather than one or two specimens of several kinds. The kinds of shrubs selected should be repeated in the various groups and masses not precisely in the same combinations but sufficiently so that the effect of one planting may be harmonious with the others. In this manner unity of effect may be obtained. Plantings should be massed about the base of the buildings, using many specimens of but few kinds rather than one or two specimens of several kinds. Bridal wreath spirea, (Spiraea Vcmhouttei.) FOR FARM AND HOME PLANTING 23 Third, — plantings should be massed about the base of the buildings, grouped about the junctions or curves in the walks, massed about the boundaries and corners of the property but not usually along the front boundary of the property. When arranged in this way, an open lawn bounded with naturalistic plantings of shrubbery and trees will be the general effect. In arranging these plantings, they may perform other desirable func- tions also. They may be arranged to shelter the house from the winter storms and the summer heat, or to frame desirable vistas and thus accen- tuate their attractiveness. Masses of shrubs may be used to take the place of an undesirable fence or hedge. They may be planted to prevent people from wearing paths across the lawns and to unify the walks, buildings and other elements of the grounds into one harmonious design. How to Plant. The planting should be done early enough in the spring so that the shrubs will be well established before the heat and drought of summer overtakes them. In preparing the beds, they should be dug to a depth of a foot or more and well manured. The distance of setting them depends largely upon the size of their growth. Japanese barberries should be planted two feet apart, spireas three and one-half feet and lilacs about four to five feet. In three years, when set at these distances, the branches should be so intermingled that their individuality in the beds is lost and a unified mass effect produced. In transplanting, keep the roots moist and prevent them from being exposed to the sun and wind any longer than necessary. Set the plants slightly deeper than they stood in the nursery and pack the best fine soil firmly about the outspread roots. If the soil is dry, water after planting. It will help to compact the soil about the roots and keep them moist. The tops may then be pruned back to balance the loss of roots, leaving a few large buds on each of the strongest shoots. WHAT VARIETIES TO SELECT Shrubs The choice of varieties is perplexing because there are so many handsome shrubs all of which seem most desirable to the home gar- den maker. A few of the good old standbys that are handled by every nurseryman and sold by the millions, that are sure to give one his money's worth and are safest for the beginner to tie to are given in the following list. Spireas. First of all there is the bridal wreath spirea, Spiraea Van- houttei, the most popular spring flowering shrub. Its remarkable freedom Shrubs planted in the corners of the entrance porch generally prove effective. 24 TREES, SHRUBS AND PLANTS of bloom and beautiful foliage produced on branches drooping gracefully to the ground makes it exceedingly attractive. This spirea, which is only one of a large group of Spireas, is very hardy and grows well upon any moderately rich and well drain- edj'soil. It attains a height of about five feet and is particu- larly adapted for mass plantings about buildings and porches, along [walks and drives or around the boundaries of the lawn. Of the other spireas, there is the double -flowered spirea that one sees everywhere named Spiraea prunifolia because its leaves resemble those of the Prunus or plum. Spiraea arguta, altho not as well known, is a most desirable early spring flowering shrub with small delicate foliage and white flowers. It is particularly ad- apted for planting in the fore- ground of other higher and coarser growing shrubs. For summer floweirng, the species is represented by Spiraea Bumalda var. Anthony Waterer that blooms quite continuously from the middle of June until frosts over- takes it in the fall. Its flowers are produced in corymbs or flat flower heads of a rosy crimson color, sometimes approaching a magenta. Where a low shrub is wanted for summer effect, this is one of the best. Thuriberg's Barberry. It would be hard to name a shrub as cosmopol- itan in its characteristics, combining as many desirable qualities as the Japanese barberry, Berberis Thunbergii. It is one of the few shrubs that is attractive at all seasons of the year. In the spring and 'summer its graceful branches are clothed with small yellowish green leaves that change to a bright scarlet in the fall. Later they are shed to expose the scarlet berries that enliven the landscape all winter. While a sandy loam soil seems to be ideal for the barberry, it will be found thriving equally well on practically all types of soils that are well drained and seems hardly more particular over exposure. The San Jose scale, plant lice and other pests seem to painstakingly avoid it. The graceful form it assumes and its low habit of growth make it suitable for filling in small spaces such as between walks or buildings or for planting in front of Spireas and other higher growing shrubs. There is nothing better to use where a low orna- mental hedge is desired than this barberry that shifts for itself after it is once established. Shrubs massed about the base of trees relieve the bareness of the trunks and tend to unify them with the surrounding lawn. FOR LAWN AND HOME PLANTING 25 Sorbaria sorbi/oh'a generally known as the Ash-leaved Spirea, is desirable for planting steep banks. The most common and still most indispensable of the shrubs is the lilac. There are so many desirable improved varieties of this old time flower that even if one were given a few bushes of the old-fashioned type by some kind meaning neighbor, one could not afford to plant them, the new improved ones are so much superior. They produce larger and better flowers over a longer season. Therefore, go to a nurseryman and get something that will be different and better than this old-fashioned type. There become acquainted with Marie Legraye, a beautiful white; Mad. Lemoine, the best double white; Dr. Regel, a handsome rosy pink; Chas. X, an attractive rosy purple; Toussant L'Ouverture, a very dark carmine colored in bud, turning to a violet-red when in full bloom and an endless list of other improved sorts of the old fashioned lilac, £2/rm0a vulgar is. Then, there are other species of lilacs that include at least one other type that should be used. For landscape effects it is to be pre- ferred to any of the former group because it seems to be more graceful in its growth with smaller leaves and large, open, gracefully drooping panicles of reddish purple flowers. This is the Rouen Lilac listed in the catalogues as Seringa rothomagensis- The purple Persian lilac is very similar to it but more dwarf in its growth. For screens and backgrounds of shrubbery masses, used in separate colors rather than mixed, lilacs produce a most attractive effect in late spring. 26 TREES, SHRUBS AND PLANTS Lilacs produce excellent effects when planted in masses on banks with a proper background of trees. Mock Orange. The mock orange or syringa bush is another large, high growing shrub that is prized especially for its fragrant white blossoms that are so abundantly produced in June. The old-fashioned variety, Philadelphus coronarius, is the most fragrant but the newer varieties such as Philadelphus coronarius grandiflorus, produce flowers over twice the size and of a purer white. The yellow leaved sorts are not as vigorous or free flowering and should be used very sparingly. The green leaved sorts are very hardy and easily grown on any soil of moderate fertility. Snowball. While the old-fashioned Snowball that was formerly planted in every yard is now considered of little value because its foliage is annually ruined by plant lice, its place has been taken by another bush called the ^ Japanese Snowball, Viburnum tomentosum plenum. The flowers of this shrub are quite similar to the common Snowball but appear more attractive and of a purer white against the heavy dark green foliage of the bush. It delights in a rich moist soil and may be planted along the north side of buildings, a northeastern exposure being ideal. Although not entirely hardy in the northern districts, its superiority over the com- mon snowball, both in foliage and flower, makes it a most desirable shrub. There are many other Viburnums also that are used by landscape gar- FOR FARM AND HOME PLANTING 27 The mock orange (Philadelphia coronarius) is one of the most cosmopolitan shrubs for home planting, being hardy, free from insects and diseases and easily grown. deners that are more particularly adapted to the planting of parks and for producing other very naturalistic effects. Most of them are not as showy in flower but produce excellent summer effects by their fruits. Bush Honeysuckle. The bush honeysuckles are very acceptable in plantings for the summer effect of their berries. While many produce beautiful spring flowering effects in white or pink, they are prized more for the red coral-like berries that color these plantings in midsummer after most of the shrubs are through blooming. Lonicera Morrowii is one of the best varieties for this purpose while Lonicera tartarica var. grandi- flora rosea is one of the most effective in flower. Weigela. A class of popular shrubs often confused with the honey- suckles, possibly because of their trumpet shaped flowers, is the Weigela or Diervilla. Although the latter is now considered the standard botani- cal name, in many of the catalogs, it is still listed as Weigela. Of the many varieties in pink, white or red that are now lasted of this group, the old- fashioned pink flowering Diervilla florida continues to lead in popularity. There is another variety, Diervilla hybrida Eva Rathke, that is also used considerably by those familiar with its qualities. This variety is more of 28 TREES, SHRUBS AND PLANTS Lemoine's Deutzia (Deutzia Lemoinei) is the hardiest of all the deutzias and excellent for planting in the foreground of shrubbery masses Flowering shrubs, such as the large flowering mock orange, (Philadelphia coronarius grandiflorus) appear ideal with a background of trees. FOR FARM AND HOME PLANTING 29 a continual bloomer than the former, with deep carmine-red flowers and somewhat darker foliage. It seems to blossom almost as profusely in the shade as in full sunlight. It is found very acceptable, therefore, for planting along the north side of buildings or in other partly shaded situations. Of the many other shrubs worthy of consideration, there are the golden bells or Forsythias, whose yellow blossoms are produced even before its leaves in the spring, so early in fact that the flowers are often caught by late freezes; also the yellow flowering currant, Ribes aureum, with its sweet fragrant blossoms, and the Japanese Rose, Rosa rugosa, with its luxuriant foliage and ever-blooming flowers. There is no trouble about having enough kinds to select from but the difficulty is in limiting the list to the ones that are best. For the home garden maker, it will be wise to stick largely to the old standard sorts. 30 TREES, SHRUBS AND PLANTS SHRUBS FOR SPECIAL PURPOSES Shrubs for Hedges *Berberis Thunbergii Ligustrum amurense Thunberg's Barberry Amur Privet Rosa rugosa Japanese Rose Spiraea Vanhouttei Lonicera tartarica Van Houtt's Spirea Tartarian Honeysuckle or Bridal Wreath Deutzia Lemoinei Thuja occidentalis Lemoin's deutzia Arbor-Vitae or White Cedar Shrubs for Border Planting a. Low Growing. Deutzia gracilis Spiraea Bumalda var. Anthony Slender Deutzia ' Waterer Anthony Waterer's Spirea Berberis Thunbergii Spiraea Thunbergii Thunberg's Barberry Thunberg's Spirea Symphoricarpos orbiculatus Symphoricarpos albus Coral Berry or Indian Currant Snow Berry Kerria Japonica Globe Flower or Corchorus b. Medium Growing. Ribes ordoratum Rosa rugosa Yellow Flowering Currant Japanese Rose Spiraea Vanhouttei Rhodotypos kerrioides Van Houtt's Spirea White Kerria or Bridal Wreath Spiraea prunifolia Deutzia Lemoinei Plum-leaved Spirea Lemoin's Deutzia c. Tall Growing. Diervilla florida Philadelphus coronarius Rose-colored Weigela Mock Orange or Syringa Lonicera Morrowii Lonicera tartarica Bush Honeysuckle Tartarian Honeysuckle Forsythia intermedia Syringa (In Variety) Golden Bell Lilac Viburnum (In Variety) Euonymus americana Strawberry Bush Shrubs for Specimen Use Corinus americanus Euonymus alata Smoke Tree Winged Burning Bush * The plant names in this bulletin are those adopted by the American Joint Com- mittee on Horticultural Nomenclature. FOR FARM AND HOME PLANTING 31 Chionanthus virginica Caragana arborescens White Fringe Siberian Pea Tree Exochorda racemosa Tamarix (In Variety) Pearl Bush Tamarick Prunus cerasifera Pissardii Cercis canadensis Purple-leaved Plum Red-bud Prunus communis Chaenomeles japonica Flowering Almond Japan Quince Shrubs for Exposed Lake Front Rosa setigera Rhamnus cathartica Michigan Prairie Rose Buckthorn Viburnum opulus Elaeagnus argentea High-Bush Cranberry Silver Thorn Tamarix (In Variety) Rosa rugosa Japanese Rose Rhus (In Variety) Syringa vulgaris Sumac Lilac Philadelphus coronarius Mock Orange Shrubs for Shady Situations Symphoricarpos albus Diervilla hybrida var. Eva Rathke Snow Berry Weigela Eva Rathke Symphoricarpos orbiculatus Viburnum (In Variety) Coral Berry Caly can thus floridus Ligustrum amurense Sweet-scented Shrub Amur Privet Cornus (In Variety) Dogwood Shrubs for Sandy Soils Rhus canadensis Rosa rugosa Fragrant Sumac Japanese Rose Caragana arboresoens Rosa setigera Siberian Pea Tree Michigan Prairie Rose Forsythia intermedia Berberis Thunbergii Golden Bell Thunberg's Barberry Tamarix (In Variety) Rhus glabra Tamarisk Sumac Cotinus coggygria Purple Fringe Lonicera tartarica Spiraea Vanhouttei Tartarian Bush Honeysuckle Van Houtt's Spirea 32 TREES, SHRUBS AND PLANTS Shrubs for Steep Banks Rosa setigera Spiraea tomentosa Michigan Prairie Rose Hardhack Rhus (In Variety) Sumac Sorbaria sorbifolia Ash-leaved Spirea Roses Hybrid Perpetuals — For cut flowers. (Half hardy, requiring some protection over winter) Frau Karl Druschki (white) Mrs. John Laing (pink) General Jacqueminot (brilliant crimson) Ulrich Brunner (cherry red) Paul Neyron (deep rose) Mrs. R. G. Sharman Crawford (deep rose-pink) John Hopper (bright rose) Marshall P. Wilder (cherry carmine) Prince Camille de Rohan (deep crimson) Hardy Climbing Roses Baltimore Belle (white tinted pink) Crimson Rambler (bright crimson) Dorothy Perkins (pink) Lady Gay (rose pink) White Dorothy Perkins (white) Roses for Landscape Effect Rosa rugosa (Japan rose) Rosa setigera (Michigan Prairie rose) Rosa rubiginosa ((Sweet briar) Rosa rubrifolia (Red-leaved rose) Hardy Bush Roses Austrian Yellow Persian Yellow Common Moss Blanche Moreau (white) Princess Adelaide (pale rose) Gracilis (deep pink) FOR FARM AND HOME PLANTING 33 TREES "Among all the materials at our disposal for the embellishment of country residences, none are at once so highly ornamental, so indispensable or so easily managed as trees or wood."* Trees are especially valuable as screens, windbreaks, backgrounds for buildings, for shade and for their own individual beauty in a design. By a natural arrangement of trees in the improvement of the country home grounds, buildings which might other- wise seem bare and bald may be made in- teresting and often picturesque. They should be disposed around our houses in groups, masses, thickets and as single trees in such a manner as to rival the most beau- tiful scenery of nature as well as to provide all the comforts and conveniences of a rural home. In selecting trees for home planting, the following requirements should be con- sidered: namely — form, hardiness, adapta- bility, rapidity of growth, shade production, freedom from insects and diseases, neatness and general beauty. In purchasing trees one should obtain healthy, well shaped trees. It is generally a waste of time and money to set poor, deformed trees. Wild trees may be used but they are less likely to withstand the shock of transplanting than those that have been previously transplanted in the nursery. In purchasing shade trees, it is possible to set out trees as large as a foot in diameter but the cost is so great that few can afford to trans- plant trees of such size. As a rule, smaller trees transplant more success- fully. Trees for street planting should be about two inches in diameter and ten to twelve feet in height. In transplanting trees, as many roots as possible should be preserved as trees with large root systems do much better than those whose roots have been severely pruned. As the tree is purchased from the nursery, the top or crown is usually already formed. This general shape of the top should be preserved in pruning after transplanting. If the root system has been severely pruned, it will be necessary, however, to cut back the branches of the top to maintain a balance between the roots and foliage, altho it is better to maintain this balance by saving the roots than by sacrificing branches. *Section III, Chapter on "Wood," Treatise on the Theory and Practice of Landscape Gardening. By A. J. Downing. This book was the first landscape gardening book published in America and is considered one of the best at the present time. It started a great popular movement toward the development of beautiful home grounds and its author by his many writings and landscape gardening work exerted more influence in the development of American horticulture than probably any other single figure. 34 TREES, SHRUBS AND PLANTS SHADE TREES. WELL DEVELOPED HEAD, GOOD LEADER, MAIN BRANCHES FORMING WIDE, NOT CLOSE. ANGLES WITH STEM. STAKE 27 INCHES BY 10 FEET DRIVEN 2 FEET IN GROUND. TREE PRUNED AS ORDINARILY REQUIRED. IF ROOTS ARE FULL CROWN NEED BE LESS CURTAILED. BASE OF PERMANENT CROWN 10 FEET ABOVE PAVEMENT. RUBBER COVERED WIRE. OR CAiMVAS\BINDEvR. BED DUG OUT 18 INCHES DEEP, THEN FILLED TO LOWER ROOT LEVEL WITH MIXTURE OF 3a GOOD SOIL AND -3 ROTTED MANURE. BASE OF TEMPORARY CROWN 7 FEET ABOVE PAVEMENT. MULCH OF PULVERIZED EARTH. PLENTT OF FIBROUS ROOTS. BROKEN ROOTS CUTOFF SMOOTH RICH EARTH PACKED FIRMLY ALL ABOUT ROOTS. ^ COURTESY N.J. FOREST COMMISSION How TO PLANT A TREE FOR FARM AND HOME PLANTING 35 During transplanting, the roots of the trees should never be allowed to become dry. If a choice is allowed, transplant a tree on a cloudy day as a bright sun or a dry wind exhausts the stored up moisture. As soon as the trees arrive from the nursery they should be "heeled-in" in moist soil until planting. Large trees may be transplanted successfully during the dormant period by digging a trench around the roots, some three or four feet from the trunk to retain a large ball of soil with the roots. In planting the tree, the hole should be dug slightly larger than is necessary to accommodate the roots without bending or twisting them. If the site, as is often the case, is on "made" ground, remove at least a cubic yard of the soil or rubbish and provide as much good loam. In planting the tree, spread a layer of fine mellow soil mixed well with about one-third its bulk of well decomposed stable manure, if available, in the bottom of the hole. Never use fresh manure. The tree should then be planted by packing the fine soil firmly about the roots, setting the tree about two inches deeper in the soil than it stood in the nursery. If the soil is dry at planting time, watering directly after planting will be bene- ficial as it will help much in packing the soil about the roots and supplying moisture. 36 TREES, SHRUBS AND PLANTS After the ball of earth has been frozen, the tree may be transferred to its proper location. DECIDUOUS TREES Oaks Of all the trees that may be used on the home grounds, the oaks are undoubtedly the best shade trees, for with few exceptions, they are beautiful, long lived and little subject to insects and diseases. They are commonly considered to be slow growing trees but when well cared for the growth of many of them is quite rapid. The white oak is probably the best known and one of the longest lived trees. While young, it has an elegant appearance and when old it generally becomes majestic and picturesque. It is especially adapted for lawn planting. The red oak seems to be satisfied with a comparatively poor soil, develops a straight sturdy trunk, a symmetrical top and its foliage turns a brilliant color in the fall. It is the most rapid growing of the oaks and well adapted for both lawn and street planting. The scarlet oak is much like the red oak, altho it is smaller in size and does well even on poorer soil. Its foliage becomes brilliantly colored in the fall and hence the name. The pin oak grows taller and more slender than most other oaks with an unusually straight trunk. The leaves are small and quite persistent through the winter. This tree thrives well upon moist ground but grows well even where the soil is quite dry. It is especially adapted for street planting and also makes a very desirable lawn tree, the foliage being less brilliantly colored than the red oak altho beautiful during all parts of the growing season. Elms The American elm is probably the stateliest tree grown in this country. Usually the tree assumes a high, upright spreading form, producing a shade that is not too dense for either lawn or street purposes. As a street FOR FARM AND HOME PLANTING 37 tree, it combines more desirable qualities than any other kind altho it grows too large for narrow streets. It prefers a reasonably fertile soil and plenty of moisture, and under these conditions, is a comparatively rapid grower. MAPLE No trees have been more widely used for planting the home grounds than the maples, as they are very satisfactory as shade, ornamental or street trees. The white, silver or soft maple is largely planted because of its rapid growth altho it is a short lived tree, very susceptible to borers and very subject to splitting and breaking. The Norway maple is the best tree for streets of moderate width and is a very desirable lawn tree. The sugar maple (Acer saccharum) is one of the best shade trees for the home grounds. 38 TREES SHRUBS AND PLANTS It is adaptable to almost any soil, hardy and little subject to serious insects or diseases. It is one of the first maples to come into foliage in the spring and the last to drop its leaves in the fall although the foliage does not take on such brilliant color effects as the sugar and red maples. The red leaved variety of the Norway maple is an especially attractive tree when properly located on the home grounds. The common red maple thrives best on a moist soil and is sometimes used as a street tree although proving more suitable for lawn planting. In the fall, the coloring of the foliage is brilliant and in the spring its blossoms make a very attractive early spring effect. The sugar maple is the most widely known and one of the best of all the maples. It is a larger tree than the Norway maple although in many other respects so much like it that the two are often hard to distinguish. It thrives in cool situations and does not do as well under adverse soil conditions as the Norway maple. Its foliage becomes brilliantly colored in the fall, varying from yellow to scarlet. The ash leaved maple or box elder is frequently planted as a lawn tree and it accom- modates itself well to adverse conditions. Like the silver maple, it is a short lived tree and not recommended for general planting. Beech. The beech makes one of the most attractive and beautiful lawn trees. It requires a rich well-drained soil and grows rather slowly. The tree branches too low to produce a desirable street tree and the crown develops such dense foliage as to cast a heavy shade. During the winter, the light gray tint of the bark produces an excellent landscape effect while in the summer the silvery effect of the foliage is very beautiful. The American beech is largely used in this country although there are many ornamental forms of the European species such as the purple-leaved, cut- leaved and drooping beeches that are also popular. In planting upon the lawn, it is well to place these trees well away from the buildings or any spot where sunlight is desired either in winter or summer. There are many other desirable kinds of deciduous trees that are all valuable under special condi- tions. Where quick temporary effects are desired the poplars are favorite trees while the attractive and graceful white birches, the golden willows, the stately syca- mores or that much over planted catalpa, may sometimes find an appropriate setting in the home planting. Evergreens There are few home grounds where a few ever- greens can- not be advantageously used for producing permanent screens, wind breaks, shelterbelts or hedges. They are very valuable if planted sparingly about the lawn as they contrast well with the deciduous trees and enliven The Norway spruce (Picea excelsd) is one of the best evergreens for lawn planting the 'landscape effects during the FOR FARM AND HOME PLANTING 39 winter season. When used too much about the grounds, they are apt to produce a somber gloomy effect. They should never be used near the south or east side of buildings where they might shade them during the winter months. When placed well in the background of shrubs or deciduous trees, they give excellent results. More spruces have been planted about home grounds than any other kind of evergreen. They are the fastest growing of all ever- greens, are very hardy and dp well on almost all kinds of soil. For quick effects under average conditions, the spruces are generally the best. They are much used for windbreaks and hedges as well as for planting about the lawn. The Norway spruce is one of the best and most planted of all the spruces. It adapts itself well to any soil and almost any condition. The tree is clean, trim and bright both in summer and winter. As windbreaks upon the farm, it is one of the very best to plant. The trees grow high and thick and will live almost indefinitely. To maintain a thick growth at the base of the tree, it is often necessary to top them. Care must then be taken to prevent the formation and growth of two leaders. The beauty of all evergreens depends upon the preservation of a good healthy growth about the base of the tree whether they are used as hedges, wind- breaks to lawn specimens. The Colorado blue spruce is one of the most beautiful of the evergreens. The branches are produced in whorls around the trunk and the foliage is dense and of a bluish color. It thrives in almost any soil and locality, is a vigorous grower and does well in cold exposed situations. These trees are propagated in the nurseries by grafting cions from the finest bluest tree on vigorous seedlings, thus producing trees that are uniformly of a comparatively intense blue color. When seed is planted of this variety, some of the seedlings come true blue while others revert to the green. White pine is the most valuable variety of pines both for planting about the home and for producing windbreaks or shelter belts. When planted for windbreaks, white pine should be placed further apart than other evergreens as the limbs grow out close to the ground and spread widely. The foliage is softer and finer than most other evergreens. The young trees look trim and neat all the year around while the old specimens are very picturesque. The Austrian pine is a variety that is especially recommended for planting in the middle west. The growth is very dense and the trees grow to a large size. As planted singly on the lawns, the trees produce a beautiful effect while when planted in groups, the dark foliage shows in excellent contrast with spruce or other evergreens. The Hemlock is also a very popular evergreen for lawn planting and for producing hedges. The foliage is very fine, producing a delicate effect and the trees are graceful and usually long lived. They stand shearing well when planted in hedges and will grow in the shade. For planting in groups with other evergreens they are also most excellent. The trees do best with a northern or eastern exposure and when protected 40 • TREES, SHRUBS AND PLANTS __ from the drying winds. They prefer a moist soil. Sometimes the trees have a tendency to grow quite straggly and should be frequently topped to maintain a dense growth of the lower branches. Arbor Vitae. These evergreens, commonly known as the white cedars, are usually small growing, formal shaped trees. They are quite different in texture from other evergreens and very beautiful when properly used. The varieties vary much as to their form, size and color of foliage but the pyramidal varieties are most largely used. These may be especially valuable in grouping with other evergreens or in planting as screens or hedges. They stand pruning very well and can be trained to almost any shape. They prefer a moist deep soil but will thrive on any moder- ately fertile, well drained soil. They may be found growing wild in many of the low moist places in the central western states and if transplanted while still small, will produce excellent specimens. TREES FOR SPECIAL PURPOSES a. Street Planting. Acer saccharum Ulmus americana Sugar Maple American Elm Acer platanoides Quercus palustris Norway Maple Pin Oak Quercus rubra Tilia vulgaris Red Qak Linden b. Trees for Specimen Planting. Acer platanoides Schwedleri Pyrus (In Variety) Purple Norway Maple Flowering Crabapple Magnolia soulangeana Cercis canadensis Soulange's Magnolia Redbud or Judas Tree Crataegus coccinea Betula (In Variety) Scarlet Thorn Birch Cladrastis lutea Prunus cerasifera Pissardii Yellow-Wood Purple-leaved Plum Cornus flprida Morus alba pendula Flowering Dogwood Tea's Weeping Mulberry Quercus (In Variety) Thuja (In Variety) Oak White Cedar Populusjiigra italica Picea (In Variety) Lombardy Poplar Spruce Sorbus americana Fagus (In Variety) Mountain Ash Beech c. Trees for Exposed Lake Front. Caragana arborescens Betula populifolia Siberian Pea Tree American White Birch Betula pendula Cratsegus Oxyacantha European White Birch May Thorn FOR FARM AND HOME PLANTING 41 Elaeagnus angustifolia Crataegus Oxyacantha coccinea Russian Olive Scarlet Thorn Pyrus baccata Populus Eugenei Flowering Crab Carolina Poplar Robinia pseudacacia Juniperus communis hibernica Black Locust Irish Juniper Firms nigra austriaca Pinus montana Mughus Austrian Pine Dwarf Pine Pinus sylvestris Sorbus americana Scotch Pine Mountain Ash Picea canadensis Quercus macrocarpa White Spruce Mossy Cup Oak Picea excelsa Norway Spruce Trees for Windbreaks Pinus strobus Pinus resinosa White Pine Red or Norway Pine Picea excelsa Pinus sylvestris Norway Spruce Scotch Pine Thuja occidentalis White Cedar or Arbor-Vitae 42 TREES. SHRUBS AND PLANTS VINES Vines are as essential in harmonizing the house with its surroundings as the trees and shrubs we plant about it. When used in this manner, their principal function is to tone down the stiff, bold angles and bare surfaces of the house, producing a softness in the landscape that could be obtained in no other way. They are also valuable in covering steep banks, walls and fences; in the production of quick screens and in the covering of stumps or conspicuous trunks of trees. The principal determinants to success in their use consists in selecting the proper places to plant the vines and the most appropriate vine for each place. As one frequently sees them used, they are covering spaces which would be far more beautiful if left open or leaving spaces exposed Vines should enhance rather than conceal the architecture. The Boston Ivy (Parthenocissus tricuspidata Veitchii) is excellent for covering brick or stone work. which should be covered, thus ruining the architectural features of the building. If correctly used, they should embellish rather than conceal the architecture. Porch columns, cornice lines, corners and angles of buildings should be left open here and there to reveal the form and design of the structure. By planting the less sightly portions and leaving the more beautiful elements of the design exposed, even the most ordinary looking houses may often become very attractive. The style of architec- FOR FARM AND HOME PLANTING 43 ture of the building will largely determine the character of the vine that should be selected to embellish it. The Dutchman's Pipe and Boston Ivy are more suitable for the development of the formal style of treatment than the freer growing vines such as the Clematis or Honeysuckle. Some of the flowering vines that do not produce a dense shade are particularly valuable for draping porch columns and training about windows or along the cornice of a porch. The flowering Clematis, Wistaria and Honeysuckle may often be used in this way, while on porches with a western exposure where a dense shade is desirable, the Virginia Creeper, Bittersweet or some of the vines producing a heavier foliage may be most desirable. The planting of vines too close to the foundation of buildings is a frequent cause of failure in their development, as the cold wall and dry soil in such a location is not conducive to the growth of vines. It is better to plant them a foot to eighteen inches from the wall where the soil is moist and the roots may develop very vigorously. Exposure is also an important consideration in planting vines. Many of the vines such as Wistaria, Climbing roses and Clematis prefer a southeastern exposure, while the Virginia Creeper, Dutchman's Pipe and the Honeysuckles will thrive in shady places or with a northern exposure. Most vines, however, will flower more freely if given plenty of sunlight. The soil is a very important factor in growing vines successfully. They require a well drained soil, fairly moist and fertile, altho they often survive and struggle along on a poor soil. If the soil is poor, it should be replaced with rich loam, if this can be obtained. Otherwise, the soil should be enriched with well decomposed stable manure or commercial fertilizer, being careful that this material is not allowed to come in direct contact with the roots. After planting, the soil should be kept well cultivated, never allowing it to become hard and dry. The dust and gases of the cities ruin many of the vines altho certain kinds such as Boston Ivy and Virginia Creeper seem to thrive even under these conditions. These vines, however, should not be allowed to climb upon wooden structures as they are apt to make the house damp and to cause the wood to decay. Vines should be found very acceptable in planting steep banks and thus preventing washing, while for covering bare and unsightly places under trees or over dead stumps, they may be made to produce excellent landscape effects. For covering stone walls, fences, arbors and in countless other ways, vines will be found most effective on the home grounds. VINES FOR SPECIAL PURPOSES a. Flowering Vines Clematis Jackmanii Roses, Wichuraiana Hybrids Purple Clematis Crimson Rambler Dorothy Perkins. Clematis paniculata Wisteria sinensis White Flowering Clematis Chinese Wisteria Campsis radicans Lonicera japonica Halliana Trumpet Vine Hall's Japan Honeysuckle 44 TREES, SHRUBS AND PLANTS b. Vines for covering brick, stone and masonry Parthenocissus tricuspidata Veitchii Boston Ivy Parthenocissus quinquefolia Engelmannii Engelmanris Ampelopsis Euonymus radicans Climbing Euonymus c. Vigorous climbing vines with heavy foliage Celastrus scandens Lonicera (In Variety) Bittersweet Honeysuckle Campsis radicans Wisteria sinensis Trumpet Vine Chinese Wisteria Parthenocissus quinquefolia Aristolochia macrophylla Virginia Creeper Dutchman's Pipe Clematis paniculata White-flowering Clematis FOR FARM AND HOME PLANTING 45 HARDY PERENNIALS Hardy perennials will always remain a most popular class of flowering plants. There is not a time during the whole flower season in which some hardy perennial is not in bloom, while during the moitths of July and August, when almost all the woody shrubs have ceased blooming, these plants are mainly depended upon for flower display. They are not fastidi- ous about the soil they grow in altho many have a preference. Under trees or shrubberies, on sloping dry banks, along the borders of ponds or brooks, suitable perennials may be selected that thrive under such conditions. Their ability to thrive with little care makes them a very cheap and desirable class of plants for the home grounds. Perennials are especially suited for border planting and when placed in front of shrubbery Speedwell (Veronica longifolia masses they are most effective. They are also var. subsessihs) , a beautiful per- -, ennial that should be more very 61- largely planted, producing beau- fectlVC- tiful spikes of intense lustrous }y used blue color. when planted along garden walks, walls, fences, against buildings and in- numerable other places about the home grounds. In planting peren- nials they should be grouped or naturalist! cally massed asthe effect produced by a colony is more at- tractive than the effect of a number of varieties scattered aim- lessly with few plants of each together. Many of the perennials can be grown from seed. It is best to sow the seed in hotbeds or cold frames very early in the spring and the seedlings may be after- wards transplanted out of doors. Usually, however, they are propa- gated more easily by division. Of the old time favorites, there are the foxgloves, larkspurs, holly- hocks, sweet-williams and phlox, all so characteristic of the early colonial gardens, that are just as desirable today. There are the columbines,, blanket-flowers cor- one most satisfactory eopsis, peonies and poppies, favor- perennials for border planting ites for their beautiful 'flowering and cut flowers. 46 TREES, SHRUBS AND PLANTS Hardy native ferns as a foundation planting along the north side of a porch. Hollyhocks should be planted against buildings, walls or in front of higher growing plants. They are difficult to transplant but easily grown from seed even on a poor clay soil. FOR FARM AND HOME PLANTING 47 effects. For planting about ponds or upon deep moist soil, there are the iris, forget-me-not, lily-of-the-valley, bee balm, trillium, cardinal flower and the ornamental grasses, while for late summer and fall effects there are the hardy chrysanthemums, golden glow, asters and anemone or wind flower. So from early spring until fall when the ground is finally covered with a blanket of snow, the hardy perennials are lending their color tints to brighten their surroundings. PERENNIALS FOR SPECIAL PURPOSES a. Standard Types for General Planting. Iris germanica German Iris Phlox paniculata Garden Phlox Paeonia Peony Delphinium Larkspur Aster Aster Rudbeckia laciniata Golden Glow Coreopsis lanceolata Lance-leaved Tickseed Dianthus barbatus Sweet William Aquilegia Columbine Chrysanthemum Chrysanthemum Altha?a rosea Hollyhock Purple Loosestrife (Lythrum Salicaria roseum), a late summer flowering perennial that delights in a moist soil, planted amid shrubbery, 48 TREES, SHRUBS AND PLANTS b. Little Known Perennials That Should Be More Largely Usad, Achillea Ptarmica var. Boule de Neige Gaillardia aristata Ball of Snow Blanket Flower Monarda didyma Narcissus poeticus Bee Balm Narcissus Hosta plantaginea Anemone japonica Day Lily Japanese Windflower Gypsophila paniculata Iberis sempervirens Baby's Breath Evergreen Candytuft Papaver orientale Aquilegia formosa hybrids Oriental Poppy Columbines Phlox subulata Chrysanthemum coccineum Moss Pink Feverfew Hibiscus Moscheutos Lobelia cardinalus Marsh Mallow Cardinal Flower Eulalias (In Variety) Plume Grasses CHOICE VARIETIES OF PEONIES White Pink Early Early Festiva Maxima Delicatissima Madame de Verneville Mid-season Mid-season Therese Baroness Schroeder Madame Emile Lemoine Late Albert Crousse Marie Lemoine Late Couronne d'Or Dorchester Deep Pink Red Early Early Alexandriana Augustin d'Hour Mid-season Mid-season Modeste Guerin Felix Crousse Late Late Livingston Henry Demay Monsieur Boncharlat Aine CHOICE VARIETIES OF PHLOX Mrs. Jenkins (early white) Fraulein Von Lassburg (large white) Jeanne d'Arc (late white) Bridesmaid (white, carmine center) Henri Murger (white, carmine center) Europa (white, carmine eye) W. C. Egan (soft pink) Selma (pink, red eye) Pantheon (brilliant rose) Rynstrom (deep salmon pink) FOR FARM AND HOME PLANTING 49 Goafs-Beard ( Aruncus sylvester), grown for its large, showy panicles of white flower and does well in a somewhat shady situation. Siebold (bright scarlet) Rosenberg (reddish violet with red eye) B. Comte (purple) CHOICE VARIETIES OF GERMAN IRIS Atropurpurea (purple) Fairy (ivory white, pale violet veins) Florentina (white, tinged with blue) early Gracchus (yellow and crimson) early King of Iris (yellow and brown) Madame Chereau (white, tinged blue) 50 TREES, SHRUBS AND PLANTS Lupine (Lupinus polyphyllus) , a very effective hardy perennial on any good garden soil, producing long spikes of deep blue flowers. Madame Pacquette (bright rosy claret) early Maori King (rich golden yellow) Mrs. H. Darwin (white, violet veins) early Pallida Dalmatica (lavender, blue) Queen of May (lilac, pink) Silver King (silvery white) early ANNUALS Annuals are always desirable on every home grounds as they are most essential in producing the best and most continuous display of flowers dunng the summer months. Their great variety and their adaptability to all soils and conditions as well as the many beautiful ways in which they may be used about the home grounds make them almost indispen- sable. As cut flowers they are the particular favorites of nearly every one and the planting of the home grounds without a few such annuals as sweet peas, asters, pansies, or nasturitums would hardly seem complete. Annuals are also especially valuable in producing quick effects as well as for enhancing the grounds of the renter or person who has not the means to plant the more expensive perennial or permanent kinds. When planted in the foreground of shrubs or among perennial, annuals are most pleasing but it is an unfortunate mistake to grow annuals in flower beds dotted over the lawn. In the free and natural style of landscape garden- ing they should be planted in naturalistic beds about the borders of the home grounds and when so arranged, enhance the beauty of the entire FOR FARM AND HOME PLANTING 51 Cobea (Cobaea scandens) is one of the most rapid growing of the annual vines and hence excellent for quick effects. grounds. They may also be appropriately placed as border plantings along garden walks, about the base of buildings or in front of walls or fences. Annuals are fortunately very easy to grow. Almost all of them may be grown successfully by sowing the seeds of the plants directly in the permanent beds, but usually better plants are obtained by seeding them in hotbeds or cold frames or in boxes of earth in the house, from which they may later be transplanted to the beds. Frequently the plants come into blossom a month earlier when grown in this manner and hence a longer flowering season is obtained. The kinds of annuals are so numerous that a selection is largely a matter of personal preference. The pansies, if sown in July or August, produce an excellent early spring display, while if seeded indoors in late winter and planted in a partially shaded location, they should bloom continuously during the summer. The sweet alyssum, dusty-miller, candytuft and lobelia make excellent edging plants, while for summer flower displays, nasturtiums, petunias, coxcomb, stocks, verbenia, annual phlox, poppies, salyia, zinnias and balsams are all easily grown and very effective. Portulaca is most accommodating in covering dry sandy banks and the heliotrope, marguerites, stocks and mignonette in furnishing the gar- dens with their delightful fragrance. For large foliage effects there is nothing to compare with ricinus or castor oil bean, while the large beau- 52 TREES, SHRUBS AND PLANTS tiful colored flower spikes of the snap dragon compare very favorably with the beauty of any of the perennials. In late summer, the asters, cosmos and burning-bush add their brilliance to the flower display and most all of such annuals continue to bloom till the frosts of the fall dis- mantle their robes of beauty. Annuals Valuable for Cut Flowers Asters, late branching Bachelor Buttons Sweet Peas Zinnias Cosmos, early flowering Snapdragon Pansies Corn Flower Nasturtiums, dwarf Heliotrope Mignonette Stocks D fan thus <% Annuals for Garden Effects Far edgings: For bedding effects: Sweet Alyssum Annual Phlox Lobelia Verbena English Daisy Annual Poppies Dwarf Cockscomb Petunia, var. Rosy Morn Dusty Miller African Daisy Ageratum Marigold Candytuft Balsam Celosia Portulaca Tall growing annuals: Castor Oil Bean Sunflower Cosmos, late Annual Vines Cyperus vine Wild Cucumber Balloon Vine Morning Glory Gourd, Ornamental Hop Vine Climbing Nasturtiums Moon Vine Scarlet-runner Bean Cobea I UNIVERSITY OF IDAHO AGRICULTURAL EXPERIMENT STATION SCHOOL OF FORESTRY Tested Forest Trees for Planting in Idaho By F. G. MILLER CIRCULAR NO. 5 JANUARY, 1918 Published by the University of Idaho, Moscow In accordance with its policy of encouraging the planting of trees in Idaho, by supplying the stock in limited . quantities to prospective planters, the School of Forestry offers for sale the following trees at the prices and in the quantities indicated. COMMON NAME Black Locust Robinia pseudacacia Honey Locust Gleditsia triacanthos Norway Maple Acer platinoides Silver Maple Acer saccharinum Sycamore Maple. . .Acer pseudo-platanus Sugar Maple Acer saccharum Box Elder Acer negundo Black Walnut Junglans nigra Russian Olive Eleagnus angustifolia White Ash Fra.rinus americana Mountain Ash Pyrus americana Red Oak Quercus rubra Purple Willow Cuttings Salix arnerican var. pupurea Golden Willow Cuttings Salix sp. SCIENTIFIC NAME COMMON NAME SCIENTIFIC NAME American Willow Cuttings Sali.v americana S-'U-er Poplar Cuttings Populus alba Austrian Pine Pinus austriaca Jack Pine Pinus divaricata Scotch Pine Pinus sylvcstris Western Yellow Pine. . .Pinus ponder osa Western White Pine Pinus monticola Eastern White Pine Pinus strobus Douglas Eir Pseudotsuga ta.vifolia Blue Spruce Picca parryona Engelrhann Spruce. .. .Picca engelmanni Norway Spruce Picea e.vcclsa Red Spruce Picea rubcns Concolor Fir Abies con color Balsam Fir -\bies balsamca Arborvitae Thuja occidcntalis The following trees may be purchased in the quantities named at 2l/2 cents each, provided that not more than 300 trees in all may he sent to any one person Black Locust, 18 to 24 inches 100 Honey Locust, 10 to 14 inches 30 Norway Maple, 8 to 12 inches 25 Sycamore Maple, 9 to 16 inches 50 Sugar Maple, 8 to 12 inches 50 Silver Maple, 7 to 12 inches 25 Black Walnut, 10 to 13 inches 10 White Ash. 12 to 18 inches 50 Red Oak, 7 to 10 inches 25 Eastern White Pine, 5 to 7 inches.. 50 Engelmann Spruce, 4 to 6 inches. ... 20 Jack Pine, 7 to 10 inches 25 Western Yellow Pine, 6 to 10 inches 25 Western White Pine, 5 to 7 inches. . 50 Austrian Pine, 5 to 7 inches 20 Blue Spruce, 4 to 6 inches 20 Norway Spruce, 4 to 6 inches 30 Douglas Fir (Rocky Mt. form), 6 to 8 inches 100 Concolor Fir, 4 to 6 inches 5 Scotch Pine, 4 to 6 inches 20 Russian Olive. 7 to 10 inches 20 Box Elder, 10 to 16 inches.. 30 The following trees may be purchased in the quantities named at 5 cents each. provided that not more tl, -in -Ml-i-i all. may be sent to any one person. Norway Ma?)le, 18 to 24 indies .?5 Red Oak, l.> IM 14 liHa- . ,.:....-,./. 10 Sycamore Ivlaple, 18 to ',10 inches... 50 Sugar Maple, 14 to 20 inches 20 Silver Maple, 24 to 30 inches 100 White Ash, 18 to 30 inches 100 Scotch Pine, 9 to 12 inches 30 Western White Pine, 12 to 16 inches 50 Eastern White Pine, 10 to 16 inches 50 Concolor Fir. 7 to 11 inches 30 Balsam Fir, 6 to 10 inches 10 Austrian Pine, 12 to 16 inches 50 Blue Spruce. 7 to 10 inches 10 Norway Spruce, 8 to 12 inches.... 20 Red Spruce, 8 to 10 inches 5 Douglas Fir (Coast form), 9 to 14 inches 5 Douglas Fir (Rocky Mt. form), 8 to 12 inches . . 40 Cypress, 8 to 12 inches 5 Western Yellow Pine, 8 to 12 inches 10 Russian Olive, 12 to 14 inches. . 10 A limited number of extra large and fancy trees as follows may be secured at prices per tree and in qnantites as listed : Norway Maple, 5 to 6 ft, 30c 12 Sycamore Manle, 5 to 6 ft, 30c 12 Silver Maple, 5^ to 6V2 ft, 15c/jL 4 Sugar Maple, 4^ to 5 ft., 30c. •.• rffa 5 Norway Maple, 3 to 4 ft, ^.//X.IT 10 Japanese Maple, 3 to 4 ft, 30c 2 White Ash. 4^ to 5 ft, 15r 25 Mountain Ash. 5 to 6 ft., 25c 2 Douglas Fir (Coast form), 18 to 24 in., 20c Arhorvitae, 16 to 24 in, 30c Scotch Pine, 2^ to 3^ ft, 20c Jack Pine, 2V2 to 3T/> ft, ?0c Norway Spruce, 14 to 18 in, lOc... Norway Spruce, 24 to 30 in, 25c. . . Douglas Fir (Rocky Mt. form), 18 to 24 in, 20c. . . 5 4 25 ?5 25 5 10 In lots of KX10 or more, the School of Forestry will furnish the following species at 1 cent each : White Ash. 12 to IS inches Douglas Fir (Rocky Mt. form), 6 to Western White Pine, 5 to 7 inches. 8 inches Scotch Pine, 4 to 6 in. Cuttings will be furnished in quantities and at prices per cutting listed below: American Willow Cuttings. 200. -He Golden Willow Cuttings. 20, Ic Purple Willow Cuttings, 200, ^c Silver Poplar Cuttings, 20, Ic All the trees offered have been thoroly tested, are choice stock, and will be shipped under an inspection tag. The prices stated include packing and drayage, but not express charges. All trees must be shipped by express, so do not fail to xirc your express office. The money must accompany all orders. It is desirable that all orders be received by March 1, so that they may be filled before the season far advanced. SUGGESTIONS FOR MAKING YOUR SELECTION For southern Idaho where the trees are to be grown without irrigation, and where the annual precipitation is not less than 15 inches, we recommend Black Locust. Russian Olive, Jack Pine, Scotch Pine, Western Yellow Pine and Douglas Fir (Rocky Mountain Form).% If the yearly precipitation is 20 inches or more, to the above may be added Honey Locust, Norway Maple, Austrian Pine, and Blue Spruce. Where the annual prccepitation is 25 inches or more, or if the trees are to be grown under irrigation, any of the trees we offer may be planted in either the southern or the northern part of the state, within reasonable altitudes, e.g., up to 4000 or 5000 feet. The spruces offered'will succeed in elevations up to 7000 feet. For narrow windbreaks, the evergreens are especially suited, sirice they hold their leaves the year round. If the windbreak is to be several rods in width, the hardwoods will prove- effective, and will grow considerably faster. Willows are especially adapted to windbreak formation. In wood lot planting, no tree is so generally adapted to Idaho conditions as the P>lacV Locust. It* rapid growth and the durability of its wood in contact with the soil, make this tree one of the most valuable that can be grown for fence posts. White Ash and Red Oak are other hardwoods that may be recommended for the establishment of woodlots. Among the conifers, the pines and Douglas Fir are well adapted to this purpose. While both the Rocky Mountain and Coast forms of Douglass Fir are grown in our nurseries, the Coast form is recommended for onlv the northern part of Idaho. The Rocky Mountain form will succeed thruout the state. The selection of trees for ornamental planting is largely a matter of individual taste. Any tree at its best is highly ornamental. Pleasing effects are more de- pendent upon arrangement than upon the choice of trees, but it is beyond the scope of this circular to enter into a discussion of this interesting phase of ornamental planting. Suffice it to say that there is little chance for mistake in choosing for ornamental purposes any of the trees offered, provided local conditions of soil, moisture, and altitude are right. If in doubt, write us. TIME TO PLANT The trees shonVl be planted as soon as the soil is readily tillable, the earlier the better, after the ground is in shape. HOW TO HANDLE THE STOCK Immediately on the arrival of the trees at your express office, they should be called for and, if possible, planted the same day. ' If necessary to hold them over, they should be unwrapped and heeled-in. This is done by digging a trench, placing the trees in it, and covering the roots with fresh, moist, earth. When planting, you should remove from the trench but a few trees at a time. This is especially import- ant with evergreens, as the exposure of the roots for two or three minutes to the drying effects of the sun and wind may kill them. The soil for the planting site should have as good preparation before planting as you would give a garden. In planting, the holes should be deep enough so that when the trees are in place, they will stand a little deeper than they stood in the nursery row. When setting'the tree, the roots should be spread out as nearly as possible in their natural position. Use the hands in replacing the first few layers of dirt, and see that it is pressed carefully and firmly about the roots. In the matter of spacing the tendency in ornamental planting is to plant too close. The object sought here is symmetrically formed trees, even in late life, which cannot be the case if the trees are' crowded. For ornamental purposes, ordinarily. the trees should not be closer than 40 feet apart, or rarely 30 feet, unless the plant- ing be along the roadside where the spacing may be 20 to 25 feet. CARE AND CULTIVATION Whatever the purpose of the planting, whether for woodlots, shelter-belts, or ornament, the trees must be carefully cultivated indefinitely. This is especially important the first several years. Level surface cultivation should be the practice* Live stock, too, must be rigidly excluded. Address all orders to F. G. MILLER, Idaho Experiment Station, School of Forestrv. Moscow. Idaho. Tree increases eecn year m height and spread of branches by adding on new growth ot twig» CROWN the prTnci ihe under, surface,; leaves *t Leaves pVepa re the food obtained from airand scu.1 and give off mo' sfure t>y trarapi ration Light ana;heat- necessary for chemical changes Heartwood inactive) gives Sapwood carries sap from root to leaves The breathing pores of the enti re tree,- on> leaves twigs, branches.trunkand roots take in oxygen Flooding, poisonous gases or smoke may kill a tree Cambium tmicroscopic) builds the cells inner barK carries prepared food from leaves to cambium **e Root tips orr»oT*air»iT«Xe up water containing sn>e« quantity Q"f minerals t&^ solution./ lU.S.DEPT OF AGRICULTURE I _ .A FOREST SERVICE. Taproofr/f^ 1 I HOW THE TREE GROWS The b<-iOS. »-oo» tips ana cambium layer- are1^© grow-i-ng Vyater corvra">>«g a srnal* quantiTy of minerals «n soJxition is absorbed by the /'pots carmeo upTnrougri -rne sapwooo to The leaves and there cora*bTrted with The afTo make food Thi» food ia cameKJ by t:heiM\n^C>t*®C'*Jto ail/ of The Tree even oown TO the root- Tips REPORTS OF THE DEPARTMENT OF CONSERVATION AND DEVELOPMENT STATE OF NEW JERSEY A Shade Tree Guide by ALFRED GASKILL State Forester Published May, 1918 Union Hill, N. J. HUDSON PRINTING COMPANY. 1918 The Board of Conservation and Development SIMON P. NORTHRUP, President, Newark PERCIVAL CHRYSTIE, High Bridge NELSON B. GASKILL, Trenton CHARLES LATHROP PACK, Lakewood STEPHEN PFEIL, Camden EDWARD S. SAVAGE, ; Rahway GEORGE A. STEELE, Eatontown HENRY CROFUT WHITE, North Plainfield ALFRED GASKILL, Princeton, State Forester and Director HENRY B. KUMMEL, Trenton, State Geologist CHARLES P. WILBER, New Brunswick, State Firewarden OFFICE, STATE HOUSE ANNEX, TRENTON. Contents. Street Trees, 5 Shade Tree Commission, 5 Old trees, 5 What to plant, 5 Trees to avoid, 7 Location, 7 Intervals, 7 When to plant, 7 How to plant, 7 How to keep trees healthy, 9 Lawn Trees, 10 Planting, 10 "Wells" and mounds, 11 Seashore Trees, 11 Fertilizer, 12 Support, 12 What to plant, 12 Nourishment, 12 Water, 13 Food, / 13 Pruning, 13 When transplanted, 13 For form, 13 For vigor, 14 Covering cuts, 14 Time to prune, 15 Injuries, 15 Broken limbs, 15 Frost cracks, sun cracks, and winter kill, 16 Abrasions, 16 Cavities, 16 Gas poison, 18 Fire, 18 Salt, Lime, 18 Electricity, 18 Diseases, 20 Wilting, 21 Bleeding, 21 Insects, 21 Biters, 22 Suckers, 22 Borers, 22 (3) Illustrations. FIGURE PAGE 1. How the Tree Grows Frontispiece 2. Young Trees Planted in Anticipation of Removal of Old Trees . . 6 3. How to Plant a Street Tree 8 4. A Young Street Tree Failing thru Lack of Care 9 5. A Young Street Tree Properly Planted and Well Cared For. . . 9 6. Use of Trees as Anchors for Guy Wires 10 7. Four Types of Tree Guards 11 8. Norway Maple Showing Very Dense Crown 14 9. Norway Maple with Superfluous Branches Removed by Pruning 14 10. Right and Wrong Ways of Treating Wounds 15 11. The Right and Wrong of Tree Doctoring 17 12. Trees Butchered to Make Room for High Wires 19 13. Trees with Crowns Saved and Wires Carried on Low Poles 20 (4) A Shade Tree Guide This bulletin will be helpful to municipal authorities and to those who wish to maintain vigorous, attractive trees on their properties. Few people realize that any tree standing beside a sidewalk, or even on a lawn, is out of its element (the forest), and that the strains and dangers to which it is subject must be counteracted in every way possible. The advice given refers particularly to New Jersey; it is applicable to most of the eastern United States. The value of shade trees. Tho it is now well established that a shade tree. has a value beyond that of its wood, or the cost of plant- ing a new one, and that neither individuals nor public service agencies can injure one without becoming liable for damages, it is advisable always to avoid such troubles. Street trees and lawn trees. It is needful to distinguish between street trees and lawn trees because only a few deciduous species, and no evergreens, can be maintained on narrow paved ways, whereas a lawn admits a variety of trees and shrubs, deciduous and evergreen, that is limited only by space and climatic conditions. On streets and lawns close to the sea the available kinds of trees are few, and extreme care in their selection and nurture is required. Street Trees Shade Tree Commission. It is always advisable to have street trees under the control of a Shade Tree Commission, such as is main- tained in many communities in New Jersey and in several other states. These organizations can secure better results than indi- viduals. Old trees. An established tree, even of poor kind, is better than a newly planted one. Unless an old tree is decrepit or a nuisance it should be saved until a new one can be started to take its place. If young trees are planted between old ones before the latter have to be removed there will be less objection to taking away the unde- sirable ones than there may be if gaps are created. (Fig. 2.) What to plant. In the choice of trees for street planting there is no room for experiments ; one must select a kind that will live, and give satisfaction, for many years under fixed, and usually unfavor- able, conditions. It is generally agreed that an acceptable street tree must be of form suited to the space, hardy and not subject to insects or disease, fairly rapid in growth, a good shade producer, and neat in that it drops no objectionable litter. The list of available trees is practically limited to the following. In most cases choice should be restricted to the kinds indicated by italic type. (5) S.HADE TREE GUIDE. Fig. 2. Young Trees Planted on an Inside Line in Anticipation of the Removal of Decadent Old Trees on the Curbing. The Best Trees for City Streets Narrow Streets. Average- Streets. Wide Streets. (less than 60 feet wide between building lines.) (60 to 90 feet wide between building lines.) (over 90 feet wide be- tween building lines.) Ginkgo Scarlet Oak White Elm Norway Maple Ginkgo Red Oak Hackberry Norway Maple Sycamore Green Ash Red Oak Tulip Poplar Red Gum Sycamore Sugar Maple Red Maple Hackberry White Oak Honey Locust Red Maple Basswood Pin Oak Red Gum Basswood Scarlet Oak White Ash Ailanthus Red Gum Sugar Maple Honey Locust Horse Chestnut STREET TREES. 7 The tree to be planted will be more likely to thrive if it comes from a reputable nursery than if it grew wild, because nursery cul- ture induces the development of compact root systems and lessens the risk of moving. The larger the mass of small feeding roots that is taken up, and the more earth that is moved with them, the quicker and better will the tree establish itself. Red Gum has very tender roots and is rarely planted successfully unless it is moved with a "ball" the same as an evergreen (p. 10). A tree of any kind should be healthy, symmetrical, and, as a rule, have a breast-high diameter of between 2 and 3 inches and a height of about 12 feet. To insure the necessary headroom for street traffic no tree that forks at less than 10 feet above the ground should be used, and no branch whose base is less than 7 feet above the pavement should be retained. Contrary to a common belief, the branches of a tree remain fixed forever at one height above the ground; their bases are not carried upward by growth. (Frontispiece.) Trees to avoid. Silver Maples, Poplars and Willows are rapid growers but short lived, easily broken and given to producing sur- face roots and suckers. Locust is thin foliaged and subject to a boring insect. Nut trees invite injury by their fruit. Location. If conditions permit it, trees usually should be planted inside the sidewalk rather than close to the curb. There they are less subject to injury, their roots have more room, their crowns are less in contact with overhead wires, and they shade the houses better. Wherever space permits it is well to depart from straight lines. Intervals. Street trees usually are planted too closely together. The proper distance will be determined to some extent by the species, the width of the sidewalk and the front width of the build- ing lots. A safe rule is so to space the trees that their crowns will never interfere, but have considerable air and light between. Thirty feet is a minimum interval ; fifty feet or more is better. When to plant. Trees can be planted at any time when they are not in leaf. They are most apt to succeed if planted in spring, as soon as the frost is out of the ground. A cloudy, quiet day is bet- ter than a bright or windy one. (See p. 10.) How to plant. Dig the hole before the tree arrives and follow instructions given in figure 3. If the local soil is poor make the hole at least two feet larger and one foot deeper than is required. Re- move the poor soil and bring good, rich loam. Cut off all broken roots but save as many as possible of the small fibrous ones. Be careful that the roots do not dry out. Put enriched earth in the hole until the tree when standing upon it will be two inches lower, not more, than it stood in the nursery. Hold the tree upright, fill in the mixed soil and fertilizer and compact it firmly about the roots. 8 SHADE TREE GUIDE. Use plenty of water to settle the earth and be sure that every root is firmly embedded. Many newly planted trees die because their roots are left in air pockets. When all is done rake the surface to check evaporation. Successful tree planting depends upon care at every point — a vigorous tree with plenty of good roots, an ample bed of good soil for root growth and careful planting are of prime importance. Then frequent watering, occasional cultivating, and fertilizer once a year. If these things are ignored a tree may live but will never thrive. WELL DEVELOPED HEAD, STRONG LEADER, BRANCH- ES SET AT WIDE, NOT CLOSE, ANGLES. DIG HOLE 18 IN.Q&MORt DEEP; THEN FILL TO LOWER ROOT LEVEL WITH MIXTURE OF 3/4 6000 SOIL AND '/4 ROTTED MANURE. BEFORE SETTING, TREE SHOULD BE PRUNED AT POINT5 INDICATED BV BLACK LINES; NOT BYCUP- "NG ENDS OF BRANCHES BASE OF PERMANENT CROWN 10 FT. ABOVE PAVEMENT. STAKE 2/2 IN. x 10 FT. DRIVETN 2 FT. IN GROUND AND SECURED WITH RUBBER COVERED WIRE, OR WITH CANVASS BASE OF TEMPORARY CftOWN 7 FEET ABOl/E PAVEMENT. PRESERVE FIBPOUS ROOJS: CUT OFF SMOOTHLY EVERY BROKEN fcOOT. OPENING IN SIDEWALK AT LEAST t> SQ.FT.; KEEP TOP SOIL PULVERIZED SET TREE SOT IT STANDS 2 IN. DEEPER THAN IT DID IN THE NUR- SERY PICH EAPTH RACKED FIRMLY ABOUT ROOTS Fig. 3. How to Plant a Street Tree. It is Important to Observe Every Point Indicated in the Diagram. STREET TREES. 9 How to keep trees healthy. 'Any tree will resist insects and dis- ease, and will recover from injury much more readily if it is vig- orous and healthy than if it is weak. Observe the following rules : Never let a sidewalk be laid closely about a tree ; a surface of bare earth (footing) at least 2 by 3 feet, preferably 4 by 8 feet, should be kept (figs. 2, 3, 5) ; when a tree is fully established this may be grassed over, tho it is advisable to keep it open. Once a year work a little fertilizer into this open space and water it at intervals as di- rected at page 13. Fig. 4. A Young Street Tree. Fail- ing Thru Lack of Care — Of Poor Form, with Branches too Low, It is Crowded in a Brick Pavement, Has no Stake and Only a Short, Frail Guard. Fig. 5. A Young Street Tree of Good Form, Properly Planted and Well Cared For — Guard, Stake, Footing as They Should Be. If a young tree is exposed to winds or other strain, keep it firm and upright by means of a stout stake to which the stem is secured in such fashion that it will not be rubbed (fig. 5). Unless the tree is so placed that it cannot be gnawed by horses maintain a stout 10 SHADE TREE GUIDE. guard about it (figs. 5, 7). Apart from the pruning required when a tree is planted most trees should be allowed to develop naturally. Pruning as frequently practiced in butchery. (See p. 19 and fig. 12.) Allow no tree to support a guy wire except under necessity. In that case, and only if the tree is strong and healthy, let an eye bolt be driven into the heart, or all the way thru, and the guy wire at- tached to that ; no form of band should be tolerated except tempo- rarily in an emergency. Fig. 6. Trees Should Not Be Used to Anchor Guy Wires Except in an Emergency. A— Never Attach a Guy in This Way. B — A Temporary Guy Should Have Wood Blocks Under the Wire. C — If a Tree is Sound, a Lag Screw Driven Into the Heart Will Hold a Guy Wire and Do Least Harm. Lawn Trees Planting. Any tree with ample space about it requires only to be secured against injury and to be supplied with food and water. Deciduous trees should be planted exactly as recommended for street trees except that stakes and guards are rarely required. Ever- green trees, and a few deciduous species with succulent roots, as Red Gum, must invariably be moved from the nursery with the roots embedded in a ball of earth. When the hole has been pre- pared and good earth supplied, loosen the bagging that encloses the ball and set the tree with the earth still about its roots. As a rule lawn trees, like street trees, do best when planted in early spring, tho evergreens allow greater latitude and often thrive when moved in August. When that is done it is important to guard the,m against strong winds in winter. Lawn trees ordinarily require less care than street trees, but a circle at least 3 feet in diameter should be kept without sod about the base of a newly planted tree of whatever kind, and the soil with- in it worked frequently, until the tree is firmly established. Grass LAWN TREES. ii may then be allowed to grow, altho it is advisable to maintain the opening continually as a guard against injuring the base of the tree by the lawn mower. "Wells" and mounds. If the level of the ground about an old tree is changed a "well" must be built in a fill to keep the soil away from the trunk and to avoid smothering the roots, or a mound left on a cut to prevent exposure. & Fig. 7. Four Types of Tree Guards. A — Standard in Washington, D. C. Made of Wood and Very Strong. It Also Serves as a Support, but is Unsightly and Not Cleanly. Cost About $1.50. B — Made of Ornamental Fence Wire. Too Frail to be of Much Value as a Guard and of None as a Support. Cost About $1.00. C — Made of Heavy Wrought Iron. Is Attractive, Strong and Durable. Cost With Grill About $10. D — Made of 1-2 inch Galvanized Iron Screen, with Rubber Hose Buffer at Top. Harbors Insects and Must be Supplemented by a Supporting Stake, but Very Popular. Cost About 80 Cents. Seashore Trees Whether along the streets or upon lawns, trees near the ocean have to contend with poverty of soil, deficient soil moisture and strong winds, those of winter in particular. It is useless to try to maintain trees where they can be reached by ocean spray — say with- in 200 feet of high water. Beyond that point it is simply a question of choosing hardy species and strengthening sterile soil. 12 SHADE TREE GUIDE. Fertiliser. It is not necessary to transport inland soil, the poor- est sand may be treated thus : Add to the native soil: Oyster shell lime 9 pounds Wood ashes 2% Composted (not fresh) manure 50 Or as a substitute for the manure, not in addition, A mixed fertilizer composed of : 2 parts tankage 2 ground fish 1 __ 2l/2 pounds 3 acid phosphate 3 " muriate potash J The quantities named are enough for 100 square feet of ground. As root spread is assumed to be equal to crown spread, a tree with a crown 6 feet in diameter will have roots covering about 30 square feet and will require three-tenths of the above. Do not use more or the trees will be injured. Apply the fertilizer every spring; the lime and wood ashes every three or four years. As a sandy soil is always porous frequent and abundant watering is necessary. Support. Until it is firmly established every tree exposed to strong winds must be firmly supported by a stout stake or by three or four wires -secured to pegs firmly driven into the ground. This is even more important in winter than in summer. What to plant. For street planting the choice of species should be limited to sycamore, ailanthus, pin oak, scarlet oak, red oak, hack- berry, honey locust, red maple, and in most situations preference given in the order named, altho it is not advisable that too many of the same kind be used. Upon lawns oaks and pines, with various hardy shrubs, are to be preferred to the firs, spruces and cypresses, and the many deciduous trees, that are available inland. Nourishment More trees suffer from starvation than from anything else. On lawns as on sidewalks a tree's natural food (fallen leaves, etc.), is taken away, water is denied and both rain and air are excluded by close pavements, or by sod. The consequent weakened condition induces disease and insect attack. Don't plant a tree unless it can have at least 6 square feet of open soil at its base. For several years' after a tree is planted this is imperative, afterwards sod, not pav- ing, may be tolerated. Frequent working of the surface soil, as in any garden, will tend to keep a tree in good condition. NOURISHMENT. 13 Water. Street trees require more water than lawn trees because their roots are apt to be restricted and because sun-heated pave- ments and buildings increase transpiration. A good rule is to see that the ground about a tree is soaked once a week. If rain fails use the hose or a pail. Sprinkling, tho done frequently, is only a little better than nothing. Too frequent soaking will exclude the air and cause the roots to rot. When the ground has dried after a wetting, rake the surface to check evaporation. If the ground does not dry within an hour too much water has been applied. Food. In the forest, and in neglected places, nature provides trees with food. Along the streets and on well-kept lawns it must be furnished. If a tree shows thin foliage, slender branches or a dead top starvation may be suspected. The best fertilizer is com- posted (not fresh) manure. In the spring spread it 2 inches deep over as much of the root extension as can be reached and fork it into the soil ; or, tho not so good, put it on December first and let it lie over winter, when what remains can be raked off. On a paved street the fertilizer must be placed in the opening at the tree base, but whenever possible it should be spread away from the trunk and beneath the foliage, where most of the feeding roots are found. If manure is objectionable, apply each spring i% pounds per 100 square feet ojf a commercial fertilizer composed as 'follows : For light soils. For heavy soils. Nitrate soda I part 2 parts Acid phosphate i " 3 " Muriate potash1 i i " Ground bone i " 2 " Distribute the fertilizer evenly and mix it with the soil; be care- ful not to use an excess else the tree roots may be burned. If it is desired simply to sustain an old tree without inducing growth, use a small quantity of manure, or from i to i% pounds per 100 square feet of a mixture containing i part nitrate soda, i part bone meal, 5 parts acid phosphate. Pruning Trees need to be pruned only (i) when they are transplanted; (2) when they interfere with other trees or structures; (3) when they are weakened by decay or by overgrowth. Much of the prun- ing done by so-called experts is useless or even harmful. Most trees should be allowed to develop according to their natural habit. When pruning is permissible the following rules apply. When transplanted, a tree must have its crown cut back to bal- ance the inevitable loss of roots. See figure 3, and observe that useless interior branches are removed entirely. Form. If a tree grows one sided, if its branches interfere with a building, or with another tree, curtail or cut out entirely the aggres- *Wood ashes may be substituted at the rate of 10 pounds to 1 pound of muriate potash. SHADE TREE GUIDE. sive member. With few exceptions trimming the ends of branches is wrong and cutting off the whole top is butchery. Branches which hang too low should not be trimmed, but cut back to the trunk or main branch. If branches grow so that they interfere with electric wires, either have the wires lowered, or re- move entirely all but the three or four most vigorous shoots and stimulate the tree to carry a crown above the wires. (See p. 19.) For treatment of heavy limbs see Injuries, page 15. Vigor. If a tree is so weakened that dry branches appear, cut out all the dead wood, and such of the living members as is neces- sary to make the tree shapely. If lack of vigor is shown by droop- ing foliage and the crown is very dense (as is common in Norway maples and sugar maples), relief will be given by removing a quarter or a third of the foliage. This should be done, not by cutting off the extremities, but by taking out interior branches entire (figs. 8, 9). When done skilfully the appearance of a tree as well as its strength is improved. After pruning for vigor a tree should always be well fertilized and watered. Fig. 8. Diagram, from a Photo- graph, of a Norway Maple Show- ing the very Dense Crown Common with this Species. The Foliage Produced Makes a Heavy Draft upon the Soil Fertility and Water and Frequently Leads to Wilting. Fig. 9. The Same Norway Maple as that Shown in Fig. 8 with Superfluous Branches Removed by an Interior Pruning. This Preserves the Natural Form of the Crown and a Frame that will Produce as much Foliage as is Desirable. Covering cuts. Unless it is properly treated every break in the bark of a tree affords entrance to disease germs. In practice clean cuts less than an inch in diameter are ignored; every larger wound should be coated with an antiseptic. The most practical is creosote followed by coal tar. Tar alone is often used, but does not pene- trate deep enough to give best results. Creosote is a dark oil and can be applied with a brush. Tar should be made liquid by heat and applied in the same way. It is advisable to avoid covering the cam- bium. INJURIES. 15 Time to prune. Pruning may be done when it is most convenient unless "bleeding" (p. 21) is induced. That is most apt to occur in early spring or early fall. Late winter is usually best because there is then little sap movement and the absence of foliage makes the work easier. (See .p. 8.) Injuries Broken limbs. Every broken limb should be cleared away promptly by a cut, or succession of cuts, that leave a wound which will heal quickly. Small limbs can be taken off by a single cut, larger ones require three, as indicated at B, figure n. It is im- portant to use a sharp saw, make the final cut close to the larger member and be careful that the bark at the bottom is not torn. A wound shaped as indicated at RIGHT, figure 10, will heal most quickly ; one shaped as indicated at WRONG will heal more slowly at the top because the arch is flatter, and very slowly at the bottom be- cause the bark is torn away. A stub as at C, figure n, should never be left. The face of the wound should be treated as directed on page 14. Cement will do harm rather than good. ,WCONG ar Fig. 10. Cut Marked RIGHT is Healing Properly and Quickly. Cut Marked WRONG is Healing Slowly, and Not at All at the Bottom, Where the Bark is Torn. Every Wound on a Tree that Can be so Treated, Whether a Mere Bark Bruise or the Stub of a Severed Limb, Should be Trimmed to a Long, Regular Oval. 16 SHADE TREE GUIDE. Frost cracks, sun cracks, and winter kill. Extremely cold weather, especially when it follows a late growing season, some- times freezes the water in the outer cells of a tree stem and causes a long crack. Thin-barked species, like sycamore and horse chest- nut, are most susceptible and any tree on. a street, exposed as it must be, is apt to suffer. Sun cracks have the same appearance but are caused by excessive heat, often reflected from a white pave- ment or wall. In large trees such cracks usually close again with warmer weather and no serious harm is done, but the wood does not unite and a scar is left. On small trees the crack is apt to per- sist until new growth covers it. There is no practical preventive, and no remedy other than helping nature by every care to heal the wound. This can be hastened by treating the crack with antiseptic, and keeping it from reopening by strong staples, driven in warm weather when the gap is narrowest. "Winter kill" occurs when the vital parts of a tree trunk are frozen and ruptured in a horizontal plane by the formation of ice about its base. There is no remedy, but the trouble can usually be avoided by having the ground slope away from the foot of a tree on all sides so that no water can col- lect there. "Winter kill" is common on the terminal shoots of many trees and shrubs and rarely does permanent harm. Abrasions. Surface wounds, made by horses, lawn mowers, blows, etc., are the starting places of most of the decay that de- stroys shade trees. It is little realized that many serious tree wounds originate between the nursery and the planting site. If the trunk of a young tree is thrown on the side-board of a wagon the tender bark and cambium are apt to be crushed, and tho the injury may not show at the time the growth of the surrounding parts reveals it. Every care should be taken to avoid these injuries. When one occurs let the injured part be cut out carefully with a sharp knife or chisel until sound wood is exposed and the edges left smooth. Then sterilize and tar the wood — not the cambium or bark, and leave the rest to nature. Cement should not be used. (See F and H, fig. n.) Cavities. Cavities in trees are invariably the result of decay. They are treated with one or all of three objects in view: (i) to stop the decay and induce healing; (2) to hide an unsightly part; (3) to support a weakened body. The belief that every cavity should be rilled is wrong, because, even with the best workmanship, a filling merely retards decay, it does not stop it. The best rule is to clean a cavity thoroly — cutting out all decayed tissue with a gouge and mallet until sound heart wood is exposed. If the cavity will not hold rain water, or the wound is not unsightly, trim the edges neatly, treat the wood surface and stop. INJURIES. PREVENT A SPLIT OR MEND A SPLIT BY CHAIN & BOLTS, NOT BY A BAND. SEC I. STUB TOO LONG FOR HEAL- THY HEALING AND DECAt WORKS INWARD. ALONG STUB LEFT. DECAY HAS SET IN & If NOT TREATED AS AT M WILL DESTROY THC MAIN LIHB. A PRUNING WOUND MADE AS B OR E HEALING PER fECTLY. A SOLID BAA WITH NUTS WILL HOLD A WEAKENED CROTCH THOUGH, IN A BIG TREE NOT SO WELL AS A CHAIN . SEE A. . WHEN A LIMB IS REMOVED AND THERE IS SLIGHT DECAY. CLEAN OUT THE WOUND ft TAR BUT DO NOT FILL IT. BAND. THE TREE CHOKED. SEEA&D TREAT A BRUISE AS H BY CUTTING OUT INJURED TISSUE, LEAVING SURFACE ft EDGES SMOOTH. TAR BUT DO NOT TILL. OR BRUISE TO BE A, LARGE CAVITY PROPERLY FILLED WITH CONCRETE. Fig. 11 The Right and Wrong of Tree Doctoring. If the cavity cannot be drained, if it is unsightly, or if the tree needs support, a concrete filling may be placed. Before doing this any but a pocket cavity should be shaped so that moisture will drain from it, and set with nails or wires to hold the concrete in place. In many cases it is advisable simply to clean the cavity, and, 1 8 SHADE TREE GUIDE. without attempting to fill it, cover the opening with cement, sheet- metal, or wood blocks (creosoted), to guide the growing callus. For small cavities a mixture of half cement and half sand is best; for larger ones one part cement, one part sand and two parts gravel, broken stone or cinder will answer. The surface of a fill- ing may be smoothed with a coat of clear cement. The sand, stone or cinder should always be free from dirt of any kind, the cement thoroly mixed and as soft as it can be handled. Gas poison. If illuminating gas escapes from a faulty pipe into the soil in which a tree grows the roots may be poisoned, cease to function and the tree be weakened or killed. The extent of the damage, and the rapidity of action, depend upon the quantity of gas, the porosity and moisture of the soil, and the chaVacter of the pave- ment or other ground cover. A little gas may find its way to the air and do no great harm; a large quantity can kill in a day every tree whose root system it penetrates. If a tree is killed while it is leafless, it may give no sign until the following spring when its foli- age fails to come out, or, coming out, is weak and soon falls. The only sure test for gas is the odor. If a leak is suspected make a hole with a crowbar or auger about two feet from the tree and two or three feet deep and apply one's nostrils to the opening. If gas is indicated the leak must be found and stopped at once. Some- times a tree subjected to gas can be saved by trenching about it and watering the soil freely, but most cases are hopeless unless only a little gas has escaped. Fire must not touch a valued tree. Even the slight heat given off by a burning leaf pile may cause serious injury. Salt, lime. Many trees are killed by having brine from ice- cream tubs, or from salt used to melt pavement ice, penetrate to their roots, and some are lost by an excess of lime water washed from nearby mortar beds. Preventive measures only are effective. Electricity. Ordinary electric currents never injure the vitality of a tree, and wires carrying a high potential current which might do damage, especially in wet weather, are bound to be properly in- sulated to save loss of power. The injury that trees suffer from electric wires is invariably a cutting or local burning caused by friction between a loose wire and a branch, or, more often, the mutilations performed by careless or ignorant linemen. The rules of the electric companies forbid their employees to use any tree without the consent of the owner and provide for expert super- vision of any tree trimming that is authorized. Linemen fre- quently ignore these rules, but no tree need suffer if its owner will take the trouble to report the case to headquarters before the dam- age is done. In many cases the company will completely trim and fix up a tree for the privilege of carrying their wires thru it. In this State an owner should always be represented by a Shade Tree Commission. STREET TREES. Fig. 12. A Row of Old Trees Butchered to Make Room for High Wires. Compare With Fig. 13. Fig. 13. The Same Trees as in Fig. 12, With Crowns Saved and Wires Carried Thru Them in Cables on Low Poles. The construction of electric lines is a necessity of our civilization ; the cost of carrying the wires underground is prohibitive except in 20 SHADE TREE GUIDE. cities where the service is concentrated; they must therefore be carried on poles along the streets and must be accommodated to ex- isting structures and trees. In making these accommodations five rules will govern : 1. Set the poles as far out of the tree line as possible, to avoid interference. 2. Use low rather* than high poles. Where the trees are small, and in line with the poles, it is necessary to carry the wires above them, but as they grow, lower the poles so that the wires may be carried, on offsets, brackets and insulators, away from or thru the firm bodies of the trees. A wire fastened so that it does not rub can do no harm ; a bolt carefully driven into the heart of a branch to support an insulator or a cross arm is always justified; but any vigorous tree will soon outgrow the practical height of electric poles. 3. Let cross arms and insulators be fastened to strong trees, rather than set poles, where the wires can be properly carried. 4. Provide guard strips on the. trees and abrasion moulding on the wires wherever there is movement and a chance that the tree and the wire will rub. The removal of small interior branches to make a clear way for a wire is more apt to be a benefit than an injury to a tree. 5. Have all cuts larger than I inch diameter made smooth and carefully treated (see p. 14), to prevent the entrance of disease germs. Prohibit absolutely the use of climbing spurs in any tree. Diseases The diseases of trees are chiefly due to abnormal soil or climatic conditions, to injuries, or to .parasitic fungi. The latter sometimes are very destructive, as in the case of the chestnut blight ; more commonly, as the sycamore anthracnose, they affect the foliage more or less seriously, but do little permanent harm. Fortunately, most diseases attack only one tree species, or one genus, — a law that makes diagnosis and control less difficult than they would be otherwise. If a tree begins to fail without apparent cause, it should be questioned (i) whether it lacks water; (2) whether it stands in sterile soil and lacks fertilizer. If either deficiency is discovered the remedy is obvious (see p. 13). If it is not, a specialist may be helpful; often he can do nothing. If the fleshy fruiting bodies of a fungus appear, the tree, or its affected member, is seriously diseased, and surgery, or the tree's removal, is indicated. It fre- quently is better to ignore the signs of internal decay than to start a cutting which may have no practical limits. Many trees live for years with their heartwood completely gone. (See Cavities, p. 16). It is important to distinguish the fungus fruits which appear only on dead wood, from those which are parasitic. A special publica- tion, "Common Diseases of Shade Trees/' can be obtained upon re- quest of the State Agricultural Experiment Station, New Bruns- wick. DISEASES. 21 Wilting. The leaves of shade trees frequently wilt out of season. Sycamores are apt to lose their first leaves in the spring from a prevalent disease, but soon get a second set and usually suffer lit- tle permanently. No specific treatment is advised. Other species, especially maples, are beset with lice or scale insects which by suck- ing their juices cause the leaves to die. If the attack is slight let nature take care of it ; if it is serious spray as directed on page 22. But most trouble of this kind is found in Norway and sugar maples ; the cause is obscure, yet there is reason to believe that too little food, sometimes too little water, is available to nourish the heavy leafage that these trees produce. Feeding and watering (p. 13) will usually prevent this trouble ; if it develops, let the foliage of the affected tree be curtailed by an interior pruning (\p. 14), then fertilize. (Figs. 8,9-) Bleeding. This frequently occurs when branches are cut while the sap is moving freely. Under such conditions stop all pruning as loss of sap lowers the vitality of a tree. Another sort of bleeding, sometimes called "slime-flux," and hav- ing an offensive odor, usually begins in a wound, or behind a filling, and is often hard to manage. Like a sore in the flesh the worst possible course is to stop it from the outside; it must be cleansed, sterilized and made to heal from the inside. Let all affected tissue —bark and wood, be cut out with a sharp chisel, the wound pointed at top and bottom (fig. 10) and all edges left smooth : sterilize the exposed surfaces with weak formalin and cover with tar; never use cement. If the trouble is due to a split crotch, clean the crack as well as possible, bolt the parts together, as at D, figure n, and treat as above. Insects Not all insects are harmful to trees: some, tho harmful, are so controlled by natural enemies that they rarely are found in num- bers great enough to do serious damage; others attack only trees that have been weakened by neglect or injury. As with diseases, harmful insects usually confine their attacks to trees of one species, or one genus. Thus the elm beetle attacks elms only, the hickory borer only hickories. It is entirely safe to say that a few insects of any kind on a vigorous tree will do little harm ; a few insects on a weak tree should be looked after, and many insects on any tree demand prompt attention. But to be always on the safe side every suspected case should be referred to some au- thority— an entomologist or a forester. Ants are rarely harmful ; their presence about a tree usually means that honey dew, decayed wood or fungus growths are available for their food. Injurious insects are grouped in three classes: biters, suckers, and borers. 22 SHADE TREE GUIDE. Biters. These commonly attack the foliage and may work as adults (beetles) or as larvae (caterpillars or worms). Control is determined by a knowledge of the life history of each species, but a general remedy is to poison their food. The best means is to spray thoroly with arsenate of lead according to directions given on the commercial packages. Banding a tree trunk with cotton or some sticky stuff is useful only when the insects are crawling up. Bag worms, tent caterpillars, etc., which form conspicuous shelters or colonies in tree crowns, and forms like tussock moths which set egg masses on nearby structures, as well as on the trees, can often be destroyed by hand or by fire even more successfully than by spraying. Suckers. These appear as minute, crawling insects, frequently protected by woolly, waxy or scaly coverings. They locate on the younger branches, or on the leaves, often in enormous numbers, and live by sucking the sap. Some forms can be washed away with a strong jet of water from a hose, but in most severe cases thoro and repeated spraying with a caustic, or with a penetrating oil, is neces- sary. Fish-oil soap suds is good for the tenderer forms, especially when reinforced with tobacco extract; lime-sulfur or soluble oil is best for those with scaly armor. Borers. Boring insects work, as beetles or worms, in the twigs or buds, in heartwood, or, most frequently, in the cambium layer between sapwood and bark. Their presence is indicated by broken branches and by small holes in the bark beneath which wood dust is often found. In our territory a few species attack healthy trees, but most seek out those whose vitality has been lowered. Control is dif- ficult because the pest is mostly out of sight, and, tho help can some- times be given, it usually is necessary to depend chiefly upon keep- ing the trees in good health. Against the locust borer anything else is useless. Any hickory tree that is seriously infested with the hick- ory borer is doomed and should be cut down and burned without de- lay for the sake of nearby trees, and the latter should be stimulated by feeding to ward off attack. Leopard-moth larvae are especially fond of young, newly-planted street trees which are struggling to establish themselves. A measure of control is possible by cutting out the boring worms, by crushing them with a wire run into the burrows, by injecting carbon bisulfid, and especially by encouraging insect eating birds. More specific advice is given in a publication of the State Agricultural Experiment Station, New Brunswick, "In- sect Enemies of Ornamental Trees and Shrubs," by Harry B. Weiss, which will be sent upon request. o DEED BEDS V for OBACCO ^ arxd OTHER CROPS &?=> E.G. B BIN HART Assisiani inTobacco I rvv G si i A&~t i o ns FARMERS BULLETIN 996 UNITED STATES DEPARTMENT^ OF AGRICULTURE /^ltt/jJ9r * Contribution from the Bureau of Plant Industry I.A.TAYLOR.,, Ckief Wasfvi^W.D.C. July, 1918 THE TOBACCO SEEDLING is subject to injury in the seed bed by weeds and a number of para- sitic enemies, among which is a fungous root-rot. It is of the utmost importance to secure beds free from weeds and to avoid the use of diseased or weak seed- lings. Methods of sterilization have been developed to control seed-bed conditions. The old method of open fires, long practiced in the South, is being re- placed by a steaming process the essential feature of which is an inverted pan used to force the steam into the soil. This method of steaming has been widely adopted in certain tobacco-growing districts and is applicable to most, if not all, of them. The process of steaming described is. the. most practical and eco- nomical method of seed-bed control yet developed, and besides eliminating diseases and improving gen- eral soil conditions, it kills weed seeds more effec- tively than the old methods. The cost of sterilizing is more than paid for by the saving in the cost of weeding. This bulletin describes the necessary equipment and method of operation, with certain special fea- tures of seasonal convenience and seed-bed prepa- ration. The method is applicable for working on either small or large seed-bed areas and can be used in all tobacco-growing districts. With necessary modifications in the apparatus which will readily suggest themselves to the truck grower, the method can be used very successfully to control soil conditions in the greenhouse, in cold- frames, or in the field. STEAM STERILIZATION OF SEED BEDS FOR TOBACCO AND OTHER CROPS. CONTENTS. Page. Importance of vigorous tobaccoseedlings 3 Root-rot in the seed bed _ 4 Old metho d of sterilizing tobacco seed beds . . 4 The steam-pan method of sterilization 5 Preparation of the seed bed for steaming . 6 Effect of frost in the soil . Fall steaming of the seed bed 6 Equipment needed for steaming seed beds. . . 7 Construction of the steaming pan 8 Page. Carrying out the steaming process 10 Temperatures secured 11 Cost of steaming 12 Important considerations 13 The formaldehyde method of sterilizing seed beds 14 Application of the steaming process to crops other than tobacco. . . 15 IMPORTANCE OF VIGOROUS TOBACCO SEEDLINGS. IN TOBACCO PRODUCTION, to grow the right sort of seedling plants is of special importance. Successful transplanting from the seed bed to the field requires vigorous seedlings, and the growth of the crop in. the field, especially in the early stages, is largely de- pendent upon the character of seedling used. Great importance is to be attached to securing strong, healthy seedlings. The young plants in the bed are liable to be injured, and therefore it is necessary to protect them from parasitic and other enemies, which may injure and retard their growth or even kill them. Chief among these ene- mies are weeds and certain fungous diseases, especially root-rot. Spots in the beds are also frequently found where the soil conditions are such that normal development can not be attained. These difficulties can be eliminated or greatly reduced by the sterilization of the seed beds, which now is recognized as an import- ant feature in tobacco growing. Seed beds are sterilized for the con- trol of diseases and to kill weed seeds and hibernating insects. When properly done, the saving in weeding costs usually pays for the whole operation of sterilization. The process has the additional advantage of insuring freedom from diseases and the production of more vigor- ous seedlings. Sterilization by surface burning has been widely practiced for generations in the South, and in fact has been used at one time or another in nearly all tobacco districts. In the southern districts it has been customary to select each year a new location for the seed 69808°— 18 3 4 FARMERS BULLETIN 996. bed- and tlit? eliief object of burning has been to free the bed from weed seeds. In- jth,e licrthei-n districts permanent seed beds with glass covers are in more or less general use, and the widespread appearance of fungous diseases, especially root-rot, has made some sort of steriliza- tion necessary. Since open fires are impracticable in these districts a process of steam sterilization has been worked out, which now is used extensively in the cigar-leaf producing districts of the Connec- ticut Valley, Pennsylvania, and Wisconsin and has been employed with success in several other sections, notably in western Kentucky and Tennessee and in the Burley district. This method is both eco- nomical and effective, and with more or less modification is adapted to practically all tobacco-growing districts. ROOT-ROT IN THE SEED BED. Within recent years the discovery of the prevalence of a root-rot in the seed bed and in the field has brought about a wide demand for a suitable method of control. The fungus1 which causes this root-rot is so small that it can be seen only with the aid of the microscope. It may attack the plant at any time after the germination of the seed, and usually can be recognized easily by its effect upon the roots. In the earlier stages brown or black spots appear on the roots. These vary in size from small dots to areas that may extend along the taproot and laterals for an inch or more. In these diseased portions spores, or reproductive bodies of the fungus, may be found by examination with the microscope. As the fungus attacks the roots the diseased parts become successively brown and black, and the root tissues die and fall away, seriously affecting the vitality of the plant. The fungus lives in the soil from year to year; hence, a bed once infested should not be used again until the disease has been elimi- nated. New seed beds may be infected by stable manure or decayed leaves used for fertilizing, or by wind-blown vegetable matter carry- ing spores of the fungus. Seedlings seriously attacked by root-rot are not fit for transplanting, and, furthermore, they may be the means of establishing the disease in the field. It is especially im- portant, therefore, that the disease be eliminated from the seed bed. An effective and economical method of control of the root-rot in the seed bed is found in the sterilization of the seed-bed soil. OLD METHOD OF STERILIZING TOBACCO SEED BEDS. For many years before the adoption of sterilization with steam, open fires on the soil had been used. The open-fire method came into use chiefly because of its value in freeing from weed seeds the spot 1 The technical name of this fungus is Thielavia basicola. STEAM STERILIZATION OF SEED BEDS. 5 selected for the seed bed. It has been practiced for a great many years in the tobacco-growing areas south of Maryland and Ohio, where it is common to locate the seed bed at the edge of or in the woods. The area selected for use as a seed bed is cleared, the ground broken, and brush and wood laid over it and burned. The degree of thoroughness with which the surface burning is done in different sections depends on the character and quantity of the fuel supply and on other local conditions. When the burning is done thoroughly the resulting heat is sufficient to free the soil of all fungi and weed seeds to a depth of several inches, but the organic matter of the soil is largely destroyed, and later the surface of the bed is likely to bake during even short dry periods, killing a large percentage of the seedlings. Barn manure and fertilizers containing organic matter must be applied after firing to prevent their decomposition in the burning, and this opens the way for adding to the seed bed material carrying fungous spores or weed seeds. If excessive quantities of ashes are left on the bed the growth of the seedlings may be affected, and sometimes the germinating seed may be killed. In order fully to accomplish the purpose of burning, it is necessary to secure a high heat over the surface of the entire seed bed. - This requires large quantities of wood, and the ever-increasing scarcity of wood in certain localities has made it practically impossible longer to pursue this method. A modification of the open-fire method is found in the portable wood-burning furnace. This furnace consists of a heavy fire box, 9 feet long, 3 feet wide, and 18 inches deep, constructed of iron and set close to the ground. On top of this is set a pan 9 by 3 feet and 10 to 12 inches deep. The whole apparatus rests at one end on a pair of wheels and at the other end on two legs. It is furnished with two handles for lifting and drawing. A fire is made in the fire box and the soil from the seed bed, to a depth of 4 or 5 inches, is shoveled into the pan and covered. The heat from the fire below brings about thorough serilization. While more effective than the open fire on the bed, the furnace has the disadvantage of being slow in operation and equally expensive in fuel consumption. It also necessitates a second handling of the soil. THE STEAM-PAN METHOD OF STERILIZATION. The steaming of the soil is the most satisfactory method of steriliza- tion \vhich has been developed up to the present time. The direct ap- plication of the steam to the soil by means of an inverted pan or hood has now been in successful operation for a number of years.1 Thus far 1 This method has been briefly discussed in Farmers' Bulletin 343, " The Cultivation of Tobacco in Kentucky and Tennessee" (1909), and in Bureau of Plant Industry Bulletin 158, " The Root-Rot of Tobacco Caused by Thielavia Basicola " (1909). 6 FARMERS' BULLETIN 996. this process has been most extensively employed perhaps in the Con- necticut Valley, but because of its many advantages and its effective- ness it is being widely adopted in other tobacco-growing districts. PREPARATION OP THE SEED BED FOR STEAMING. The seed bed is thoroughly prepared in the usual manner for sowing the seed. The soil is well worked, the fertilizers spread and mixed in the soil, and the bed brought to fine tilth, so that after the steaming is completed it is only necessary to rake the bed lightly before sowing the seed. It is important that nothing but the seed and the diluting material, also sterilized if necessary, should be added to the bed after sterilization. A comparatively dry bed is the first requisite for successful steam- ing, as it is practically impossible for the steam to penetrate wet soil. Glass-covered beds may be dried with comparative ease by covering them with sash several weeks before steaming. The bed is protected from the rains and snows of spring, and the sun's rays warm the soil and drive off excessive moisture. Cloth-covered beds may be protected for two weeks before steaming when rain or snow threatens by stretching over them cloths which have been painted with a thin mixture of linseed oil and drier. EFFECT OF FROST IN THE SOIL. The presence of frost in the surface soil retards the penetration of the steam and makes it necessary to continue the process for an unusually long period. The ground must first be thawed before the desired heating can be brought about, and this causes a fuel con- sumption more than double that required where the soil is in proper condition. Where there is frost in the surface soil the steam does not penetrate more than a few inches, because of the condensation of the steam in the cold ground. In order to thaw out the seed beds before steaming, a good practice is to cover them with glass for several weeks, as has been suggested for wet beds. The glass allows the heat from the sun's rays to be confined within the bed during the day, warming the soil and put- ting it in a mellow condition. Without such preparation even par- tial sterilization would be impossible in some sections till late in the spring. FALL STEAMING OF THE SEED BED. Steaming has been done in the fall by many growers because of the disadvantages experienced in the spring due to rains and snows or the frozen condition of the ground. Usually the seed-bed soil can be put in excellent condition in the fall when the land is dry and before the air temperature is low enough to freeze the ground. An STEAM STERILIZATION OF SKKD BEDS. 7 added advantage is found in the seasonal distribution of labor, mak- ing it desirable to do the work at this time, when there is no par- ticular rush to complete the steaming. Fall steaming has the disadvantage that infected material and weed seeds may be blown into the beds during the winter, but where windbreaks of high, tight board fences are placed around the beds this disadvantage is reduced to the minimum. There also is the added disadvantage in certain cases, particularly where the seed beds are located on low ground, of the ground becoming flooded during winter or spring thaws. The surface water may carry spores from adjoining infected land to the sterilized seed bed. It is necessary at all times to have thorough drainage in and around the seed beds. Especially in regions of clay soils wyhere glass frames have not come into general use fall steaming finds particular favor because of the practical impossibility of drying the seed-bed soil early enough in a wet spring. Where the work is done in the fall all preparations are made as for spring steaming. If manure is used, the quantity added in the fall should be a little more than that ordinarily used in the spring, because of the possible loss by leaching. Commercial fertilizers can be applied safely in the spring. EQUIPMENT NEEDED FOR STEAMING SEED BEDS. The equipment recommended for steam sterilizing seed beds under average conditions consists of the following: A portable boiler of ijO-horsepowor or larger capacity. Heavy f-inch steam hose, 25 feet. Iron f-inch pipe sufficient in length to carry the steam from the boiler to all parts of the beds. Heavy canvas or burlap, 216 square feet. A steaming pan to cover an area of about 72 square feet. Attachments for the steaming pan, consisting of 4 ring bolts 6 inches long, with 3-inch rings; 4 bars or ax handles; felt packing 2 inches wide, sufficient in length to extend around the pan ; the same length of 4-inch hoop iron or of 2-inch angle iron; one 5-inch nipple 6 or 7 inches long, threaded on both ends; two f-inch leather gaskets; two 5-inch nuts or threaded washers. The boiler is the item of greatest expense, the rest of the equip- ment being comparatively inexpensive. With proper care the entire apparatus should last for a number of years. A boiler of sufficient capacity is the essential factor in successful sterilization, because large volumes of high-pressure steam are re- quired. Experience has shown that a boiler of at least 20-horsepower is necessary for efficient steam production when using a steaming pan of the size mentioned above. In some localities, where seed beds have been sterilized with steam for a number of years, farmers are & FARMERS' BULLETIN 996. supplied with their own boilers; in other places one boiler is used cooperatively by several planters. Road rollers, steam tractors, and packing-house boilers are frequently called into use for seed-bed work. In some sections the owners of steam tractors or portable boilers go from place to place, sterilizing beds at fixed prices. Such operators are usually supplied with all necessary equipment, though sometimes they provide only the boiler and a fireman. CONSTRUCTION OF THE STEAMING PAN. In the permanent seed bed the pan is of such width as to fit snugly within the sides of the frame, and its length varies according to requirements. A pan having an area of 72 square feet is sufficient for a 20 or 25 horsepower boiler, and a larger pan is difficult to move. On a bed 6 feet wide the pan should be 12 feet long. Where only a PI6I IT PIG. 1. — Inverted wooden pan for the steam sterilization of seed beds, showing the con- nection of the steam hose. Note the fine preparation of the seed-bed soil. A light raking only will be necessary before sowing the seed, as all fertilizers are applied before steaming. small boiler is, available, the area of the pan should be correspond- ingly reduced, so that the boiler can maintain the desired pressure of at least 80 pounds. Sterilizing pans made of galvanized iron have been extensively employed, but as wooden pans are cheaper and are easily made at home, wood is the material now coming into general use. The wooden pan further possesses the distinct advantage of reducing the loss of heat by radiation. The pan is siniply a shallow box, 4 inches being the preferred depth. If it is deeper, much of the desired effect is lost through the more rapid cooling of the steam in the larger space exposed above the soil. The frame is made of 2 by 4 inch material ; across this are laid matched boards (J by 4 inches). It is advisable to put white lead in the grooves to prevent the escape of steam. The boards must be securely nailed in the tongue and at the sides to prevent drawing, as they swell by absorption of moisture during the process of steam- ing. These cover boards are further secured by two boards or planks STEAM STERILIZATION OF SEED BEDS. 9 which are laid over them on the outside, at right angles to them, extending the length of the box, and which are very securely nailed at the ends (fig. 1). The cover boards are then nailed from the inside to the outside planks, the object being to prevent the swelling and warping of the cover boards. A good view of the inside con- struction of the box is shown in figure '2. Two ring bolts are set in each side of the frame on the top, one near each corner. Through the rings ax handles or bars are thrust to serve as handles in moving the pan along the bed, as shown in the title-page illustration. A strip of J-inch felt packing, 2 inches wide, is placed along the lower edge of the frame, on the outside, to prevent the escape of the steam. The hoop iron is then laid on the packing and PI609T Fi<:. 2. — The under side of a wooden sterilizing pan made of 2 by 4 inch frame and g-inch matched cover boards. Hoop iron laid over thin felt and lapped over the edge sur- rounds the outside of the frame, forming a knife-edge joint in the soil to prevent the loss of steam. A i-inch nipple is inserted in one end, through which the steam enters. nailed every 4 inches, one-half its width extending beyond the lower edge of the frame, as shown in figures 2 and 3. When the packing can not be had, the iron is nailed to the inside of the frame instead of the outside. Instead of the hoop iron, 2-inch angle iron is some- times used. This is fastened to the lower side of the frame, to form a tight joint when the box is laid on the soil. A piece of thin pack- ing serves to prevent the escape of steam between the iron and the bottom of the wooden frame to which it is nailed. Angle iron, be- cause of its heavier character, will not bend and is better than hoop iron, but it requires careful working to fit it to the frame. In the middle of one end of the frame is set a f -inch pipe-threaded nipple, 6 or 7 inches in length, through which the steam is delivered into the pan. The nipple should project 3 inches from the box, to 10 FARMERS BULLETIN 996. afford a convenient attachment for the hose, and it should be held securely in place on the 2 by 4 inch end frame by lock nuts, closing on leather gaskets, as shown in figure 3. The pan is placed on the bed, open side down, the hoop iron or angle bar cutting into the ground to form a knife joint, and the steam leaving the boiler under pressure enters the pan and quickly penetrates the soil. The iron sterilizing pan which is sometimes used is similar to the wooden pan in shape and size. It has the advantage of lighter weight, making it easier to move. It is made of 16 or 18 gauge gal- vanized iron, sup- ported by ribs of 1^-inch angle bars. The pan is made 4 inches deep, but 1J inches should be added all around, to jgK be turned in to serve •f &r Jw Slta^ji as a ^anSe on the bottom. To this flange is attached a IJ-inch angle iron, which rests upon the soil, forming the seal when the pan is placed upon the bed. The angle iron also serves as a rib for the lower part of the pan. Other ribs of angle iron are run across the top, two in the middle and one on each edge, holding the pan rigid. A f-inch nipple is firmly secured by flanges and solder in the middle of one end for the hose connection. Ring bolts for lifting are attached by flanges on the sides near the ends of the pan, which is rendered steam tight by close riveting and solder. CARRYING OUT THE STEAMING PROCESS. The boiler is placed close to the bed and where practicable at an equal distance from each end. Steam traction engines and portable boilers have a marked advantage, because they can be easily moved as the work progresses, allowing the use of a short pipe, giving a PI6I3T FIG. 3. — Nipple inserted in the middle of one end of the frame of the sterilization pan. Note the leather gasket secured under the lock nut to prevent the escape of steam. Another gasket is similarly held by the nipple on the inside. STEAM STERILIZATION OF SEED BEDS. 11 minimum loss of heat by radiation. The pan is -set on one end of a bed with its inlet nearest the boiler. The hose is attached to the pan and to the pipe leading from the boiler. Soil is banked around the edges of the pan to prevent the escape of the steam. The title-page illustration shows the boiler and apparatus connected for operation. It is desirable to maintain a pressure in the boiler of 100 pounds, and if the pressure drops below 70 pounds the steam should be shut off, as this is the minimum for successful sterilization. Steam of high pressure has much greater penetrating power than steam of low pressure, and it is important to realize that the efficiency of the operation is greatly increased by dry high-pressure steam. A little experience in firing the boiler and operating the pan is necessary before one .can maintain high pressure while supplying steam to the pan. Experienced operators can hold 100 to 125 pounds pressure for continuous operation 24 hours per day. The outlet valve should be opened only part way, so that the pressure of the boiler can be kept uniform and unnecessary blowing of the soil in front of the inlet prevented. A great volume of steam is not so essential as great penetrating power. After 30 minutes the steam is shut off and the pan moved along the bed to the next area. One end of the pan should slightly over- lap the area just steamed, thus leaving no strip unsterilized. Four attendants, one man at each corner, are usually required to lift the pan, using bars 'or ax handles inserted through the ring bolts. Im- mediately after moving the pan, the steamed area is covered with a canvas or burlap blanket. This is important, because the heat must be conserved in the surface soil to allow it to reach the lower soil by conduction. It is desirable that covers be supplied for the entire bed, so that each area will be covered for several hours after steaming. Experienced operators have found it advantageous to use two pans alternately, eliminating the necessity of moving the pan immediately after the steam is shut off. The moving of the pan immediately after operation is quite disagreeable to the workers because of the volume of steam held under the pan. There is also a considerable loss Of heat when the pan is moved before the heat has reached the lower soil layers. TEMPERATURES SECURED. In sandy soils, after 30 minutes' steaming, the temperatures to be ex- pected in the upper 2 inches of soil directly under the pan are ap- proximately 208° to 212° F., at 3 to 4 inches 170° to 180°, and at 6 inches 120°. Two hours after the removal of the pan the temperature at 6 inches should be about 160° F. If a thermometer is not available, the efficiency of the steaming operation can be easily determined by burying a potato 4 inches under the surface of the soil. The potato should be well cooked when the pan is removed, and this is a common 12 FARMERS' BULLETIN 996. method of determining the work done by a steaming outfit. Although the temperatures reached directly under the pan are quite high, little heating effect is to be noted away from the edges of the pan. Clay soils, because of their heavier texture, require longer periods for ^teaming than sandy soils. Steam penetration and heat conduc- tion are not as rapid as in the more open sandy loams, and it is espe- cially important that these soils be as dry as possible at the time of steaming. The moistening of the soil by rainfall or snow just before steaming prevents the rapid heating of the soil and the full penetra- tion of the steam, and the efficiency of the work is greatly reduced. COST OF STEAMING. Contractors who furnish the boiler and a fireman may charge ac- cording to the area steamed at an average rate per 100 square feet, or they may charge a flat daily rate. The charges for this work vary in the several tobacco-growing sections, ranging from 50 cents to $1 per 100 square feet, or from $6 to $12 a day, and the contractor may or may not furnish the pan and fuel. The fuel consumption is usually reckoned at one-half ton of soft coal for every 1,000 square feet of seed bed. Where the grower owns the boiler, the costs of operation are some- what lower. The average area covered in a 10-hour day is 1,000 square feet and the cost is approximately $6. It is also better to use two pans, so that there may be no delay in steaming due to the shifting of the pan. One attendant is required constantly to fire the boiler ; three others must be ready at intervals during the day to help him move the pans. The labor cost can be reduced considerably by using a rack for lift- ing the pan. For this rack two pairs of buggy or light wagon wheels set on axles a little longer than the width of the pan are joined to- gether by a light frame. This frame should be 4 feet shorter than the pan. A long rod or lever is attached in the middle of each end of the frame, to allow for the easy lifting of the pan. The lever is provided with a hook at the end of its resistance or lifting arm. To the ring bolts at each end, a substantial rope is fastened with suffi- cient play for the hook of the lever to hold the rope conveniently, By hooking the rope and using the frame of the carriage as a ful- crum, the pan is lifted. The lever arms can be hooked in position by a wire or clutch after the pan is lifted. The sides of the seed-bed frame form a guide for the wheels, thereby making it a simple op- eration for one man to handle and move a pan. On account of the possible occurrence of rains and snows during the period for sterilizing, it is advantageous even on small farms to operate 24 hours per day in favorable weather. Large growers do this because of the convenience and economies in fuel and labor. STEAM STERILIZATIOX OF SEED BEDS. 13 The permanent seed beds are usually equipped with a water-supply system; where this is not the case the transportation of water for the boiler is an additional item of expense. In considering costs, one should bear in mind the fact that a thoroughly steamed seed bed is practically free from weed seeds, thereby eliminating the cost of weeding. The amount saved in weed- ing will probably more than cover the cost of sterilization, as two good weedings usually cost more than $G per 1,000 square feet. Figure 1 illustrates the effectiveness of the steaming-pan method in killing weed seeds. On the right of the partition it will be seen that the sterilized area is practically free from weeds, whereas the unster- ilized portion on the left was worthless because the weeds had forced out nearly all of the tobacco plants. Additional advantages are that the plants are more vigorous and are ready for transplanting 10 to 14 days earlier than plants in unsterilized beds. As has been stated, where root-rot or other fungous diseases are present, some form of Pi645T FIG. 4. — A tobacco seed bed, showing a partition between the steamed and the unsteamed portions. Both sections were sown at the same time with similar seed, but the weeds in the unsteamed section (at the left) practically killed the tobacco seedlings. No weeds grew on the steamed part. sterilization is essential for the production of healthy seedlings, and steaming is decidedly the most effective process yet developed for insuring the elimination of these diseases. IMPORTANT CONSIDERATIONS. Sterilization so improves the soil conditions that less fertilizer is necessary than on unsterilized ground. One should exercise caution against reinfecting the soil by walking on the steamed bed, using in- fected rakes, water from stagnant ponds, a solution of manures, or seed sown with unsterilized vegetable matter, such as decayed wood, punk, or decomposed leaf tissue. Finely sifted raw bone meal, thoroughly sterilized punk, and land plaster are excellent materials for spreading the seed. They should be very slightly moist to spread well between the fingers and to retain the seed in the mixture. Root-rot is found in some seed beds that have been thoroughly steam sterilized. Such infection may have been carried by fertilizers ap- plied after the steaming, by decayed vegetable matter used to spread 14 FARMERS' BULLETIN 996. the seed in sowing, or by contamination \vith adjoining diseased soil if the bed has not been kept covered after having been sterilized. Diluting material, like punk, can be readily sterilized at the time of steaming the soil by placing it in a bucket inserted under the pan, or it may be kept in the oven of a kitchen stove for several hours at a moderate temperature. The seed may be safely sown 12 hours after the steaming of the beds. Dry seeds only should be used. There is a temporary injurious action in the soil after steaming which retards the growth of the young plant for 10 to 14 days and sometimes longer. Sprouted seed is more readily injured by this temporary effect of steaming, but when dry seed is sown the effect has largely disappeared when the first shoots appear. This condition may sometimes retard the develop- ment of the plants appreciably during the first three weeks after sow- ing, but this is followed by a decided stimulating action, so that plants in sterilized beds are usually ready for setting two weeks earlier than plants on unsteamed beds. Steamed seed beds require much more water to produce a crop of seedlings than untreated seed beds. The surface soil is inclined to dry or crumble, and because of this tendency it is advisable to locate the seed beds near an easily available water supply. During clear, bright weather the beds should be inspected late in the morn- ing and again in the middle of the afternoon, as the soil is very likely to dry out, killing young seedlings. Because steamed soil re- quires larger quantities of. water the tendency is to overwater. In this, care must be used, especially if the beds are sown rather thickly, since there is danger of the occurrence pf damping-off under certain conditions. It is an advantage to keep the seed beds occupied after the tobacco plants are taken off. Steamed beds are especially adapted for growing late vegetable crops, which practice tends to keep the beds free from weeds. THE FORMALDEHYDE METHOD OF STERILIZING SEED BEDS. When steam sterilization can not be used, formaldehyde may be employed to control seed-bed diseases. One gallon of commercial 40-per-cent formaldehyde solution is diluted in 50 gallons of water. This solution is applied at the rate of 2 quarts per square foot of seed bed, using a common sprinkling can. The seed bed should be prepared for sowing, and to do the most effective work the soil should be dry enough to absorb all of the formaldehyde solution. To prevent the washing of the soil, the necessary quantity should be put on in a number of applications at intervals of, say, 20 to 30 minutes. When all the solution is ab- sorbed the bed should be covered with blankets for 24 hours to STEAM STERILIZATION OF SEED BEDS. 15 confine the fumes. It should then be aired for 8 or 10 days to allow the escape of the fumes from the soil. The seed should not be sown so long as there is a trace of the formaldehyde, for this will kill the germinating seed or young seedlings. The use of formaldehyde is recommended only when steam sterilization is not practicable. Its cost is greater than the cost of steaming, and it is usually less effective. APPLICATION OF THE STEAMING PROCESS TO CROPS OTHER THAN TOBACCO.1 The steaming of greenhouse soils with coils of pipes embedded therein had been practiced for a number of years prior to the de- velopment of the inverted-pan method of steaming as applied to tobac- co seed beds. Since its adoption on tobacco seed beds the inverted-pan method of steaming has been demonstrated to be effective for green- house work, and, further, it is easily seen that the method can be applied to hotbeds and coldframes for various other crops. It is especially valuable in the production of vegetable crops where it is desired to control damping-off and other fungous diseases which may be in the soil. The special requirements for any particular situation will readily suggest themselves, and the apparatus de- scribed for tobacco seed beds can be 'easily modified in size and shape of pan and arrangement of piping to suit almost every condition of soil steaming in greenhouses, outside frames, or even in open fields. 1 It is upon the suggestion of Dr. W. A. Orton, Pathologist in Charge of Cotton, Truck, and Forage Crop Disease Investigations, that the attention of the truck grower is directed to the application of the inverted-pan method of steaming for the control of certain vege- table diseases. THE FARMERS OF THIS COUNTRY are as effi- cient as any other farmers in the world. They do not produce more per acre than the farmers in Europe. It is not necessary that they should, do so. It would perhaps be bad economy for them to at- tempt it. But they do produce by two to three or four times more per man, per unit of labor and capital, than the farmers of any European country. They are more alert and use more labor-saving devices than any other farmers in the world. And their response to the demands of the present emer- gency has been in every way remarkable. Last spring their planting exceeded by 12,000,000 acres the largest planting of any previous year, and the yields from the crops were record-breaking yields. In the fall of 1917 a wheat acreage of 42,170,000 was planted, which was 1,000,000 larger than for any preceding year, 3,000,000 greater than the next larg- est, and 7,000,000 greater than the preceding five- year average. But I ought to say to you that it is not only neces- sary that these achievements should be repeated, but that they should be exceeded. I know what this ad- vice involves. It involves not only labor, but sacri- fice; the painstaking application of every bit of scientific knowledge and every tested practice that is available. It means the utmost economy, even to the point where the pinch comes. It means the kind of concentration and self-sacrifice which is involved in the field of battle itself, where the object always looms greater than the individual. And yet the Government will help, and help in every way that is possible. — From President Wilson's Message to the Farmers' Conference at Urbana, 111., January 31, 1918. WASHINGTON : GOVERNMENT PRINTING OFFICE; 1918 RODENT PESTS OF THE I'FARM- DAVID E. LANTZ Assistant Biologist Columbia Ground Squirrel BI23M FARMERS' BULLETIN 932 UNITED STATES DEPARTMENT OF AGRICULTURE Contribution from the Bureau of Biological Survey E. W. NELSON. Chief Washington, D. C. Issued July, 1918 Show tliis bulletin to a neighbor. Additional copies may be obtained free from the Division of Publications, United States Department of Agriculture WASHINGTON : GOVERNMENT PRINTING OFFICE : 1918 THE ANNUAL losses from rodent pests in the United States have been estimated as fully $300,000,000. About two-thirds of the damage is inflicted by house rats and mice (both introduced from the Old World) and the remainder by native species. This enormous waste of resources may be greatly reduced and largely prevented through systematic and organized campaigns against the noxious species. The bounty system effects no permanent relief from rodents and is far more costly than the use of poisons. The Bureau of Biological Survey has developed and perfected practical methods of extermination which have been successfully applied over wide territory. The Bureau cooperates with the public in organ- izing and carrying out systematic campaigns against animal pests and invites correspondence on the subject. Protection of their natural enemies is urged as an important aid in controlling rodent pests. RODENT PESTS OF THE FARM. CONTENTS. Page. Introductory 3 Harmful native rodents 4 Short-tailed field mice 4 White-footed mice 7 Cotton rats 7 Kangaroo rats 8 Pocket gophers. Harmful native rodents — Continued. Page. Prairie-dogs ............................... 15 Woodchucks .............................. 17 Rabbits ................................... 18 Other native rodents ...................... 19 Introduced rodents ............................ 20 Relation of carnivorous animals to rodents ____ 21 Ground squirrels .......................... 11 Cooperation in controlling rodents ............. 22 INTRODUCTORY. RODENTS are among the most, persistent and aggressive of the animal enemies of the tiller of the soil, and against them he is often more helpless even than against insect pests, because he has had less instruction as to their habits and the means of fighting them. To assist him by giving short accounts of the more important rodents that injure farm, ranch, and orchard, together with brief practical directions for destroying the pests, is the purpose of this bulletin. The rodents of North and Middle America include about 77 distinct groups called genera, 44 of which have representatives north of Mexico. These 44 groups include about 750 forms that inhabit the United States and Canada. Many of them live in deserts, moun- tains, and swamps and rarely come in contact with cultivated crops. These, therefore, can not be classed as injurious; and, indeed, many of them are beneficial to the soil, as they stir it up and fit it for future agricultural uses. A few rodents feed largely upon insects and help to keep a check upon the hordes of grasshoppers and similar pests. Certain of the rodents, too, as the beaver and the muskrat, have a decided economic value as fur bearers; while some, as the rabbits and the tree squirrels, afford sport in hunting and are useful as human food. The noxiousness of rodents depends largely upon the locality in which they live and upon their relation to man and his interests. All are chiefly vegetarian in diet and by reason of their rapid repro- duction are capable of becoming pests; but it is only when they are actively injurious that means of control are needed. 3 4 FARMERS' BULLETIN 932. Probably no term applied to animals has been so generally mis- used as the word " vermin." Originally restricted to small creeping Animals, wormlike: in their movements, and especially to insects, the term has 'bee'n * broadened by English gamekeepers to include all [ehfcirtiiies of igroiu>cl game. Usage now sometimes applies the term to all animals that are supposed to be either harmful or useless. Writers on game protection are often vehement in their condemna- tion of " vermin," forgetting that what may be so considered by one person may from the standpoint of another be highly useful. The interests of the sportsman or gamekeeper often run counter to those of his farmer neighbor, and they frequently clash on such matters as rabbit protection and the enforcement of trespass laws. A better understanding of the habits of birds and mammals, especially of their food and the interrelation of species that prey and are preyed upon, will greatly restrict the number of animals that may properly be called "vermin." Under natural conditions few can rightly be so designated; but man has interfered with nature until he has dis- turbed its balance. He has introduced artificial conditions and so changed the environments of animals that some have prospered while others have been driven out. The species that have been most favored by man's activities are, unfortunately, those that have been most harmful to his interests. As a result he must now make warfare upon foes that were once inoffensive. HARMFUL NATIVE RODENTS. Only four of the many forms of wild rodents found within the United States have been introduced ; the others are indigenous to the country. Among harmful native rodents are included the short- tailed field mice, white-footed mice, cotton rats, kangaroo rats, pocket gophers, ground squirrels, prairie-dogs, woodchucks, and rabbits. A few others occasionally do slight damage to crops or other prop- erty. SHORT-TAILED FIELD MICE. Several groups, or genera, of short-tailed field mice occur in the United States and Canada, but only two of them have, by reason of their abundance in cultivated regions, become serious pests. These are commonly known as meadow mice 1 and pine miee 2 (fig. 1). Meadow mice are widely distributed, inhabiting most parts of the Northern Hemisphere. In the United States we have many species, but, fortunately, have thus far had no widespread plagues of the animals like those that have occurred abroad. However, there have been many local outbreaks, notably that of 1907-8 in the Humboldt Valley, Nevada, where much of the alfalfa crop was utterly ruined. Fortunately, few of our species come in contact with farm operations, i Genus Microtus. 2 Genus Pitymys. RODENT PKSTS OF THE FARM. but these few sometimes multiply enormously ard^inflict heavy fl&ir*- aiiv by attacking and girdling fruit trees and by 'destroy ing oil KM- crops. Their presence is indicated by their many MU'face trails; undpr dead grass, weeds, or other trash. The animals usually avoid open' spaces, where they are exposed to such enemies as hawks and owls, birds which make these mice the chief part of their diet. Depredations by meadow mice may be greatly lessened and serious outbreaks prevented by clean cultivation, the elimination of old fence rows, and the prompt burning of dead weeds and other trash. Pine mice, like moles, burrow underground, where their tunnels are similar in extent and intricacy to the surface runways of meadow mice : but as their natural habitat is the woods, they come less fre- quently in contact with farm crops. Their most serious depredations FIG. 1.— Pine mouse. are in orchards, although they often do great damage in lawns and plantations adjacent to woodlands by eating bulbs and gnawing the roots of shrubbery. In such situations they also frequently destroy potatoes, peanuts, and newly planted seeds of truck crops. Their concealed operations permit them to do much harm before their pres- ence is suspected. For this reason, also, they are less often the victims of birds of prey. Ordinary mouse traps of the guillotine type, baited with rolled oats and set in runways of either meadow or pine mice, will free a small area of the animals (fig. 2) ; but for large areas or for opera- tions against considerable numbers of these mice, poisons are more effective. For poisoning meadow mice on large areas the following methods are recommended : Drti-f/niin formula. — Mix thoroughly 1 ounce powdered strychnin (alkaloid), 1 ounce powdered bicarbonate of soda, and J ounce (or less) of saccharin. FARMERS BULLETIN 932. Put the mixture ,ivi *.i rin pepperbox and sift it gradually over 50 pounds of cruvsh£d wbefct, or 40 pounds of crushed oats, in a metal tub, mixing the grain constantly so that the poison will be evenly distributed. Dry mixing has the aclv?VRt?.£e that* Ui° grain* may be kept any length of time without fermentation. If it is desired to moisten the grain to facilitate thorough mixing, it will be well to use a thin starch paste (as described below, but without strychnin) be- fore applying the poison. The starch soon hardens, and fermentation is not likely to follow. If crushed oats or wheat can not be obtained, whole oats may be used, but they should be of good quality. As mice hull the oats be- fore eating them, it is desirable to have the poison penetrate the ker- nels. A very thin starch paste is recommended as a medium for applying poison to the grain. Prepare as follows : Wet-grain formula. — Dissolve 1 ounce of strychnin (sulphate) in 2 quarts of boiling water. Dissolve 2 tablespoonfuls of laundry starch in \ pint of cold water. Add the starch B53M FIG. 2. — Meadow rilouse caught in guillotine trap. to the strychnin solution and boil for a few min- utes until the starch is clear. Pour the hot starch over 1 bushel of oats in a metal tub and stir thoroughly. Let the grain stand overnight to absorb the poison. The poisoned grain prepared by either of the above formulas is to be distributed over the infested area, not more than ateaspoon- ful at a place, care being taken to put it in mouse runs and at the entrances to burrows. To avoid destroying birds it should whenever possible be placed under such shelters as piles of weeds, straw, brush, or other litter, or under boards. Small drain tiles 1J inches in diameter have sometimes been used to ad- vantage to hold poisoned grain, and old tin cans with the edges bent nearly together will serve the same purpose. Chopped alfalfa hay poisoned with strychnin was successfully used to destroy meadow mice in Nevada during the serious outbreak of the animals in 1907-8 : Alfalfa formula. — One ounce of strychnin (sulphate) dissolved in 2 gallons of hot water was found sufficient to poison 30 pounds of chopped alfalfa pre- viously moistened with water. This bait, distributed in small quantities at a place, was very effective against the mice and did not endanger birds. KODKXT I'KSTS OF THE FARM. 7 For poisoning mice in small areas, as lawns, gardens, seed beds, vegetable pits, and the like, a convenient bait may be prepared from ordinary rolled oats, as follows : Ontnical fortn-uln. — Dissolve iV ounce of strychnin in 1 pint of boiling water and pour it over as much oatmeal (about 2 pounds) as it will wet. Mix until all the grain is moistened. Put it out, a teaspoonful at a place, under shelter of weed and brush piles or wide boards. The poisoned oatmeal is adapted for killing either meadow or pine mice, but for the latter sweet potatoes, prepared as follows, have proved even more effective : Potato formula. — Cut sweet potatoes into pieces about the size of grapes. Place 3 quarts of these cut baits in a pan or bucket, and from a tin pepperbox slowly sift over them £ ounce of powdered strychnin mixed with an equal quantity of baking soda, stirring constantly so that the poison is evenly dis- tributed. Poison should be applied as soon as potatoes are cut and bait should be put out while fresh. The bait, whether of grain or pieces of potato, may be dropped into the pine mouse tunnels through the natural openings or through holes made with pieces of broom handle or other stick. Bird life will not be endangered by baits thus placed. WHITE-FOOTED MICE. AVhite-footed mice, or deer mice,1 are of many species and'are pres- ent in almost all parts of the country. They live in fields and woods, and while they feed on grain to some extent, they rarely are present on cultivated lands in sufficient numbers to do serious harm. Occa- sionally they invade greenhouses or hotbeds and destroy seeds or sprouting plants. In the seed beds of nurserymen, and especially in those of the forester who tries to grow conifers, they often do much injury. They are, in fact, the most serious pests known to the conifer nurseries of the Forest Service. In ordinary places white-footed mice may be readily poisoned by the methods recommended for meadow and pine mice. Unfortu- nately the seed of the pine is the favorite food of these animals and whore it is planted in abundance they refuse to take grain baits. Crushed pine seeds poisoned with strychnin by the " wet-grain for- mula," given above, have proved effective in such places. Preliminary poisoning of these mice on- areas to be seeded to pine is highly recom- mended. For seed beds, poisoning on surrounding areas two or three times a year will usually prevent the approach of mice and give immunity to the planted seeds. COTTON RATS. In parts of the Southern States a large native mouse, or rat, com- monly known as the cotton rat2 (fig. 3), often becomes a field pest. 1 Genus Pcrompscus. 2 Genus 8igmod<»>. 8 FARMERS BULLETIN 932. Of some 28 known forms of this animal, 7 occur north of Mexico, in Texas, New Mexico, Arizona, Oklahoma, and southern Kansas and along the Gulf coast from Louisiana to Florida. Cotton rats damage growing crops to some extent, but are espe- cially destructive to grain in shocks. In many of their habits they are similar to meadow mice, and they multiply fully as fast. They chiefly inhabit weedy borders and areas covered with old grass, where they are sheltered from enemies. They do not often attack the bark of trees, but, being larger than meadow mice, are capable of destroying much more grain in a short time. They ruin melons and other truck crops and have been a serious pest to date 'growers in Arizona. Cotton rats are easily poisoned by the same methods recommended for destroying meadow mice. KANGAROO RATS. Fifty-nine known species and races of the kangaroo rat (fig. 4), belonging to three groups, inhabit North America, and 45 of them occur north of Mexico. Two groups1 are widely distributed in the West; they differ in anatomical characters, but are much alike in general appearance and habits. A third group 2 includes three species and one race of very small ani- mals, all of which are rather restricted in range and of slight economic im- portance. Kangaroo rats are gentle, easily tamed, and make sprightly and interesting pets. They live mostly in deserts, sagebrush country, and sandy places and are harmless until pioneer agriculture- is pushed into these regions. They feed to some extent on green vegetation, but mainly on seeds. As they do not hibernate, they lay up large stores of winter food in their burrows. They are gregarious but, being noctural in their activities, are seldom seen by day. In the sand-hill and sagebrush country of the West there is much complaint of destruction of pioneer crops by kangaroo rats. ^The areas first cultivated are usually small, and the animals sometimes destroy an entire crop. Where corn is planted they take all the seed, securing not only food for present use, but storing in their caches large FIG. 3.- B3743 Cotton rat (dead) and nest, Pecos Valley, Tex. 1 Pcrodipus and Dlpodomys. 2 Genus Microdipodovs. BODENT PESTS OF THE FARM. 9 quantities for the future. They are destructive to other grains also and dip up newly planted melon and other seeds. Vegetable garden- ing is an impossibility where kangaroo rats are abundant. The choice is between making warfare on and destroying the animals or abandoning cultivation. Fortunately they take poisoned grain readily and are easily trapped with baits of this kind. The poison recommended for prairie-dogs is well adapted to destroy kangaroo rats. Trapping with guillotine traps, although successful, is usually too slow to be practicable. In some instances farmers in the sand-hills of the West prevent depredations by kangaroo rats and succeed in growing crops of corn by stirring the seed in hot water in w. Whitewash and lead arsenate. 7. Strong bordeaux mixture. S. ('heck. No treatment. The concentrated lime-sulphur was nsed at full strength. Knough lead arsenate was nse:l to make a strong poison. The mixtures con- tained much more poison than is ever used for spraying purposes. Sulfocide was not diluted. The whitewash and other mixtures with which lime was used were made of about the same consistency as rather thick cream. The bordeaux mixture was made by the 10-10-50 formula and then thickened with slaked lime. 77/r Trees. Large sized nursery trees, ilin-r years old, were used for this work. The variety was Wagener. Seven or eight trees were painted with each 24 • MICHIGAN AGRICULTURAL COLLEGE material and eighteen trees were left untreated as checks. The mater- ials were applied with a brush and the entire trunk was covered from the roots up to a point above where any injury would occur. Each tree was labeled to indicate the material used on it. The trees were set in the ground in two groups between the rows in an orchard of dwarf apples. This orchard was heavily mulched. They were set in rows, with the trees about one foot apart in the row and were distributed so that those treated with any particular material were not grouped to- gether. After setting, the trees were well mulched with straw and cornstalks. They were set on February 15. There was no frost in the ground at lhat time. Itvsultis. , On May 7th the mulch was removed and the trees examined. The trees -were classified according to the degree of injury or the lack of injury. A tree was classified as "slightly injured" if only a small spot on one side had been chewed by the mice. Any injury worse than this was classed as "severe." The number of trees in each class is listed Total No. Trees Trec^ injured by mice No. Injury Severely Slightly Lime-sulphur Limp-sulphur and lime 8 8 7 7 8 8 7 18 7 4 0 7 7 1 13 1 U ,[• i-1 1 1 4 0 0 0 2 0 1 1 Lime-sulphur and lead arsenate . Sulfocide .... Whitewash Whitewash and lead arsenate Thick Bordeaux . . Check in the accompanying table. These figures show that the injury was very severe on every lot of trees regardless of the material used. The lot of trees painted with thick bordeaux was injured least but there was so much injury even on these trees that its use is not recommended. \ Recommendations. None of the materials used in this experiment are recommended for use on fruit trees to prevent injury by field mice. Better results might be secured by frequent applications but the expense for labor and ma- terials would probably be greater than for good wire protectors. The application of any of these materials would also be difficult when there is snow around the trees as it would be necessary to cover the trunk of the tree to the ground. Field mice will work under the snow and the injury is usually close to the ground. Wire Protectors A very satisfactory protector can be made from quarter-inch square mesh galvanized wire netting. Bands not less than eighteen inches in width should be placed around the tree trunk. They should lap enough QUARTERLY BULLETIN 25 A ycung apple tree girdled by field mice. Desirable type of tree protector. It is made of inch square mesh galvanized wire netting. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919 BY W. C. BUTTON INTRODUCTORY This bulletin contains reports of the results of a series of dusting and spraying experiments conducted by the Horticultural Section dur- ing the seasons of 1918 and 1919. This work included comparisons of dusting materials, lime-sulphur solution, bordeaux, dry lime-sulphurs, lead arsenate, calcium arsenate and magnesium arsenate. These mater- ials were used on apples, cherries, plums, peaches, currants and pota- toes. EXPLANATORY NOTES The meaning of several terms used may not be familiar to all. To avoid repetition, the following explanations are in order: DUSTING TERMS 90-10 mixture. A dusting mixture containing 90% dusting sulphur and 10% dry lead arsenate. 85-15 mixture. One containing 85% sulphur and 15% lead arsenate. 3 in 1 dust. A mixture containing sulphur, tobacco dust and lead arsenate. 50-40-10 mixture. One containing 50% sulphur, 40% filler (usually hydra ted lime) and 10% lead arsenate. Concentrated dust. A mixture containing only sulphur and lead arsenate. Usually made by the 85-15 or 90-10 formula. Dilute dust. A mixture containing 40 to 50% sulphur, 35 to 50% filler (hydrated lime, talc or gypsum) and 10 to 15% lead arsenate. SPRAYING TERMS 1 to 40. This refers to lime-sulphiy of 31 to 33 degree Beaume test used at the rate of 114 gallons in .~0. 4-4-50 bordeaux. This refers to bordeaux made of 4 pounds stone 4 EXPERIMENT STATION BULLETIN. lirne (or G pounds kydrated lime), 4 pounds copper sulphate and 50 gallons water. GENERAL TERMS Check plbt or tree. Trees or plants which are left untreated to indi- cate the amount of injury by insects or disease that would develop when not sprayed or dusted. Count trees. In much of the work, particularly with apples, the fruit from one or more trees in each plot was sorted and classified according to the presence of any injury by insect or disease or by its freedom from such injury. Trees were selected for this purpose that w-ere as uni- form as possible. Location of the tree and the size and - uniformity of the crop were points considered in selecting them. The number of trees in any plot was in no case limited to the trees from which counts were actually made. The total number in a plot varied from nine to fifty or more. Pink or cluster application. The application made on apples just be- fore the blossoms open, but after the buds have separated in the clus- ter. Calyx application. In the work here reported the calyx application was usually made immediately after the petals . had fallen. It could be safely delayed a few days and still control the coddling moth but earlier application insures better control of apple scab. Other Insects. This term is used in several of the tables showing re- sults of work with apples. This means injury to the fruit by any chew- ing insect other than coddling moth, such as the lesser apple worm, Tus- sock moth, fruit worms, etc. Calcium arsenate. The same as arsenate of lime or arsenate of cal- cium. ACKNOWLEDGMENTS Much of this work was done at several places in the state in orchards belonging to fruit growers. The Horticultural Department is indebted to these growers for their assistance and co-operation in carrying on this work. They are Geo. Winegar & Son, Morrice; B. F. Hall, Beld- ing ; Oscar Braman, Grand Rapids ; C. W. Garlock, Grand Ledge ; James Boyce, Holland; J. C. Maynard and Ed. O'Brien, Grand Rapids. Much of the actual work with experiments on the College grounds was done by Harold Lackey. The duster used at the College was furnished by the Corona Chemical Company, Milwaukee, Wisconsin. R. E. Loree and M. M. Brown assisted in securing records in 1918. The picture on the front cover is used by the courtesy of D. F. Fisher of the United States Department of Agriculture. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. EXPERIMENTS WITH APPLES The work done with apples in 1918 was largely a comparison of the dusting and spraying methods of application. Tests were also made with calcium arsenate and Sherwin-Williams dry lime-sulphur. In 1919 the work consisted mainly of tests of the dry. lime-sulphurs and of several arsenicals. Some dusting was also done. EXPERIMENTS IN 1918 COMPARISONS OF DUSTING WITH SPRAYING AND CALCIUM ARSENATE WITH LEAD ARSENATE AT MORRICE In the orchard at Morrice, belonging to Geo. Winegar and Son, dust- ing and spraying experiments were continued. Experimental work had been carried on in this orchard during 1915, 1916 and 1917. The results of this earlier work have already been published.* The entire 2 B B 2 B B B B 5 B B B B B B S 2 B B B 7 B B 1 E B B S 46 B B B B B B S B B . B ~C~] 8 B B B B B B B B B S 9 0 0 0 B 0 0 0 Q 0 0 0 0 0 0 0 0 S 0 0 0 0 0 0 0 0 S S S 0 0 0 0 0 0 s s 0 0 0 S S S 0 0 0 000 o 6 0 0 0 s s s It s s S S s s s s s 16 0 s s s s s S 00 14 s S 0 s 3 0 s 0 S 12 o s 3 S S 0 s 11 0 s s s 0 13 3 S s S 3 s S s 0 0 S S s S B 0 S s s 0 s S S 15 s 17 b s s s s s s s s S 3 s 3 s s s OSS 18 S S s 3 s s 5 s s S S S S Plot 1 Plot 2 Plot 5 3 s s 3 S S S S 3 S CHART I. Diagram showing arrangement of trees and plots in the Winegar orchard at Morrice. B, Baldwin; S, Stark; C, check; O, other varieties. The numbers indicate count trees. Plot 1, dusted; Plot 2, sprayed with lime-sulphur and calcium arsenate; Plot 3, sprayed with lime-sulphur and lead arsenate. * Special Bulletin No. 87. Dusting and Spraying Experiments with Apples. 6 EXPERIMENT STATION BULLETIN. orchard was used, but trees of any variety other than Stark and Bald- win were not considered in the results. Materials. The orchard was divided into three plots with check trees for each variety. They were arranged so that both Stark and Baldwin were included in each plot. The arrangement of trees and plots is showrn in Chart I. The different plots were treated as follows: Plot 1. Dusted. 90-10 mixture. Plot 2. Sprayed. Lime-sulphur, 1 to 40 and calcium arsenate (dry), 1 Ib. in 50 gal. Plot 3. Sprayed. Lime-sulphur, 1 to 40 and lead arsenate (paste), 2i/2 Ibs. in 5.0 gal. Applications. The four regular application were made at the follow- ing periods: 1st. Pink or cluster application. 2nd. Calyx application. 3rd. Sixteen days after second. 4th. August 1st. RESULTS Foliage. On dusted trees the physical condition of the foliage was very good. There was no injury that could be attributed to the dust- ing materials. A small amount of scab developed on the foliage of the Stark trees, but very little on Baldwin. On trees sprayed with lime-sulphur and lead arsenate there was very little foliage injury. There was really not enough to consider so far as the effect upon the trees was concerned. Trees sprayed with lime-sulphur and calcium arsenate showed much more foliage injury than wrhere lead arsenate was used. This was not so severe as in some other orchards where this material was used. There was practically no scab on the foliage of any of the sprayed trees. On the check trees, the physical condition of the foliage was very good. On Baldwin foliage there was a little scab and on Stark foliage it was quite noticeable. Fruit. With Baldwin there was so very little injury by disease or insects that no accurate comparison can be made as to the value of the different materials. Dusting gave slightly better control of insects, other than coddling moth, than either lead or calcium arsenate applied with water as the carrier. Of this type of injury there was 7.5% on the check, 3.8% on both sprayed plots and 1% on the dusted plot. ,There was no coddling moth injury where the trees were dusted or sprayed. On the check tree there was only 3.8% injury. This is too low a per- centage of wormy apples to be of any value as a check. With Stark, dusting and spraying -both gave satisfactory control of scab. Dusting held injury by scab to less than 2%. In the lime-sulphur- calcium arsenate plot, there was only 2.5% of scab injury. The lime- sulphur-lead arsenate plot showed 5.4% of scabby fruit. This was prob- ably due, in part at least, to part of the count trees being in lower DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. TABLE I.— RESULTS WITH BALDWIN AT MORRICE, 1918. Treatment. No. of Trees in Plot. Count Tree Number. Total No. Apples. "S| F -t> 1 i& 02 Codling. Per cent. Other Insects. Per cent. Dusted 26 1 2 3563 3679 98.88 98 15 0.39 0 78 0 0 0.73 1 06 3 4873 97.66 0.98 0 1.35 Totals 12115 98 16 0 75 o 1 08 Sprayed Lime Sulphur and Calcium Arsenate "1 4 5 3929 3565 93.63 96.52 1.78 0.39 8 4.58 3.08 1 6 1968 95.93 0.35 0 3.71 Totals 9462 95 20 0 96 0 3 83 Sprayed Lime Sulphur and Lead Arsenate nl 7 8 6035 4574 94.86 94 95 1.72 0 80 § 3.41 4 24 9 2745 95.70 0.36 0 3.93 Totals 13354 95 06 1 13 o 3 80 Check 1 c 2282 87 42 1 14 3 85 7 58 TABLE II.— RESULTS WITH STARK AT MORRICE, 1918. Treatment. No. of Trees in Plot. Count Tree Number. Total No. Apples. "Ss §* 02 I* Codling. Per cent. Other Insects. Per cent. Dusted BSJ . 10 11 3853 3595 97.69 98 38 1.81 1 00 0 0 02 0.49 0 58 1 12 2437 95.65 3.48 0 0.94 Totals 9885 97 54 1 93 0 01 0 63 Sprayed Lime-Sulphur and Calcium Arsenate ill 13 14 2666 2351 93.92 94 51 3.37 1 99 0.15 0 OS 2.55 3 44 1 15 2802 96.71 2.31 0 0.963 Totals 7819 95.10 2.58 0.07 2.25 Sprayed Lime-Sulphur and Lead Arsenate ^T 16 17 1535 1849 93.81 92 37 4.36 6 16 0.06 0 21 02 1 24 i 18 4077 92.61 5.32 0.36 1.74 Totals 7461 92 .SO 5.33 0.26- 1.63 Check i c 1229 52 31 16 48 27 50 5 45 ground. For insects, other than coddling moth, all materials • gave nearly complete control. All materials gave almost perfect control of coddling moth. The amount of injury — 27.5% — on .the check tree was high enough for a good comparison. The tabulated results of all counts are given in Tables I. and II. COMPARISON OF DUSTING WITH SPRAYING AND CALCIUM ARSENATE WITH LEAD ARSENATE AT MUIR Work was continued at Muir in the Northern Spy orchard belonging to Mr. Oscar Branian. The principal object of this work was to get further information as to the effect of the different materials on the foliage. EXPERIMENT STATION BULLETIN. s s s s 3 s S 3 S s s s s s S 3 s 1 2 s S s S S S s s s s s S S s 5 S s s s T S S s s s s s S S s s s 3 s s S S s 333 s 3 s s Plot 1 s s s S s s S S s S S S 4 S s s 5 s s S 3 s s 3 s S C : s S S P~l r\4- s s 3" s s s s s s 5 s 333 S 1 -LO u 3 s 6 S s s s s 3 S 3 s 333 s S s S CHART II. Diagram showing arrangement of trees and plots in the Braman orchard at Muir. S, Northern Spy; C, check; T, water tank. Numbers indicate count trees. Plot 1, sprayed with lime-sulphur and lead arsenate; Plot 2, sprayed with lime-sulphur and. calcium areenate.. The entire orchard of 40 acres, except Plots 1 and 2 was dusted. Materials. The main part of the orchard was dusted by Mr. Braman. A block of 36 trees near the middle of the orchard was used for the spraying materials. One of these trees was left untreated as a check. The block of 36 trees was divided into two plots and treated as follows : Plot 1. Lime-sulphur, 1 to 50, and lead arsenate (dry), iy2 Ibs. in 50. Plot 2. Lime-sulphur, 1 to 50, and calcium arsenate, 1 Ib. in 50. Plot 3. This included the entire orchard other than Plots 1 and 2. For the first two applications, a 3 in 1 mixture was used and for the last two an 85-15 mixture was used. The arrangement of the trees and plots is shown in Chart II. Applications. Four applications were made on all plots. They were made at the following periods: 1st. Pink or cluster application. 2nd. Calyx application. 3rd. Two weeks after second. 4th. First week in August. The spraying was done with a spray gun. 200 to 225 Ibs. pressure was maintained. All dusting was done at night, except the last appli- cation, by Mr. Wolverton, the man directly in charge of the orchard. For each application, material was applied to one side of each row dur- ing one night and to the opposite side the next night. The fourth application was made in the same manner, only during calm periods in day time. RESULTS Foliage Injury. The foliage on all dusted trees was in excellent physical condition and free from disease. The foliage of the trees in the lime-sulphur-lead arsenate plot was in- jured some, but not seriously. Only a small percentage of the leaves showed any injury. There was no disease. The foliage of trees in the lime-sulphur-calcium arsenate plot was severely injured by the calcium arsenate, but not badly enough to cause many leaves to drop during the summer. There was no disease on these leaves. FIG. 1. DUSTED. Typical leaves from Northern Spy trees dusted with sulphur and lead areenate. They are vigorous and free from injury. FIG. 2. CALCIUM ARSENATE. Typical leaves from Northern Spy trees sprayed with lime- sulphur and calcium arsenate. There was considerable arsenical injury. FIG. 3. LEAD ARSENATE. Typical leaves from Northern Spy trees sprayed with lime-eulphur and lead ar^enate. There was some injury but not so severe ae where calcium arsenate wae used. 10 EXPERIMENT STATION BULLETIN. None of the foliage of sprayed trees was in the same clean, bright condition as that on the dusted trees. The foliage of the check trees was in very good physical condition. There was a small amount of scabby leaves. TABLE III.— RESULTS WITH NORTHERN SPY AT MUIR, 1918. Treatment. No. of Trees in plot. Count Tree - Number. Total No. Apples. Sound. Per cent. il CG Leaf Roller. Per cent. Codling. Per cent. Other Insects, Per cent. Dusted... Entire orchard j 1 1C06 96.32 2.49 0.79 0.20 0.20 1 except 36 trees \ 2 1096 94.54 1.27 2.46 0.27 1.46 Totals 2104 95.39 1.85 1.66 0.24 0.86 Lime-Sulphur and Lead Arsenate » ( 3 4 1538 2118 95.90 93.81 0.39 1.04 3.64 5.05 0 0.05 0.64 0.05 Totals 3656 96.69 0.77 4.46 0.03 0.05 Lime-Sulphur and Calcium Arsenate. . . « { . 5 6 7535 1027 97.07 94.55 0.51 2.43 2.22 3.02 0 0 0.19 0 Totals 2562 96.06 1.29 2.54 0 0.17 Check I c 540 88 33 5 93 5 56 o 0 18 ' Fruit. Because of the very low percentage of scabby apples on the check tree, no comparison can be made as to the fungicidal value of the different materials. The same is true with regard to insects. There is some difference in the amouftt of leaf roller injury, but this is probably due more to a spotted infestation than to the insecticide used. The fruit from two dusted trees, two trees in each sprayed plot and from the check tree was sorted and counted. The results are shown in Table III. A COMPARISON OF DUSTING WITH SPRAYING AT BELDING. A comparison was again made of dusting and spraying at Belding in the Baldwin orchard belonging to Mr. B. F. Hall. The object of this work was to compare the fungicidal and insecticidal value of the two methods of application, also to study the. effect upon the foliage of the different materials. The experimental plots were located in the south- east corner of the 100-acre orchard. The trees are eighteen years old. Materials. A block of eighty trees was divided into two plots. One plot was dusted and the other one sprayed. A tree was left untreated as a check. The plots were treated as follows: Plot 1. Sprayed. Lime-sulphur, 1 to 40, and lead arsenate (dry), 114 in 50. Plot 2. Dusted. 85-15 and 3 in 1 mixtures. The 85-15 mixture was used for the first two applications and the 3 in 1 mixture for the last two. There was no 85-15 mixture available for these applications. All the dusting materials were furnished by Mr. Hall. The arrangement of the plots is shown in Chart III. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 11 B B B 3 B B B B 1 2 B B 4 B B B B B B B C | B B B S B B B B B Sprayed " B B a B S E B 5 B B B B B B B B B 6 B B B B B B B 7 B S S S 8 S B B B S S S Dusted B B B B B B B CHART III. Diagram showing arrangement of treeii and ploty in the B. F. Hall orchard at fielding. B, Baldwin; C, check; S, small trees. Numbers indicate count trees. Applications. Four applications were made as follows: •1st. The pink or cluster application. 2nd. The calyx application. 3rd. Two weeks after second. 4th. First week in August. The dusting was done with a large power duster. The trees were dry when all dusting was done, except for the last application. The trees were wet from a light shower which fell just before the dusting was done. The spraying was not always done uniformly as the sprayer frequently did not maintain a satisfactory pressure. RESULTS. Foliage. On dusted trees there was no foliage injury but a very small amount of scab. On sprayed trees there was no scab but a small amount of foliage in- jury. The injury wras very slight. On the check there was no injury but some scab. TABLE IV.— RESULTS WITH BALDWIN AT BELDING, 1918. .2 . I |^ .j ^ 4 yo _• Treatment. ?! || *| 11 .1 *J 11 ... « o H OQ CQ O O ( 1 1315 89.58 9.20 0 1.29 Sprayed Lime-Sulphur and Lead Arsenate 33 2 1915 90 28 9 39 o 0 57 3 1031 90.59 8.92 0 0.48 ( 4 991 92.73 5.14 0 2.12 Totals 5252 90.63 8.39 0 1.02 5 1144 95.45 2 09 ft 1 49 Dusted 31 6 1746 96 25 1 87 0 22 1 65 7 2141 98.36 0.70 0.18 0.75 8 1272 96.22 2.83 0.08 0.86 Totals 6371 96.81 1.71 0.31 1.16 Check 1 c 1324 62 08 36 02 0 53 1 36 12 EXPERIMENT STATION BULLETIN. Scab control. Dusting gave almost complete control of scab on the fruit. There was only 1.7% of scabby fruit on the count trees. On the sprayed trees there was nearly 6% more of scabby apples than on dusted trees. The failure of the sprayer to work satisfactorily at all times was probably responsible for some of the scab on these trees. On the check tree there was 30.0% of scabby apples. This was high enough to give a good check on the treated trees. Insect Control. There was so little insect injury, on the check tree, that no comparison can be made. The tabulated results of all counts are given in Table IV. EXPERIMENTS AT GRAND LEDGE Spraying experiments were continued in the orchard near Grand Ledge belonging to Mr. C. W. Garlock. The work done there in 1917 has already been reported.* The work here in 1918 was in two parts: (1) a test on Baldwin of Sherwin-Williams dry lime-sulphur and (2) a test of calcium arsenate on Ben Davis. A TEST OF DRY LIME-SULPHUR ON BALDWIN Materials. There were three rows of Baldwin trees with ten trees in a row. Each row was used as a separate plot. The dry lime-sulphur was used at two strengths and standard liquid lime-sulphur was used for comparison. The plots were treated as follows: Plot 1. Sherwin-Williams dry lime-sulphur, 5% Ibs. in 50. Plot 2. Sherwin-Williams dry lime-sulphur, 3 Ibs. in 50. Plot 3. Liquid lime-sulphur, 1 to 40. D D D D 1 D D S D .5 2 D D D S D D S D D D D D 4 Plot D D 4 3 \Plot s D S C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o B B 5 S B 6 B Plot B 5 B B B B B 7 8 B B Plot B % B B B 9 B B B 10 Plot B 1 B B 0000000000 CHART IV. Diagram showing arrangement of trees and plots in the Garlock orchard at Grand Ledge. D, Ben Davis; B, Baldwin; C, check; O, other varieties; S, small tree. Numbers indicate count trees. Plot 1, Sherwin-Williams dry lime-sulphur, 5£ in 50; Plot 2, Sherwin-Williams dry lime-sulphur, 3 in 50; Plot 3, dilute lime-sulphur; Plot 4, calcium arsenate; Plot 5, lead arsenate Lead arsenate (dry) was used on all plots at the rate of 1% pounds in 50 gallons. The arrangement of the plots and trees is shown in Chart IV. * Special Bulletin No. 87. Dusting and Spraying Experiments with Apples. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 13 The results from the use of dry lime-sulphur on Northern Spy in 1917 were not so satisfactory as where the standard lime-sulphur solution was used. It was thought at that time that if the amount used in each fifty gallons was increased so as to contain the same amount of actual sulphur as is found in 1% gallons of standard lime-sulphur solution, that the results would be better. Accordingly, it was used at two rates in 1918. First, at the rate of 3 pounds in 50 gallons, which is the maxi- mum strength recommended by the manufacturers, and second, at the rate of 5% pounds in 50 gallons. This gave about the same amount of sulphur as would be found in 1% gallons of lime-sulphur solution test- ing 32 degrees Beaume. Application. Four applications were made as follows: 1st. Pink or cluster application. 2nd. Calyx application. 3rd. Two weeks after second. 4th. First week in August. All spraying was done with a spray gun and with high pressure. RESULTS Foliage Injury. There was very little foliage injury in any plot. The foliage of trees sprayed with dry lime-sulphur was in slightly better condition than where the standard lime-sulphur solution was used, but the injury was so slight in any case that it was of little importance. TABLE V.— RESULTS WITH BALDWIN AT GRAND LEDGE, 1918. Treatment. No. of Trees in Plot. Count Tree Number. Total No. Apples. Sound. Per cent. f Codling. Per cent. Other Insects. Per cent. Standard Lime-Sulphur Solution '{ 5 6 1852 2644 94.38 93.04 0.32 1.62 0.54 0.64 4.75 4.69 Totals , .... 4496 93.59 1.09 0.60 4.71 Dry Lime-Sulphur, 3 in 50 '{ 7 8 1989 3100 92.11 94. 2ft 1.91 2.16 0.85 0.55 5.13 3.03 Totals . . 5039 93 42 2 06 0 67 3 85 Dry Lime-Sulphur, 5| in 50 10 ( 9 16S9 93.72 1.18 0.77 4.32 \ 10 25S3 95 . 97 0.97 0.54 2.52 Totals 4272 95 08 1 05 0 63 3 23 Check .. j c 2116 63 71 7 28 15 93 8 08 Control The amount of scab on the check tree was so small that no comparison could be made as to the fungicidal value of the dif- ferent materials. Counts were made on the fruit from two trees in each sprayed plot and from the check tree. The tabulated results of the counts are shown in Table V. CALCIUM ARSENATE ON BEN DAVIS Materials. Rex calcium arsenate was used on a small block of Ben Davis to determine its effect on the foliage and its insecticidal value. 14 EXPERIMENT STATION BULLETIN. FIG. 4. CALCIUM ARSENATE injury on Ben Davis foliage. Defoliation was severe. FIG. 5. MAGNESIUM ARSENATE injury on foliage of apple. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 15 For comparison, one plot was sprayed with lead arsenate. Check trees were left. The materials were used as follows: Plot 4. Calcium arsenate (dry), 1 Ib. in 50 (no lime). Plot 5. Lead arsenate (dry), 1*4 Ib. in 50. They were both used in combination with lime-sulphur diluted at the rate of 1 to 40. The arrangement of the trees and plots is shown in Chart IV. Applications. The four regular applications were made as follows: 1st. Cluster or pink application. 2nd. Calyx application. 3rd. Two weeks after the second. 4th. First week in August. All spraying was done with a spray gun and with high pressure. RESULTS Foliage Injury. The trees sprayed with lead arsenate were in good condition. There was very little foliage injury. The foliage of trees sprayed with calcium arsenate was severely burned. The leaves were badly spotted and many leaves dropped. _ The injury was not of the yellow-leaf type. TABLE VI.— RESULTS WITH BEN DAVIS AT GRAND LEDGE, 1918. Treatment. No. of Trses in Plot. Count Tree Number. P Sound. Per cent. # to A "g£ Other Insects, Per cent. Lead Aisenate with Lime-Sulphur 11 ( 1 3093 90.33 6.24 2.36 1.07 I 2 1072 97.20 1.21 0.56 1.03 Totals 4165 96 15 1 16 0 83 1 86 Calcium Arsenate with Lime-Sulphur 13 { 3 2730 95.13 1.65 0,66 2.56 I 4 1837 97.66 0.43 1.09 0.82 Totals 4567 96 15 1 16 1 86 0 83 Check 1 c 2060 38 13 13 49 46 84 3 34 Insect Control. Both materials gave very good insect control. 46.8% of the apples on the unsprayed tree were affected by codling moth. This gave a good check on the insecticidal vvJue of the different materials. The results of counts are given in Table VI. EXPERIMENTS IN 1919 The work with apples in 1919 was done in two orchards near Grand Rapids. The work consisted of a comparison of dusting with spraying and testing several dry lime-sulphurs and some of the newer arsenicals. A TEST OF SULPHUR DUSTS LIME-SULPHUR SOLUTIONS DRY LIME-SULPHURS AND B. T. S. A Duchess orchard of about 125 trees was used for experimental tests 16 EXPERIMENT STATION BULLETIN. with sulphur dust, lime-sulphur, Sherwin-Williams dry lime-sulphur, Dow dry lime-sulphur and B. T. S. The dry lime-sulphurs and B. T. S. are not applied as a dust, but are dissolved in water and applied as any other spraying material. This orchard is about fifteen years old and is on the fruit farm belonging to Mr. J. C. Maynard. It is located about two miles west of Grand Rapids. There is a number of Wealthy trees in the orchard but they were not used for experimental purposes. Materials. The orchard was divided into eight plots as shown in Chart V. The plots were treated as follows: Plot 1. Dusted. 3 in 1 and 90-10 mixtures. Plot 2. Sprayed. Lime-sulphur solution 1 to 40. Plot 3. Sprayed. Sherwin-Williams dry lime-sulphur, 3 Ibs. in 50. Plot 4. Sprayed. Sherwin-Williams dry lime-sulphur, 5% in 50. Plot 5. Sprayed. Dow dry lime-sulphur, 3 Ibs. in 50. Plot 6. Sprayed. Dow dry lime-sulphur, 5% Ibs. in 50. Plot 7. Sprayed. B. T. S., 4 Ibs. in 50.* Plot 8. Sprayed. B. T. S., 1 Ibs. in 50. Lead arsenate (dry) at the rate of 1*4 pounds in 50 gallons was used with all spraying materials for all applications. Black Leaf 40 was used on all sprayed plots for the first application. The dry lime sulphurs and B. T. S. were used at two rates. First, at the maximum rate recommended by the manufacturers for summer sprayed of apples, and second, at the strength which gives about the same amount of actual sulphur as is contained in one and one-fourth gallons of lime-sulphur solution, testing 32 degrees Beaume. The rea- son for using these materials at the increased strength has been stated on page 13. Applications. Three applications were made. The August applica- tion was omitted as the fruit was nearly ripe at that time. They were made at the periods listed below: 1st. Cluster or pink application. 2nd. Calyx application. 3rd. Two weeks after second. The dusting was done with a large power duster. Dusting material was always applied from two directions. The foliage was usually dry when the work was done. The 3 in 1 mixture was used for the first application and the 90-10 mixture was used for the second and third. The spraying was done with spray guns and when the foliage was dry. RESULTS Foliage Injury. The foliage of the dusted trees was in excellent physical condition. Early in the season a little scab was found but this did not develop further. All sprayed trees showed a small amount of foliage injury and the leaves did not have the same clean, bright appear- ance as on dusted trees. The injury was not severe. There was no noticeable difference in the amount of injury in the different sprayed plots. *B. T. S. is manufactured by the General Chemical Company. The letters are the Initials of the words "barium tctra-sulphide." This is the chemical name of the material. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 17 Plot 1. tf S D S D S D S £ D D W I) 2 D 3 D 77 D D D W S I D D 3 W D D D 3 D D D D D W D D W S | D D S S 3 D D S w 4 D D D S W D D D w D D D D D W D D S W D D D D D f S D D W ^D D S D D D w D S W W S D •S D S S W D w D D S 5 D D D W » D D W D 15 17 D 12 W w D D 9 D W D S S D 13 S w 14 I> D S D S D D 10 G W S w D 8 D S D D 7 D S D w D D D D S D D D D • 11 D S D ?/ D 6 D D D S 7i I) S D S 16 D W D D S D S D S Plot 2 5 4 5 6 7 8 CHART V. Diagram showing arrange- ment of trees and plots in the Maynard orchard at Grand Rapids. D, Duchess; C, check; W, Wealthy; S, small tree. Numbers indicate count trees. Tree 16 is a check tree. The plots are indicated by the numbers at the top and bottom of the chart. Plot 1. Dusted. Plot 2. Dilute lime-sulphur. Plot 3. Sherwin-Williams dry lime-sul- phur, 3 in 50. Plot 4. Sherwin-Williams dry lime-sul- phur, 5 % in 50. Plot 5. Dow dry lime-sulphur, 3 in 50. Plot 6. Dow dry lime-sulphur, 5£ in 50. Plot 7. B. T. S. 4 in 50. Plot 8. B. T. S. 7 in 50. 18 EXPERIMENT STATION BULLETIN. FIG. 6. FROST INJURY. This injury on Duchess was caused by a severe freeze before the blossoms were open. FIG. 7. SPRAY INJURY. This injury on Duchess was caused by sulphur sprays. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 19 Injury to Fruit. There was a slight russeting found on the fruit from most sprayed trees. This was more noticeable where B. T. S. was used. The fruit from dusted trees was very smooth. Frost injury was found throughout the orchard. This was entirely different from the russeting just mentioned. Insect Control. There was so little aphis injury on the check that no comparison can be made. Dusting and spraying both gave very good control of codling moth and other chewing insects. The amount of in- jury on the check trees was not very severe, but there was enough for a check on the different materials. Scab Control. Sulphur dust and lime-sulphur solution gave about equal control of scab. Control in those plots was nearly complete ex- cept for an early infection which took place before any dusting or spray- ing was done. Dusting gave more uniform control than spraying. The dry lime-sulphurs and B. T. & failed in every case to give satis- factory control of scab. The increase in strength of these materials gave very little benefit. The tabulated results of all counts made are shown in Table VII. In this table no results are given for the plot sprayed with B. T. S. at the rate of 4 pounds in 50 gallons. The row which was sprayed with this material had several Wealthy trees in it and the Duchess trees that were there did not produce full crops, so no counts could be made. TABLE VII.— RESULTS WITH DUCHESS AT GRAND RAPIDS, 1919. Treatment. No. of Trees in Plot. II ta 3 g^ Total No. Apples. "O t, e 55 1" 1 .a S 1 |" Codling. Per cent. Other Insects. Per cent. Dusted „{ 1 2 1698 3219 86.63 86 70 12.77 13 11 0.11 o 0 o 0.47 0 19 1 3 1268 88.17 11.27 0 0 0.55 Totals 6185 86.98 12.64 0.03 0 0.34 Lime-Sulphur, 1 to 40 "( 4 5 1320 2046 91.13 79 81 8.64 19 16 0 0 10 0.07 0 10 0.15 0 83 I 15 1956 84.15 15.44 0 0.05 0.36 Totals 5322 84 22 15 18 0 04 0 07 0 49 Sherwin-Williams Dry L-S, 3 in 50 »( -6 14 1184 1050 64.10 70.19 33.44 29.33 0.51 0 0 0.19 2.03 0.28 Totals 2234 66 96 31 51 0 27 0 09 1 21 Sherwin-Williams Dry L-S, 5i in 50 »{ 7 17 1133 667 71.05 85.00 27.54 14.84 0 0 0.18 0.15 1.23 0 Totals 1800 76.22 22.83 0 0.16 0.78 Dow Dry L-S, 3 in 50 M 8 9 3214 3482 60.42 61.57 38.52 37.33 0 n 0.09 0.08 0.96 1.01 Totals 6696 61.02 37.90 0 0.09 0.98 Dow Dry L-S, 5} in 50.- M 10 11 1773 2146 63.06 64.54 36.60 34.29 0 0 0 0.19 0.33 0.97 Totals 3919 63.87 35.34 0 .10 0.69 B. T. S., 7 in 50 *{ 12 13 1708 1018 78.81 64.93 20.43 34.77 0 0 0 0 0.76 0.29 Totals 2726 73.62 25.79 0 0 0.59 Check 2 16 1153 21.59 62.36 3.72 9.97 27.67 20 EXPERIMENT STATION BULLETIN. FIG. 8. APPLE BLOSSOM BUDS. This shows the stage of development of the buds when the "pink" or "cluster" application is usually made. FIG/ro. APPLE BLOSSOM BUDS. If the i buds remain in this stage for several days because of cold weather and conditions are favorable for scab development, an extra application will probably be profitable. It should be followed by the regular cluster ap- plication. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 21 In comparing the percentages of scabby fruit on any of the plots it will be well to consider the following facts. In the spring the blossom buds opened slightly, just enough so that the individual buds could be easily distinguished, and remained in this condition for a week or more be- cause of cold weather. During this period conditions were very favor- able for scab development. No dusting or spraying was done until the buds had separated into the cluster stage. When the fruit was harvested and counted, there was found on the apples from all plots an early infection of scab. This scab was in small spots which were on or partly on the calyx lobes. On fruit from the dusted plot there was very little scab of any later infection. On fruit from the plot sprayed with lime-sulphur solution there was a small amount of scab on other parts of the apples. In all the dry lime-sulphur and 15. T. S. plots there was much more on other parts of the apples. The later infections had nearly always developed with larger spots. This early infection undoubtedly occurred before the first application was made. On the plots treated with sulphur dust and lime-sulphur solution there was very little scab of any later infection. This condi- tion indicates two things: (1) an early or "pre-pink" application would have prevented the early infection of scab and (2) sulphur dust and lime sulphur solution prevented practically all development of later in- fections but the dry lime-sulphur and B. T. S. did not. A TEST OF SEVERAL ARSENATES ON APPLES A block of mature Stark trees was used for testing several arsenates. This block of Stark trees is part of an orchard of several varieties be- longing to Mr. A. D. O'Brien and is located about three miles west of Grand Rapids. Materials. The block of trees was divided into four plots of about nine trees each and each plot was sprayed with a different poison. The materials and the strengths at which they were used are listed here : Plot 1. ' Corona calcium arsenate (dry), 1 lb. in 50 gal. with 3 Ibs. hydrated lime added. riot 2. Corona lead arsenate (dry), 11/4 Ibs. in 50 gal. Plot 8. Dow magnesium arsenate (dry), 114 Ibs. in 50 gal. Plot 4. Xiiliexforin lead arsenate (dry), 1% Ibs. in 50 gal. Two tiers were left uusprayed as checks. Lime-sulphur solution, diluted at the rate of 1 to 40, was used in com- bination with all the poisons, for all applications. Black Leaf 40 was used on all plots for the first application. The arrangement of the trees and plots is shown in Chart VI. Applications. Four applications were made according to the regular schedule. 1st. The pink or cluster application. 2nd. Immediately after petals had fallen. ."»i'd. Two weeks after second. 4th. July 30th. All spraying was done with a spray gun and with 200 to 225 pounds pressure. 22 EXPERIMENT STATION BULLETIN. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 Plot s 4 0 p p p p p s s s Plot 3 1 s S S 4 3 s s s Plot 6 2 3 s s 5 S s s s Plot S 3 7 8 s S C s s Plot 1 4 S S s 0 0 p p P 0 0 0 0 0 0 CHART VI. Diagram showing arrangement of trees and plots in the O'Brien orchard at Grand Rapids S Stark; C, check; O, other varieties; P, peach tree. Numbers indicate count trees. Plot 4 is in two parts. Plot 1, calcium arsenate; Plot 2, Corona lead arsenate; Plot 3, Magnesium arsenate; Plot 4, Nurexform lead arsenate. The check tree next to the small portion of Plot 4 was used as a cjunt tree. RESULTS Foliage Injury. The foliage of all trees sprayed with lead arsenate., both Corona and NuRexform, was in very good condition throughout the season. There was very little injury which was traceable to lead arsenate. The trees sprayed with calcium arsenate showed foliage injury but not enough to be classed as serious. Magnesium arsenate caused very severe foliage injury. This was not evident until after the calyx application. In a few days after this ap- plication, many leaves were spotted, turned yellow and dropped. The effects of the injury caused by the calyx application had about passed when the third application was made. The same process of leaves turn- ing yellow and dropping developed again and continued for about two weeks. The same thing happened again after the fourth application. These trees lost fully half their foliage because of the injury by mag- nesium arsenate. TABLE VIII.— RESULTS ON STARK AT GRAND RAPIDS, 1919. ' Material. ' H *| 6^ £ Count Tree Number. Total No. Apples. Sound. Per cent. •si y Other Insects. Per cent. Corona Lead Arsenate 9 \ 5 6 3765 2676 97.90 96.45 1.56 2.72 .53 .82 Totals 6441 97.30 2.04 .65 NuRexform Lead Arsenate" Li 2 1 4136 3159 97.97 97.06 1.81 2.37 .21 .56 Totals 7295 97.57 2.05 .37 Corona Calcium Arsenate 9 ( 3 2313 94.38 5.44 .17 \ 4 3553 93.55 5.43 1.01 Totals 5866 93 88 5 43 68 Dow Magnesium Arsenate 8 ( 7 1698" 85.22 12.01 2.76 \ 8 2517 87.48 11.32 1.19 Totals 4215 86 58 11 60 1 82 Check 2 c 2284 15 53 81 17 3.45 DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 23 Insect Control. Both kinds of lead arsenate controlled all insects very satisfactorily. Calcium arsenate did not give quite so good control as lead arsenate. Maynesium arsenate failed to give satisfactory insect control. The tabulated results of counts made are given in Table VI IF. SI .M.MAKV OF RESULTS OF EXPERIMENTS WITH APPLES DUSTING *<-ni!i<>d trees showed no evidence of leaf-blight until late in Septem- ber and then the development was only very slight. ConlotJii/riu-m on Cherries. When the fruit was being harvested it was noticed that many Morello cherries were drying up and hanging onto the trees. Some had nothing left but the pit covered with the dry cherry skin; some were partly dry and others were in just a slightly wrinkled condition. It was found that around the base of the stem of all atl'ected fruits there was a cankered area which apparently had girdled the stem so that the sap supply was shut off. None of this trouble was found on Montmorency trees. FIG. 13. CONIOTHYRIUM ON SOTH CHKHUY. A small branch from tin English Morello tree afTcctt-d by ( 'oniot li.vrinm. Photo July 1">, 191!). All the all'ected cherries hung tightly to the tree throughout the sum- mer and were still there in December. The trouble was found to be caused by a species of < •oniothyrium and might have come from a planting of black raspberries which stood just south of the cherry orchard. There was considerable cane blight in the berries which is caused by a fungus known as Coniothyrhim Fuckelii.* Control of Coniotlnjnnm- on Clicrricx. All trees in the dusted plot which bore fruit had cherries all'ected by this trouble. No affected *The fungus on the cherries was identified by Ray Nelson of the Botanical Department. 32 EXPERIMENT STATION BULLETIN. cherries were found on trees sprayed with lime-sulphur. This indicates very strongly that dilute lime-sulphur will prevent the first or primary infection of 'this disease and that sulphur dust will not. No statement can be made at this time regarding the control of this disease after it has become established in the trees. Cane-blight is frequently found on black raspberries so it will be well not to plant them as an intercrop in cherry orchards or in close proximity to them. SUMMARY OF RESULTS OF EXPERIMENTS WITH CHERRIES AND PLUMS Foliage Injury ~by Arsenicals. In 1918 Moore's Arctic plums and Early Richmond cherries were sprayed with calcium arsenate in com- bination with dilute lime-sulphur. Lead arseuate was also used for comparison. Neither material caused any injury on either cherries or plums. In 1919 Lombard, Shropshire Damson and Moore's Arctic plums were sprayed with Corona dry lead arsenate, Corona calcium arsenate, Dow magnesium arsenate, rex calsium arsenate and Nu Rexform lead arsenate. These materials Avere used in combination with lime- sulphur. There was considerable foliage injury on all sprayed trees but it was of the type of injury frequently found when lime-sulphur is used during hot weather. The temperature was high when part of this spraying was done. There was some arsenical injury but it was not .confined to the trees sprayed with any one material. These results indicate that sour cherries and plums (not including Japanese varieties) are not so susceptible to arsenical injury to the foliage as some other fruits. Dusting Japanese Plums. Trees of several varieties of Japanese plums were dusted during the season of 1918 to determine if the foliage would be injured in any way by -dusting material composed of sulphur and lead arsenate. There was no injury at any time to the Japanese varieties nor was the foliage of several varieties of native plums in- jured. Dusting and Spraying Cherries at the College. An orchard of Mont- morency and English Morello cherries was used for a comparative test of spraying with dilute lime-sulphur and dusting with sulphur dust for the control of shot-hole fungus. The work with Montmorency gave no conclusive results as no disease developed on the check trees. The work with Morello, however, gave definite results. Dilute lime-sulphur con- trolled shot-hole fungus satisfactorily. Dusting did not control it. In the dusted plot a disease caused by Coniothyrinm developed seri- ously but there was none of it on trees sprayed with dilute lime-sulphur. DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 33 EXPERIMENTS WITH PEACHES The experimental work with peaches was all clone in 1919. There were three separate experiments. One at Saugatuck for the control of leaf-curl by dusting, one at Grand Rapids comparing dilute and con- centrated dusts with self boiled lime-sulphur and lead arsenate' and the third at Grand Rapids as a test of magnesium arsenate in comparison with lead arsenate. / DUSTING TO CONTROL PEACH LEAP CURL A test was made to determine if leaf curl can be controlled by the dusting method. This work was done in the orchard belonging to Mr. Jas. Boyce which is located about one mile from Lake Michigan and five miles north of Saugatuck. The variety was New Prolific. The trees. wrere four years old. Materials. About fifty trees were used for the experiment. They were divided into two plots and treated as follows: Plot 1. Niagara Soluble Sulphur (for dusting). Plot 2. 90-10 mixture of sulphur and lead arsenate. Several trees were left untreated as checks. The lead arsenate in the 90-10 mixture was probably of no value except as a sticker. It would not have been used had any other mixture been available at that time. Spraying. The main part of the orchard was sprayed by Mr. Boyce with Sherwin-Williams dry lime-sulphur. This material had been held over from 1918 and was used at double the strength recommended by the manufacturers because it apparently had deteriorated in quality. Application. The dusting was done on March 7. The material was applied very liberally and from two directions. The spraying was done late in March. There were several dajrs of quite warm weather soon after the dusting work was done and the buds undoubtedly swelled enough to allow an infection of leaf curl. RESULTS. The leaf -curl injury was very severe in this orchard as weather condi- tions were ideal for its development. The condition of the trees early in June in the several plots was as follows : ClH'rk trees. TMie untreated trees were practically defoliated except for some new terminal growth. Dusted. 90-10 inli-iurc. Trees dusted with this mixture were in only slightly better condition than the check trees. Dusted. Niagara Soluble Kuli>1iur. The trees in this plot were in a slightly better condition than those dusted with the 90-10 mixture. The difference, however, was only very small. 34 EXPERIMENT STATION BULLETIN. Sprayed. The development of leaf-curl on the sprayed trees was severe, but the condition was much better than that of the dusted trees. The failure to control the disease on the sprayed trees was probably due to two factors : First, the warm weather before the spraying was done, and, second, the material used possibly was not effective. No definite tests have been made with dry lime-sulphur to control leaf-curl but since it has not given satisfactory control of apple scab it is doubtful if it would control leaf -curl. MAGNESIUM ARSENATE ON PEACHES A block of Early Michigan peaches on the Graham Experiment Sta: tion farm at Grand Rapids was used for testing magnesium arsenate. For comparison, one plot was sprayed with lead arsenate and another left unsprayed. Materials. The block of trees was divided into four plots of from fifteen to twenty-five trees each and treated as follows: Plot 1. Check. Unsprayed. Plot 2. Corona dry lead arsenate. 1 Ib. in 50 gal. and 3 Ibs. hydrat- ed lime added to each 50 gal. Plot 3. Dow magnesium arsenate. 1 Ib. in 50 gal. No lime added. Plot 4. Dow magnesium arsenate. 1 Ib. in 50 gal. and 3 Ibs. lime added to each 50 gal. The materials were used as listed above for the first application. For the second application Plots 2, 3 and 4 were all sprayed with self-boiled lime-sulphur and the poisons were used in combination with it. Applications. Two applications were made: — 1st. As the last of the "shucks" were falling. 2nd. Two weeks after the first. The spraying was done under high pressure -and with a spray gun. RESULTS Check plot. The foliage of the trees in this plot was in excellent con- dition throughout the season. Lead arsenate plot. The foliage of all trees in this plot was in very good condition. There was practically no injury; only an occasional small spot could be found. There was no loss of leaves from these trees. The condition was the same after both applications. Magnesium arsenate. No lime added. Within two or three days after the first application the foliage began dropping. Practically every leaf showed injury and defoliation was very severe. Many small limbs were entirely defoliated so that the limb died and the fruid dried up. Magnesium arsenate. Lime added. The effect upon the trees in this plot was much the same as where no lime was used but the injury was not so severe. Magnesium arsenate with self-boiled lime-sulphur. The effect of this combination was about the same as when used with lime. The combined effect of two applications on Plot 3 resulted in almost DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 35 complete defoliation. On many trees, after the effects of the magnesium arsenate had passed, the only foliage left was the new growth that had developed after the spraying. In Plot 4 the total injury was not so great and resulted in less per- manent injury to the tires. A COMPARISON OF IHLl'TH A \ 1 > ( '< >.\< MOXTIIATKD IH'ST MlXTl'RKS WITH SKi.F-noiu:i> Li.MH-st i.riiru A block of Crosby peaches on the (Irahani Experiment Station Farm at 0 CDS CD -o'-l O) H* *rf 3 3 a' H- «/Of? /on rw? \ .' ,' 1 f/res not t?i/rn/ng. ~ Temperature at 5 foot eterat wiTh f/res bur/ring. Temperature at 35 foot e/eva w/ff? fires &vr/?//x? \ j I (' \ i " 1 1 ; / U s / vv V J \ / < eg' ^NfS 2 AT FIG. 4. — Continuous records of the temperature 5 feet and 35 feet above ground on a tower in a pear orchard. Note the large difference in temperature at the two levels before the orchard heaters were lighted at 4 a. m. By 5 a. m. the temperature was practically the same at the two levels, showing that the heat from the burning oil had been nearly all expended in raising the temperature of the air within 35 feet of the ground. This point is further illustrated by the fact that at 5 a. m. when most of the heaters were extinguished, the temperature at the 5-foot level fell rapidly, while it remained practically stationary at the 35-foet level. The amount of this temperature inversion varies greatly from night to night, and in different localities. It is mainly determined by the amount of fall in temperature from afternoon to early morn- ing. If the afternoon temperature is high and the temperature falls to freezing on the following morning the inversion in temperature is likely to be great. A large number of small fires will be found to be more efficient in raising the temperature than a small number of large fires, especially in localities where the temperature inversion is relatively slight. The heated gases leave the large fires at a high temperature and tend to rise some distance above the ground, while the gases from a num- ber of small fires are mixed with the surrounding cooler air until the 16 Farmers' Bulletin 1096. temperature of the whole mass of surface air is raised slightly, al- though remaining still relatively low. Another and probably the most important factor in protection by heating is the amount of air movement near the ground. When the air is calm the air warmed by the heaters remains over the fired area and the maximum results in raising the surface temperature are obtained. When the air is in motion, even though it is moving only a few miles per hour, the heat is steadily carried away and a greater quantity of fuel must be consumed to obtain the same effect on the surface temperature. The matter of reinforcing the borders of an orchard with one or two extra rows of heaters is of the greatest importance. When the air is in motion, if there is no border row of fires, the heat from the first two or three rows of heaters on the windward side is carried into the orchard, leaving the outside rows practically unprotected. In such cases the temperature in the outside rows may show a rise of only 1° or 2° due to the firing, while the remainder of the orchard may be benefitted by a 5° or 6° rise. To secure the maximum amount of protection for border trees, a row of heaters, 10 feet apart, should be placed about 40 feet to the windward of the outside row, with a similar row about 20 feet to the windward. The smoke cover has very little influence on the* loss of heat by ra- diation and the effect of smudge fires of damp straw or manure on the temperature is practically negligible. However, a smoke screen is of some value in shading the fruit and blossoms from the morn- ing sun and preventing a too rapid thawing. Smudging and Pollination. — In some deciduous fruit districts it has been asserted that the smoke from the open oil heaters interferes with pollination. However, the experience of a large number of fruit growers, who for many years have smudged their trees while in full bloom, does Hot bear out this contention. Pollination usually takes place on the day the blossom opens and even if considerable soot is deposited within the flower on the following night, no dam- age results. As a matter of fact there is seldom enough soot de- posited in a blossom to hinder pollination, even when firing is con- tinued for several hours. During the seasons of 1917 and 1918 Mr. B. B. Lowry, of Medford, Oreg., cooperating with the county pathologist, smudged six pear trees, including practically all varieties grown commercially in the district, every night from the time the buds began to open until the fruit had set, in order to note the effect on pollination. Three open lard-pail heaters were placed almost directly under each tree and the blossoms were coated with soot to an extent that would never be found in actual practice. The experiment was carefully checked by the writer during the 1917 season. All the smudged trees bore Frost and the Prevention of Damage by It. 17 heavy crops both years and the yield of near-by trees that were not smudged was not noticeably larger. (See figure 5.) FIG. 5. — Fine crop of perfectly shaped Bartlett pears on tree used in experiments to determine the effect of smudging on pollination. This tree was smudged heavily every night from the time the buds began to open until the fruit had set. Photograph taken soon after spraying. Statements that bees will not work in blossoms that have been smudged may be due to a lack of understanding of the habits of the 18 Farmers' Bulletin 1096. bee. It is well known that bees will often not work on even moder- ately cool days; if the afternoon temperature is below a certain point, namely about 60° F, the bees may remain in the hive. On days following the occurrence of a frost heavy enough to make smudge protection necessary the temperature is likely to be suf- ficiently low to keep the bees from working to any great extent. On warm sunshiny days following heavy frosts, however, the writer has often observed great numbers of bees working in blossoms that had been heavily smudged on the previous night. The smoke from the open heaters is very dense and in some locali- ties the residents of towns have objected to orchard heating on account of the resulting dirt. The smoke problem has been partially solved by the development of improved heaters, but no practical heater has yet been devised that will burn under orchard condi- tions without giving off some smoke. The newer types are rather complicated and are" too expensive to be used for the protection of crops that do not bring a large return. *fhere are few com- mercial fruit districts in the country that do not suffer severely from frost damage at intervals, and in most localities people are willing to put up with some inconvenience from smoke on a few nights a year in order to avoid the business depression likely to follow the loss of a large portion of the crop. Protection of Olives. — In some parts of California the olive crop is often damaged severely by fall frosts when the fruit is being picked. In some olive-growing communities as much as TO per cent of the crop has been lost in some seasons in this manner. Many growers have hesitated to resort to orchard heating to save the crop for fear that the oil smoke would affect the flavor of the olives. Mr. F. Mier, of Fair Oaks, Calif., has been protecting his olives with open oil heaters for several years and has never been able to note any effect on the flavor of the fruit. Practically his entire crop has been packed ripe and has always been of the highest quality. It is unlikely that the oil flavor ever penetrates the thick, tough skin of the olive, but even if this were possible, the treat- ment with lye which the fruit is given to remove the bitter ele- ment would undoubtedly remove it. Relative Value of Different Fuels.— The kind of fuel most suitable for use in a given locality depends on a number of factors. The firsf consideration is the relative cost of the different fuels. On the Pacific coast oil is used almost exclusively on account of its low cost as compared with coal or wrood. In most other parts of the country coal is the cheaper fuel. The acreage protected by wood fires is relatively small. Because of the ease with which it may be lighted and extinguished, handled and stored, oil is to be preferred when its cost compares favorably with that of other fuels. Frost and the Prevention of Damage by It. 19 Fuel oil of from 25 to 28 gravity is the most satisfactory for use in cither the lard-pail or improved type of heater. This oil leaves very little residue and burns practically as long as heavier oils. Types of Oil Heaters. — Up to the present time few deciduous fruit crops have been valuable enough to warrant the use of any but the simplest and cheapest types of heaters for protection against frost. Since good results can be obtained with these heaters (the lard-pail type) when a sufficient number to the acre is used, the only incentive to change to a more complicated type of heater is the abatement of the smoke and soot. The indications are that the smudge does not injure deciduous blossoms or fruit to any measur- able degree and its elimination is desirable only on account of the resulting dirt. The small open lard-pail heaters are not well suited for the pro- tection of citrus fruits because (1) at the time protection is necessary the fruit is almost ready to be picked and even a small deposit of soot is likely to impair its marketing qualities, and (2) protection is necessary in midwinter, when the temperature is likely to remain below the danger point continuously for 10 or 12 hours and heaters of large capacity and long burning time are required. A 5-quart lard-pail heater will burn about 2J hours, but as the oil gets low the amount of heat given off is greatly decreased. The 2-gallon lard-pail heater will burn about 4 hours, but little heat is given off after 3^ hours. The length of time the larger heaters will burn depends altogether on the amount the drafts are open. To combat the long cold periods, that sometimes visit the citrus districts, without refilling during the night, heaters of a capacity of about 7 gallons should be used. These will burn from 8 to 10 hours at near their full rate. More than a score of more complicated heaters have been developed with the idea of improving combustion and reducing the amount of smoke. These run all the Avay from the 3 or 4-gallon capacity short- stack heater (fig. 6) to the high-stack heater of from 7 to 20 gallons capacity (fig. 7). The stacks on the smaller heaters are from 4 to 10 inches high, while on the larger heaters they are from 3 to 5 feet high. With one or two exceptions the "down draft" principle is used in all the improved types. Air is admitted through the top of the oil reservoir, causing the oil to burn there and raise the tempera- ture sufficiently to change some of the oil to gas. The gas then passes upward and is burned as it rises through the stack. A supply of air to support combustion is admitted through holes cut in the base of the stack. In order to burn clean and supply the desired amount of heat the gas must be given some time to burn before its temperature is ir,0830°— 20— Bull. 1096 I 20 Farmers' Bulletin 1096. reduced by mixing with the cold outside air. This is the function of the tall stack. Generally speaking, the high-stack heaters burn with less smoke and soot than any other type in general use. The short-stack heaters throw off less smoke than the lard-pail type, but the amount is large enough to be object ion able. The high-stack type of heater is open to the objections that the heat is released too far above the ground, at too high a temperature and with too great an upward velocity to obtain the best results. These objections would probably be serious in localities where the temperature inversion is slight, but in southern California, where these heaters are in most general use, the temperature is often 20° higher on a cold night at a height of 200 feet above the ground than at the ground. FIG. 6. — Short-stack oil heaters in orange grove. The one on the left has cover removed and draft open. This type of heater has given great satisfaction where there is not too much objection to the formation of heavy smoke. There is no doubt the heat should be liberated as near the ground as possible in order to obtain the best results. However, at the present time the use of the high stack is the only practicable means of obtaining fairly perfect combustion. Some of the heat from these heaters is undoubtedly lost through its rising too high above the ground, but this is probably nearly offset by the additional heat ob- tained through the more complete combustion. The smoke and soot given off by other types of heaters are more or less completely con- sumed in the high-stack heater. It is estimated that from 40 to 50 per cent of the heat in the oil is made available in the lard-pail type, as against TO to 80 per cent in the high-stack type. Frost and the Prevention of Damage by It. 21 The plan of using small oil heaters which burn slowly and setting them directly under the trees has not met with much success up to the present time. There is always danger of severely injuring the tree if the heater burns too high, and the problem of distributing the heat uniformly throughout the tree has not yet been solved. Protection by Direct Radiation From Heaters. — Though protec- tion from frost is afforded mainly through raising the temperature of the air by mixing with the hot gases from the heaters, direct FIG. 7. — Two types of high-stack oil heaters. Air is admitted through a draft opening in the cover of the bowl, supporting combustion at the surface of the oil. The hot gases then burn while rising through the stack, the necessary air being admitted through the perforations near the base. At the left of the heater on the right is shown a lighting torch of the type in most general use. It consists of an ordinary oil can with a long spout, into the end of which is inserted a wick of asbestos wrapped in small mesh wire screen. The lighting fluid is ignited while flowing through and around the wick and falls in flaming drops. radiation of heat to the plants or trees is important in some cases. This is particularly true when the high-stack heaters are used. When these are burned at a moderate rate at least a portion of the stack is likely to be heated to redness. The heat radiated from the stack to the fruit and foliage serves to counterbalance the loss of heat through outgoing radiation. The amount of radiant heat reaching the tree 22 Farmers' Bulletin 1096. depends on the distance from the heater. With increasing distance the radiation intercepted decreases very rapidly. Experiments conducted by Prof. H. H. Kimball show that when the high-stack heater is burning at a moderate rate with only the lower section of stack red-hot, the heat radiated directly to the tree is sufficient to counterbalance outgoing radiation at a distance of 10 feet. When the entire stack is red-hot the outgoing radiation will be counterbalanced at a distance of about 15 feet. With the short stack and lard-pail heaters radiation is not of so much importance unless the plants to be protected are very near the heater. A large percentage of the radiant heat given off by an orchard heater is lost directly to the sky without appreciable effect on the temperature of the air or of the plants. As radiant heat travels in straight lines and is completely absorbed or reflected by fruit and leaves, any fruit shaded from the heaters by leaves or branches can receive practically no direct benefit from the radiated heat. It is plain, therefore, that to obtain the greatest amount of protection from the same amount of fuel, heaters which are most efficient in raising the temperature of the air should be used if possible, rather than those which radiate most of their heat and are not so effective in raising the temperature of the air. Distribution of Heaters. — For the best distribution of the heat throughout the orchard it is better to have the heaters placed in every row, if possible, instead of concentrating them in every fourth or fifth row. This makes for a more general intermixing of the warmed air from the heaters with the cold air surrounding them. If rows of heaters some distance apart are lighted through an orchard on a calm morning, from the edge of the fired area it is possible to note " arches " in the smoke over the fired rows, with depressions in between. If the air is moving steadily from one direction, even slowly, the heat will be spread out and mixed so that this " chimney " effect will not occur, even if rows some distance apart are lighted. In some parts of southern California, where the air drift is prac- tically always continuous from the same direction during a cold night, firing along " check lines " is practiced. Mr. Willis S. Jones, of Claremont, Calif., is the originator of this plan and has had great success with it on his own 40-acre orange grove. His plan is as follows (see fig. 8) : The air movement in his grove is generally steady and is normally from the north. It sometimes shifts to the northeast and east, but practically never blows from a southerly or westerly direction. On the northern and eastern borders of the grove three short-stack citrus heaters are placed to each tree, and on the line immediately inside Frost and the Prevention of Damage bij It. 23 these heaters are placed one to a tree. The remainder of the orchard is divided into checks 16 trees square and a double row of heaters is distributed along each check line. The remainder of 3,800 heaters are placed one to each tree in the colder parts of the orchard and one to two trees in the remainder of the orchard. "When the time to fire arrives, the direction of the air drift is noted, and the outside row to windward is fired first so that the heat One _ Two freaterj per free,. Three. footers per free. rn;. s. — Diagram of 40-acre orange grove owned by Willis S. Jones, near Claremont, Calif., illustrating his system of firing orchard heaters along check lines. Dots repre- sent orango trees, spaced 20 feet apart on the square. Tho normal- direction of the air drift on cold nights is shown by the arrows. is carried into the orchard. (See fig. 9.) Three more east and west lines are fired immediately afterwards, and if the temperature con- tinues to fall, three north and south lines are fired. The 40 acres are then divided into 16 checks of 256 trees each, surrounded on all sides except the extreme west and south by lines of fires '20 feet apart. If the temperature still remains low in the colder parts of the orchard, 24 Farmers' Bulletin 1096. the eighth rows east and west are fired. This has been necessary on only two occasions -in four years. During the four seasons from 1914 to 1917, more than 580 heaters were never lighted at one time on the 40 acres. The heaters are burned at their maximum rate at all times. Mr. Jones advocates this system of firing on account of— 1. Easy and rapid lighting; one man can light 250 to 300 heaters per hour. 2. Easy and rapid refilling the next day. The firing on the 40- acre grove is easily handled by two men. In experiments carried on during the winter of 1918-19 in co- operation with the Pomona Valley Frost Protective Association and Mr. Jones it was found that the temperature 5 feet above the FIG. 9. — Outer check line of fires on the north of Willis S. Jones orchard, photographed about 3.30 a. m. on a cold morning. An exposure of about 15 minutes was required. The absence of any flame on the right (north) side of the heaters indicates the steadi- ness of the air drift. ground and TO feet inside the two outside check rows can be raised from 2° to 4°. With several check rows across the line of drift burn- ing it is probable the temperature at the leeward side of the orchard is raised a somewhat greater amount. In adopting this system of fir- ing, the space between the check lines should contain at least one heater to every two trees for use in an emergency, when the fires on the check lines may fail to hold the temperature above the danger point. The heated air from a fired orchard often drifts through neighbor- ing orchards which are not fired, affording them in some cases even more protection than the fired orchard itself. (See figs. 10 and 11.) Number of Heaters per Acre. — The number of heaters to the acre necessary for protection depends on the location of the orchard with Frost and the Prevention of Damage by It. 25 regard to surrounding topography. For deciduous orchards in the colder sections there should be not less than 100 of the 5 -quart lard- pail heaters to the acre, and if exceptional cold is likely to be expe- rienced frequently, about 140 to the acre should be used. Of course all the heaters are practically never lighted at once ; some are always held in reserve to be used when others burn out. In the warmer de- ciduous fruit regions, where the temperature is not likely to fall be- low 25° at any time, these heaters should be set about 80 to the acre. N X I ^ * * \ * x ' x ** *x" x '*' "*' * . * . .*. .x. .x. . .* ' x @X * * * * x " " x " "x* "x . x . . * . . x . . x ! . x . X X ! x ." X. ! x " x ' * x X. .*. .X. .X. .X. ,K. " x. x x! x* '** *x' x .x. !x. !x. X !x! .x. .x. .x. X *x .x x x. ,x. **. .x. .x. ,'x. X x *x' *x' *x* *x* *x •x. .x. ,x! X X X X x* 'x x' *x* x • x- «x. «x. . *• .x. .x, ,x. .x. . x *x* *x" ** x x x n x x x x x x*"x'*x* FIG. 10. — Plan of lemon groves where temperature records shown in figure 11 were obtained. Dots represent lemon trees, spaced 20 feet apart ; crosses represent high- stack oil heaters. Squares marked H and C show locations of thermometers in heated and unheated groves, respectively. The number should not be much less if 2-gallon lard-pail heaters are used. The larger heaters have a longer burning time, but the amount of heat released in a given time is not much greater. (See fig. 12.) The number of the newer improved type of heater necessary for protection depends on the location of the orchard and on the kind of fruit to be protected. Orange groves on low ground, where tem- peratures as low as 20° may occur as often as every five or six years, should have at least one large capacity heater to each tree. On the higher slopes the number may be reduced to 80 per acre, but if ex- 26 Farmers' Bulletin 1096. tremely heavy frosts, like those of 1913 in California, are to be fought successfully, dependence should not be placed on a much smaller number. Some growers have successfully protected their orange crops for several years with as few as 30 or 40 heaters to the acre, but no exceptionally heavy frosts occurred during that time. (See figs. 13 and 14.) Lemons are more susceptible to frost damage than oranges, but where a large acreage is protected it is usually possible to save the large fruit with 100 large capacity heaters to the acre when the tem- perature falls to 19°. A portion of the blossoms and young fruit is likely to be frozen when the temperature remains at this point for five or six hours, even with 100 heaters to the acre. Care of Oil Heaters. — The amount of attention given to storage and care of oil heaters varies greatly in different parts of the country. In parts of California where the annual rainfall is light, many fruit growers leave the heaters in the orchards during the entire year, 8f>M 9PM. JOf>M. J/P.M SAM MM 4/t.M SAM M. 7/4M SAM. 30., 'I .1 Temperature of cnec/r statxn, not /nfA/enced ty f/r/ng. Temperature at stat/on H. ___ Temperature at station C Heaters /grr/ted FIG. 11. — Continuous records of the temperature at stations H and C in figure 10 and at a third station located in an unheated orchard about 500 yards to the southeast. When the fires were lighted at station H about 10 p. m., the wanned air drifting across to station C raised the temperature there almost as much as at station H inside the fired area. At the end of the season the fruit at station C was in better condition than that at station H, due to the protection afforded by the firing in the neighboring grove. Note that the temperature at stations H and C ran nearly 2° lower than at the third station before the fires were lighted. setting them up close to the trunks of the trees affer the danger of frost is past. Trees are sometimes injured or even killed through oil from leaky heaters penetrating the soil around the roots. For this reason, heaters left in the orchard should be emptied at the end of the season. Lard-pail heaters are usually covered with a film of oil, which helps to prevent rusting, and the rate of deterioration is little, if any, greater than is the case when they are stored under cover. Where there is considerable annual rainfall, lard-pail heaters should be emptied, dipped in heavy oil, and stored under cover when not in use. With ordinary care heaters of this type will last 10 years or longer. Several orchardists have used them 14 and even 16 years without losing more than a small percentage through deteriora- Frost and the Prevention of Damage by It. 27 tion. Some fruit growers prevent contact between the bottoms of the heaters and the ground by placing the heaters on small square pieces of board. The cost of the larger heaters is so great that it is good practice to give each one a coat of good stack paint at intervals of 2 or 3 years to prolong its life. Mr. Willis S. Jones, of Claremont, Calif., has his heaters thoroughly brushed with a steel brush to remove rust and dirt. Each heater is then placed on an iron grating under which one or two heaters are burning until it is brought to a high temperature, after which the paint is applied hot. At the end of each season the heaters usually contain a small quan- tity of a mixture of soot and asphaltum, which sticks to the bottom 44 43' 42' 4/' 40' 39' 38" 37' 36' 35- 34' 33' 32' 3/' X' 29' 28' 27' 26' PS' 8PM. &P.M. 0PM. //P.M. A^OT /AM. ?AM. 3A.M. 4AM SAM. 6AM 7AM. MM. ^S b\ Te/npgrafurf a f check stef/cr? outside fieofed arc/*. Temperature //? fteaffd arc/Jord before fir/ng. 9 rtfafers fo acre farm/iy. (8 ., » - •yd V\ »— *— x S v a \ \\ \ \ *\ 1 .O I " V, V AA \ i ^ A/V _j x \\ i n \l \ \ A . /! j 'r^ i\A or, .^ vHf \ A \ 1 ( 7f - y -A i \ / V AT FIG. 12. — Continuous records of the temperature inside and outside a heated pear orchard, showing the effect of the firing on the temperature. Five-quart lard-pail oil heaters were used. Note that the temperature in the heated orchard ran about 2° lower than at the check station before the heaters were lighted. and is difficult to remove when cold. The usual method of removing this material has been to burn it out with distillate. In doing this accidents often occur and piles of several hundred or more heaters sometimes catch fire, ruining the heaters and endangering surround- ing property. At the Bear Creek Orchard, Medford, Oreg., the manager, Mr. B. B. Lowry, has a trench covered with sheet iron on which he treats the empty heaters at the end of the season. A fire is built under the iron, using the residue from the heaters for fuel, which burns fiercely. A large inclined flue carries away the smoke from the fire and creates a draft. The heaters, a dozen at a time, are placed on the sheet iron 28 farmers' Bulletin 1096. until they become hot and the residue is loosened, when they are re- moved with tongs one by one and rapped against a post, causing the residue to fall out. They are then examined for leaks by holding them upward toward the sun. The work can be handled very rapidly in this way and there is little danger of accident. Coal Heaters. — Coal is burned in open piles on the ground, in wire baskets and in specially designed sheet-iron heaters. Coal heaters possess some advantages over oil heaters in that the heat can be applied near the ground, there is no strong up-draft and usually not much soot or smoke after the first few minutes of burning. On the other hand, coal fires are often difficult to light and hard to regu- late; the fires often have a tendency to smolder slowly or burn out N . X • X • X •<*• X « X • X .*•*•*•* •^•X-X >X*X*lt»X«X«X*X* x • x • x • x . x • x • v • x .y..**x»****x*x*x: • x • x • x • * • x »/x • x • ng • <* ' ' x «x • x «x • x . x *x« x »x -x Hr* •x.x*x»x«x*x*x«x* xlx . x-x . x -x . * . x • x • *•*•*••*.*. *•*•*•*•*•'*•* ••*••*•*. *.*.x > #00 ft to ConM $to. C FIG. 13. — Plan of orange grove where temperature records shown in figure 14 were obtained. Dots represent orange trees spaced 20 feet apart ; crosses represent low-stack oil heaters. The square marked II shows location, of thermometers in fired orchard. The check station was located about 800 ifeet to the eastward to avoid the influence of the fires. The air drift on cold nights was normally from a northerly direction. with a rush. When firing is required for several hours it is neces- sary to replenish the fuel in the heaters. The labor costs are rela- tively high, as a large number of men are required to attend to this work. In California reserve supplies of coal for each heater are kept in wooden boxes set under the trees. At the end of the sea- son the heaters are placed on top of these boxes and are left out all the year. The number of coal fires to the acre should be about the same as when the lard-pail oil heaters are used. Lighting Equipment. — Orchard heaters of all kinds can be lighted easily and rapidly with torches burning a mixture of gasoline and Frost and the Prevention of Damage by It. 29 distillate or gasoline and fuel oil. (See fig. 7.) These torches drop the burning liquid into the heaters, starting combustion immedi- ately. Lard-pail heaters when new are sometimes difficult to light. If the burning liquid from the torch is poured in a ring on the edge of the heater, no difficulty will be experienced. After three or four firings the carbon deposited on the rim of the heater acts as a wick and a little burning liquid dropped anywhere in the oil will ignite it readily. Many fruit-growers hire school boys to light the heaters and have been able to place great dependence on them. Coal fires should be carefully built up with oil-soaked waste or paper and a small amount of kindling. If a portion of the fires fail to burn a great deal of valuable time is lost in going back over the same territory again. 9PM. 34.M. ___ 4'A.M __ SAM. 6A.H. J L J L Temperature of sfaf/on fi £>efare firing Tefnpcrafire a/ yror/orf C otrrstd* /reared orchard. Terrtperafure 'of sfarfsart fi *r/rr> heaters tvrniry. FIG. 14. — Continuous records of the temperature at stations shown in figure 13, showing the effect of firing on the temperature. Low-stack oil heaters of the type shown in figure 6 were used. Storage of Fuel. — In order to carry on orchard heating success- fully it is necessary to have enough fuel within reach to last through the longest cold spell likely to be experienced. Too many instances have been noted where the crop has been protected successfully through several cold nights at considerable expense, only to be lost on one cold night on account of lack of fuel. Where orchard heat- ing is practiced by many growers in a community it is a good plan to buy and store large quantities of fuel oil on a cooperative basis, as is done in southern California. Orchards located near the storage tanks can haul directly from them, but in the case of those located a mile or more distant, storage tanks should be provided in the orchard. The necessity of pumping oil from storage tanks should be avoided by raising the tanks high enough above the ground so that the oil 30 Farmers' Bulletin 1096. will flow into the wagon tanks by gravity. Where the ground is not too flat, the storage tank can be so located that the oil can be put into it and taken out by gravity. If more than 5 acres are to be fired with oil a portable tank from which to fill the heaters is almost a necessity on account of the saving in time and labor. Three men with a tank wagon can fill heaters very rapidly, one man driving and two men drawing oil into 5 -gallon buckets and pouring it into the heaters, filling two rows at the same time. The owners of two adjoining orchards often use the same tank wagon. Owners of small orchards often handle the oil in metal drums of about 50 gallons capacity. The heaters are filled directly from the drums, which are hauled through the orchard on sleds. IS ORCHARD HEATING PROFITABLE? This question can be answered only by the individual grower, as the factors to be considered in drawing a conclusion vary greatly, sometimes even for orchards within a few miles of one another. The most important points to be considered are as follows : 1. What has been the average loss from frost damage in your orchard dur- ing-a period of years — as long a time as possible? Unless these data are avail- able from personal experience they will usually be difficult, if not impossible, to obtain, although neighboring fruit growers may sometimes be able to supply some information, As a general rule, few records of this kind have been kept. 2. How many times during this period of years would it have been necessary to light the heaters in order to have saved the entire crop each year? If de- pendable temperature records have been kept for a number of years somewhere in the immediate vicinity and are still being kept at the same location, a com- parison of records from the orchard and from the station with the long record for the same season may make it possible to gain a fairly accurate conception of what temperatures have been experienced at the orchard in question. 3. Will the value of the fruit lost through frost damage more than pay in- terest and depreciation charges on an investment for all necessary heating equipment, together with all costs of operation? 4. Is your locality likely to be visited by short periods of extremely cold weather during the growing season that may badly injure or kill the trees? This question can probably be determined from Weather Bureau records from some station in the vicinity. There are two conditions under which orchard heating will not be profitable. The orchard may be located where frost damage is too slight in the long run to pay the expenses of heating, or the orchard may be in an exceptionally cold section where damaging frosts occur so often that the costs of protection are too great to be borne by the crops. The number of cases of the first-mentioned type is smaller than would appear at first thought. The saving of one season's crop, which would otherwise have been a total loss, will justify the expense of heating for a good many years. Some practical growers consider it Frost and the Prevention of Damage by It. 31 good business policy to have frost-fighting equipment, even though it is necessary to use it only one season out of five. In cases of the second type it is obvious that the frost hazard is so great that fruit growing will not be profitable in the long run and the trees will eventually have to be removed. The statement is often made that the policy of growing fruit on the colder low ground is wrong and that orchards should be confined to the higher and more frost-free locations. This is not always true. In some parts of southern California the difference in the cost of irrigation more than makes up for the ex- pense of protecting the orchards on the lower ground from frost. In addition to this the cost of cultivating steep hillsides is greater. The same is true of certain deciduous fruit districts in Oregon. On a farm near San Francisco po- tatoes have been grown successful 1 y during the winter months for several years with the aid of open lard -pail oil heaters. Irrigation water necessary for crops grown during the summer is scarce and expensive, while the rainfall during the winter months is ample. The new crop is harvested in the spring, and reaches the market so early that exceptionally good prices are obtained. The degree of success attained in protecting potatoes at this place indicates that low-lying crops may be protected against ordi- nary spring frosts by using the small open lard-pail heaters, set from GO to 80 to the acre. In addition to the heating of the air over the plants, the direct radiation of heat from the heaters FIG. 15. — Young lemon tree almost entirely stripped of foliage by frost. The fruit was a total loss and most of the the remaining leaves dropped later. 32 Farmers' Bulletin 1096. aids considerably in protecting the plants immediately surround- ing them. In planting a field to a low-growing crop that is to be protected with heaters, vacant spaces about 18 inches square should be left at the points where the heaters are to be placed, as the plants very close to the heaters are likely to be scorched. Orchard heating has been practiced for six years on one of the largest lemon groves in the country, located in southern California. During the season of 1912-13, a season when the citrus crop in many parts of southern California was practically a total loss and thou- sands of trees were killed outright, the lemon crop from this grove brought $734,318.07 f. o. b. California. On higher ground on the same ranch 5-year-old lemon trees which were not protected were frozen to the ground. The mana- ger of this ranch states it is his belief that the business would not have been profitable since 1912 without means of protection from frost. MAXIMUM COST OF FIRING Records on the cost of protecting 220 acres on this place during the past six years are shown below. (Table 1.) It will be seen that the returns from the fruit saved in 1913 alone would pay the costs of protection for many years. About 500 acres of lemons are now being protected here. TABLE 1. — Average cost per acre for protecting heaters.1 acres of lemons with oil Y€ iar. Total 6-vear 1913 1914 1915 1916 1917 1918 average, per acre. Labor, man and horse, filling and light- ing pots per acre $45 70 $10 55 $10 65 $21 45 $20 60 $22 15 $21 85 38.35 12.70 4.20 23.20 26.15 17 75 19 55 Depreciation 19 30 19 10 17 40 15 60 14 30 13 00 16 45 17 85 17 45 15 50 13 40 13 45 11 25 14 80 Upkeep 11.55 7.95 7.65 1.10 5.65 3 70 6 25 Total 132. 75 67.75 55.40 74.75 80.15 67 85 78 90 Number of times fired 19 2 7 20 27 21 i Small open heaters used in 1913; down-draft, short stack type in later seasons. This ranch is located on both high and low ground, but only the low ground is protected. Lemons are more easily damaged than oranges, and as the small green fruit is protected here, the fires are lighted oftener than in most other orchards. The costs given above are for firing about the maximum number of times that would be necessary anywhere in the country. AVERAGE COST OF FIRING Mr. Willis S. Jones, of Claremont, Calif., has kept accurate records on the cost of firing his 40-acre orange grove, which is on rather Frost and the Prevention of Damage 'by It. 33 high ground and is fired only a few nights each year as a general rule. These cost figures, given below (Table 2), are for firing a number of times per year which is probably slightly below the average. It is impossible to estimate present-day costs of equipping an orchard from any of the above figures on account of the increase in the price of all materials used in the manufacture of heaters and other equipment. Mr. Jones's orchard was not equipped with heaters in 1913 and his crop was a total loss. At the prices prevailing at that time he esti- mates he lost fully $10,000 worth of fruit in the two seasons prior to 1913, and $25,000 worth of fruit in 1913. In addition, so many of his trees were severely damaged that he experienced a heavy loss in reduced crops during the next several years. Since putting in heating equipment, including the severe season of 1918-19, his losses from frost damage have been negligible. TABLE 2. — Detailed costs of protecting JtO acres of oranges ivitTi oil heaters. EQUIPMENT INSTALLED NOVEMBER AND DECEMBER, 1913. Storage : 21,000-gallon galvanized iron tank $298. 90 Concrete foundation 45. 92 Pipe line 164. 46 Laying pipe line •_ 7. 85 $517. 13 Distributing system : Wagon 51. 50 Two 575-gallon tanks, complete 161. 70 4 buckets , 6. 2p 1 dozen lighting torches 9. 00 228. 40 Heaters : 3,800 heaters at $0.58 2, 204. 00 Painting heaters at $0.02 76. 00 2, 280. 00 Thermometers 42. 00 42. 00 Total investment 3, 067. 00 OPERATING EXPENSES. Interest : 6 per oent on $3,067, original cost $182. 85 Depreciation : Storage tank, 5 per cent on $298.90 $14. 93 Pipe line, 3 per cent on $164.46" 4.93 Wagon, 10 per cent on $51.15 5. 15 Wagon tanks, 8 per cent on $161.70 12.93 Buckets and torches, 20 per cent on $15.20 3.04 Heaters, 12J per cent on $2,204 275. 50 Thermometers, 5 per cent on $42 2. 10 318. 58 Operation : Oil, 1913, 25,095 gallons at $0.03 752. 85 Hauling, at $1.50 per 1,000 37. 63 $790.48 34 Farmers' Bulletin 1096. TABLE 2. — Detailed costs of protecting 40 acres of oranges ivith oil heaters — Con. OPERATING EXPENSES — Continued. Operation — Continued. Oil, 1914, 13,725 gallons at $0.03 $401.75 Hauling, at $1.50 per 1,000 20.58 $422. 33 Oil, 1915, 575 gallons at $0.03 17.25 Hauling, at $1.50 per 1,000 . 75 18. 00 Oil, 1916, 15,525 gallons at $0.04 621. 00 Hauling, at $1.50 per 1,000 23. 28 644. 28 Total for four years 1, 875. 09 Credit oil on hand, 17,173 gallons, at $0.04 686. 92 Hauling, at $1.50 per 1,000 25. 75 712. 67 Net cost, 4 years 1, 162. 42 Average cost per year $290. 60 Distributing, filling, firing, taking in, cleaning, and painting heaters : 1913-14 , 199. 88 1914-15 204. 63 1915-16 340. 90 1916-17 336. 70 Total cost for four years 1, 082. 11 Average cost per year 270. 52 Total annual cost for 40 acres 1.062.55 Average annual cost per acre r 26. 56 Detailed average annual cost per acre. Interest $4. 57 Depreciation . 7. 96 Operation : Fuel 7. 26 Labor 6. 76 $26. 55 BEST METHODS OF HANDLING ORCHARD HEATING The fact can not be emphasized too strongly that if orchard heat- ing is to be practiced successfully, it must be handled with as much care and attention as spraying, fumigating, or any other necessary farm work. The secret of success will be found in adequate equip- ment, good judgment, attention to detail, and extreme vigilance. An inadequate number of fires to the acre may often be worse than none at all, as the costs of firing may have to be added to the loss of the crop. Whenever the temperature approaches the danger point the thermometer in the orchard should be watched closely and, if pos- sible, the rate at which the temperature is falling should be deter- mined. If the temperature is falling rapidly the firing must be begun early if the heaters are to be all lighted before the danger point is reached. With a little practice it is often possible to tell with considerable accuracy by inspection of the fruit or blossoms, Frost and the Prevention of Damage by It. 35 when the danger point has been reached, regardless of the tem- perature. When small apples or pears commence to freeze minute blisters will begin to form on the skin. By keeping constantly on the watch for the first appearance of these blisters on the fruit in the coldest part of the orchard, the firing can be begun at exactly the right time ; no fruit will be lost and no oil wasted. By carefully cutting the blossoms of deciduous fruit it is generally possible to note with ice crystals first begin to form in them, and thus regulate the beginning of firing. When oranges begin to freeze, the section of the skin exposed to the sky takes on a transparent appearance, generally known as the "water-mark," probably caused by the water in the rind freezing and leaving the oil separated. On the following day these oranges can be picked out easily and are called " shiners." By timing the firing with the first appearance of the " water-mark " in the orchard, it is possible to save the fruit and yet prevent waste of oil. Some experience is necessary before the fruit grower is able to use these methods of timing the firing; but the importance of saving oil is well worth giving the matter close attention. If the small lard-pail heaters are set 100 to the acre, alternate heaters in every fourth row should be lighted first, followed im- mediately by alternate heaters in every second row if the tempera- ture has been falling rapidly. The effect on the temperature should then be noted and decision made as to whether additional firing is necessary at that time. As soon as a row of heaters begins to burn low, reserve heaters should be lighted, as the amount of heat given off during the last half hour of burning is small. If the large capacity down-draft heaters are used, all may be lighted at once if desired and the consumption of oil regulated by manipulating the drafts. During a cold night an isolated cloud passing overhead, by cut- ting off radiation and to a certain extent reflecting radiation from the earth, may cause the temperature to rise. As the cloud drifts toward the horizon the temperature falls again. Likewise, sudden temporary rises in temperature are caused by gusts of wind of short duration which mix the upper and the surface air. As a general rule the temperature falls rapidly after the wind or cloud has passed and cases are on record where entire crops were lost through ex- tinguishing the heaters at such a time. If clouds are overspreading the whole sky or a sudden rise in temperature due to wind occurs just before sunrise, the heaters may be extinguished, but if the sky re- mains clear and sunrise is an hour or more away, the temperature should be watched closely during the remainder of the night. 36 Farmers' Bulletin 1096. Although it is sometimes difficult to find time to keep records on heating operations during the rush of firing, it should be done when- ever possible. The temperature when firing is begun, time of ini- tial firing and number of heaters fired, time of firing additional heat- ers, the lowest temperature recorded during the night, can all be jotted down from time to time as the work goes on. On the follow- ing day an estimate can be made of the amount of oil consumed and the extent of the damage to the fruit, if any. Eecords of this kind will be found to be of great value in regulating later firing ; the more information of this kind gathered, the more efficiently can the firing be handled. Records of this kind will also help to determine whether protection is profitable or not, a question which every grower should solve for himself at the earliest possible time. If orchard heating is carried on in a careful, painstaking manner, with ample equipment, there are probably few commercial fruit- growing districts where the heaviest frost likely to be experienced can not be successfully fought with orchard heaters. FROST AND MINIMUM TEMPERATURE FORECASTS General forecasts of frost for large areas are issued by the Weather Bureau during the growing season, and in certain rather small dis- tricts where protection against frost damage is practiced on a large scale, forecasts of the minimum temperature to be expected from night to night are issued. Farmers or fruitgrowers who have a means of protecting their crops should arrange with the nearest Weather Bureau station to obtain forecasts of the kind available in their community. INJURIOUS TEMPERATURES So many factors must be taken into consideration in determining whether a given temperature will cause damage that the matter is one of great complexity. The length of time the low temperature persists, the vigor and stage of advancement of the plant, the kind of weather preceding the frost, and the rate of thawing all have considerable influence on the amount of damage that will be done. Other conditions being the same, a weak, undernourished plant will show more injury than a strong healthy one after both have been subjected to the same low temperature. Pure water has a higher freezing point than water carrying foreign substances in solution. For example, the freezing point of a strong solution of common salt may be 23° or lower, depending on the concentration; the weaker the solution the higher the freezing point. When the weather is warm and sunshine and moisture plentiful, plants make a rapid growth and the sap is likely to be Frost and the Prevention of Damage by It. 37 watery and its freezing point high. For this reason a frost which follows a period of weather favorable for rapid growth will cause more damage than the same frost following a period of cold cloudy weather and consequent slow growth. When a plant freezes a portion of the cell sap is withdrawn from the plant cells, gathering in the intercellular spaces in the form of ice. If thawing takes place gradually and the cell walls have not been ruptured, this moisture is again taken up by the cells as it is melted, without serious damage. If thawing takes place rapidly, however, the intercellular ice is liquefied faster than it can be ab- sorbed by the cells; a part of it is lost by evaporation and the cells are broken down. When fruit crops are damaged by frost the greatest damage is often found on the portion of the tree where the morning sun strikes first. When clouds gather on the eastern horizon before sunrise and obscure the sun for a few hours in the morning after a cold night, damage to vegetation is likely to be slight, provided the temperature does not fall much below the critical temperature. Heavy smoke from orchard^ heaters or smudge fires may also lessen damage from frost through causing a slow thawing. Of course, if the temperature falls sufficiently low a great deal of damage may be done even when the rate of thawing is slow ; in other words, the prevention of a rapid rise in temperature in the morning may often not be sufficient in itself to prevent injury. It is possible that some of the protection from frost damage ob- tained by irrigating is due to making available to the damaged plant cells a larger supply of water through increased flow of sap, to replace that lost through freezing. INFLUENCE OF HUMIDITY ON RATE OF FREEZING Fruit growers in nearly all sections are convinced that with the same temperature the amount of damage by frost will be greater when the humidity is low than when it is high. Recent studies by I. G. McBeth, of the Leffingwell Rancho at Whittier, Calif., indicate that under certain conditions citrus fruits will be damaged in a shorter time when the humidity is high than when it is low, the temperature being the same in both instances. It was thought this was due to greater conductivity of moist air, the heat being con- ducted away from the fruit more rapidly, causing the temperature of the fruit to fall more nearly at the rate at which the temperature of the air was falling. However, in making these investigations allowance was not made for the influences of radiation and the liberation of heat by condensa- tion. Under orchard conditions, blossoms and leaves exposed to the sky lose their heat rapidly by radiation and their temperature may 38 Farmers' Bulletin 1096. fall several degrees below that of the surrounding air. The tem- perature of mature citrus fruits falls more slowly than that of the sur- rounding air but the rate of fall follows more closely that of the outside air when radiation is rapid than when it is S!OWT. Growers of citrus fruits are familiar "with the fact that the first fruit to be damaged is that which is exposed to the sky ; fruit on the interior of the tree and screened from the sky by leaves or branches often will show no injury with air temperatures several degrees lower. Radia- tion goes on more rapidly when the air is relatively dry than when it is moist and the temperature of the fruit is likely to follow more nearly that of the surrounding air when the humidity is low. On nights when the humidity is high, considerable ice is de- posited on the fruit or blossoms. When this moisture condenses and freezes, some of the latent heat liberated tends to retard the rate of fall in temperature of the fruit. After sunrise the thawing of the ice and evaporation of the resulting water retard the thawing to a slight extent and this has a tendency to lessen the damage. It is possible that under actual orchard conditions, these influences which tend to lessen the amount of damage on a night with relatively high humidity more than counteract the influence of the increased conductivity of the moist air. DECIDUOUS FRUITS Damage by frost to deciduous fruits usually takes place in the spring when the trees are in bucl or blossom or shortly after the fruit has set. The stage of advancement is of the greatest importance in estimating resistance to low temperature; the same degree of frost that causes little or no damage to fruit in bud, may injure the greater portion of the crop two or three days later. In the case of most deciduous fruits, the same temperature will cause far more permanent damage after the fruit has set than during the period when the trees are in full bloom, and the later the frost after the fruit has set, the greater is the actual loss. This is due to the fact that there is nearly always a great overproduction of bloom and usually from 50 to 90 per cent of the blossoms can be killed without materially reducing the final crop of fruit. This fact often causes orchardists to overestimate the amount of damage to their crops early in the season. One or two uninjured blossoms in each cluster are usually enough for a good crop. With some small fruits and nuts a larger percentage of the blossoms must mature in order to obtain a full crop and damage during full bloom is more serious. Another point to be considered is the fact that the blossoms do not all open at once ; there are often unopened buds and small fruits on the trees at the same time. Even though a heavy frost at this Frost and the Prevention of Damage by It. 39 stage may kill all or most of the more advanced blossoms, there may still be a sufficient number of unopened buds left to insure a crop of nearly normal size. However, fruit from late bloom is usually undersized and of poor quality. In the process of natural thinning the number of fruits on the trees is steadily and rapidly reduced after the period of full bloom and the loss of a large percentage of the fruit retained on the tree at this time is likely to reduce seriously the size of the crop harvested. It is obvious from the above that the greatest need for protection comes after the period of full bloom. While a single night's frost during the period of full bloom may not seriously reduce the size of the final crop of apples, peaches, apricots, or pears, when the amount of bloom is reasonably heavy, each one of a series of heavy frosts at this period may kill a certain portion of the remaining uninjured blossoms, until not enough sound blossoms are left to make a full crop. Where an orchard is equipped with heating devices the only safe policy is to hold the temperature high enough at all times so that only a few blossoms will be injured. Apples and pears are often badly injured by frost but remain on the trees and mature. Such fruits are mis-shapen and more or less seedless and are not marketable as first grade. Frosted pears enlarge abnormally near the stem and lose their characteristic pear shape, while injured apples become rough and their shape irregular. In- jured fruit of this kind often remains on the trees until a month be- fore maturity and then drops. The blackening of the centers of blossoms or of small apples and pears does not necessarily mean that they will not mature, though the cha-nces are greatly in favor of their dropping before the end of the season. The injured tissue is often gradually absorbed until the blackening entirely disappears. Different varieties of the same fruit often differ considerably in degree of resistance to frost damage and when the same critical tem- perature is given for all varieties, it is applicable only in a very gen- eral way. The best possible arrangement to be followed by the orchardist who protects his orchard is to keep in touch with the local county agricultural agent or horticultural commissioner as the season progresses and obtain opinions from him from time to time as to the temperatures that will cause damage. These officials are likely to have had considerable experience in noting the effect of low tem- perature in the local district and are also familiar with the condition of the fruit or blossoms as they have been affected by previous weather conditions. It will pay the individual grower to keep careful records of the temperature in his orchard on cold nights, together with notes on 40 Farmers' Bulletin 1096. the effect on the size of the final crop. After a few seasons, he will have collected enough data to enable him to know with considerable accuracy how low it is safe to allow the temperature to fall before lighting the heaters. The following table of critical temperatures as recorded by a well exposed thermometer in the orchard is meant to give a general idea of what the blossoms will endure for a half hour or less without injury. Temperatures endured by blossoms for 30 minutes or less. Fruit. Closed but showing color. Full bloom. After fruit has set. °F. 25 °F. 28 ^ 1 1 E 1 ^ N?V/\ | vv^ -v li V \ ~ N V li \ / / ' ^^ >\ / > // Vlv ^s^ ro-s^ 72 \^ ^r a.T diation takes place vary greatly on different nights, but every in- dividual substance has its own rate at which it radiates heat. There- fore, under conditions favorable for radiation, a thermometer of dark metal would show a lower temperature than one of mercury inclosed in glass. 35' 34-' J3' 32' 31' 30' 29' 28' 27' 26' 25' ?4' f>3' 7P.M SP.M. SP.M X>#M. //PM MDT //f.M 2AM 3AM 4A.M. S4M pertrfe/r« //?f/red orchard (*/J wMe f/rfs were tvrm/Ty I 1 •y__ 1 | .\ i . i *s V.' IL \ / k / ^ N y \ 1 \ K 'T J M J i I \ 1 E25 TI \ \ . V M£L ^ 1 \ \,/ \f s / \ ^>> J ^ \ A- 1 \ \ I V \ ^/ ^s ^•^y \^ 1 ' V/ ^"^ N ^ 1 IT The only method whereby temperature measurements which are at all comparable can be secured is to obtain, not the temperature of the thermometer under radiation conditions, but as nearly as pos- sible the temperature of the free air surrounding the thermometer. Frost and the Prevention of Damage by It. AYe have seen that a relatively large amount of heat is required to change liquid water to water vapor. Evaporation is going on at all times, even when the air is saturated, although when saturation has . 7PM. 4PM. 9PM. X>fiM. //f>M. MOT /AM PAM 3A.M. 4AM. SAM 6AM 7AM 84Af 9AM 1 I Temperature at check star/an farcre *2) outsjde f/red area — Terrperafun? m f/red orchard (*/) fie fore f/res were tgf?ted .. Temperature w f/red orchard (*/)fvhVe f/res Here fiurr>/na. I 1 [| / \ ^ A /lrv r-A /J 1 ^vv 5 / — ' \ ^ S"' ^NT'""1 -/ j 1 & 7 E ~ / v/V. VA-J 2 \ i 1 ^ y \ rS \ fN , [J XV- j Ltr. /OP.M //f!M. MPT" /AM Temperature at crteck sfaf/or/ (Grove *2) outsxte f/red area. /j Temperature /n f/red orchard (*/) before f/res were SJgftted. Tempfrafurff /r/ f/red orchard (*/) H/r/iJff f/res were burrs/ng a ,Y fc 3<^\ // w \ fJ/\? A\ j»J^ \ _^ x / J £ \ ^ ^A^ -JV; '' Va./ *r\ ^j / ^ '/ ^ A ^ ,. 1 c \J V v ""' / ^C / v/ V ^^ ^\ 2 V . — ' \ k^yxj ^^ ^~^ AT 33' 7PM 8PM. 3PM: K>PM. //P.M. MOT >AM. SAM 3A.M. -4A.M. 5A.M. 6AM. 7A.M 8 AM. i i 1 /' Temperature arc/reck stot/orr fyrore *2) ot/fe/de f/red area Temperafure //7 f/red orc/rard /"*/)£& fore f/res were //&/?/cd Temperate/re /n f/red orchard (*/) w/?//e f/res were frurn/ng. / / OJ { ^\J\ / ! 1 ip'' / -A ^^/' v ". '! \r~ A A / - / kQJ>> ^ 1 _s r . S z XV»^ />W 7^ \ / ^'"i / (\ / U ^ ™ /A f 'V V V /J \ J ^^Is 7 Vx FIG. 17. — Continuous records of the air temperature inside standard instrument shelters in the two orange groves for which the comparative yields are given above. The grove at station C was not protected. The grove at station II was partially protected with coal heaters, set 50 to the acre. Station H was located in a row which contained no heaters and the temperature was probably somewhat higher in the rows containing heaters while firing was in progress. Note that the temperature .fell as low as 23° for a short time, without any permanent injury to the fruit. As the weather had been cold for some time before these low temperatures occurred, however, the trees and fruit were considerably more resistant to cold than usual. been reached, the condensation of vapor balances the evaporation. Evaporation also takes place directly from ice. When a thermometer is covered with a film of water or ice, or contains frost on the bulb, 44 Farmers' Bulletin 1096. the evaporation that is taking place absorbs heat from the ther- mometer and cools it to below the temperature of the air. The amount of cooling depends on the amount of moisture in the air and on the rate at which the air is moving past the thermometer. It is plain that if .a thermometer is to register the temperature of the air, it must be sheltered from the sky and from direct sunlight, and also must be ex- posed in such a way that moisture from any source is not likely to gather on it. Free circulation of the air is also an im- portant requirement for a satisfactory thermometer e x p o- sure. If a shelter offers much obstruc- tion to air circulation the " air inside the shelter may cool at a slower or faster rate than the outside air and the thermometer in the shelter will then fail to indicate the true temperature of the outside air. It is essential, therefore, that a thermometer shelter allow as free a circulation of the air as possible with- out sacrificing the ele- ments of protection f trom SUmiglli }iqUi(J Or frozen mois- ' rrn i i ture. The standard Weather Bureau shelter has a double roof to prevent undue warming of the inside air by the sun's rays, and the bottom is as open as possible. The sides are louvred, the openings being as wide as possible without allowing the direct sunlight to reach the interior. (See fig. 18.) All thermometers used in determining temperatures in orchards should be exposed with the foregoing principles in mind. A simple FIG. 18. — Standard type of instrument shelter used by the Weather Bureau. The shelter is always placed so that the door opens toward the north so that the sun can not shine directly on the instruments when the door is open. Frost and the Prevention of Damage by It. 45 but fairly satisfactory method of sheltering a thermometer which is used only at night is to place a large thin flat board horizontally directly above it. The thermometer should be placed close up under the board so as to cut off as much of the sky as possible. In reading a thermometer on a cold night, care should be taken not to breathe directly on it. Whenever possible, an electric flash-light FIG. 19.— Types of thermometers used by the Weather Bureau to register the highest and lowest temperature. should be used in making readings. When matches or candles are used to illuminate the thermometer, the temperature may be raised a degree or more before the reading can be made, which may in some cases results in loss of fruit through not lighting the heaters in time. Every orchardist who has frost-fighting equipment should have at least one accurate dependable thermometer to be placed in the coldest part of the orchard, preferably one which will register the minimum temperature. (See fig. 19.) Cheaper thermometers can be scat- tered throughout the remainder of the orchard. These should be carefully compared with the standard thermometer at least once each year and inaccuracies noted. Those which are found to be in error more than one degree near the freezing point should be discarded. Cards showing the corrections to be applied at different points on the 46 Farmers' Bulletin 1096. FIG. 20. — Sling psy - chrometer used to determine the amount of mois- ture in the at- mosphere. scale to make the readings agree with the standard should be attached along- 0 side all thermome- ters which are not strictly accurate. MEASUREMENT OF ATMOS PH ER I C MOISTURE. On an earlier page of this bulletin ref- erence has been made to the impor- tant influence of the water vapor in the atmos- phere on the amount of fall in temperature during the night. A knowledge of the amount of mois- ture in the atmosphere is therefore of considerable value to the orchardist. The temperature of the dew point is a direct index to the amount of water vapor in the atmos- phere and also indicates the point at which dew or frost will begin to form as the temperature falls. The simplest instrument for accurately deter- mining the temperature of the dew point is the sling psychrometer. (See fig. 20.) This consists of two ordinary thermometers mounted side by side on an aluminum strip and provided with a handle for whirling. The bulb of the lower ther- mometer is covered with thin muslin. When an observation is to be made, the muslin is thor- oughly moistened in clean water and the instru- ment is whirled rapidly for a short time. Imme- diately after the whirling is discontinued both thermometers are read as quickly as possible, the wet-bulb thermometer first. These readings are kept in mind or noted on paper and the psychrome- ter is immediately whirled again and more read- ings are taken. This is repeated several times, until two readings of the wet-bulb thermometer agree closely or until the wet-bulb temperature begins to rise. In other words, it is desired to Frost and the Prevention of Damage by It. 47 obtain readings of the two thermometers after the wet-bulb ther- mometer has reached its maximum depression. If the wet-bulb temperature falls to 32° F. and remains at that point, the whirling should be continued for some time later, even FIG. 21. — Improved high-stack heaters in place in orange grove. though two or three successive whirlings fail to cause it to read lower. When the water in the muslin begins to freeze, sufficient latent heat is liberated to keep the temperature at 32° until all the water on FIG. 22. — Short-stack oil heaters in place in an orange grove. the thermometer bulb is frozen. After this occurs, the evaporation from the ice may cause the wet-bulb thermometer to read below 32°. After the final readings have been made the wet-bulb temperature is subtracted from the dry-bulb temperature and the temperature of 48 Farmers' Bulletin 1096. the dew point is found by referring to special tables, usually fur- nished with the psychrometer. The psychrometer should be whirled and read in the shade. FIG. 23. — A corner of a frozen orange dump after a cold season. Thousands of dollars worth of otherwise perfect fruit a total loss through frost damage. Considerable heat is required to evaporate water, and the heat removed from the bulb of the wet thermometer for this purpose causes its temperature to fall. The less moisture already in the at- FIG. 24. — Frozen oranges dumped in lemon grove to be plowed under for fertilizer. Very little frozen fruit is used in this way, as most growers believe too much acid is added to the soil. mosphere the more rapidly the evaporation goes on and the lower is the temperature of the wet bulb. When the atmosphere is saturated the readings of the dry and wet bulb thermometers are the same. o Bulletin Vol. V, No. 2 February, 1920 Whole No. 50 Ohio Agricultural Experiment Station CONTENTS Page v What Shade and Ornamental Trees Shall We Plant? . . 35 .Culture and Feeding of the Apple Orchard 43 Recent Tests of Materials to Control San Jose Scale. . . 49 Horticultural Notes from the County Experiment Farms of Ohio 52 Selecting Nursery Stock 58 Smudging to Prevent Frost 63 OHIO AGRICULTURAL EXPERIMENT STATION Wooster, Ohio, U. S. A. A spring scene in Portage County A satisfactory home picture MONTHLY BULLETIN OF THE Ohio Agricultural Experiment Station VOL. V, No. 2 FEBRUARY, 1920 WHOLE No. 50 WHAT SHADE AND ORNAMENTAL TREES SHALL WE PLANT? Selection of Varieties, Adaptation, Planting and Care W. E. BONTKAGER Hardwood species have first choice. — With the passing of wintry days and the approach of the spring planting season, the question of making a suitable selection of trees for beautifying the lawn, street and avenue once more becomes of paramount interest and importance. Well-selected hardwood trees, although in some instances of slow growth f6r a few years after planting, have a permanence worthy of serious consideration when the choice of planting materials is being made. When once thoroughly estab- lished the rate of even the slowest species becomes accelerated and it is safe to assert that at the age of 25 years the oaks will approxi- mate in size most other species that were planted at the same time. On the grounds of the Experiment Station the oaks are becoming the leading trees in a planting scheme designed and planted pri- marily to illustrate the value of native planting materials. Nursery-grown stock quite satisfactory. — True it is that such trees when transplanted from a shaded spot in the forest require several years in which to become established, but if nursery-grown stock of the same species be utilized the results will be much more speedy and satisfactory. When properly grown in the nursery, young elms, oaks and maples become accustomed at an early time to having the direct sunlight on all sides and therefore are checked very little when removed to their permanent quarters. The slight additional cost will be much more than offset by the resulting rapid, vigorous growth. The nursery-grown specimen is almost always a well-furnished, stocky young tree, quite in contrast with the slen- der, poorly-developed weakling brought in from some crowded thicket. (35) 36 OHIO EXPERIMENT STATION: MONTHLY BULLETIN Superiority of the elm and the oaks. — Of the larger trees suit- able for lawn and street planting, few of the exotic kinds compare in all-round utility and durability with many of the trees native to the forests of Ohio. It is an encouraging sign to note that the planting of distinctively foreign species is giving way to the utili- zation of the finer native kinds. For alluvial lands and all rich soils the American white elm is unrivaled in majesty and grace. A moderately fast grower, the elm lives to a very old age, its beauty increasing from year to year. For street planting the elm is unex- celled where soil conditions are suitable. Our oaks are trees of much dignity, are extremely long-lived and are endowed with a landscape value such as few trees possess. For streets and avenues oaks compare very favorably with the elm and can be grown on a greater variety of soils. One of the finest is the red oak, which has been more widely planted in Europe than any other of our oaks and which is probably the most rapid of all the oaks in its rate of growth. The pin oak is an extremely grace- ful oak, native to moist lands, that grows well almost everywhere and makes a perfect specimen for the lawn or formal avenue. One of the finest avenues of trees in this country is the celebrated one of pin oaks in Fairmount Park, Philadelphia. The bur oak, scarlet oak and white oak are all good trees that are known to succeed in the latitude of Wooster and over the entire State. Less well known but equally choice and desirable are the chestnut oak, the willow oak, from the South, and the shingle oak (Quer- cus imbricaria) , sometimes called the laurel oak, which is one of the richest and handsomest of all oaks in its garb of glossy, dark green leaves. The willow oak, though most abundant in the southern states, has proved to be entirely hardy and satisfactory in Ohio. A typical American white elm WHAT SHADE TREES SHALL WE PLANT? 37 A variety of trees. — The cucumber tree is a large northern representative of the magnolias, a group of trees native to a region farther south. The cucumber is a striking, stately species that ultimately develops into a magnificent specimen for the park or roomy lawn. Its foliage is exceptionally large, clean and pleas- ing. Somewhat similar in size and habit is the tulip tree or white- wood, indispensable where groups and collections of the finer native trees are being assembled. For foliage tropical in its luxuriant richness the great-leaved magnolia (M. macrophylla) , with leaves often 2 feet long, should be selected. This species ought to be given a sheltered corner to protect the heavy foliage from wind injury. The white ash, the American linden or basswood and American beech are trees having a high landscape value and known to succeed over a wide range of country. Maples have value. — Probably no group of our native trees has been more popular for lawn planting than the maples. The most lasting of our native species is undoubtedly the sugar maple, although the soft or silver maple has been more commonly planted on account of its rapid growth. Sugar maples ought always to be transplanted before they exceed 2 inches in diameter. For securing early results the silver maple has few equals but it can scarcely be considered a sat- isfactory permanent tree. The soft, brittle wood is easily damaged by high winds and most old specimens are very much dilapidated. Wier's cut- leaved silver maple is a won- derfully graceful variety of silver maple with a pendulous, weeping habit. The scarlet or rock maple does best on low, moist lands and colors up in autumn extremely well. Gas and smoke resisting trees. — A few trees from for- eign countries have high value for street planting through their resistance to dust, gas and smoke. Foremost of these is the Oriental plane or Euro- The red oak 38 OHIO EXPERIMENT STATION: MONTHLY BULLETIN pean sycamore, a large, spreading species somewhat similar to its American prototype but in most regards a finer, more desirable tree. The foliage of the plane is quite free from the fungous dis- eases that disfigure the American tree, while its head is much more adequately supplied with limbs and branches. The Norway maple is another good smoke and gas resister whose merits appear now to be pretty generally recognized. Remarkably free from the ravages of pernicious insects, the foliage of the Norway persists long after the branches of most trees are bare. China has contributed the Ginkgo, a unique tree whose leafage endures city conditions but as yet the Ginkgo has not been extensively used in the formation of avenues. r A group of liquidambar, or sweet gum trees Trees for restricted areas. — In -many villages and towns the lawns are so restricted in size that space can only be spared for medium to small trees. Under such circumstances the liquidamber or sweet gum, from the South, the yellow-wood, a rare flowering tree, the flowering dogwood or perchance a tree or two of birch will be all that can be accommodated. Birches stand much cold, flourish on poor soils and are extremely artistic. The paper or canoe birch and the European white are two very desirable ones, while the cut- leaved variety of the latter, B. alba pendula laciniata, is .one of the handsomest weeping trees known. The red or river birch has WHAT SHADE TREES SHALL WE PLANT? 39 curious, loosely-attached bark and is at home alike on marshy soil and on well-drained upland. Another small tree that is almost a total stranger on lawns is the American persimmon, which assumes much the same shape and size of the common sour cherry and has good, clean, rather glossy leaves. Ornamental species. — Flowering and distinctly ornamental trees have a legitimate place in lawn planting and are requisites in almost every well-balanced planting scheme. Flowering dogwood, service, judas tree, small magnolias, like soulangeana and others of the Chinese type, the birches, native hawthorns and Chinese flower- ing crabs are easily handled and are objects of surpassing beauty at certain seasons of the year. The native wild crab apple, the scarlet thorn (Crataegus coccinea) and the black haw (Viburnum prunifolium) are native trees of great excellence. For improving the banks of a pond or stream the Wisconsin weeping willow has superseded the Babylonian willow which is lacking in hardiness in the North. Red birch and American larch or tamarack are at home in such positions. The long period of hot weather which we have in late summer and autumn is remarkably favorable to the coloration of leaves and the chief value of a number of our native trees is due to the rich hues which their foliage takes on at this season. For outstanding brilliancy none surpasses the sour gum (Nyssa sylvatica) whose flaming canopy is visible for a long distance. The flowering dog- wood, too, becomes a study in crimson and scarlet, illuminating splendidly the locality where it is growing. Scarlet or rock maple, sugar maple, ashes and oaks blend into shades and tones of color which are invaluable in the composition of an autumn landscape. Pruning and spacing. — The pruning of shade trees is a subject concerning which information is often desired, and in a general sense it is safe to say that the matter is usually overdone. During the earlier years of a shade tree's existence but little cutting will be required beyond such as needed to remove broken or otherwise injured limbs or to preserve a moderately symmetrical, well- balanced head. As the specimens grow older and often encroach upon each other or sustain injury from storms, heavy cutting will sometimes need to be done. The indiscriminate topping and head- ing in of trees, particularly such as is in evidence along most village streets, cannot be too severely condemned. The heavy, unsightly stubs thus produced afford openings through which the germs of decay enter and speedily work havoc to the larger branches and to 40 OHIO EXPERIMENT STATION: MONTHLY BULLETIN the trunk. If properly spaced when planted crowding would have been avoided, little or no pruning needed and the lives of the trees would have been very much prolonged. As to the distance for spacing trees along roads, streets and avenues, the interval between the individual specimens will depend much upon the species and somewhat upon the width of street or road. Along most streets the trees have been planted too closely and very little thinning has been done, hence the presence of tall, pinched, ill-shapen maples and elms in unlimited numbers. Very Normal development can only be secured when trees are properly spaced large trees, such as white elm and red oak, should be spaced 60 feet for the former and 45 to 50 feet for the latter. A space of 45 feet will suffice for most other oaks. Tulip tree and cucumber tree should be given 50 feet. American white ash and pin oak should stand 30 or 35 feet. Sugar maple and silver maple should have 40 feet. Ginkgo and liquidambar ought to have a space of 30 feet. Theoretically, the plan of spacing closely and thinning by taking out alternate trees when they begin to crowd is a most admirable one, but reluctance to thin them at the right time generally defeats the original good intentions of the planter. Care of young trees and planting. — A few words as to the pro- cess of planting may not be amiss. When received from the nur- WHAT SHADE TREES SHALL WE PLANT? 41 sery, young stock should be unpacked carefully and heeled in near to the place of planting. For most trees a hole 2 feet across and 15 to 18 inches deep will be about the right size. In this hole the young tree should be set so as to stand about 2 inches deeper than it grew in the nursery. No manure should be used about the fine, fibrous roots, among which the soil ought to be intimately worked and finally well compressed from the top. A mulch of manure, grass or straw will be of great value in carrying the newly-planted trees through extended periods of drought. Sunshine and pure air are freely admitted here On the lawn trees should be grouped naturally anu irregularly, no straight lines being allowed to appear. The planting of many large trees closely to a home is not advised. When this is done, sun- light is shut out and a free circulation of air is prevented. It is a good plan to group most of the larger trees along the sides and at the rear of the lawn, placing an occasional specimen near the residence for shade. When a planter is imbued with a determination to practice rigorous thinning at the right time, it is a very good plan to choose long-lived hardwood trees for the lasting effect and among these intersperse a limited number of some rapid grower like silver maple, to be removed when the planting begins to crowd and inter- fere with the normal, healthy development of the permanent trees. 42 OHIO EXPERIMENT STATION: MONTHLY BULLETIN Production of two rows of Rome Beauty containing eight trees each, at right, fertilized, yielded 21 barrels; row at left unfertilized, 9 barrels. Benedict orchard Row Row on right, fertilized; row on left, unfertilized. Broom sedge has densely invaded the unfertilized plot, but has not crossed over the plot boundary line into the fertilized plot HORTICULTURAL NOTES 57 lighter-pruned trees invariably gave the higher averages in early and generous fruit bearing. Orchard fertilization. — Fertilization experiments are now being planned for the young apple orchards at the Clermont, Hamilton, Mahoning and Washington County farms, and for the substation farm in Meigs County. Fertilization work also will be begun at the Belmont County farm within the next year. Landscape improvement. — Improvement of residence grounds, in connection with the county and district experiment farms, also is a part of the horticultural department's service. Measuring, mapping, planning and planting are being accomplished as rapidly as limited time, scarcity of help and widely scattered farms will permit. There are twenty-one separate residence grounds at the ten county and two district farms at which some planting has been done. A single visit to all of these farms necessitates very nearly 800 miles travel. From the horticultural viewpoint the county experiment farms, so recently established, could not reasonably be expected to be pro- ductive of much interesting data for some years ; but, when results begin to appear, these farms surely will be a source of abundant material for illustrative and educational purposes. COSTLY CLOVER SEED AIDS ALFALFA CULTURE The high price of red clover seed is likely to cause farmers to grow more alfalfa, according to specialists at the Ohio Experiment Station. Alfalfa seed costs about the same as red clover seed but when a good alfalfa stand is secured it will produce abundantly without reseeding for three to five years and a larger tonnage of hay to the acre may be grown generally with alfalfa than with clover. Alfalfa thrives well where good drainage is provided, where there is plenty of lime in the soil and where the soil is in a fair state of fertility. Alfalfa culture methods differ. In the western part of the State the alfalfa is frequently sown in regular rotation similarly to red clover. In eastern Ohio it is generally sown as a regular crop in midsummer — last of June to the first of August — and allowed to remain 4 or 5 years or as long as the stand will justify. Ten pounds to the acre of seed at the Ohio Experiment Station has given better results than when sown at the heavier rate. The seed should be inocu- lated. > SELECTING NURSERY STOCK Standard Varieties, Locally-grown Plants and Clean Trees Required PAUL THATEE Varieties. — It is always safe to choose from the standard varie- ties. Novelties come and go; or most of them go. Occasionally a new variety, like the Elberta, is really valuable and enriches everyone who has the courage to plant it while still untested. For every one of this kind, however, there are several much-heralded novelties that prove to be a bitter disappointment to the planter. Standard varieties have been tested out on different soils and under widely varying conditions; they have their weaknesses which are well understood, but they have withstood the competition of past years and represent the "survival of the fittest." Local conditions often govern the selection of varieties. The orchardist who plans to sell the crop as a whole in the orchard should confine his varieties to three or four, while the grower who expects to depend upon local markets usually plants a succession of varieties ripening throughout the season. Shipping quality, which is of prime importance in the former case, might be left out of consider- ation in selecting varieties for the local trade. "Pedigreed plants" is a catch- word used by several nurseries to secure trade or to justify the prices charged. It has been defi- nitely proven by Prof. Shamel, of the Bureau of Plant Industry, that with citrus fruits, such as the orange and lemon, there is a wide variation between trees of the same variety and that this can, to some extent at least, be transmitted by grafting. Unfor- tunately the first half of this theory almost nullifies the last half. All trees of any variety have grown from pieces (scions) of the original tree or from the other trees propagated from it. If these vary so as to give us "superior" and inferior trees will Mean and extremes in nursery stock not the Same law affect the (58) SELECTING NURSERY STOCK 59 (graft) descendants of these "superior" trees? In other words, can we say that bud variation has given us improved strains but will now cease to exert any influence and permit us to propagate from these improved types with perfect assurance that "like pro- duces like"? For further advice as to varieties one may turn to the publica- tions of the agricultural colleges and experiment stations. De- pendable Fruits, 313, and Apple Varieties, 290, of the Ohio Experi- ment Station, give much of value for Ohio planters. Besides bulle- tins there are nursery catalogues, reports of horticultural societies, and discussions in the agricultural press. Nursery. — Always buy trees or plants direct from the nursery, never from an agent, unless the agent is personally known to you and is one in whose judgment and integrity you have enough con- fidence to make him your agent. There is a little advantage in attempting to get trees true to name in buying from from the small nursery over the large one when the proprietor of the small nursery gives his personal attention to the work of propagation. This is only true when the small nurseryman grows his own stock. Every time a nursery tree changes hands it increases the possibility of error and decreases the responsibility of the dealer who finally sells it to the planter. In studying nursery c a t a lo g s discriminate against those making ex- travagant claims or list- ing marvelous new "bug- less" and "blight-proof" varieties. The list of truly desirable varieties does not change much from year to year or Crown gall on roots of young tree OHIO EXPERIMENT STATION: MONTHLY BULLETIN from catalog to catalog. Each year a very few meritorious, new varieties appear but any catalog listing a lot of wonderful new kinds is to be looked upon with suspicion. The location of the nursery is unimportant except in two par- ticulars. There is a distinct advantage when the nursery is near enough so that the buyer may visit it and personally select the stock and thus know just what he is getting. Berry plants, es- pecially black caps and strawberries, do not stand shipment as well as trees and vines and if poorly packed or delayed in transit they may arrive in poor condition. For this reason it is best, whenever possible, to get these plants from plantations near home. With potatoes and some garden seeds there is some difference in behavior, depending upon the latitude in which the seed was grown and this has led many to believe that a similar difference might exist between nursery stock from different sections. In order to maintain our variety fruit collections at the Ex- periment Station we annually order trees and plants from probably between 25 and 50 different nurseries located in all parts of the country from Ontario to Georgia and Texas and from Maryland to Oregon. We have failed to find any evidence to prove that a tree or vine from Georgia or Texas is in any way inferior to the same variety from Ohio and New York. Many southern varieties are unsuited for northern culture and behave differently here than in their native state so that one must make allowance for the descriptions of southern varieties in south- ern catalogs, but duplicate lots of trees from Georgia, Ohio and Ontario, if equally mature and equally rooted would grow equally well and be equally hardy. It is advisable, however, to avoid planting southern-grown trees in northern latitude in the fall. This is because southern-grown trees do not mature early enough to be planted in the fall in cold climates. Woolly aphis causes distorted growth SELECTING NURSERY STOCK 61 Trees and plants. — Having selected the list of varieties and the nursery from which they are to come, there remains only the selec- tion of the plants themselves. If the nursery is within easy reach it is well if the planter can personally select his own trees. The experienced planter will not be so much concerned that the bodies be perfectly straight and smooth as he will that the roots be numer- ous, well spread and stout and the top and roots be clean and vig- orous. Never plant a cull or second grade tree. There is, however, a world of difference between a second grade tree and a second size tree. A second size tree has all the possibilities of the first size •••BHBHt Nursery stock heeled in for winter tree but simply grew in a more crowded portion of the row. In this connection note the three peach trees in the illustration on page 58. The horizontal line shows where the three trees should be normally headed at planting. If this is done the heavy one at the left will be cut back beyond the strong buds, and dependence will have to be placed upon the weak branches which are so often injured in packing, or upon adventitious buds, for the top. The middle tree is a medium-sized tree. Topping at the indicated height will leave a number of strong buds to form the head. The third tree, scarcely discernible against the background, does not reach the line and is too weak to waste room upon in the orchard. City people are more susceptible to the charms of oversize trees than experienced orchardists. 62 OHIO EXPERIMENT STATION: MONTHLY BULLETIN One year from the bud is the usual age for peach trees. Apple, pear, plum and cherry trees may be 1 or 2 years old. Occasion- ally older trees are offered for sale but they should be avoided under ordinary conditions. Year-old trees are slender, straight whips which may be headed at any desired height and made to conform to the idea in the mind of the planter. On account of their size they are easily lost amid the weeds and easily fall victims to the disc harrpw or the mowing machine. The 2-year-old tree was topped when a year old and has a number of branches from which to select the one desired for the head of the new tree. The tree is larger, less easily injured and a little more able to withstand unfavorable conditions. Not so much is heard now about the relative value of budded and grafted apple trees. In certain sections,, such as the prairie states, the method of propagation may be of importance but it is immaterial to the Ohio orchardist. Clean nursery stock important. — Above all, one should plant clean trees. The three pests to be found most commonly on nursery stock are crown gall, woolly aphis and San Jose scale. The last is the least dangerous since it can be destroyed by spraying or dipping the tops of the young trees in the solutions used for the regular dormant spray given in the spray bulletins. Single scales appear as circular dots about the size of the head of a pin, usually on a slightly-sunken area of bark, the bark being frequently tinged with red. On badly-infested trees the scales give the limb an ashy gray appearance ; they may be rubbed off with the thumb nail or the back of a knife blade. The woolly aphis is not so easily controlled and any trees show- ing signs of infestation with this pest should be rejected. The indi- cations of woolly aphis are marked swellings on the roots and some- times grayish masses of aphis clustered between the roots. Some- times a small root, when badly attacked, is swollen so that it resembles a string of beads. Equally objectionable are trees infested with crown gall, or hairy root as one form of it is called. This disease appears in the form of wart-like excresences on the body limbs or roots of trees. The most common location is at the base of the trunk where the trees was grafted or budded. When this growth occurs beneath the ground it frequently puts forth a mass of fine fibrous roots. While sometimes the crown gall does not seem to injure the tree, it often causes severe injury and affected trees are not fit for plant- ing and should be rejected. SMUDGING TO PREVENT FROST W. J. GREEN The protection of fruit and vegetable plants against frost has been widely practiced, especially in the coast regions of the extreme west. It has not been so generally practiced in the eastern states but there are few localities where the plan has not been tried to some extent. At one time smudging was looked upon by many as one of the essential horticultural operations but belief in it as a practical and necessary item of orchard practice is less firmly held than formerly. The main reason for the change in opinion is because of the cost of such work and uncertainty as to results. The temperature can be raised in this manner but it often happens that when one has spent considerable time and money in smudging against a looked-f or frost the temperature does not fall below the danger line. This makes smudging of very doubtful utility, even though it is some- times the means of saving a valuable crop. Wood and coal are not satisfactory materials for smudging as they require too much labor and respond too slowly when it is desired to raise the temperature quickly. Crude petroleum, burned in suitable heaters, will raise the temperature quickly and hold it for a considerable time, but one cannot be sure that a frost will occur even though it is predicted by the officials of the weather bureau. Just when to begin lighting the heaters can be determined only approximately even though a constant watch is kept through the night. Heating in winter to protect fruit buds is even less prac- ticable than heating to protect blossoms in spray time. Mulched strawberry beds may be set on fire unless a consider- able space around each fire pot is left uncovered. There is danger, also, of setting fire to grass and straw with heaters in mulched orchards. While it is true that there are considerable losses by burning oil in orchards when not needed it may be due, in some cases, to over zealous orchardists who are anxious to try something new. The fact should not be overlooked, however, that orchard heating is an expensive operation even when no unnecessary work is done. (63) PUBLICATIONS OF THE OHIO AGRICULTURAL EXPERIMENT STATION The publications of this Station are now issued in three series, namely: 1. The Monograph Bulletin, each number of which is a record of progress in a single line of investigation. This series is a continuation of both the ordinary and the "Technical" series heretofore issued and is largely technical in character. 2. The Monthly Bulletin, each number of which contains several brief and timely reports of progress in different phases of the Station's work, including nontechnical abstracts of the Monograph Bulletins. 3. A Weekly Press Bulletin, containing brief notes on the Station's work, prepared for newspaper circulation. The more important of these notes are' republished in the Monthly Bulletin. These publications are sent free on request. The addresses of those who request that their names be placed on the mailing list will be entered for the Monthly Bulletin only, unless either of the other series is definitely requested. Address Mailing Room, Experiment Station, Wooster, Ohio. RECENT MONOGRAPH BULLETINS No. 321 — Tomato diseases in Ohio: Descriptions and control measures recommended for rhizoctonia, Fusarium wilt, bacterial wilt, stem rot, leaf spot, blight, anthracnose, rot, "leak," leaf mold and other diseases common to grow- ing tomatoes. No. 322 — Feeding experiments with laying hens: — Range vs. confinement, variety vs. simple rations, various amounts of protein, methods of feeding, date of hatching, corn vs. wheat. No. 323 — County Experiment Farms in Ohio: Annual reports for 1916 and 1917. No. 324— Ohio weather for 1917. No. 325— Thirty-seventh annual report: Projects under investigation, financial statement for 1917-1918, index to technical bulletins. No. 327 — Clover vs. alfalfa for milk production: Discussion and summary tables of feeds, production, groups of cows used and individual summaries. No. 328 — Livestock vs. grain farming: Relative profits in livestock and grain farming, labor required in both types, crops and fertility considerations. No. 329 — The peach tree borer: Life history and habits, natural enemies, testing of remedies for control, recommendations for control. No. 330 — The mineral metabolism of the milch cow: Minerals needed by dairy cattle, feeds that supply minerals, the practice of feeding bone flour, the necessity of legumes in the ration. No. 331 — The farmers' elevator movement in Ohio: Early history, loca- tion, methods of operating and suggestions for organizing companies- No. 332 — Destructive insects affecting Ohio shade and forest trees. No. 333 — Apple blotch, a serious fruit disease. No. 334 — Dairy production in Ohio: Results of cooperative tests, costs in production and suggested methods of fixing milk prices. No. 335 — Effect of age of pigs on the rate and economy of gains. No. 336 — The maintenance of soil fertility: A quarter century's work with manure and fertilizers. No. 337— Ohio weather for 1918. No. 338 — Thirty-eighth annual report : Projects under investigation, finan- cial statement for 1918-1919, index to technical bulletins. \ CIRCULAR NO. 36 FEBRUARY, 1919 MICHIGAN AGRICULTURAL COLLEGE EXPERIMENT STATION HORTICULTURAL SECTION PLANTING THE RURAL. SCHOOL GROUNDS . By C. P. HALLIGAN EAST LANSING, MICHIGAN 1919 PLANTING THE RURAL SCHOOL GROUNDS General Aim Any plan for the improvement of the school grounds should first of all be simple. No elaborate or pretentious effects should be attempted in their development. The primary aim should be to retain and increase the natural beauty of the surrounding scenery, making the grounds a beauty spot in the rural landscape, rather than a formal, artificial, or imported element in the scenery. A school ground should possess the same general character of beauty as is indigenous to the neighborhood, making it appear not as some- thing separate and distinct from the surroundings, but as an attractive and pleasing portion of the general landscape. Use of Native Plants . For these reasons the trees, shrubs, and plants that are used to develop the rural school grounds can well be of the kinds found in the neighboring fields and woods. Such plants will be naturalistic and harmonious in the landscape, and better adapted to the climatic and soil conditions of the place than some exotic plants that might be purchased from a nursery. Therefore, the expense that might be incurred in purchasing plants for this work should not detain ambitious teachers from developing the school grounds. Nursery plants of the kinds most adapted to the conditions are easier to transplant successfully because of their more branched and fibrous root systems, but similar kinds from the fields may be successfully trans- planted if the work is carefully and properly done. The interest and enthusiasm of children may be aroused for this work by arranging field excursions in the early spring, — which is the season when the plants should be transplanted, — to fields and woods, where they may be found, and where under the teachers' direction they may be carefully dug and then transferred to the school grounds. The earlier in the spring this work is done, the better are the chances of success. The aim in digging should be to retain as many of the roots as practicable and to keep them moist and protected from exposure to sun and wind. In so far as it is some- times difficult to identify many of the plants in early spring when there is no foliage upon them, it is often desirable to have field excursions in the early fall while the leaves are still on the plants and to mark such plants as are desired for spring planting. Such an excursion could be made in con- nection with a lesson in Botany or Nature Study work. The Planting Plan Before the planting is started a plan should be drawn to a definite scale (say of 1" to 100, showing the size and location of all existing buildings, walks, drives, plantings and boundaries of the property. With this data as a basis a complete planting plan of the property may be made. The execu- EXPERIMENT STATION BULLETIN. 3 lion of the plan then may be gradual. 'The most important parts may be (leveloi)e(l first and the others a* circumstances permit. Such a plan will ihen serve as a definite record for future reference, and will tend to insure the progressive development of the scheme that otherwise might be for- gotten. Where to Plant Trees should be planted about the boundaries of the property for shade and general protection against the winds; also in the rear of the buildings to produce a proper back ground. The trees may be arranged to enframe the building and tr hide undesirable views either within or without the property. 1 lardy shrubs are especially desirable in masses or groups about the boundaries of the Uvvvn, and about the foundation of the school building; also in front of the out-buildings and other undesirable elements, as screens, and sometimes as a hedge to take the place of an undesirable fence. Vines may be used to cover walls, fences, out-buildings, banks or may be trained about the entrance of the porch. With wooden buildings they should not be used to cover the sides of the structure as they are very apt to induce the wood to decay. Rules for Planting- The following general rules should be observed in planting: 1. Preserve as many of the fibrous roots as possible. 2. Expose the roots as little as possible to the drying influences of the sun and wind. 3. Prepare the roots for planting by cutting away the bruised and broken portions. 4. Plant an inch or two deeper than the plant stood in the field. If the soil is very sandy, the plants may be set two to four inches deeper. .">. Dig the hole in which the plant is to be set deep enough to receive two or three inches of fine top soil before putting the plant in place, and make1 it wide enough to allow the roots to spread in their natural position without, crowding. 6. See that good friable surface soil is firmly packed beneath and over the roots. Native Plants Available A suggestive* list is here given of the more common native plants, that may be available in neighboring fields, for improving the rural school grounds : NATIVE TREES Sandy Soil . Medium to Heavy Soils Jack Pine Sugar Maple Elm \\hite Pine White Spruce Red Maple Carolina Poplar White Oak Linden Red Oak Beach Alder Sassafras W'hite Cedar Hemlock Large-toothed Aspen Tulip tree Swamp Oak White Birch Iron-wood Peach-leaved Willow Red Cedar American Ash Black Willow Hawthorn Black Walnut Flowering Dogwood Sycamore Sheepberry Hop-tree 4 PLANTING THE RURAL SCHOOL GROUNDS. NATIVE SHRUBS AND HERBACEOUS PLANTS Prairie Rose (Rosa Setigera) Wild Rose (Rosa Carolina) Staghorn Sumac Black-berried Elder Dwarf Sumac Hazel Sand Plum Button Bush Prairie Willow Red Dogwood Bush Honeysuckle Winter Berry or Black Alder Common Juniper Shad Bush Trailing Juniper Spice Bush Sweet Fern Willows (Several native varieties) Common Braken Fern Flowering Raspberry New Jersey Tea Black Haw Wild Rose (Rosa Humilis) Arrow-wood Red Elder (Shade) Hardback Meadow Sweet Bladdernut Snowberry Indian Currant Sweet Gale Christmas-fern (Shade) Ostrich-fern (Shade) NATIVE VINES Bitter Sweet Virginia Creeper Honeysuckle Moonseed Wild Grape A420-220-15M-L TEXAS AGRICULTURAL EXPERIMENT STATION AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS W. B. BIZZELL, President CIRCULAR NO. 20 FEBRUARY, 1920 PATCH-BUDDING LARGE LIMBS AND TRUNKS OF PECAN TREES B. YOUNGBLOOD, DIRECTOR College Station, Brazos County, Texas CIRCULAR No. 20. FEBRUARY, 1920. PATCH-BUDDING LARGE LIMBS AND TRUNKS OF PECAN TREES BY J. A. EVANS.* It is sometimes estimated that there are 100,000,000 wild pecan trees in Texas. Certainly it would be within the mark to say there are half that number, and possibly one-half of these trees are small enough in size to make it practical from an economic standpoint to top-work them. A pecan tree to be classed as good, must, first of all, be a heavy and regular bearer. After that, it must bear nuts of fair to large size, of thin shell, full meat, and rich flavor, and the shell must crack easily and part readily from the kernel. From time prehistoric to the present, every such tree has been known and visited by the whole nut-eating range of the animal kingdom — from jaybird to wild turkey, from squirrel to wild hog, and from Indian to sorry white man — and very few, if any, of the nuts escaped to germi- nate. It was the little hard nut that got by and produced the next generation of trees. Thus it can be seen that the general trend in the process of evolution has been one of deterioration in point of fruit. Out of all the millions of trees in Texas there are probably not more than twenty that are really worthy of propagation by budding and graft- ing— that is to say, there is a very limited number of trees of surpass- ing excellence from which buds should be taken, and from none other. Since it is possible by the use of these buds to transform a tree that bears a light crop of poor nuts into a tree that will bear a heavy crop of good nuts, something of the importance of this work may be com- prehended. Realizing this importance, some of the pioneers in pecan culture set about the work some twenty years ago, but with very limited success. The universal custom in the beginning was to cut the trees back severely — in fact to mere stumps — in order to force out new sprouts on which to bud. Some of these sprouts were removed, being very numerous, and the others were Dudcled when large enough. It was very weaken- ing to the tree to be deprived of most of its leaves during the season, but that was not the end of it. The budded sprouts must in turn be cut back in order to force new growth from the inserted buds. Thus the tree was deprived of most of its leaves the second season, and con- tinued to suffer an in sufficiency for two or three years more. In their weakened condition the trees fell easy prey to borers, and many of them *Pecan Specialist, Extension Service, A. and M. College of Texas, in cooperation with Texas Agricultural Experiment Station. Figure 1. — The patch bud. — 5— dii-d during drouths. Of those that managed to live, few regained their former vigor. The first improvement over the old system came with the introduc- tion of the bark graft. Why not insert a graft under the bark at the ends of the stubs when the tree was cut back early in the. spring? If the graft should unite and grow, the second cutting would not be neces- sary : and if it failed to unite, the sprouts would come just the same. Unquestionably this was an improvement; but still the first cutting was necessary, and a high percentage of success was very difficult to obtain with the bark graft. Moreover, the nature of the union was such as to render splitting-oflf likely by the force of the^wind against the vigorous new growth. TT jiving in mind the importance of the work and the weak points in the systems previously followed, the Texas Agricultural Experiment Station set about finding a mean? of top-working trees of considerable size without cutting them back, while at the same time securing a high percentage of successful operations. Tt lias been discovered that it is not necessary to have young sprouts with thin bark as stocks for budding. Buds can be successfully placed on limbs of any size, theoretically, though it is not practical to place them where the limbs are more than two inches in diameter, as the wound made by cutting back, after the bud has united, will be too long in healing over. The limiting factor in the size of limb or trunk to be budded is the -wound made by cutting back, just as is the case with grafting. Any limb that is not too large to be cut b&ck for grafting is not too large to be budded. Figure 1 will make the operation of patch-budding in thick bark quite clear. Before the bud from the scion is inserted, the bark of the stock should be trimmed down thin to match the bark of the bud. The pared place should be about two inches long and one and a half inches wide. « One must be careful not to cut through the phloem cells in the bark of the stock while doing the paring. After the bud-patch from the scion has been placed in the matrix and tied in as shown in Figure 1, the whole pared surface, including the edges of the matrix, should be lightly waxed over to prevent drying out through evaporation. It is not necessary to wax jover the bud segment as its outer bark has not been disturbed. Following is the recipe for the wax used: "Rosin two parts and beeswax one part. Melt together and set off to cool. When it is nearly ready to resolidify, pour in wood alcohol, stir- ring all the while. Continue till the mass is bright yellow in color and quite soft. The quantity of alcohol necessary is about two-thirds the volume of the other combined materials. Grain alcohol is best; wood alcohol will do, but denatured alcohol will not do. The binding strings should be cut about three weeks after the buds were put on. The strings are likely to cut into the bark and interfere with the circulation if left for a longer period. In fact, it is thought that many buds are killed by the strings in this way. Experiments with rubber bands instead of strings showed a higher percentage of living buds. If the rubber bands are used they need not be cut at all, as they will decay from the action of the wax and will break before the three- weeks period is out. — 6— Figure 2. — Pecan tree after budding. —7— The buds will have formed a good union by the end of three weeks if they are ever going to do so and the budded branches should then be cut off at a point a foot beyond the buds in order to force them out. Some branches just above the buds should &lso be cut off close to the tody of the tree so as to let in the light and air and to leave room for the new growth from the buds. iMgure 2 is a photographic reproduction of a tree worked by this method on the grounds of the Experiment Station at College Station, Texas, April 7, 1919. The tree is six inches in diameter a foot above the ground, and the four budded limbs range from an inch to two inches in diameter near the body of the tree. Each of the four branches grew toward one of the cardinal points of the compass, and their arrangement, one above another, obviates the formation of a crotch. Not so much as a single leaf of this tree was cut at the time of budding, and had the buds not lived the tree would have been neither mutilated nor weakened. Examination three weeks after budding, however, showed the buds to have united, and the branches were then cut as above suggested, and all branches above the budded ones were removed for a distance of three feet. The growth from the buds is now (November 26, 1919) from two to three feet in length, and is in vigorous condition. The top of the tree will be cut out just above the topmost budded limb before the sap rises in the spring, and the forced growth of the budded portion will soon provide leaves enough to perform the full functions of a top. A tree three inches in diameter that had grown in a forest and had no low branches for budding had a new head formed in this way. The buds were placed on the trunk of the tree five or six feet above ground, and were forced out, not by cutting off the top of the tree, but by wounds just above the topmost inserted bud. Each wound was a slight saw-cut directly above the bud to be forced. The combined effect of the wounds was not sufficient to entirely obstruct the passage of elab- orated plant foods, but each wound did obstruct the pathway of passage to its particular bud, and thus forced it out. The top of this tree will be removed before spring. All remarks about forcing buds apply, in point of time, to only those operations performed before midsummer. Buds put on after that time should be left dormant till the following spring, when the same methods of forcing should be applied. BULLETIN No. 466. SEPTEMBER, 1919. (4 *i& orlt Jyrioilittral ^^m , 1ST. Y. SPRAYING LAWNS WITH IRON SULFATE TO ERADICATE DANDELIONS. M. T. MUNN. PUBLISHED BY THE STATION. BOARD OF CONTROL. GOVERNOR ALFRED E. SMITH, Albany. COMMISSIONER CHARLES S. WILSON, Albany. IRVING ROUSE, Rochester. FRANK M. BRADLEY, Barkers. CHARLES C. SACKETT, Canandaigua. CHARLES R. MELLEN, Geneva. JOHN B. MULFORD, Lodi. C. FRED BOSHART, Lowville. PARKER CORNING, Albany. OFFICERS OF THE BOARD. COMMISSIONER CHARLES S. WILSON, WILLIAM O'HANLON, President. Secretary and Treasurer. STATION STAFF. WHITMAN H. JORDAN, Sc.D., LL.D., GEORGE A. SMITH, Dairy Expert. Director. GEORGE W. CHURCHILL, Agriculturist and Super- tendent of Labor. REGINALD C. COLLISON, M.S., Agronomist. JAMES E. MENSCHING, M.S., Associate Chemist (Agronomy). JAMES D. HARLAN, B.S., Assistant Agronomist. WILLIAM P. WHEELER, First Assistant (Animal Industry). ROBERT S. BREED, PH.D., Bacteriologist. HAROLD J. CONN, PH.D., Associate Botanist. JOHN BRIGHT, M.S., GEORGE J. HUCKER, M.A., Assistant Bacteriologists. FRED C. STEWART, M.S., Botanist. WALTER O. GLOYER, M.A., Associate Botanist. MANGEL T. MUNN, M.S., Assistant Botanist. Lucius L. VAN SLKYE, PH.D., Chemist. RUDOLPH J. ANDERSON, PH.D., Bio-Chemist. ARTHUR W*. CLARK, B.S., RICHARD F. KEELER, A.B., Associate Chemists. MORGAN P. SWEENEY, A.M., OTTO MCCREARY, B.S., WILLIAM F. WALSH, B.S., WALTER L. KULP, M.S., HAROLD L. WEINSTEIN, B.S., Assistant Chemists. Address all correspondence, not to individual members of the staff, but to the NEW YORK AGRICULTURAL EXPERIMENT STATION, GENEVA, N. Y. The Bulletins published by the Station will be sent free to any farmer applying for them. FRANK H. HALL, B.S., Vice-Director; Editor and Librarian. PERCIVAL J. PARROTT, M.A., Entomologist. HUGH GLASGOW, PH.D., *FRED Z. HARTZELL, M.A., (Fredonia), Associate Entomologists. ROSSITER D. OLMSTEAD, B.S., C. R. PHIPPS, B.S., Assistant Entomologists. ULYSSES P. HEDRICK, Sc.D., Horticulturist. *FRED E. GLADWIN, B.S., (Fredonia), ORRIN M. TAYLOR, Associate Horticulturists. GEORGE II. HOWE, B.S.A., WILLIAM C. STONE, M.S., EDWARD H. FRANCIS, M.A., T. E. GATY, B.S., Assistant Horticulturists. F. ATWOOD SIRRINE, M.S., (Riverhead), Special Agent. JESSIE A. SPERRY, Director's Secretary. FRANK E. NEWTON, WILLARD F. PAT CHIN, LENA G. CURTIS, MAE M. MELVIN, MAUDE L. HOGAN, K. LORAINE HORTON, Clerks and Stenographers. ELIZABETH JONES, Computer and Mailing Clerk. *Connected with Grape Culture Investigations. BULLETIN No. 466 SPRAYING LAWNS WITH IRON SULFATE TO ERADICATE DANDELIONS. M. T. MUXN. SUMMARY. Experiments made at the Station during the past eight years demonstrate that dandelions may be eradicated from lawns, at rela- tively slight expense and without material injury to the grass, by proper spraying with an iron sulfate solution. Ordinarily, four or five applications are required. The first spraying should be made in May just before the first blooming period. One or two others should follow at intervals of three or four weeks; and, finally, one or two more in late summer or fall. During the hot, dry weather of mid-summer spraying should be discontinued because of the danger of injury to the grass. A conspicuous blackening of the lawn which follows each application soon disappears if the grass is growing vigorously. Of the other common lawn weeds, some are killed while others are but slightly injured by the spraying. Unfortunately, white clover, also, is killed. Spraying should be supplemented by the use of fertilizers and the application of grass seed in the spring and fall of each year. With proper management it is necessary to spray only about every third year in order to keep a lawn practically free from dandelions. The cutting-out method of fighting dandelions is laborious and ineffective unless the greater part of the root is removed. Shallow cutting, unless done frequently, is worse than none at all, because each cut-off root promptly sends up one or more new plants. Tests of certain after-treatment measures in the form of reseeding, liming of the soil, and fertilization with commercial fertilizers and stable manure, used in conjunction with the spraying operations, gave results which serve highly to recommend their use either singly or in combination on lawns. A study of seed production in the common dandelion shows it to be partheno genetic, that is, capable of producing viable seeds with- out fertilization of the ovules by pollen. [21] 22 INTRODUCTION. From experiments conducted at this Station during the years 1909 and 1910 by G. T. French, then Assistant Botanist, and reported in Bulletin No. 335, the conclusion was drawn that the spraying of lawns with iron sulfate solution to kill dandelions is unlikely to prove successful in New York. The apparent failure to kill large, vigorous plants was explained upon the ground that spraying merely kills the leaves, and therefore has only a starving effect upon the roots in the same manner as frequent cutting. However, a survey of the literature of the subject prior to 1912, the time the experiments dis- cussed in this bulletin were started, revealed the almost unanimous recommendation of the use of iron sulfate solution as an effective means of controlling dandelions in lawns. Ir>. 1907, Bolley, in North Dakota, reported the results of experiments conducted between 1896 and 1907. It was stated by this author that a new method of fight- ing dandelions, namely, spraying them thoroly at stated intervals with a differential spray solution made by dissolving two pounds of iron sulfate in one gallon of water will give success, and that the grass need not be injured. This work was more fully discussed in 1908 and some additional measures of control suggested. Again, in 1909, Bolley reported that on large lawns spraying dandelions with iron sulfate is quite practical and the cost, using field sprayers, is less than for mowing. Note was also made of the fact that the iron sulfate has a beneficial effect upon the grass in the direction of the preven- tion of certain diseases of blue grass. In Rhode Island, Adams (1909) found that dandelions may be held in check and practically eradi- cated from lawns by spraying four or five times during the season with a twenty per ct. solution of iron sulfate, but that complete eradication cannot be expected because of the fact that the lawns are reseeded by wind-blown seeds. This investigator reported no injury to the grass when the spraying was done about two days after mowing. Experience demonstrated that the most effective spraying was made in the spring when leaf growth was vigorous and the first buds ready to open. Reseeding of the lawn after spraying was also advised. According to the report of Pammel and King (1909) two sprayings with a twenty per ct. solution of iron sulfate killed many of the dande- lion plants in a plat of lawn at Ames, Iowa. Chickweed, also, was killed. 23 Moore and Stone (1909) reported satisfactory results in Wisconsin from the use of a twenty per ct. solution of iron sulfate sprinkled on lawns with a sprinkling can. Plants not killed by the solution were sprinkled with dry iron sulfate soon after the spraying. This appli- cation killed nearly all the remaining plants and apparently caused no injury to the grass. In South Dakota, Olive (1909) reported that the results obtained from spraying dandelions with iron sulfate were not as favorable as those reported by other experimenters. However, young plants were killed by one application, while old, large plants required three or more applications. This worker suggested that, possibly, continued use of the spray for two seasons would give better results. Selby (1910) mentioned the fact that, in Ohio, tests of iron sulfate show that the first spraying should be made before blossoming of the dandelions, and stated that two or three later sprayings would prob- ably be found advisable. At the time of the preparation of this bulletin for publication »a survey of the literature reporting recent work on dandelion spraying shows that nearly all investigators are agreed that iron sulfate has considerable value as a dandelion eradicato.r. In Canada, JFyles (1913) sprayed dandelions with a solution of iron sulfate, two -pounds per gallon of water, and reported that after the third application the weeds were still living altho much of their foliage was destroyed. After the third application the spraying was discontinued since the injury to the surrounding grass was greater than to*the weeds. No mention is made of the location of the trials, but jt is inferred that they were made on lawns. A little later, however, Howitt (1913) reported that after six sprayings with a twenty per ct. solution (two pounds per gallon) of iron sulfate applied with a knapsack sprayer to plots of lawn containing 168 square feet the dandelions were reduced in number over ninety per ct. Aside from the black discoloration which immediately followed spraying and disappeared in a few days, no permanent injury was caused to the grass. Jn fact, it -was noted the following spring that the grass on the sprayed plats was greener and more luxuriant than on the unsprayed plat. In 19.13 a one- eighth-acre plat was sprayed six times with a power sprayer using a solution of similar strength. The results obtained were said to be as satisfactory as those secured with a knapsack sprayer. At least ninety per ct. of the dandelions were destroyed. The method is 24 recommended for lawns badly infested with dandelions. Reseeding of the lawn is advised as a supplementary measure. During 1914, Arthur reported that, in Indiana, on one area sprayed with iron sulfate four times in 1913 and three times in 1914, most of the dandelions were killed, but that they again appeared during the next three months and later became quite abundant. On another area, sprayed four times during 1914, approximately one-half of the dandelions were killed. After-treatment measures, in the form of liming the soil and reseeding with blue grass seed, were used in these experiments. In a recent and very complete bulletin, Longyear (1918) discussed the life.histqry of the dandelion and some methods of eradication used in Colorado. This experimenter concludes that there is no easy, certain method of exterminating the dandelion or of holding it in check for any considerable length of time. However, it may be kept under control by persistently employing one or more of the fol- lowing methods: (a) careful establishment of the lawn and later heavy reseeding; (b) applying a small amount of gasoline or kerosene to the crown of each individual plant; (c) deep digging of the entire plant; (d) prevention of seed production on the premises; and (e) by spraying infested lawns with a solution of iron sulfate. The last- named method, labor costs considered, proved to be the cheapest and most effective method of eradicating dandelions. THE DANDELION. SPECIES. In New York lawns the common dandelion (Taraxacum officinale Weber) with its showy flowers and ragged, mussy foliage is the one generally found. However, the red -seeded dandelion (T. erythros- permum Andrz.) occurs occasionally. The red-seeded dandelion is readily distinguished from the common dandelion by its smaller, sulphur-yellow heads, glaucous bracts, more finely cut leaves and bright red or red-brown seeds with very fine grayish- white pappus. The common dandelion has orange-yellow heads, coarsely pinnatifid and bluntly lanceolate leaves, and olive-green or brownish seeds with short .hard points. In both species, when the blossom appears, the double row of bracts which encloses the many-flowered head spreads apart and exposes them. The inner involucre closes after 25 blossoming, and the slender beak of each flower elongates and raises the pappus of capillary bristles while the fruit is forming. The whole involucre, which is a double row of bracts, is then reflexed, exposing the nearly mature naked achenes or fruits with the pappus in an open globular head ready to be widely distributed by the wind. PROPAGATION. The dandelion is propagated by seeds. However, when once it has gained possession of the soil it will hold on to it persistently, per- petuating itself by heavy seeding, and also by its large, thick, fleshy, deeply-penetrating roots which resist occasional cutting by sending up new sprouts as discussed later in this bulletin. PARTHENOGENESIS AND SEED PRODUCTION. Seed production is an important phase in the life history of the dandelion since it is the one important means of distribution of the plant. At the outset of the work with dandelion eradication a study of the problem of seed production was started. The belief seems to be quite generally prevalent that the transfer of pollen from the stamens to the stigma of the pistil is necessary before seeds can be produced on the dandelion. However, in the common dandelion (Taraxacum officinale), at least, pollination is not only unnecessary, but may be, perhaps, altogether unimportant as a factor in seed production. Evidently, parthenogenesis, or apagamous development of the embryo, occurs in this species. As early as 1903, Raunkiaer performed some experiments on several forms of Taraxacum by employing a method of castration in which both anthers and stigmas of unopened buds were sliced off with a sharp knife. From the results of his work he announced that dandelions in Denmark are parthenogenetic; that is, they produce fruit freely without fer- tilization. Juel (1904), and later, Murbeck (1904), followed up the work of Raunkiaer with careful cytological investigations of the tetrad formation in the ovule, and found that parthenogenesis does occur in the genus Taraxacum. Murbeck studied Taraxacum vulgare which produces abundant, but imperfect pollen, and T. speciosum which produces no pollen at all. However, Dahlstedt (1904) stated that, in Belgium, there are two or three species of Taraxacum in which pollination seems necessary. Schkorbatow (1910), as a result of his studies of parthenogenesis in the genus Taraxacum, stated that 26 the removal of the anthers of the flowers does not in any way affect the germination of the seeds. According to Ikeno (1910), Handel- Mazzetti, in a monograph of the genus Taraxacum, states that hybrids appear among the species of the genus. Therefore, normal fertil- ization may be expected among certain species of Taraxacum. Ikeno (1910) also reported that K. Tanaka, in unpublished results of some work done in Japan during 1908 and 1909 in which Raunkiaer's castration method was used, stated that T. albidum formed seeds parthenogenetically while T. platycarpum did not. Later investi- gations by Ikeno confirmed Tanaka's findings in that T. platycarpum does not form seeds parthenogenetically, while in other forms of Taraxacum both normal fertilization and parthenogenesis occur. All of the experiments and studies concerning seed production made by the writer and herewith reported were made with Taraxacum officinale Weber. During the month of May, in the years 1914 and 1915, a number of dandelion buds were enveloped within parchment paper sacks just before they opened. At the time the heads on the same and adjoining plants had produced seeds the sacks were removed. Seeds apparently normal in size, color, and all other respects were formed on the heads enveloped within the sacks, indi- cating that parthenogenesis, cross-fertilization between flowers of the same head, or self-fertilization had occurred. Some experiments designed to test the effect of pollen from other dandelion flowers yielded inconclusive results, tho giving some indication that fertili- zation with pollen may occur. On May 26, 1919, a considerable number of dandelion plants which still held unopened buds were located. With a sharp razor the stamens and pistils together with the upper portion of the two sets of green bracts were sliced off as close as possible to the ovary, and then the head was enclosed in a parchment paper envelope which was secured upright to a stake driven beside the plant. After a number of plants were treated in this manner a series of buds were castrated in like manner and left uncovered; that is, they were not enclosed in envelopes. On June 5 both the bagged and unbagged heads had produced seeds. The seeds from each head were collected in separate bags and later (on June 11) placed in a germination chamber along with separate lots of seeds from adjoining untreated seedhheads which served as checks. The germination tests of these seeds were made by placing them between sheets of blue blotting paper 27 in a germination chamber maintained at a temperature of 20° C. for the first 18 hours and 30° C. for the remaining six hours of each day. The results of a single test will be given here. They are as follows: TABLE 1. RESULTS OF GERMINATION TESTS OF SEEDS FROM CASTRATED AND UN- CASTRATED DANDELION FLOWERS. DATE. NUMBER OF SEEDS GERMINATED. Flowers castrated and bagged Flowers castrated but not bagged. Check. June 11 Test started June 17 5 18 13 6 44 11 5 39 58 10 1 1 0 0 14 4 1 19 50 3 4 5 1 1 24 11 9 33 55 9 June 19 June 23 June 26 June 30 July 5 July 9 July 14 July 19 July 21 Total number germinated 209 761 970 21 93 73 166 56 152 62 214 71 Total number not germinated Total number tested Percentage germinated From the results of these tests it seems quite evident that parthen- ogenesis does occur in Taraxacum officinale. This conclusion is in accord with the evidence produced first by Raunkiaer and later by other investigators. Also, it appears that a certain amount of normal fertilization may occur if one is to base judgment upon the difference in germination percentage between the seeds of check plants and those of unbagged castrated flowers. The lower ger- mination of seeds from bagged flowers as compared with unbagged, castrated flowers may have been due to certain factors or abnormal conditions resulting from bagging. GERMINATION OF THE SEED. In germination tests of dandelion seeds collected from lawns it was found that some of the seeds were matured sufficiently to ger- 28 minate as soon as they begun to bave the plant; and the percentage of germination increased directly in proportion to the degree of maturity. Flower heads cut off with a lawn mower immediately after blossoming failed to produce seeds capable of germination. Therefore it seems safe to conclude that a lawn clipped regularly and at least once a week will not be a source of contamination for clean lawns in the neighborhood. However, some seed heads which lie close to the ground escape the mower blades. These must be removed by hand picking or with a dandelion rake if seed formation is to be entirely prevented. In the germination tests of the seeds used in the study of partheno- genesis it was found that a quicker response was secured when the range of temperature was greater than that ordinarily used, i.e., when the temperature was permitted to rise to 38° C. for a very short time. Also, it was found advisable to place a small piece of folded blotting paper along with the seeds between the folds of paper to facilitate aeration. DANDELION ERADICATION EXPERIMENTS. ERADICATION EXPERIMENTS AT THIS STATION PRIOR TO 1912. The results of lawn spraying experiments conducted by French (1911), while showing the iron sulfate treatment to be partially successful, did not seem to warrant its recommendation as a practi- cable method of control. A strip of lawn was sprayed six times during each of two successive seasons, using, the first season, 1.5 pounds, and the second season, 2 pounds of iron sulfate in each gallon of water. While this treatment prevented blooming of the dandelions, and even killed many of the plants, a considerable number remained alive when the experiments were necessarily discontinued at the middle of the second season because of severe injury to the grass. Apparently, the stronger solution used the second season caused considerable injury to the grass as mid-summer approached and the rate of growth of the grass decreased owing to unfavorable weather conditions. In summarizing the results of his experiments with iron sulfate solution, French stated that it was not clear why dandelion spraying should fail in New York when it had been successful elsewhere. He further stated that " the failure of the treatment seemed to be due to the great vitality of the dande- lion roots." In an attempt to throw some light upon the question of the vitality of the dandelion roots French removed the tops from two plants by cutting just below the crown. This was done suc- cessively as soon as new leaves had unfolded for eight times when both plants succumbed to the treatment. French reasoned from these results that if dandelions could withstand six or seven cuttings they could survive as many sprayings, or possibly more, since spraying did not remove the tops as completely as did the cutting. THE EXPERIMENT IN 1912. Since the experiments of 1909 and 1910 had not met with the success which seemed to be characteristic of the trials with iron sulfate on dandelions conducted elsewhere, it was deemed advisable to give the method a further test. Work was continued this year by laying off a plat 15 feet wide and 100 feet long in an old lawn which was well sodded over with Kentucky blue grass and red top grass, but badly infested with dandelion plants. This lawn was on a clay loam soil and in all particulars typical of the average lawn in this state. This strip of lawn was sprayed with iron sulfate seven times during the season and at the rate of approximately 100 gallons per acre, slightly over four gallons of the solution being, used on 1500 square feet at each application. The spray solution was applied with a compressed-air sprayer and contained one and one-half pounds of iron sulfate to each gallon of water. The spray was applied at intervals of three weeks for the first three months, or during the vigorous growing season, and approximately once per month -during the remainder of the season. The last spraying was made on Sep- tember 20. The first spraying was made on May 4, at a time when the first blossom heads were opening. After each application of the solution the grass in the sprayed area was badly blackened, and remained unsightly for several days. It was noted, however, that the weather conditions at the time of the application had con- siderable to do with the extent of blackening and the period of time which elapsed before the normal appearance of the lawn was regained. The blackening of the grass was more marked and was retained longer following the sprayings made in the mid-summer months when periods of dry weather prevailed. It was during these periods when the severest injury to the tips of the grass leaves occurred. 30 Shortly following the fifth spraying, made late in July, it was noted that the grass in the sprayed area showed a darker green color than did the adjoining unsprayed lawn. This darker green color appeared to be cumulative as the season advanced. At the time of the last spraying, September 20, the sprayed area was very clearly dis- tinguished by the darker green color of the grass (Plate I, fig. 1), also there were but few living dandelion plants remaining in the plat. The final spraying for the season killed the foliage on all the dandelion plants in the sprayed area to such an extent that less than thirty plants showed any green foliage when the fall season came to a close. As far as the killing of the dandelion plants was concerned, the ex- periment was a decided success. Experience seemed to indicate that five sprayings or, possibly, fewer would have secured the same results. The sprayings which could well have been omitted were those made during the latter part of July and in August. THE EXPERIMENTS IN 1913. PLAT 1. In the spring of this year, at the active blooming period, the clear sod of the sprayed area of this plat presented a marked contrast to the adjoining untreated area which contained countless numbers of dandelion plants in bloom (Plate I, fig. 2; also Plate II). The eradication of the dandelion plants in this plat was so complete that it was unnecessary to spray this season. However, it was evi- dent that the bare spots left by the dead dandelions would soon be reoccupied by other dandelions from seeds unless something were done to prevent it. Clearly, the advantage gained by spraying should be followed up next spring by reseeding with grass seed to cover the bare spots before dandelions could take possession of them. Also, it was evident that the lawn grasses had been slightly injured leaving some of the coarse weed grasses, such as crab grass, more in evidence. During this season various tests in the form of after-treatment measures were conducted, having in view the hastening of the healing of the scars left by the dead weeds, and the renovation of the turf. These treatments consisted of the use of fertilizers alone, seed alone, and combinations of fertilizer and seed upon sections of lawn s • 5 '~. w £ PH **"> X o> [V] M o o 2 2 £ CD §•3 31 (25x45 ft.) which included both sprayed and unsprayed areas. 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Live oak Chinese arborvil Arborvitae Rosedale arbon C —12— DESCRIPTION OF TREES MAPLES — There are six maples which grow naturally in Texas, only two of them being desirable shade trees, however. These are the silver maple and the sugar maple. Another species, the ash-leaved maple, or box elder, has been successfully introduced in some parts of the state. SUGAR MAPLE (Acer saccharum)—Th]s is a hardy tree with a compact oval crown; native in East Texas. It is an excellent tree in good noil with plenty of moisture, but will not do well under city con- ditions. In suburban situations and on lawns it has a distinct value, SILVER MAPLE OR SOFT MAPLE (Acer saccharinum)—^ fast growing tree with leaves dark green above and silvery beneath. The tree is rather short-lived with brittle branches. It is difficult to keep silver maple trained properly, and, furthermore, it is often injured by scales and borers. BOX ELDER (Acer negundo) — A tree similar in most characteris- tics to silver maple. The leaves are not silvery on the under side. The same advantages and drawbacks which apply to silver maple are also applicable to box elder. TREE OF HEAVEN OR PARADISE TREE (Ailanthus glandu- losd) — An Asiatic tree introduced to this country many years ago. It is a very rapid grower in its youth but soon becomes straggly and un- kempt. The leaves are compound and frond-like. Male and female flowers are borne on separate trees. While the seeds of the female plants are a nuisance they are less objectionable than the disagreeable odor of the staminate flowers. Its habit of sending up root suckers makes the tree of heaven rather undesirable, but under severe city conditions where smoke, dust and insufficient root space make it impossible to plant other trees the tree of heaven will survive and do fairlv well. HARDY CATALPA (Catalpa speciosa)— There are two catalpas native in the central states. However, common catalpa is a very un- satisfactory shade tree. It may be distinguished from hardy catalpa by the narrow pointed tuft of hair on the ends of the seeds, whereas hardy catalpa has a broad tuft. Catalpa is moderately fast growing and short-lived, quickly developing an uneven crown with bare branches crowned by bunches of large heart-shaped leaves. PAPER MULBERRY (Broussonnetia papyrifera) — A small Asiatic- tree with cordate or three to five lobed leaves, hairy beneath. This tree is rather short-lived and inclined to be bushy, having a round head. It is liable to frost injury but is able to stand severe drouth and soil alkalinitv. •fc HACKBERRY (Celtis occidentalis)—The hackberry is a medium- sized drouth-resistant tree with an oblong open crown. In Eastern Texas it is severely attacked by borers and leaf gall insects. The hack- berry is short-lived except under favorable soil and moisture conditions,, and accordingly other trees should be given preference in general. It reaches its best development as a street tree in Central Texas. —13— SUGARBERRY (Celtis mississippiensis) — A tree with habits sim- ilar to hackberry. The leaves are large and smoother and the tree reaches a larger size and greater age than the huckberry. Useful in Central and Southwestern Texas. DESERT WILLOW (Cliilopsis Unearis)—A native of the West Texas draws. It stands drouths and much alkali. It is a small tree with showy flowers and long cylindrical seed pods. The leaves are linear. It is not regular in form, being similar to mesquite and willow in this regard. A desirable tree under severely dry conditions. ORANGE (Citrus sp.) — Various citrus fruit trees are used to ad- vantage as shade trees along the coast below Corpus Christi. Abovo Corpus Christi citrus trees are often seen but they do not reach the same development that they attain further south and are frequently injured by frost. They are medium sized to small trees with even rounded crown and dark green glossy leaves, being more useful for lawns than for street planting. They will not stand much frost. RUSSIAN OLIVE (Elaeagnus angustifolia) — A handsome silvery- leaved medium sized tree. It has a broad rounded head with a rather irregular branching system similar to willow or mesquite. It stands drouth and alkali, showing remarkably fast growth. It needs some pruning to make a good shade tree for street purposes. BLUE GUM (Eucalyptus globulus^ — Useful for planting along the gulf coast. Freezes back at Port Arthur. A tree reaching great size and age, of very rapid growth, causing roots to ruin walks, sewerage systems and street pavements. Should be planted on wide avenues where it can have some protection, as it will not endure a temperature below 24 degrees Fahrenheit when young. It needs a humid climate with good soil for proper development. With shallow soil or insufficient soil moisture the growth of all eucalyptus trees is seriously retarded. Other varieties may prove successful in Texas but have not been tried out extensively as yet. RED GUM (E. rostrata) will stand a temper- ature of 13 degrees after it becomes established and shows some promise for the Southern coastal region. WHITE ASH (Fraxinus americana) — This ash is native in East Texas, growing in moist rich soils. The white ash is a large, well-formed tree, fairly clean except for the seeds and a good shade tree, more at home on lawns than on city streets, however. GREEN ASH (Fraxinus lanceolata)—This is one of the best shade trees which will grow in West Texas and the Panhandle. It is some- what smaller and shorter lived than white ash and stands a dry climate with alkali very well. It is fairly clean, does not break up and makes a shapely tree. MAIDENHAIR TREE OR GINGKO (GingJco Uloba)—This is a Chinese tree introduced into the United States a number of years ago. Although it has not been planted extensively in Texas it has shown promise in the northeastern and central black land districts. It cannot be recommended strongly as yet because sufficient data on its adaptability is lacking. The pecan is the State tree. This one is a vigorous young specimen on the A. & M. College grounds. Except in Southwest Texas and the Panhandle the pecan is one of our best shade trees. The bois d'arc forms an excellant broad spreading crown. This tree in Denton, Texas, is growing in the region of its best development. — 15— HONEY LOCUST (Gleditsia triacanthos)—A tree with light feath- ery foliage bearing long seed pods which are somewhat of a nuisance. It has a rounded head with stout branches and a strong root system. The thorns are objectionable, but a thornless variety (G. inermis) is offered for sale by most nursery dealers. It is a desirable tree for dry regions. PECAN (Hicoria pecan} — The pecan has been designated the official state tree and as such it deserves a special mention. An excellent shade tree and a valuable nut tree, this species is an unusually desirable one to plant in the region of its best development. In the western part of the state it will thrive if given some cultivation and water. The pc-can is rather hard to transplant and its growth is not rapid but it produces a uniform oval crown, is fairly resistant to insects and disease, and is an abundant producer of excellent nuts. This last fea- ture is objectionable where trees are along highways because of the break- age which results when nuts are clubbed off, a situation which frequently arises. HICKOEY (Hicoria spp.) — There are several varieties of hickory which grow in East Texas, bitternut, shagbark, pignut, nutmeg and others. All of these would make fair shade trees were it not for their exceptionally slow growth. They require good moist soil and cannot compete with elm, ash, sweet gum and many other faster growing trees. BLACK WALNUT (Juqlans nigra)—The walnut is an exceUent shade tree. It has a dense crown, is hardy, grows fairly fast, produces- excellent nuts and the most valuable wood of any tree grown in Texas. It needs considerable cultivation and should be planted where it will receive a good supply of moisture. VARNISH TREE, PRIDE OF INDIA (Koelreuterw paniculata) — This tree is an exotic from Asia. It appears to stand alkali and low precipitation. It is grown in Kansas and Missouri and should do well in Western Texas. The varnish tree is rather short-lived and does -not reach a great size but should be well suited to narrow streets. SWEET GUM, RED GUM (Liquidamber styradflua)—The swept gum is one of the best trees for shade in East Texas. It has a sym- metrical oval crown, star shaped leaves, and bears small spiny balls of seeds which are attractive in winter. It is a rather fast grower, long- lived and reaches a large size. It should be used in suburban situations since it is not adapted to severe city conditions. TULIP TREE, YELLOW POPLAR (Liriodendron tulipifera)- The largest broad-leafed tree of the Atlantic coast. Although not native to Texas it makes an admirable shade tree where the .soil is rich with good drainage. It has a round head with persistent cone-like fruits. It is hard to transplant and needs plenty of room. CHTNABERRY (Melia azedarach) — The chinaberry is an Asiatic tree which is much used for a shade tree throughout the state. It is a densely foliaged tree, with. brittle wood, and irregular open crown and an abundance of white waxy fruits which make it an untidy tree for planting near sidewalks. It grows remarkably fast but quickly de- —16— teriorates, being especially susceptible to wind breakage and subsequent rot. It is a tree which should be used only where quick results are desired and then more permanent trees, should be used also, to succeed it after a few years. UMBRELLA CHINABERRY, TEXAS UMBRELLA (Melia azeda- rack umlraculifera} — This is an horticultural variety of the preceding species. It develops a flat umbrella-like crown, very dense and regular. It is a very handsome tree and a useful one for formal effects. How- ever, it has most of the defects that the chinaberry has ; brittle branches, much litter, and short period of attractiveness. WHITE MULBERRY (Morus alba)— Introduced from Europe. It does well on dry lands but prefers a moist soil. It is a small tree with a round head, fairly well adapted for street planting, but the berries are objectionable on sidewalks. This is the silk-worm tree of Europe. RED MULBERRY (Morus rubra) — A native tree somewhat larger than the above named species. The red mulberry is hardy and makes a good shade tree in dry regions. The fruiit attracts flies and is a dis- agreeable feature. RUSSIAN MULBERRY (Morus alba tartarica)— This tree, a native of Asia, is hardier than any of the other mulberries, and although it is a small bushy tree, still it has some Advantages for the treeless portion of the state. At elevations, above 1800 feet it is apt to be killed back by late frost. It is not long-lived but is a fairly rapid grower and not a heavy bearer, which is an advantage for shade purposes. OLEANDER (Nerium oleander) — A large shrub or small tree with a wealth of flowers. It thrives along the coast where the winters are not too severe and does well under severe city conditions. SOUR GUM, TUPELO (Nyssa sylvatica)—A. tall tree with slender droo'ping branches. The foliage is dark green and lustrous, assuming attractive shades in the fall. It is a slow growing tree suited to wet situations. The fleshy fruits are a disadvantage. The COTTON GUM (Nyssa aquatica) is very similar to the sour gum. HUISACHE (Acacia farnesiana) — A small thorny tree with fragrant yellow flowers. It makes a fair street tree in Southwestern Texas but is a slow grower and has a somewhat irregular crown. SYCAMORE (Platanus occidentalis) — One of the largest and best shade trees over most of the State. It is a fast grower, develops a large round head of stout branches, and although susceptible to leaf diseases, yet these may be easily controlled by spraying. It is not attacked by insects nor affected by adverse city conditions. Furthermore, although best adapted to wet situations it will thrive with very little moisture and care. ORIENTAL PLANE TREE (Platanus orientalis)—A European tree more enduring of city conditions, and possessing a more compact crown than sycamore, but otherwise similar to it. It is a better tree than sycamore for city purposes, not being affected by leaf blight. —17— COTTONWOOD (Populus deltoides)—A large native tree with trem- bling leaves, found around water courses. It has a shallow extensive root system, suckers badly, and produces considerable "cot-ton," all of which is objectionable in a street tree. It is not a desirable tree for city streets and should be used only in exceptional cases and where plenty of water is available. CAROLINA POPLAR (Populus eugenia.)—A more desirable tree than the preceding species since it grows faster and has a more regular crown. Useful for quick effects on narrow streets. LOMBARDY POPLAR (Populus nigra var. italica)—A tall, slen- der, rapid growing poplar used for formal planting on very narrow streets. It is short lived, shallow rooted, liable to send root suck- ers and objectionable because of the "cotton." EMPRESS TREE, PRIDE OF INDIA (Paulonia imperaUs)—A small, fast growing, Asiatic species with purple flowers. It has large leaves of a tropical appearance and is poorly adapted to planting along streets. MESQUITE (Prosopis juliflora) — The mesquite is a fairly good shade tree in the southwestern part of the state. It is a rather slow growing tree with an irregular crown of light foliage. Its only advan- tage is that it is very hardy and needs very little care. POMEGRANATE (Punica granatum) — A small bushy tree suited to the lower coastal region but not especially adapted to street planting. OAKS — The oaks, as a class, are excellent street trees. They are with a few exceptions strong, well formed, long-lived and not subject to insect attacks. WHITE OAK '(Qmrcus alba) — A rather slow growing, long-lived, round-headed tree, sturdy, resistant, and cleanly. It makes an ideal street tree where there is plenty of water. * BLUE JACK OAK (Quercus cinerea) and BLACK JACK OAK (Q. marylandica) — Slow growing, short-lived trees of the sand hills, poorly suited for street purposes or lawn planting. SPANISH OAK (Quercus digitata)—A tree of good form, long- lived, suited to medium or wide streets. It needs considerable moisture. TEXAS OAK (Quercus texana) — Is similar to the Spanish oak. OVERCUP OAK (Quercus lyrnta] , BURR OAK (Q. rrcacrocarpa) , COW OAK (Quercus michauxM], BLACK OAK (Quercus velutina}, and YELLOW OAK (Q. muhlenbergii) are all desirable shade trees. RED OAK (Q. rulra) SCARLET OAK (Q. coccinea) are also ex- cellent trees for Northeast Texas. WATER OAK (Q. nigra) and WILLOW OAK (Q. pliellos) are fast growing excellent shade trees, but cannot do much on dry sandy land. POST OAK (Quercus minor} — This is a very slow growing but long- lived species. Much prized on lawns where it occurs naturally, but Desirable introduction from the Orient. Japanese varnish trees on the Texas A. & M. College campus. The large leaves, light green, smooth bark and high heads make these good trees for streets or lawns. Poplars and cottonwoods are fast growing trees but are short-lived. This picture was taken on the Texas A. & M. College campus where the compact soil makes it difficult to grow large well -formed trees. —19— seldom planted because of the difficulties encountered in transplanting and raising young trees. BLACK LOCUST (Robinia pseuilocana} — A rapid growing, short- lived, light foliaged tree standing considerable drought and alkali. It makes a handsome .-hade live and is much used in the Panhandle and West Texas. It has a number of drawbacks, however, since it suckers badly and creates considerable litter with the seed pods. Furthermore, in places it is being exterminated by the locust borer (Cyllene robinae). Where the borers are not present it is a valuable lawn and street tree. BLACK WILLOW (Salix nigra) — A fast growing tree useful near water. It is not long-lived, and is too susceptible to disease and insect attacks to make it a good shade tree. Moreover, it is untidy in appear- ance and the shallow roots are ,a nuisance, breaking up walks, killing out grass, and when planted too close to ditches the roots tend to fill them up. CHINESE TALLOW TREE (Sapium sebiferum)—The tallow tree is an Asiatic species which does well in Texas. It makes a medium rate of growth but does not reach any great size. It has leaves similar to cottonwood, making a rather attractive small tree for narrow streets. PAGODA TREE (Sophora japonica) — An Asiatic tree of medium size which makes a moderately fast growth and stands a dry climate. The pagoda tree is a good tree for narrow streets in West Texas. JAPANESE VARNISH TREE (Sterculia platanifolia)—The Jap- anese varnish tree is another Asiatic tree which has found favor in this country. It is a moderately fast growing tree with smooth, light green bark and large leaves, resembling those of the sycamore. It does not form a full crown, but the dense clusters of large leaves on the ends of the branches make a satisfactory shade. This appears to be a desirable shade tree. BALD CYPRESS (Taxodinm distic'hum)—T}ie cypress is a tree best suited to swamps but occasionally excellent specimens are found along road sides and in towns. The cypress is best used where formal effects are desired. It is a rather slow growing tree but a long-lived one, not affected by insects to any extent. SALT CEDAR, TAMARISK (Tamarix spp) — There are several vari- eties of salt cedar all introduced from foreign countries. They are re- markably hardy and make a good growth. Most varieties are shrubs but with training some may assume tree form. They have light feathery fcliiage similar to the cedars but the leaves are shed in the winter time. Only valuable for street purposes where other trees do not grow, par- ticularly in the Trans-Pecos region. BASSWOOD, LIXDEN (TiVn j removed the remaining trees have become crippled and have had their oiMwn symmetry impaired. Parts of the crowns have been suppressed and the trees cannot recover even when the interfering trees are removed. Therefore, the safest thing to do is to space properly in the beginning. The distance apart will vary for different species and for the same species in different soils and climates. In East Texas and in rich bot- tom lands the trees will need ten to fifteen feet more room than in dry situations with poor soils. Trees suited to narrow streets should be spaced about thirty feet apart, those for medium width streets forty feet -and those adapted to wide streets will need fifty or more feet of space when they are mature. Normally trees are planted abreast on opposite sides of a street, but where wide spreading trees are planted along narrow streets it may be advisable to alternate them. On lawns, trees are best planted informally in groups rather than in rows. In no case should trees be placed at the corner of intersecting streets, since in such locations they are especially liable to injury by pedestrians or by teams and automobiles if there are no curbings. Furthermore, who ii the trees are young they will obstruct the view of vehicles and interfere with traffic. Trees should be uniformly spaced in regular rows for 'Symmetrical results. They should be so placed that they will not interfere with wires, otherwise they will be mutilated by linemen, or to avoid this it will be necessary to cut the tops back below the wire. On lawns and private grounds a row of trees or a group may be needed to screen an outbuilding or to give a sense of privacy to the home. In general, there will be no formal planting in rows or along geometrical lines. Informal grouping to simulate the natural occurrence of trees in parks should be done. Trees in cities are living under unnatural conditions. A deficiency in moisture and sun light, combined with excessive smoke and dust, make it imperative that the soil conditions be as favorable as possible. A hole four feet square arid three feet deep should be dug. Ordinarily sterile subsoil is thrown up to form parkings when streets are built. Therefore good top soil should be secured to fill in with. If the park- ing space is narrow or the rainfall insufficient, pipes or tiles should be secured for sub-irrigating. The best time for planting trees is between November and March. It is merely necessary that the tree be dormant and the ground un- frozen. February is the planting month for the whole state and the date for Arbor Day has been well chosen — February 22. Ideal condi- tions prevail when the day is cool and cloudy right after a rain while the ground is moist. The feeding roots are very tender, being easily dried out and killed, especially the roots of evergreens. In order to avoid this, roots ought to be "puddled" ; that is, they should be coated with thick mud before being taken to the planting site. They should be kept covered and protected from sun and wind as much as possible, since an exposure of five minutes is fatal to pine seedlings, and other trees will stand very little more. After all preparations for planting have been made a cone of earth should be piled in the middle of the hole and the tree set down so that it will be as deep in its new situation as it was before transplanting. The roots should then be spread out in a more or less natural position T&EE PL 4 NT/ KG C A 77 O /VS. Se/ec f /o ng- //>ao^ h &ra(/j we//- J frees cyc/apfec/ to jour so/ c//rr>cyfuf cove />? botforv roofs oo /. //o/e J/ce/ deep M w/fh fer?/'/*, fop JO/'/. —25— and the dirt piled in slowly and packed down well around them. Care should be taken that no large stones or pieces of dry roots, bark, wood or grass come in contact with the roots to cause air spaces, since these cause the roots to dry out. The top layers may have some rocks and coarser dirt, but the better the earth the better the tree growth. The last dirt to be thrown in should not be packed, and over it some loose hay should be spread to act as a mulch. SUBSEQUENT CARE All nursery- stock is pruned before it is received from the dealer, but when unpruned deciduous trees are received they should be cut back in order to balance the shock caused by the failure to get the whole root system. Evergreens, especially conifers, such as pines, spruce and fir, cannot be pruned, which accounts somewhat for their higher mortality at planting time. The diagram on page 24 illustrates correct pruning and planting. If the planted sapling is to develop into a desirable ornamental tree it must be given considerable attention and care. It is not advisable to water trees very frequently, but when they are watered a thorough job should be dene. Frequently a mound of dirt around the tree will be enough to make this possible. Three inches of water can be •easily turned in and will gradually soak down to the roots. Surface irrigation tends to draw the roots to the surface, however, and makes them susceptible to slight droughts, while sub-surface irrigation will prevent this largely by attracting the roots to the water level. A good thorough watering every ten days in dry weather should be sufficient for even those trees which require considerable soil moisture. Even more important than irrigation is cultivation. Frequent culti- vations during the growing season is a great benefit to a tree. Weeds and grass sap the moisture and fertility from the soil and must be kept •down. A space at least four feet in diameter must be kept clean and mulched. Only a few trees develop naturally into the desired form. Most trees become twiggy, bushy, or stragglv. They need pruning or training in order to direct the growth into those branches which will give the tree a symmetrical appearance. Pruning is also essential for the removal of dead, diseased, or injured limbs. Dead limbs may be removed at any time, but live limbs should be cut during the winter if possible. They may be cut at other seasons, "but during early spring, pruning will cause the tree to "bleed" and will injure it somewhat, while late summer pruning may stimulate growth and n.-ake the new shoots liable to frost injury. In pruning it is desirable to maintain the natural form of the tree, merely removing limbs where they are too thick or raising the head by rcrroving branches pn the under side of the lower limbs. The weight of large limbs will often cause them to split and rip the l)ark when a straight cut through from the upper side is attempted. The safest way to prune is to make three cuts as shown in figures on page 28. The first or undercut prevents the limb from splitting past where the final cut is to be made. In all events the cut must be made as nearly fiush with the main or parent limb as can be. No stub should he left isolated from the flow of sap to ultimately harbor rot and weaken the tree. —26— should be pruned very sparingly. Dead or dying limbs must be lemoved, of course, and occasionally a limb should be taken off to prevent a crown from becoming one-sided. Lower limbs should not be removed from small trees as a general rule, as this spoils the sym- metry of the tree and makes them top heavy. This is true of the coni- fers, but the broadleaf evergreens, like live oak and magnolias, may be handled like the deciduous trees. It is highly desirable to use fertilizer to maintain the food materials in the soil. Too often trees are starved to death. Commercial fer- tilizer should be applied rather sparingly since it is easy to get too much and thus injure instead of benefit the tree. TREE TROUBLES AND REMEDIES City trees are subject to many injuries, diseases and insect attacks due to their unnatural surroundings. They must be carefully watched and kept in as thrifty a condition as possible so that they may be re- sistant to a great extent or able to recover quickly in case they do suffer some reverse. INSECTS Insects are the bane of a tree's existence in the forest and even more so in the city where natural parasites are lacking and birds are rela- tively scarce. The insects which attack trees may be classed under three general heads according to their various feeding habits. These three classes are known as sucking insects, borers, and defoliators. Each class must be combated in a different manner. The sucking insects include scales, mealy bugs, and plant lice. They feed on plant juices through sucking mouth-parts. Scales are minute hard-bodied flat or slightly convex insects which fasten themselves closely to the trunk, twigs, or leaves, and usually are unable to move around after they assume the adult form. The younger stages of scale insects may fly and migrate, however. . The oyster shell scale is a well known example of this class of insects. Another is the cottony maple scale, which is much larger than most of the scales and which secretes a mass of white waxy threads. Mealy-bugs are soft-bodied small insects which are characterized by the waxy, cotton-like covering which they exude. Citrus mealy bugs attack many orange trees in this state. Plant lice are soft-bodied insects, too well known to require further description. They feed only on young tender shoots and are often found injuring willow and poplar. Scales. — Since the control methods are essentially the same for all scales they will be considered as a group. They are best combated in winter, since stronger sprays may be used and more satisfactory results obtained. Lime-sulphur is the most useful spray against scale insects, and, fur- thermore, it has some value as a fungicide. Lime-sulphur may be se- cured ready made, needing only dilution to be ready for use. Usually 10 per cent stock solution to 90 per cent water will give satisfactory results. Lime-sulphur may be made at home if desired but the com- mercial product is preferable. —27— FORMULA FOR LI M K-SULl'IIUR SPRAY Unslaked lime -10 Ibs., flowers of sulphur 30 Ibs., water 100 gallons. Ilcai the water, and to oJie-Jiall' the quantity add the lime. The slak- ing linir will boil the water, to which the sulphur, mixed as a paste with a little water, should be added and the whole, stirred. Finally add the rest of the water and strain before using in the sprayer. Another good remedy is kerosene emulsion prepared as follows : KEROSENE EMULSION Whale oil soap ^ pound, kerosene oil 2 gallons, water 1 gallon. Boil water, dissolve soap and add kerosene, pumping vigorously until the oil goes into emulsion, forming a creamy stock solution, which should be diluted with fifteen to twenty times its bulk of water for use in sum- mer spraying for soft-bodied insects. Some miscible oils are on the market which do not require hot water or strenuous pumping before being ready for use. Men 1 1/ l/ugs should be sprayed with kerosene emulsion or with carbolic acid solution, which is prepared as follows: CARBOLIC ACID EMULSION Whale oil soap iO pounds, crude carbolic acid 5 gallons, water 35 gallons. Heat the water and add the soap. After it is dissolved add the acid and boil for twenty minutes. Use twenty parts of water to one of the stock emulsion. This is good for soft scales and plant lice as well as- mealy bugs. Plant Lice. These insects multiply very rapidly and do severe dam- age to the tender growing parts of trees. They should be sprayed with carbolic acid emulsion, kerosene emulsion, or soap wash. SOAP WASH Whale oil soap or hard laundry soap 1 pound, water 5 gallons. Borers may be divided again into bark borers and wood borers. Bark borers are specially dangerous as they attack a tree in the cambium layer right below the inner bark. This is the growing part of the tree, and if the cambium is girdled the circulation of plant food is cut off, causing death. Borers are worm-like grubs which develop into moths or beetles after spending most of their life cycle m the bark of the tree. Their presence can be detected by the entrance or exit holes, by the boring du.-t, and in the spring of the year by the flow of sap from the boring galleries. Bark-borers frequently kill out large trees, and should be promptly combated. They commonly breed in dead or dying trees, so the first step is to get rid of all trees which constitute a public nuisance by harboring insect pests. This will largely eliminate the source of snpplv. There is no positive preventive for borers, but whitewash or cement paint will act as a deterrent. WHITEWASH FOR BORERS Quick lime 3 pounds, caustic potash 2 ounces, crude carbolic acid, 1 ounce, water 2 gallon?. R EPA /P. C> / orrcc-/ r^funi —29— CEMENT PAINT Portland cement, skimmed milk. Add enough milk to reduce the cement to the consistency of thick paint. Either of these two applications should be painted on the trunk and larger branches as far up as the insects are likely to attack, usually ten or twelve feet. If the bark is rough and scaly it should be smoothed off first. Cement paint is good for one whole season, but whitewash should be applied twice during the growing season for best results. It is very difficult to eliminate borers once they have obtained a foot- hold. The individual boring holes must be probed with wires or sat- urated with carbon bisulphide (high life) squirted in with an oil can, after which the hole must be plugged up with clay, putty, or some other handy material. The third alternative is the obvious one of gouging out the holes until the worm is found and killed. Wood borers are found boring through the heart and sap wood of healthy, dead, and dying trees. They are only slightly less dangerous than bark beetles, causing the death of many large veteran trees and often weakening the limbs of others so much that they are readily broken off in a heavy wind. They may be controlled to some extent by the same means that are used against bark borers, mentioned above. Defoliating insects are easy to control but if left unmolested the strip- ping of the leaves will seriously weaken the tree. Three successive de- foliations will usually kill a deciduous tree, while one complete defolia- tion may kill coniferous evergreens, which are not very resistant to the attacks of these insects. It is sometimes practical to creosote egg-clusters or to collect the nests and burn them, but the usual way to attack this class of insects is to spray the foliage on which it feeds with arsenate of lead, which can be procured in any town. Two and one-half pounds of poison to forty gallons of water is the strength commonly used. Red spiders are best controlled by lime-sulphur dust, which is a powder composed of equal parts of flowers of sulphur and dehydrated lime. Banding is occasionally useful, to prevent insects from crawling up trees. Such insects as the bag-worm, the female of which cannot fly, may thus be prevented from gaining access to trees already free from their attacks. BANDINO MIXTURE Resin 16 pounds, castor oil 1 gallon. Heat until the resin is melted, then dip ropes in the mixture. The ropes, covered with the banding compound, should then be tied around the trees about four or five feet above the ground and renewed every ten days or oftener if the mixture begins to dry and harden. FUNGI The next most important cause of injury to shade trees is fungus or rot. Funprus diseases come under six heads: heart rot, sap rot, root rot, canker, bark diseases, and leaf blight. Heart rot commonly occurs in old trees, which may be so badly affected that the heart wood is entirely disintegrated, leaving the hol- low tree to be supported by the outer shell of bark and sap wood. Since the heart wood of the tree is dead wood its onlv function can be to —30— brace and support it. Accordingly the removal of the heart wood does not necessarily result in the death of the tree. Death in such cases may result from windbreak. Heart rot gains access to a tree through branch stubs, through roots, or through deep scars and injuries. It often gets a start in street trees through the dying back of a stub in the top caused by poor pruning at the time of planting and subsequent neglect. It is common practice to top back forest grown trees to a point where the main stem is from one inch to three inches in diameter. The new growth is apt to start several inches below the cut, thus allowing the end to die and become infected. Such dead ends should be removed and the scar painted. Sap rots usually result from the spread of heart rots or occur in < lying- trees. They are serious since the function of the sap wood is to serve as a transporting medium for the food material from which the wood cells are built. By killing out this layer the circulation of sap is in- terfered with and if the rot extends completely around the tree the host may be killed. Heart and sap rots are prevented by careful pruning, followed by covering the wounds with paint, tar, or creosote. All insect o-alleries serve as a point of access for fungus spores. Such holes should be drained and painted. There are three methods of treatment for cavities and diseased places in shade trees. They are called the open cavity, cement filling, and asphalt filling treatments. At the present time the tendency is to do as much open treatment as possible. Excavating Rots. In repairing a tree affected by rot the first step is to bore in at several places to locate the exact extent of the rot. It may be feasible to excavate from one hole entrance or again two or more may be needed. In cutting out decayed wood it is essential that all the rot be removed. The so-called 'rots" often extend several inches into apparently sound healthy wood. It ig frequently impos- sible to tell whether the decayed portion has been entirely cut out, but if the cavity is left open a subsequent examination will clear up all doubts. Excavating Tools. A mallet, a half round gouge, and two or three chisels of various sizes are handy tools for this work. Large cavities may be opened to advantage with hand axes. After all the decayed part has been removed the bottom of the cavity should be provided with drain- age to prevent water from standing there. It is not essential to have the walls absolutely smooth, but they should not have large crevices that may harbor insects. The mouth of the cavity should be made regular, and where possible the shape should be oval, tapering toward the top and bottom. This type of hole heals over quickest, while square ends often result in dead areas adjoining the hole due to the failure of the sap to properly nourish them. Painting. There are several good covering substances on the market for painting over wounds. The creosote compounds penetrate well and act as antiseptics. Tar is good, and roofing or asphalt paints are very satisfactory. Ordinary house paint is better than nothing, but is apt to crack, affording an opening for moisture and disease spores. Car- bolineum is an excellent antiseptic paint. Sheet Metal. A modification of the open cavity treatment is the use of sheet metal nailed across the cavity opening. In such cases the bark —31— and the cambium layer, which is the growing part of the tree just below the bark, should be cut back to form a shelf to which the metal is nailed. It is necessary to have the metal shaped to the opening and care must be taken that it does not overlap the cambium or bark anywhere since then the new wood would work in under and pry it up instead of closing in over it. The open cavity treatment or this modification of it is use- ful for very large cavities and where stress or bending might cause inl«-ry McAllen Henderson Nursery Athens Hendrix & Glass Farmersville 1 fereford Nursery Co Hereford ITcrrlc. J. J. A Houston llick< & Culver.. . .Mt. Pleasant —36— Name of Firm. Postofflce. Hillsboro Nursery Co Hillsboro Hoffman, R. H. .' Denton ETolbert, Chas. E Arcadia Holbert, Mrs. E. W , . Arcadia Howard's Montopolis Nursery Austin Iron Ore Nursery Denison Johnson Orchard & Nursery Co Dallas Johnson, Bart . . . ,. Comanche Kaufman County Nursery Terrell Kearney, S. W San Antonio Kerr, Jno. S Sherman Kezer, H. A El Paso Kieswetter, A. H Houston Kirby, S. B Bullard Kirtly, C. C Cameron Lampasas Nursery Co Lampasas Lang Floral & Nursery Co Dallas Laredo Nursery Co Laredo Lewis, S. G Lufkin Lloyd, L. J Nursery MacDaniel, W. F San Augustine McGinney Nursery Co Tyler McKee Nurseries Mt. Selman MeKee, The J. E., Nursery Co Texarkana McKee, S. R.5 Nurseries ,....' Jacksonville McKinney Nursery Co Dallas Martin, W. M ' Handley Mary Austin Nursery Alta Loma Mignon, E Navasota Moore Nursery Co Tyler Moss Bros Hico Mosty, L. A., & Son Center Point Munson Nurseries Denison Myrtle Springs Nursery Co Wills Point Northeast Texas Nursery Pittsburg Oak Grove Nursery : Denison Palacios Nursery Co Palacios Pearfteld Nursery New Ulm Pilot Point Dewberry Farm ........ Pilot Point Pine Springs Nursery Tyler Plain\7iew Nursery Co Plainview Planters Nursery Denton Pomeroy, Eltweed Donna Potter Floral Co El Paso Riverside Nursery Fort Worth Rockdale Nursery Rockdale Rosedale Nursery , Brenham Rosedale Nurseries El Paso Rose Hill Nursery Co Texarkana Rusk County Nursery Henderson Saibara, K Webster —37— Name of Firm. Postofflce. Saltillo Nursery Co ' Saltillo Samf ord, A. M . Tyler San Angelo Nursery Co San Angelo San Benito Nursery Co San Benito Sinton Nurseries Sinton Shamburger Nursery Tyler Shary, John H Mission Shell, C. L , Georgetown Smith County Nursery Co Tyler Stephenson, H. F Brownsville Steinbring. S. W New Braunfels Stockwell Nursery Alvin Stone, Mrs. E. E Dickinson Sulphur Springs Nursery Sulphur Springs Teas Nursery Co Houston Terrell Nursery 'Co Terrell Texas Nursery Co Sherman Texas Kose Garden Eockdale Thomas, J. E '. • Atlanta Thompson, J. M Waco- Verhalen, Geo. F Scottsville Volz, Chas » Mission Waco-Tyler Nursery Co '. Waco Waxabachie Nursery Co Waxahachie Wahrli, Robert Dallas Western Home Nursery Weatherford West Tyler Nursery. ." Tyler Whall, Walter I San Antonio Wichita Floral & Nursery Co Wichita Falls Wright Nursery & Floral Co El Paso • Wright, A. P. Mission Russian mulberry in West Texas and the Panhandle makes a fast growth and is very hardy as well. The silvery foliage makes this a very desirable ornamental shade tree. This tree is in Amarillo, Texas. Young green ash in the foreground and Carolina poplars behind in the forest tree nursery at the Denton Experiment Station. Some scores of new trees are being tried out each year at these stations to determine those suited to Texas conditions. LIST OF BULLETINS ISSUED BY THE STATE FORESTER Copies may be secured free of charge from the State Forester, Col- lege Station, Texas. Bulletin 1. Grass and Woodland Trees. (Supply exhausted.) Bulletin 2. Tree Planting Needed in Texas. Bulletin 3. General Survey of Texas Woodlands, Including a Study of the Commercial Possibilities of Mesquite. Bulletin 4. First Annual Eeport of the State Forester. (Supply ex- hausted.) Bulletin 5. Forest Resources of Eastern Texas. Bulletin 6. Forest Fire Prevention in Co-operation with the Federal Government. (Supply exhausted, replaced by bulletin No. 9.) Bulletin 7. Farm Forestry. (Extension bulletin.) Bulletin 8. Second Annual Report of the State Forester. Bulletin 9. Forest Fire Prevention in East Texas. Bulletin 10. Farm Forestry in the Shortleaf Pine Section of East Texas. Bulletin 11. Shade Trees in Texas Towns and Cities. Bulletin IS. Forestrv Questions and Answers. J. TREES INCREASE THE VALUE OF YOUR PROPERTY. 2. TREES PROTECT YOUR HOME AND YOUR STREETS FROM THE HEAT OF THE SUN. 3. TREES PROTECT YOU FROM THE COLD WINDS OF WINTER. 4. TREES GIVE OFF OXYGEN, THUS PURI- FYING THE AIR. 5. TREES AFFORD AN ATTRACTIVE SET- TING FOR YOUR HOME. 6. TREES MAKE YOUR CITY MORE LIVE- ABLE AND LOVEABLE. UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BULLETIN NO. 176 NURSERY AND ORCHARD INSECT PESTS L. HASEMAN FIG. 1. — San Jose Scale; much enlarged, showing different stages of development COLUMBIA, MISSOURI OCTOBER, 1920 UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE Agricultural Experiment Station BOARD OF CONTROL, THE CURATORS OF THE UNIVERSITY OF MISSOURI EXECUTIVE BOARD OF THE UNIVERSITY H. J. BLANTON, Paris JOHN H. BRADLEY, Kennett JAS. E. GOODRICH, Kansas City ADVISORY COUNCIL THE MISSOURI STATE BOARD OF AGRICULTURE OFFICERS OF THE STATION A. ROSS HILL, PH. D., LL. D., PRESIDENT OF THE UNIVERSITY F. B. MUMFORD, M. S.( DIRECTOR STATION STAFF OCTOBER, 1920 AGRICULTURAL CHEMISTRY C. R. MOULTON, Ph. D. L. D. HAIGH, Ph. D. W. S. RITCHIE, A. M. E. E. VANATTA, M. S.2 R. M. SMITH, A. M. T. E. FRIEDMANN, B. S. A, R. HALL, B. S. in Agr. E. G. SIEVEKING, B. S. in Agr. A. B. CULBERTSON, JR., B. S. in Agr. B. W. MANNING, B. S. in Agr. G. W. YORK, B. S. in Agr. AGRICULTURAL ENGINEERING J. C. WOOLEY, B. S. MACK M. JONES, B. S. ANIMAL HUSBANDRY E. A. TROWBRIDGE, B. S. in Agr. L. A. WEAVER, B. S. in Agr. A. G. HOGAN, Ph. D. F. B. MUMFORD, M. S. D. W. CHITTENDEN, B. S. in Agr. PAUL B. BERNARD, B. S. in Agr. A. T. EDINGER, B. S. in Agr. H. D. Fox, B. S. in Agr. BOTANY W. J. ROBBINS, Ph. D. E. F. HOPKINS, Ph. D. DAIRY HUSBANDRY A. C. RAGSDALE, B. S. in Agr. W. W. SWETT, A. M. WM. H. E. REID, A. M. SAMUEL BRODY, M. A. C. W. TURNER, B. S. in Agr. D. H. NELSON, B. S. in Agr. ENTOMOLOGY LEONARD HASEMAN, Ph. D. K. C. SULLIVAN, A. M. S. R. MCLANE FIELD CROPS W. C. ETHERIDGE, Ph. D. C. A. HELM, A. M. L. J. STADLER, A. M. O. W. LETSON, B. S. in Agr. E. O. POLLOCK, B. S. in Agr. B. B. BRANSTETTER, B. S. in Agr. RURAL LIFE O. R. JOHNSON, A. M. S. D. GROMER, A. M. R. C. HALL, A. M. B. H. FRAME FORESTRY FREDERICK DUNLAP, F. E. HORTICULTURE V. R. GARDNER, M. S. A. H. F. MAJOR, B. S. H. D. HOOKER, JR., Ph. D. J. T. ROSA, JR., M. S. F. C. BRADFORD, M. S. H. G. SWARTWOUT, B. S. in Agr. POULTRY HUSBANDRY H. L. KEMPSTER, B. S. SOILS M. F. MILLER, M. S. A. H. H. KRUSEKOPF, A. M. W. A. ALBRECHT, Ph. D. F. L. DULEY, A. M. R. R. HUDELSON, A. M. WM. DEYouNG, B. S. in Agr. H. V. JORDAN, B. S. in Agr. RICHARD BRADFIELD, A. B. O. B. PRICE, B. S. in Agr. VETERINARY SCIENCE J. W. CONNAWAY, D. V. S., M. D. L. S. BACKUS, D. V. M. O. S. CRISLER, D. V. M. A. J. DURANT, A. M. H. G. NEWMAN, A. M. ZOOLOGY GEORGE LEFEVRE, Ph. D. OTHER OFFICERS R. B. PRICE, M. S., Treasurer LESLIE COWAN, B. S., Secretary SAM B. SHIRKEY, Asst. to Dean O. W. WEAVER, B. S., Agricultural Editor J. F. BARHAM, Photographer Miss BERTHA KITE, A. B.1 Seed Testing Laboratory *In service of U. S. Department of Agriculture. 2On leave of absence. Nursery and Orchard Insect Pests Since the establishment of the Plant Inspection Service by the Legislature in 1913 the work of control of nursery and orchard insects has been given special attention. The San Jose scale, which since the early 90's has been re- sponsible for much of the loss and damage to the fruit industry of Missouri, was taken in hand first of all. Remarkable results have already been secured in eliminating this pest from the nurseries of the state as well as from the im- portant orchard centers. The various other less well-known insects and plant diseases have also received attention. Except for certain pests of the fruit itself, practically every pest that is of importance in the nursery on the young trees, also attacks the older bearing trees in the orchard. For this reason it has seemed advisable in this report to deal with the various pests and their control both in the orchard and in the nursery. For the same reason it is of vital importance that the Plant Inspection Service be maintained and that adequate provisions be made to effectively pro- tect Horticulture and Agriculture against future losses from insects and plant diseases. The problems of the fruit grower and nurseryman, in this respect, are identical, and to make the work most effective we must continue to have close cooperation between them. A neglected orchard will endanger a neighboring nursery as well as increase the difficulties of nearby fruit growers. In this report the pests of apple, peach and other fruits will be taken up separately. Where a pest is of importance both in the orchard and nursery it will be so considered. INSECT PESTS OF THE APPLE Apple insects may be conveniently discussed as those of the roots, trunk and limbs, foliage and fruit. This method makes it easy for a fruit grower or nurseryman quickly to analyze his trouble. Apple Root Insects In Missouri there is only one insect of importance on the roots of apple trees. This is the Root Louse or Wooly Aphis, (Schizoneura lanigera). It is quite generally distributed thruout the state, breeding commonly on apple, haw, crab, and on elm foliage. It is a small reddish-brown louse which usually keeps its body covered with a white cottony secretion. It feeds by extracting sap from the roots and bark thru a piercing beak. On the roots this causes swellings to form and on the trunk and limbs slight depressions. CONTROL. — In the nursery it helps to grow apple trees in fields which were formerly used for cultivated crops, and well isolated from old orchards, neg- lected apple trees, haws, crabs and elms. Also make sure that roots and scions are free from infestation when the grafts are made. Apple trees showing the 4 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 presence of lice should not be disposed of until properly treated. Such trees may be fumigated with hydrocyanic acid gas as recommended for San Jose scale or the roots dipped in a solution containing one part of 40 per cent nicotine sulphate to 500 parts of water. One and two-year apples are less likely to be infested than older trees. In the orchard make sure that the young trees when planted are free from lice. Use land that is not newly cleared but which has been cultivated for several years. If possible do not have old worthless apple trees, haws and elms too near the young orchard. For the first few years after setting out the FIG. 4. — Flat-headed Ap- ple-tree Borer; a, Borer; b, pupa; d, adult beetle. (From U. S. Dept. Agr.) FIG. 2. — Root-louse of apple, showing typical root injury (After Stedman) FiC. 3. — Round-headed Apple-tree Borer; a, Borer; b, pupa; c, adult beetle. (From U. S. Dept. Agr.) NURSERY AND ORCHARD INSECT PESTS 5 young orchard scatter tobacco stems or tobacco dust about the base of the young trees and work it into the soil. On the large bearing trees this may also be done but it is especially important to young trees free from the louse. Insect Pests of the Trunk and Limbs In this group are included some of the most vital pests of apple; such as the borers and scale insects. Round-headed Borer (Saperda Candida).— This pest works just at the surface of the ground, throwing out of its tunnel sawdust-like cuttings. It is worse on neglected bearing trees in the orchard but also at times may appear on older apple trees in the nursery. It requires three years to complete its de- velopment from egg to adult. When full fed the fleshy, whitish grub or borer is an inch long and as large around as a pencil. The tunneling and girdling work weakens the tree and permits rot to set in. CONTROL. — In the nursery make sure that nearby old trees are not serving as breeding places causing infestation on the nursery trees. Also avoid carry- ing over scion trees or other unused trees until they become sources of infesta- tion. In the orchard cultivate about the trunks of the trees to keep down grass and other rubbish as it seems to attract or protect the pest. Also go over the trees in the fall and in the spring and carefully dig out, or destroy with a wire, borers where present. During the early summer months keep the base of the trunks painted with whitewash to which enough lime-sulphur solution is added to give a distinct odor. In Arkansas asphalt paint applied, at the temperature of about 115 degrees Centigrade, to trees four years old or older gave good results. Where possible it is cheaper and better to prevent infestation thru proper orchard management than to clean up the orchard once the trees are infested. Flat-headed Borer (Chrysobothris femorata). — This pest is smaller than the round-headed borer and confines its work to the bark and growing layer of trunk and limbs. It is common on nursery trees and also in orchards. As a rule it works where mechanical injury, sunscald or canker is at work on a tree. The grub or borer is whitish in color and has the segments of the thorax expanded so as to appear to have an enlarged head which gives it. its common name. It completes its life cycle in one year. It is not confined to the apple tree, which makes it all the more difficult to control. CONTROL. — During the early part of summer examine trees for signs of injury on trunk or larger limbs. If present carefully remove borers, disinfect wounds and paint over patches. As a precaution keep nursery and orchard as far from woods as possible and eliminate old worthless apple trees as well as haws and other trees from the vicinity of the orchard. Shot-hole Borer (Scolytus rugulosus). — This small beetle and its tiny grub may attack all kinds of fruit trees and other trees. It is most important in the orchard but on weakened nursery trees it may also appear. The female beetle makes a tunnel between the bark and wood and lays eggs along either side of this. In time the small borers extend their work, often girdling limbs or the trunks of small trees, causing weakening or death of such trees. As a rule it is a weakened tree that is most likely to suffer injury. 6 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 CONTROL. — Since the pest thrives best in weak or dying trees or limbs, keep all orchard primings removed from the orchard. In the nursery avoid the use of left-over trees for filling draws and the like alongside the growing stock. Remove and burn trees which are too seriously injured by the pest to be saved. In the orchard promptly prune out affected limbs and destroy them. The regular summer sprays with arsenate of lead and lime-sulphur for fruit insects will tend to repell this pest where spraying is thoroly done. a bed FIG. 5. — Shot-hole Borer; a, Adult; b, side view of same; c, pupa; d, borer; all enlarged. (From U. S. Dept. Agr.) San Jose Scale (Aspidiotus perniriosus). — This imported scale insect is the most notorious one that attacks fruit trees. It came from the Orient some thirty years ago and has been in this state for about twenty-five years. It had much to do with the establishment of State and Federal Plant Inspec- tion Services and hastened the day when regular orchard spraying was abso- lutely necessary. In thirty years it has destroyed thousands of orchards and has cost nurserymen millions of dollars. It is a sap-sucking insect which secretes over its back a protecting scale or armor. The female gives birth to the young and in a day or two they insert their beak, begin to extract sap and to secrete the protecting armor. The fe- males never move from the point where they begin to feed, tho later the males emerge as small two-winged insects. In from thirty to forty days the insect FIG. 6. — San Jose Scale; portion of peach limb showing scale incrusting it. Enlarged NURSERY AND ORCHARD INSECT PESTS 7 matures, so there are a number of generations maturing between spring and fall. The pest passes the winter as 'a half-grown nymph in the so-called black stage. CONTROL. — Since the pest may be spread readily in the young nymph stage from orchard to orchard or to nursery stock by birds or other means, the State Plant Inspection Service has done all in its power to eliminate the pest from orchards and other grounds in the vicinity of the nurseries. This clean up work has now largely removed the immediate danger to the regular nurs- eries. Under especially favorable seasons, however, the pest may multiply and spread more than usual, requiring special effort in the way of clean-up work. In the orchard one or two regular dormant sprays will so reduce it that it is then easily kept in control. No one hopes to absolutely exterminate it once it FIG. 7.— San Jose Scale; blossom-end of apple enlarged slightly showing scale infestation becomes well established. For the dormant spray use the regular concentrated lime sulphur solution which gives a Beaumeau reading on the hydrometer of 30° to 33°, at the rate of one gallon in eight gallons of water. Some prefer miscible oils and when used they should be mixed at the rate of one gallon of oil to twelve gallons of water. Some report good results with dry lime sulphur used at the rate of about 1 pound to 4 gallons of water. However, the writer's experience leads him to believe that in their present form the brands of dry lime sulphur will not control this pest as effectively as the better brands of lime sulphur solution. A badly infested orchard should receive one application in November or December and a second one just as the buds swell in the spring. Where the infestation is light the spring application is sufficient. Select a warm day when there is little or no breeze. Use plenty of pressure and a nozzle throwing a 8 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 reasonably fine spray, yet one which will penetrate into protected places. The spray solution kills by contact so each scale must be touched. Spray thoroughly therefore and be sure the tips of all twigs are thoroughly coated. Spray all the way thru the tree from all angles. Blotching of fruit is often the first signs of infestation the grower observes. However, other insects may cause blotches on fruit so this is not always a sign that the scale, is present. In case of doubt send twigs and blotched fruit to the Agricultural Experiment Station for examination. In the nursery the use of dormant sprays is not sufficient to insure against the possibility of spread of scale on nursery stock. Dormant sprays may con- FiG. 8. — San Jose Scale. Spraying infested peach orchard, using small barrel outfit trol the pest but it is humanly impossible to hit and kill every individual. For this reason inspection laws require the destruction of visibly infested trees and the fumigation or dipping of all other susceptible trees or shrubs before dis- tributing them. For fumigation use an air-tight room and hydrocyanic acid gas. Subject the trees to the gas for from forty to sixty minutes. The gas is made by using one ounce of potassium cyanide 98% or sodium cyanide 130%, one ounce of commercial'sulphuric acid, and two or three ounces of water for each one hundred cubic feet of space. If the stock is dipped, a miscible oil diluted with twelve parts of water has given best results. In spite of the most careful work of inspection and treating of nursery stock there is the chance that some scale may escape, resulting in infestation in the orchard where trees NURSERY AND ORCHARD INSECT PESTS 9 are planted. However, it should be remembered that in recent years most new infestations in orchards come from other infested orchards in the vicinity rather than on the young trees from the nursery. While the scale has done much injury to fruit growing it is now possible to control it very effectively and in good orchard management it is no longer feared as a dangerous scourge. The above discussion of the pest on apple holds true for other tree fruits as well. Other Scale Insects. — The oyster shell scale, the scurfy scale and the Forbes scale are also at times common on apple trees in the nursery and in the orchard. Neither of these, however, are likely to cause serious injury to bear- ing trees. In the nursery, on the other hand, they are undesirable and at times decidedly injurious. The scurfy scale has a light-colored flaky, armor, the oyster shell has a dark oyster-shell-shaped armor and the Forbes a circular armor with a shiny orange-colored center or exuvae. CONTROL. — In the propagation of nursery stock select scions free from scales. Where nursery stock shows infestation do not use it in filling orders. To most fruit growers a scale is a scale and a nurseryman does not want the name of distributing scale infested stock. Dipping nursery stock in a miscible oil or fumigating with hydrocyanic acid gas will prevent the possibility of spread of these scales on the stock. In the orchard where these scales are troublesome a dormant spray as for the San Jose scale is helpful, especially for the Forbes scale and spring applications of contact sprays as for plant lice, just when the young scales are crawling is very effective in controlling the scurfy and oyster-shell scales, since they pass the winter in the egg stage. Buffalo Tree-hopper (Ceresa bubalus). — In old neglected orchards the bark of small limbs and twigs is often found to be badly pitted and roughened. This is caused by this small insect. In the fall, by means of a small drill or ovipositor, the female places her eggs under the bark and this causes small scars on the bark. The injury is similar to the work of the Cicada, tho the punctures do not go beyond the bark. These eggs hatch in the spring and the young nymphs soon leave the twigs and feed on the sap of herbaceous plants, grass and the like about the orchard. The only damage done is due to the egg lay- ing and in severe cases it may be considerable. Certain varieties suffer more than others. In the nursery this injury is usually slight, tho it may be quite noticeable especially on scion trees in places where surrounding conditions are favorable for breeding. CONTROL. — Where this pest is abundant clean culture in the orchard and surrounding fields will help to check the pest and its injury. Repeated mowing of grass and weeds in the orchard will help where cultivation is not advisable. Periodical Cicada (Tibicen septendecim).—This peculiar insect, as is well known, reappears at definite intervals in the form of broods. One form re- appears every thirteen years and the second every seventeen years. In Mis- souri several broods appear, tho only the two heavy 13-year broods are of special importance. One of these appeared in the spring of 1920 and will next appear in the spring of 1933. The second appeared last in the spring of 1911 and will next appear in the spring of 1924. These two broods are sufficiently heavy and widely distributed as to cause a certain amount of damage to the fruit-bearing twigs of apples and other fruits over most of the state. This is especially true 10 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 if orchards and nurseries are near tim- ber land. In this case again the dam- age done is entirely due to injury caused by the splitting of the twigs for placing the eggs. No injury is done by the in- sect feeding on the trees. Newly planted orchards and nursery stock suffer most. On bearing trees it simply serves as extra twig prunning and no serious damage results. CONTROL. — There is no very effective treatment to check injury once the adult insects arrive in the orchard or nursery. Systematic driving will help to some ex- tent. As a precaution one can deter- mine in advance when the next brood will appear and if a young orchard is to be started select land that has been in culti- vation for more than seventeen years if possible and select an orchard site as far as possible from timber. This will insure the least possible number of Cicadas in the orchard later when the pest appears. Insect Pests of Apple Foliage This includes a very large group of caterpillars, grasshoppers, plant lice, leaf- hoppers, plant bugs and other more or less destructive foliage pests. Where ap- lications of sprays are recommended they are included in the regular spray sche- dule gi\e in connection with the control of the codling moth on page 22. Canker Worms (Alsophila pometaria and Paleacrita vernata). — There are two species of canker worms, the fall and spring canker worms. The first appears as the adult in the fall and lays eggs while the latter appears in the spring. The female moth is wingless. The caterpillars are common dark- colored, span worms and do their destructive work just before, during and following apple blooming time. They often completely destroy the foliage and crop of fruit. There is one generation of the pest a year. The caterpillars when full fed leave the trees and pupate in the soil or rubbish. Here they remain until late fall or early spring, depending on the species. CONTROL. — The pest is controlled effectively by spraying with an arsenical just before the blossoms open, or on isolated trees banding with tangle foot, or screen-wire cones is effective since the females are wingless and must climb up the trees to deposit eggs. Occasionally these caterpillars may do some damage to nursery stock and when they do apply arsenical sprays promptly. Bagworms (Thrldopteryx ephermeraeformis}. — This peculiar cater- FIG. 9. — Periodical Cicada; limbs split by female Cicada for placing eggs (After Riley) NURSERY AND ORCHARD INSECT PESTS 11 FIG. 10. — Bagworm; limb with a number of winter cases containing eggs FIG. 11. — Bagworm; small apple tree showing work of young bagworms 12 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 pillar, while not primarily a pest of the orchard and nursery, is often a very troublesome and destructive pest in the nursery or orchard. It passes the winter in the egg stage in the larger bags suspended from twigs. In the spring the eggs hatch and they begin feeding soon after trees come into foliage. Each caterpillar makes for itself a bag or case as a protection and later it pupates in this. Where abundant it will strip apple trees of their foliage. The adult male moth develops wings, while the female remains within her protecting case where late in the fall she deposits her eggs. CoNTROiv. — The calyx spray for the codling moth will also control this pest. In the nursery spray early in the spring so as to poison the young worms. Hand picking of the bags in the fall after the foliage is off will also help con- FIG. 12. — Apple-tree Leaf -roller; two larvae slightly enlarged (After Stedman) FiG. 13. — Apple-tree Leaf -roller; pupa slightly enlarged (After Stedman) FIG. 14. — Apple-tree Leaf -roller; adults much enlarged (After Stedman) NURSERY AND ORCHARD INSECT PESTS 13 trol the pest. It attacks various evergreens, shades and ornamental shrubs worse, as a rule, than apple trees. Leaf-roller (Archips argyrospila). — This small caterpillar is often very destructive to foliage of nursery trees and occasionally to bearing apple trees. It may have three or four broods a year in this state and when abundant the small yellowish millers are conspicuous about the nursery or orchard trees. The small active caterpillars roll or fold the leaves on which they feed. It may also feed to some extent on the fruit, especially around the blossom or stem end or where two fruits touch. CONTROL. — In the nursery arsenical sprays applied just as the broods of young worms begin their work has proven entirely effective in one of the larger nurseries in the state. The development of the pest should be carefuly fol- lowed and the spray applied before the young worms fold or curl the leaves too much. In the orchard the regular summer applications of poison sprays, will control any ordinary outbreak of the pest. The pest passes the winter in the egg stage. The eggs are deposited on limbs or twigs in small circular light patches. Some have used oil emulsion sprays to destroy the winter eggs with fair results while others find them ineffective. Leaf-crumpler (Mineola indigenella). — The leaf-crumpler is one of the most common foliage feeding caterpillars on young trees in the orchard or nursery. The caterpillar is a small reddish or brownish colored caterpillar which prepares, and lives within, a slender, coiled case. The case is usually attached to a twig and has one or more leaves attached to it. It passes the winter as a half grown cat- erpillar and transforms to the adult early the next summer. It feeds on the foliage of other trees, fruits and haws. CONTROL.— It is most abundant on small trees and in the fall or win- ter when the leaves are off the trees it is an easy matter to see and re- move by hand the winter cases con- taining the small caterpillars. An arsenical spray applied soon after the foliage appears in the spring is also effective. In the nursery this is the most practical remedy. In the bearing orchard the regular summer arsenical sprays control this as well as other common foliage-feeding caterpillars. Leaf-miners (,$>/>.). — There are a number of small caterpillars which live and develop within the cellular structure of the leaf. The serpentine, blotch, trumpet and tentiform leaf-miners are the most common ones found in the foliage of apple trees. Besides these the pistal and cigar case-bearers and FIG. 15. — lyCaf-crumpler: a, Tube with larva head protruding; b, cluster of tubes; cr head of larva, enlarged; d, moth, enlarged 14 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 the ribbed cocoon makers are also common some seasons. In this state these small caterpillars do not often cause serious damage. In 1911 and 1912 the unspotted tentiform leaf-miner was very abundant and injured foliage seriously tho fortunately it becomes most abundant late in the fall after the crop and most of the growth has been matured. In the nursery where apple trees are dug and sold as one, two or three-year trees, these caterpillars do no serious damage. In the bearing orchard the regular arsenical sprays for fruit pests help some and natural parasites also help to prevent serious damage. As a rule, therefore, special treatments are unnecessary. Other Foliage Caterpillars. — Besides the foregoing foliage caterpillars there are a number of very common species in the nursery and orchard which some seasons may attract. much attention but which as a rule do not require special treatment. The yellow-necked and red-humped apple worms, the fall web-worm, apple tent-caterpillar and white-marked tussock moth are the more common caterpillars in this group. Every year we have some of these present but the amount of foliage they consume is usually not sufficient to "war- rant spraying or applying other treatments. CONTROL. — In the bearing orchard the regular arsenical sprays are entirely effective. In the nursery or when injurious on young orchard trees the worms may be collected by hand or shaken off and crushed under foot or an applica- tion of an arsenical spray may be made just as the worms begin to attack the foliage. Grasshoppers (Spp.*). — During seasons of heavy grasshopper infestation, orchard and nursery trees are sure to suffer where the grasshoppers are per- mitted to migrate from adjoining pastures, meadows or other crops. There are three common species of grasshoppers which do this damage, the red-legged, differential and two-lived. Where injury occurs it is usually soon after hay harvest. The foliage is often completely devoured and serious injury may result where the hungry grasshoppers attempt to appease their appetites further by gnawing the bark from the twigs and even the trunks of small trees. CONTROL. — Where grasshoppers are abundant on crops near the orchard or nursery one should take precautions early in the summer to prevent trouble later. Poison bran bait sown broadcast in infested meadows and other crops when the hoppers are yet small will rid the community of the pest. Poison bran bait is prepared by mixing dry 50 pounds of bran and two pounds of white arsenic or Paris Green and moistening this with about 8 gallons of water with which are mixed 4 quarts of cheap sorghum and the juice and chopped up rinds of six. lemons. Sow this at daybreak so the hoppers will get it for break- fast while yet moist and attractive. Where this precaution is not taken and the hoppers are feeding on the foliage spray the trees heavily with an arsenate of lead solution. Plant Lice (Spp.). — The foliage of apple trees may be seriously in- jured by two common green lice and one rosy louse. The injury is usually heaviest early, from the time the buds open until the fruit is well set. During the winter the lice eggs may be found attached to limbs and twigs, especially in the leaf scars and other protected nooks. The lice feed by extracting sap from leaves, blossoms and setting fruit. This causes a curling of the leaves and a knotting and dwarfing of the fruit. In severe cases the crop of foliage and fruit may be practically all destroyed. Since the lice are sap feeders, ar- NURSERY AND ORCHARD INSECT PESTS 15 senical sprays have no effect on them since it is impossible for them to take poison into their stomachs. CONTROL. — In the bearing orchard where the plant lice are injurious spray FIG. 16. — Plant lice: 1, Winter eggs on twig- 2, lice on tip of apple twig; 3, development of louse, enlarged FIG. 17. — Plant lice; apples dwarfed due to plant louse injury. (After Talbert) 16 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 with a nicotine solution promptly. It may be combined with the regular cluster or calyx sprays. Commercial nicotine sulphate containing 40% nicotine used at the rate of one pint to one hundred gallons of water or combined with one hundred gallons of regular spray mixture is very effective. On young orchard trees the same solution may be used. In the nursery where the buds, leaves and growing tips are being injured spray promptly with the nicotine solution or where practical dip the infested tips in the solution. Leaf-hoppers. — Apple trees in the nursery and orchard are attacked by two common leaf-hoppers. In the orchard the rose leaf-hopper and the apple leaf-hopper are often both very 'troublesome while on nursery stock the latter is especially injurious. Since 1910 the apple leaf-hopper (Empoasca mali) has repeatedly attracted attention in the nurseries of the state. In 1911 and 1912 it was especially in- jurious. Like the plant lice it feeds by extracting sap from the young leaves both as the immature nymph and as the adult. This causes a curling of the leaves attacked somewhat like plant louse injury. The characteristic white speckled appearance on the upper surface of injured leaves on bearing trees is less pronounced on the young vigorous nursery trees tho in severe cases it may show up some. This species passes the winter in the adult winged stage in dry grass and other protection about the orchard or nursery. In the spring FiG. 18. — Apple Leaf -hopper; trap used for running over rows of nursery trees to catch adult leaf-hoppers NURSERY AND ORCHARD INSECT PESTS 17 they fly to the apple tree to feed and deposit eggs. During the summer in Missouri this species develops three or four broods usually increasing in abun- dance towards fall. Besides apple it also breeds on and injures the foliage and young growth of Norway and hard Maples as well as certain vegetables. In Missouri the rose leaf-hopper (Empea rosea) seldom attracts attention in the nursery but is very abundant toward the close of the season on bearing apple trees. This fall (1920) the pest was so abundant in orchards in central Missouri that much of the apple foliage was badly injured and the air was often so full of the adult hoppers that they annoyed one working in or passing thru the orchard. This species is creamy white to light yellow in color with a tinge of orange on the face of the male. It passes the winter in the egg stage under the bark of apple and rose. It is also multiple brooded and is most abundant in late fall. CONTROL. — Tn the nursery, leaf-hoppers may be controlled with a fair de- gree of success by using a large trap including sticky shields for catching the adults as well as the older nymphs. In this state spraying with nicotine solu- tion or oil emulsions have not proven to be practical on any large scale. One thorough application of a contact spray to control the first brood of nymphs in the spring will reduce later injury but a trap with sticky shields can be run more economically and effectively and where used by nurserymen it has re- placed the use of sprays. In the orchard spraying is usually unnecessary and at best not very ef- fective. Thorough destruction of the overwintering adults of the apple leaf- hopper where they collect in grass and other protection is a more practical check on this species. This is not effective against the rose leaf-hopper, how- ever, since it passes the winter as the egg under the bark. Fortunately the rose leaf-hopper becomes alarmingly abundant only toward fall when its injury to foliage is less important. Tarnished Plant-bug (Lygus pratensis), — This pest is one of the most im- portant pests of budded nursery stock. It does injury in the orchard, too, but its most prominent injury is in the nursery. It is a world- wide pest of various crops and plants and is a most difficult pest to completely control. In the nursery the injury is done early in the spring when the overwinter- ing adults suck sap from and blight the young buds and growth. Peaches are especially subject to their attack tho cherry, pear and other stock also suffer. The insect is multiple brooded and lives thru the winter in rubbish as the adult winged bug. Typical "stop-back," "bush-head" and other similar injury to nurs- ery stock is largely the work of this pest. Often entire blocks of nursery stock are so attacked that few or no trees of marketable grade may be saved. Hundreds of acres of nursery stock are damaged every year by this pest. CONTROL. — This pest breeds primarily on weeds in or near the nursery and passes the winter in rubbish near the nursery. The first treatment to consider, therefore, is clean culture in the nursery and make sure that draws, fence rows and neighboring fields do not serve as breeding places for this pest. Then make sure that all harboring places are burned over or plowed under during the late fall or winter. This will prevent much of the danger. When the pest begins its destructive work on the trees in the spring sys- tematic driving or heavy rains or other means of driving the pest from the trees will check injury. If the injury does not occur until growth has well 18 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 FIG. 21. — Tarnished Plant-bug; life cycle of pest showing egg, five nymph and adult stages. Enlarged NURSERY AND ORCHARD INSECT PESTS 19 started one can reshape injured trees by pruning. However, young buds or budded stock may be killed outright and the trees lost. In the orchard the FIG. 22. — Tarnished Plant-bug; a, injured peach trees in nursery rows; b, close view of tree showing bush-head or typical injury done by the pest pest seldom requires attention but weeds and winter rubbish should always be destroyed so as to prevent the pest from ever becoming abundant. Apple Fruit Insects In Missouri the apple worm or codling moth and the plum curculio are the two most important insects attacking the fruit. The San Jose scale in scale infested orchards also settles on the fruit seriously damaging it. Of the less important fruit pests, we have plant lice, lesser apple worm, apple curculio, apple maggot and a number of caterpillars which may feed on the surface of the fruit thruout the season. However, the spraying schedule, directed especially at the codling moth and plum curculio, is so arranged as to protect the fruit also from those pests of lesser importance. Codling Moth (Carpocapsa pomonclla). — This small pest in the pink- worm feeding stage is known to all who eat apples. It has been a pest of apples from the early days and in neglected orchards it ruins most of the fruit. Its development and injury to fruit is influenced both by climatic con- dition and its geographical location. In Missouri the pest develops normally two full broods and at times three, or in the Ozark section even a partial fourth brood, some claim. However, the control measures in the past have been di- rected primarily at the spring and summer broods. MOTH. — The adult moth expands about three-fourths an inch and is not often observed about the trees. When at rest its wings are folded over the back and the irregular gray and brown bands on the fore wings give it a gray- ish-brown appearance. It becomes active about dark and deposits its eggs mostly on the leaves surrounding fruit clusters, tho occasionally on the side of fruits. EGG.— The egg is a pearly-white, scale-like object which can be detected 20 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 only after careful search. The eggs hatch in about a week, depending upon the temperature. LARVA. — The young larva, like the egg is small and difficult to see with the unaided eye. If hatched near fruit the larva in time may reach the fruit and gain entrance. In time it makes its way to the core and later feeds on the seeds and surrounding part of the apple. The larva at first is light but usually takes on a more or less distinct pink color. It feeds for about one month and when full fed is about three fourths an inch in length. On maturing the larva leaves the fruit, spins a cocoon in some protected place, such as under the bark of the tree and in time pupates. PUPA. — The pupa is a small brownish object very similar to other related species. It is about one-half an inch long and is found inside a small but rather firm cocoon. In the. summer it usually remains in the pupa stage for from about one week to ten days and1 then emerges as the adult. The insect passes the winter in the larval stage in the cocoon protected under the bark of the tree or about apple boxes, pens or where apples were stored for a time after picking. The larvae pupate just before apples begin to bloom and the adults emerge soon after the blossoms drop. Eggs are soon deposited and the first young larvae begin to hatch about two weeks after the blossons are all off. Those worms which gain access to fruit become fullfed in about a month, when they leave the fruit, spin their cocoon and later emerge as the summer brood moths. In central Missouri these usually appear on wing during the first ten days of July. However, they may be has- tened or retarded in thier develop- ment by temperature so each fruit of emergence of the summer brood FIG. 23. — Codling moth; stages of devel- opment and injury to apple (After Riley) grower should determine the date of moths in his own orchard. This he can do either by collect- ing a few wormy apples in June, and putting them in a tight box or other container where later the emerging of the moths can be observed or by putting rag bands on a few trees under which the worms will collect to pupate, and where the first emerging of adults can easily be determined. It is impor- tant to know when the July or summer brood of moths emerge so as to prop- erly time the July application of spray. Where a third brood develops the moths emerge late in August and the small worms may be found in the fruit at picking time in the fall. In the southern part of the state spring opens earlier and the pest has a longer breed- ing season. This permits the pest to develop more broods and to do more damage to the fruit. During the present spring, summer and fall conditions in Missouri have NURSERY AND ORCHARD INSECT PESTS 21 FIG. 24. — Codling moth. Apples at proper stage for applying calyx spray. (After Talbert) FIG. 25. — Codling moth; Apples too far advanced for calyx spray. (After Talbert) 22 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 been somewhat abnormal and an unusually large number of worms appeared late and the fall injury hag been unusually severe, even in some sprayed or- chards. CONTROL. — In the control of this pest we depend primarily on spraying. Some relief comes from the proper disposal of wormy fruit and the attraction of insectiverous birds to the orchard, but the real relief comes from a system- atic use of insecticides. The spray schedule for apple is arranged first of all to reach the codling moth, but the different applications are so timed and so combined as to reach all the important fruit and foliage insects as well as those fungi which also must be controlled. This schedule may include all or part of the following applications, depending on conditions in the orchard. DORMANT SPRAY. — This spray is needed only when San Jose scale is pres- ent. It may be either a lime-sulphur solution or an oil emulsion as outlined tinder the control of San Jose scale. CLUSTER SPRAY. — This is given just before the blossoms open but after the cluster buds separate. If plant lice, canker worms and apple scab are also to be controlled, the spray solution should include one and a half gallons lime sulphur solution, one pound powdered arsenate of lead or two pounds of paste arsenate of lead and one-half pint of 40% nicotine sulphate to fifty gal- lons of water. CALYX SPRAY. — This is given just after the most of the blossoms are off and before the calyx ends of the young fruits close. It includes the same ma- terials as the cluster spray, except, where the louse is under control, omit the nicotine sulphate. CURCULIO OR SECOND APPLE- WORM SPRAY. — Where curculio or apple blotch are not important, repeat the calyx spray in about two weeks. Where curculio is bad apply this spray in about one week after the calyx spray and repeat it two or three weeks later. If apple blotch is present use 3-4-50 Bordeaux mix- ture for the one and a half gallons of lime sulphur solution in this and the following spray. Local conditions will necessarily vary the time of application and the mix- ture for this and the one or two additional sprays which it may be necessary to apply in close succession. It is well for all fruit growers to keep this in mind and consult with the spray specialists of the College of Agriculture when conditions are abnormal. JULY SPRAY. — This is applied just before the apple worms of the second or summer brood hatch and begin to enter the fruit. It usually includes one and a half gallons of lime sulphur solution and one pound powder or two pounds paste arsenate of lead to fifty gallons of water. If blotch is present the Bordeaux is used as the fungicide in place of the lime sulphur solution. Where additional broods of the codling moth or where summer and fall fruit diseases are destructive it may be necessary to put on additional ap- plications and the College of Agriculture should be consulted regarding these. Plum Curculio (Conotrachelus nenuphar).— This small snout beetle is abundant thruout the state. It breeds primarily in plums and peaches but often does serious damage to apples. It attacks apples both for feeding and . for ovipositing, but only a small percentage of the eggs deposited in apples suc- ceed in maturing. The crescent gashes made by the adult beetle usually heal over later tho often they serve as entrance places for the small apple worms and for various fungi. NURSERY AND ORCHARD INSECT PESTS 23 The adult is about the size of a garden pea and is blotched with brown, gray and black. It has a short, stout snout and rather distinct humps or bumps on the back. It passes the winter in the adult stage in rubbish and other pro- tection. In the spring about two weeks after apple blossoms fall or when wild- goose plums are the size of the tip of ones small finger, the adult appears on the fruit, cutting crescent gashes for egg laying or circular pits for feeding. When these eggs hatch especially in stone fruits the yellowish white footless grub bores down into the fruit to feed. It is the typi- ^^^Brfjjj^jj^^ cal slightly curved worm found in plums i<^ which ripen prematurely and in wormy peaches. The fullfed worms in central Missouri leave the fruit in about three «*^ & ^ weeks after the eggs are laid. These en- ter the soil to pupate, and around the mid- dle to the last of July they again emerge as the adults. These may feed on fruit un- til Fall and are usually responsible for most of the plum cruculio injury to apples. There is normally one brood a year, tho often in unusual years as in 1920 larvae may be found feeding in peaches as late as September. CONTROL. — This pest can be controlled in part by poison sprays, and the spray applied one week after the calyx spray is so timed as to reach the adults while making the egg and feeding punctures soon after the fruit sets. It should be remembered, however, that sprays are less effective for this pest than FIG. 26. — Plum Curculio; adult curculio, much , enlarged. (After Stedman) I FIG. 27. — Plum Curculio; apple showing typical crescent gashes made by plum curculio for placing eggs. (After Talbert) for the apple worm. For this reason the sprays should be supplemented by the practice of clean culture to destroy the overwintering adults, the prompt dis- posal of wind-fall fruit with the enclosed worms and, where practical, shallow cultivation under stone fruit trees during July to destroy the soft, helpless rest- ing stage of the pest. On small trees it is possible to jar the adults onto sheets, when they begin to attack the fruit, and thereby destroy them. Since this spe- 24 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 cies breeds largely in stone fruits, injury to apples can be greatly reduced if peaches, plums and cherries are not planted in or near the apple orchard. San Jose Scale. — As previously mentioned, the scale settles on the fruit as well as on the foliage and the timber of the tree. The crop on scaly trees may be practically ruined. Its market value is reduced and the quality of the fruit is also injured. If remedial measures previously discussed are applied to protect the tree the fruit will also be protected. The dormant spray is neces- sary as the summer sprays are too weak to control the pest to any extent. Plant Lice (Spp.). — When the plant lice are abundant on buds, foliage and twigs at blooming time and soon thereafter the young fruit is also sure to suffer. The lice sucking sap from the young 'fruits cause a dwarfing or com- plete check in its normal growth. This. reduces the yield as well as quality. If necessary sprays to protect foliage and growth are applied, the fruit also will be protected. Lesser Apple Worm (Hnormonia prunivora). — This small caterpillar somewhat resembles the real apple worm, tho it is smaller and usually of a deeper pink color. It feeds just under the skin of the fruit producing a mined- like effect. Its life cycle and feeding habits are quite similar to those of the apple worm and the regular spray applications for the latter will control it as. well. For the past several years in Missouri this pest has been of comparatively little importance. Apple Curculio (Anthonomus quadrigibbus) . — This snout beetle, may become, very destructive to apples, tho as a rule it is the work of the plum curculio that causes most damage in Missouri. Its life cycle is similar to that of the plum curculio except that it seems to enter hibernation quarters earlier and thereby does less injury to the fruit by feeding in the summer and fall. It makes a small circular opening in the surface of the fruit and hollows out below in the flesh of the young apple a cylindrical egg cavity. The surrounding tissue then hardens, causing a characteristic deformity of the fruit. CONTROL. — Spray applications help some as with the plum curculio but they must be supplemented with clean orchard practices and prompt disposal of infested windfall apples early in the season. Other Fruit-feeding Caterpillars (Spp.). — Some seasons green and ripening apples are more or less injured by different caterpillars. The green fruit worms and the apple leaf-roller are often quite troublesome. They may eat rounded holes in the fruit or irregular gashes about the stem or blossom end. Where a regular system of summer sprays, including an arsenical, is ap- plied year after year, these caterpillars do little damage. INSECT PESTS OF THE PEAR In Missouri the pear is attacked by only a few of the worst pear pests. San Jose scale, codling moth, curculio, and blight are most commonly com- plained of on pear. Pear slug may do considerable damage but pear psylla and blister mite are seldom of serious consequences. The discussions 'on apple in- sects covers also pear injury and a separate discussion is unnecessary here. In the nursery do not grow pear trees near old blighted trees and do not permit wild haws to stand in or near the pear blocks. Pear trees should be carefully gone over so that all trees which may show the least signs of blight are detected and thrown out. NURSERY AND ORCHARD INSECT PESTS 25 Pear Slug (Eriocampoides limacina). — This pest attacks the foliage of pear and cherry often very badly. It is a small greenish, slimy worm similar to the rose slug and related species. Often a dozen may feed on one leaf, con- suming the surface layer, which causes the leaf to dry up. The pest develops two broods a year, the adults of the first appearing in June while the adults of the second appear in August. The first brood is most destructive. The pest attacks the foliage of trees both in the nursery and in the orchard. As a rule cherry is attacked more severely than pear. FIG. 28. — Pear slug: a, Adult female sawfly; b, larva en- larged; c, back view of same; d, injured leaves with larvae, natural size. (After Marlatt) CONTROL. — Where the regular summer sprays are applied to bearing trees the pest will be controlled. On nursery stock the pest can be controlled by dusting or spraying with an arsenical. INSECT PESTS OF THE PEACH The peach in the nursery and orchard is not subject to as many pests as is the apple, however, there are a number of important peach pests. Of these the peach-tree borer, the San Jose scale, the plum curculio, the tarnished plant- bug, the peach twig-borer, the shot-hole borer, and black peach aphis are usually the most important. Peach-tree Borer (Sanninoidea exitiosa). — This is a caterpillar borer which, while especially important in the orchard, may at times attack older peach stock in the nursery. Its presence is usually readily recognized by the appear- ance of peach gum about the base of the tree. . The borer varies from a very tiny whitish caterpillar to one an inch long and of a yellowish-white color. It works between the bark and the wood from a few inches above the ground usually to a few inches below ground. The adult moth resembles a wasp in appearance and action. The male has transparent wings and the body steel- t>lue in color with yellow on the tip while the female is larger, wings more 26 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 completely covered with blue scales and the body is steel-blue with a distinct orange band. The pest passes the winter in the larval stage. In some cases the larva may be very small while in other cases it may be almost mature. In the peach belt of the Ozarks the moths begin emerging from the more advanced over- wintering larvae around the last of May but the heavy emergence and egg laying usually comes between the middle of June and the first of August. CONTROL.— The peach-tree borer is no exception to the rule that fruit tree borers are difficult and expensive to control. Worming by hand and the use FIG. 29. — Peach tree Borer: Crowns of peach trees showing borers and injury. (After Chandler) of repelling or protecting paints should always be supplemented by clean culture and the removal of old worthless, borer-breeding peach trees and snags. In the nursery do not hold over any old trees as breeding places for borers and keep the young peach blocks as far as possible from old peach or plum trees. Do not sell peach trees which show signs of being infested with borers, unless they are fumigated. Badly infested trees should be wormed in the fall and again late in May before the moths begin to emerge. Dig away the dirt and gum and with a knife blade locate and destroy the borers without injuring the tree more than necessary. After the borers are removed in late May paint or spray the trunk NURSERY AND ORCHARD INSECT PESTS 27 and exposed roots with one part of lime-sulphur solution to ten parts of white wash solution. If applied with a sprayer it should be made thinner than if painted on. When dry, mound up about the trees. One pound of arsenate of lead may be added to every ten gallons of the paint or wash. San Jcse Scale. — This pest and its control on peach is largely a duplication of its work and control on apple. Peach nursery stock infested with or ex- posed to the scale should be treated the same as apple stock. Plum Curculio. — The life cycle and habits of this pest have already been discussed under apple insects. The pest breeds most abundantly in peaches and plums and special effort should be made to prevent it from developing in these fruits. Clean culture, destruction of wormy windfalls, jarring where practical and shallow cultivation in July should be supplemented with the use of arseni- cal sprays to poison the adults as suggested on apple.. The peach foliage is more easily burned than that of apple so greater care must be taken with mix- ing and applying sprays to peaches. The fuzzy nature of the peach enables it to hold the poison better than either apple or plum. Where curculio injures peach the spray application given when most of the shucks of collars are off the young fruit and the application given one week to ten days later are the most effective applications. They should include about one pound powdered or two pounds paste arsenate of lead to fifty gallons of the 8-8-50 self-boiled lime-sulphur solution. Do not use the ordinary commercial lime sulphur for spraying peaches when in leaf as it injures foliage. As a dormant spray, how- ever, it is all right for controlling San Jose scale. Tarnished Plant-bug. — This pest has already been discussed more espe- cially as a pest of nursery stock. Peach nursery stock suffers more than other FIG. 30. — Peach-twig Borer • showing larva, pupa and injured peach bud. (After Marlatt) FIG. 31. — Black Peach Aphis; peach tree showing lice on roots (After Smith) 28 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 types tho pear, cherry, and apple may also suffer from the pest. In the bearing orchard peach does not suffer much injury. Peach Twig-borer (Anarsia lineatella}. — This small caterpillar is often very injurious to buds and new growth on both nursery and orchard trees. Bearing trees are usually more seriously injured than younger trees. In the summer and fall it is also often quite troublesome, working into the fruit around the stem end or where fruit cracks. Late peaches suffer most. It passes the winter as a young larva in a small chamber made in the bark usually at the fork of two small twigs. In the spring these larvae bore into buds and tips of new growth often killing several buds before maturing. These pupate in curled leaves or other protection and the small, dark-gray moth soon emerges to lay eggs for the next generations. . The later generations work more in the fruit and less in the twigs. CONTROL. — This pest is usually most abundant on neglected trees tho well kept peach orchards may become seriously injured. The best means of reaching the pest is to apply the lime sulphur spray in the spring just as the young larvae are leaving their winter quarters. The spray may be applied, after the buds begin to open but before the blossoms are open, with effective results on the borer and yet not seriously injure the peach foliage. SHOT-HOLE BORER. — This species has been discussed under the apple insects and the same treatments recommended there will control the pest on peach trees. Black Peach Aphis (Aphis persicae-niger). — This louse has been re- ported on peach in Missouri but thus far no serious injury has occurred. It works on the roots and in the summer some may come up on the leaves and twigs. It resembles other plant lice in feeding habits by extracting sap. It is a very dark-colored louse. CONTROL. — If nursery stock becomes infested it should be thoroughly fumi- gated before being disposed of. In the orchard nicotine sulphate sprays are effective where the louse appears above ground and tobacco dust is suggested for the root form where injurious. Thus far this species has not done any appreciable injury in the state. The most up-to-date peach orchards of the state usually receive clean cul- ture which materially reduces the favorable conditions for various insects. It is usually the neglected orchard where the above insects are most abundant and injurious. INSECT PESTS OF PLUM AND CHERRY Plums and cherries are subject to about the same insects as peaches. The San Jose scale attacks certain types of plum and sweet cherries very badly. The plum curculio attacks the fruit of plums and cherries often completely destroy- ing the crop. The peach-tree borer may also do some damage on both plum and cherry. The peach terrapin scale also attacks plum. The plum louse and the cherry louse are also injurious some seasons. The cherry scale often becomes injurious.. The cherry maggot is seldom injurious to cherries in the state as is also true of the apple maggot or railroad worm in apples. Where plum and cherry are attacked by pests discussed under apple and peach insects simply refer to recommendations given under those fruits. Rusty Brown Plum Louse (Aphis setoriae}.— This dark-brown louse NURSERY AND ORCHARD INSECT PESTS 29 is usually most injurious early in the season. It also attacks peach. It attacks the leaves and young growth. Where abundant one application of the regular nicotine spray will control the pest. It is not often that sprays are necessary on nursery stock. Cherry Louse (Myzus cerasi}. — This pest is most severe on sweet cherry trees in the nursery. Injury on bearing trees is usually slight. Prompt applications of the nicotine spray or the dipping of the tips in the solution will give relief. Cherry Scale (Aspidiotus forbesi). — This scale is found commonly on both bearing cherry and apple in this state. Occasionally it seriously encrusts cherry trees. It may also appear on young trees in the nursery, especially ap- ples where the scions are taken from trees showing infestation. Nursery stock showing any signs of this scale should be discarded. Bearing trees showing any serious infestation should be given one thorough application of lime sul- phur as for San Jose scale. Apply it in the spring as growth starts. Cherry Fruit-flies. — Where injury from these result, it is the work of the white maggot stage in the fruit. In the east these maggots do much dam- age to cherries but in this state it is seldom that they are found in the fruit. Where cherries are found to be wormy it is usually the work of the footless grub of the plum curculio as discussed earlier under apple insects. The fruit flies feed on sweets for a time after emerging in the spring and later deposit eggs in the green fruit. To control the pest therefore a small quantity of a poisoned sweet syrup, consisting of four pounds arsenate of lead to one hundred gallons of water sweetened with cheap molasses may be sprayed or sprinkled on the cherry foliage at the time the flies are emerging. Some claim that one or two applications, of two pounds of powdered arsenate of lead to fifty gallons of water, to the foliage just as the flies are emerging gives results. INSECT PESTS OF GRAPES In this state the grape scale, leaf-hopper, various leaf feeding beetles and caterpillars, fruit worm and curculio are the more troublesome pests on grape in the nursery and vineyard. Unfortunately the grape is not grown as abun- dantly in the states as it should be. However, as a consequence of this the insect problem on grape is not so important a one with us as is the case in large grape-growing sections of the country. Grape Scale (Aspidiotus uvae}. — Not infrequently in the vineyard this small armored scale injures or kills grape vines outright. It works on the canes more or less protected by the loose bark on the older growth. Where injurious, it can be controlled by pruning and spraying, when the vines are dormant, with lime sulphur solution diluted with eight parts of water as for the San Jose scale. Where the loose bark is abundant tear it away before spraying. In some cases San Jose scale, which is a close relative of the grape scale attacks and destroys grape vines in this state. In the nursery grape scale is of no serious consequence. Grape Leaf-hopper (Typhlocyba comes").— This small yellow and red marked leaf-hopper is common on grapes and related vines every year, seriously injuring the foliage and thereby affecting the growth of the vines and the crop. The nymphs and adults extract sap from the lower surface of the leaves causing them to appear specked with white spots and where the injury is se- 30 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 vere the leaves turn brown and drop prematurely. This is perhaps the most common and most injurious pest of grapes in this state. The pest passes the winter in the adult winged stage in rubbish in the vine- yard or nearby along fences or where dry grass, leaves or other protection is found. Early in the spring the adults may extract sap from other plants until the grape foliage develops when they attack it and lay their eggs in the lower surface of the leaves. Virginia creeper on buildings is also similarly attacked. In Missouri several generations are developed each year, the pest becoming more abundant and injurious toward fall. CONTROL. — Clean culture in and near the vineyard especially in the winter to destroy the overwintering adults is the first practical treatment to apply. When the pest is abundant spray with nicotine sulphate using one-half pint to fifty gallons of water when the early brood of nymphs begins to appear on the lower surface of the leaves. Use a penetrating mist spray and make sure that the lower surface of the leaves are thoroughly sprayed. If not entirely effec- tive repeat it later for succeeding generations of nymphs. It is not effective in killing the winged adult. Sticky shields have now largely given way to sprays. In the nursery the pest can be very effectively controlled with the nicotine spray. Leaf-feeding Beetles and Caterpillars (Spp.*). — In Missouri, the rose chafer and the grape-vine flea-beetle are the two most important beetles attack- ing grape foliage. . The grape root-worm and the adult leaf-feeding beetle is present but thus far has done no appreciable injury. Of the caterpillars, the leaf-folder, the eight-spotted forester, and the plume-moth are most commonly found injuring the foliage of grape. A number of other species feed on grape but only rarely destroy much foliage. In the nursery the leaf-roller is usually the only species that requires attention. CONTROL. — Where the foliage of grape is being injured by chewing insects one or more applications of an arsenical spray will usually destroy the pest and save the foliage and fruit. In case of the rose-chafer poison sprays are less effective. For this pest use three pounds of powdered arsenate of lead and two quarts of a cheap grade of molasses to fifty gallons of water. The molas- ses hides the taste of the poison and the stronger spray will kill many of the beetles. However, one should supplement the sprays with hand work as the foliage may be badly damaged in a few hours in case of a severe outbreak. Where sprays are to be applied do not wait until the leaves are folded or until the pest has done serious damage. On a few vines hand work will prove en- tirely effective. Grape-berry Moth (Polychrosis viteand). — This small caterpillar is more or less injurious every year on the fruit. . It is to the grape what the codling moth is to apple. There are normally two generations a year. The winter is passed in the pupa stage on the grape leaves. The adults emerge and lay eggs so that the young worms are ready to begin feeding on the young set- ting fruits. These mature and the second generation of worms work on and in the fruit toward ripening time. The caterpillar varies in color from greenish-brown to purple and when full fed is nearly one-half an inch long. The adult is smaller and darker than tho somewhat resembling the codling-moth in general wing markings. The presence of the pest on grape is easily detected by the reddish blotches on NURSERY AND ORCHARD INSECT PESTS 31 unripe fruits and the small worm feeding inside the fruit or where two fruits touch. CONTROL. — Where this pest is injurious an arsenical spray, combined with Bordeaux mixture for grape diseases, should be applied just after the blos- soms are off and young fruits begin to set well. It is well to repeat this in 10 days and where injury is especially severe spray again early in July just as the worms of the second generation begin to hatch and attack the fruit. One pound of powdered arsenate of lead in fifty gallons of 4-5-50 Bordeaux should be used. Supplement the sprays each year by gathering and burning or plowing under all grape leaves in the late fall. Grape Curculio (Craponius inaequalis). — This small snout beetle is often very injurious to the fruit, especially in the southern part of the state. There is one main generation each year. The beetles begin making egg punc- tures after the fruits are about half grown and may continue until the earlier varieties ripen. The adult feeds to some extent on the foliage and where arsenical sprays are applied at regular intervals to keep poison on the foliage the pest can be successfully controlled. The adults pass the winter in rubbish, so clean culture in and near the vineyard during the fall and winter will reduce the number of adults that appear in the vineyard the next summer. The sec- ond spray for the grape-berry worm will help materially with the curculio. In Missouri our larger nurserymen grow comparatively little of their grape stock so that the nurserymen's problem of handling insect pests on grape stock is a comparatively small one as compared with other types of nursery stock. INSECT PESTS OF GOOSEBERRY AND CURRANT Only three insects are of special importance on gooseberries or currants in Missouri. The San Jose scale is often found on currants and the imported currant worm and currant louse are to be met with every year. The various other insects reported as attacking the stems, foliage and fruit have in the past been of little importance in this state. San Jose Scale. — In the nursery and in the garden currants may become infested with the scale and it soon proves fatal to the bushes. Dormant sprays as on fruit trees will control it. Infested plants in the nursery should be promptly destroyed. Imported Currant Worm (Pteronus ribesii). — Every spring as soon as the leaves of gooseberry and currant are out the dark wasp-like adult appears to place her eggs in the veins of the leaves. The pest passes the winter in the cocoon usually as the larva and the adults appear early. The eggs hatch in about ten days and the young worms begin to eat holes in the leaves usually down in the center of the bush where they are less easily seen. As the worms increase in size they devour all edible parts of the leaves often leaving the bare stems with partly developed fruits and leaf stem. The common green and black spotted worms are familiar to all who grow currants and gooseberries. When full grown the larvae are three-fourths an inch long and spin a small oval cocoon near the ground or under rubbish on the ground. A second and even a third generation is said to develop but in this state the only damage done is due to the work of the spring brood of larvae. CONTROL. — This pest is easily controlled. Dust or spray with arsenate of 32 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 lead as soon as the foliage is well out and no damage will be done by this pest. Too often one waits until the worms show up and by that time usually con- siderable damage has already been done. Currant Louse (Myzus ribis). — This louse in recent years has done considerable injury to foliage especially of currant in this state. Its presence is easily detected by the appearance of reddish blotching on the surface 'of in- fested leaves. Where the lice are feeding on the lower surface of the leaves they cause an upward projection of the surface of the leaves or a pocket-like formation. Except in severe cases the leaves do not crumple up or develop knot-like formations. On currants the lice appear shortly before the fruits begin to ripen in this state. CONTROL. — As with other plant lice one or two thorough applications of nicotine sulphate will give relief. If a sprayer is not at hand double the strength of the nicotine solution and apply it to the lower surface of the leaves with a wisp of grass or dip the infested shoots where they are not bearing fruit. Here again much of the gooseberry and currant stock used in Missouri is propagated in the east and north. The Federal regulations affect the move- ment of currants from state to state, since it may carry the white pine blister- rust. These regulations are given in full in Missouri Agricultural Experiment Station Circular No. 99. INSECT PESTS OF BLACKBERRIES AND RASPBERRIES In Missouri the red spiders, which are not true insects, and the snowy tree- cricket are the only pests that attract special attention on blackberries and raspberries. The rose scale may at times do some injury. The nurserymen, however, are also interested in the two important plant diseases, namely, anth- rachnose and blackberry rust, since both these can be spread on nursery-grown plants and both are classed as dangerously injurious diseases by the various state nursery inspection departments. Red Spiders. — The common red spiders are very small mites related to common spiders and to the scab or mange mites of live stock. When they cause trouble on blackberries or raspberries, it is due to favorable, dry, hot, climatic conditions. In a normal summer in this state no injury results but in dry summers these crops often suffer severely. The red spider spins some silk as protection and usually feeds on the lower surface of the leaf. The epidermis is broken and the liquid content of the leaf cells is consumed re- sulting in a yellowing of the leaf in spots and eventually its complete drying up. CONTROL,. — Where mites cause trouble and a liberal supply of water can not be applied to the affected patch, dust with powdered sulphur when the dew is on. Snowy Tree-cricket (Oecanthus nigricornis). — This small active white cricket is common in the state and at times may do considerable damage to the young raspberry canes that are to produce fruit the following summer. However, it is of much less importance with us than various reports show it to be in other parts of the country. Where injury results it is due to the work of the female in placing her eggs in the canes. This results in a splitting and dying of many canes where extensive oviposition occurs. The eggs are deposited in the fall, they hatch the following spring and the nymphs feed all NURSERY AND ORCHARD INSECT PESTS 33 summer on the foliage of different plants before maturing to deposit eggs for the following year's crop of young. CONTROL. — Where this pest is troublesome remove and burn injured canes containing the overwintering eggs. Also practice clean culture in and near the patch thruout the year. INSECT PESTS OF STRAWBERRIES In this state strawberries may be attacked by a large number of insects and diseases but the root louse, leaf-roller, slugs, weevil, crown-borer, tarnished plant bug and white grubs are the most important. Some years the leaf-roller may practically ruin the crop over the important strawberry belt of the states. To nurserymen, the .louse, leaf-roller and the leaf-spot disease are of special importance, since they may be spread on the young plants. Root Louse (Aphis forbesi). — This louse has been reported as injuring strawberry fields in the state but it has not shown up in any of the fields where FIG. 32. — Strawberry Leaf -roller; strawberry leaf showing leaflet folded by pest plants have been grown for distribution. In the early part of the season the lice hatching from overwintering eggs on the foliage feed by extracting sap from the young growth but later ants carry them underground where they feed on the root system. Where the lice cause trouble in strawberry patches care should be taken not to spread infestation on plants shipped to growers. Dip plants in nicotine solution before setting in the spring and spray infested patches after the overwintering eggs hatch and before lice are carried to the roots by ants. Also destroy old strawberry beds as they may serve as breeding places for lice and other pests of strawberry. Leaf-roller (Ancylis comptana}.— This small active caterpillar has been the most destructive pests of this crop in recent years in the state. It may also attack raspberries and blackberries. The insect is multiple brooded, having 34 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 176 probably four broods a year in the southern counties of the state. However, the big damage comes before and at picking time. The winter is passed ap- parently largely in the larval stage. The moth expands slightly more than one half an inch and when seen on wing has a brownish appearance, the fore wings being also marked with lighter and darker streaks. The strawberry grower readily detects these in the patch and speaks of them as brownish moths or millers. CONTROL. — Arsenical sprays are effective if applied at the right time. Watch for the appearance of the moths early in the spring usually the latter half of April in the southern strawberry belt, and spray promptly with two pounds of arsenate of lead powder to fifty gallons of water. The plan is to poison the young worms before they have folded over the two halves of the leaflets as protection while feeding. If this early spray is not effective repeat it after the crop is off and the next broods of moths appear in the patch. Some prac- tice mowing and burning over patches after the crop is off. Where this is done it should be so timed as to catch the pest in the pupa stage about the last week in July in southwest Missouri. Destroy old abandoned patches and volunteer plants. Strawberry Slugs. — Two species of slugs are reported on strawberries, tho the black-marked species (E. maculata) is the more important in this state. It is the larva of a sawfly related to the im- ported currant-worm. The larvae begins to attack the foliage when the crop of ber- ries is about half developed. One thorough application of two pounds of arsenate of lead powder to fifty gallons of water at that time will usually end the trouble. FIG. 32.— Strawberry Slug; Adult This spray and the one for leaf-roller may much enlarged be combined where both pests are at wor"k on a patch. Strawberry Weevil (Anthonomus slgnatus). — This pest does not do much damage in this state tho some complain of it. Where present it cuts the stems of blossoms after the egg is deposited in the blossom bud. CONTROL. — Clean culture in and about the patch with the setting of new patches often and the plowing under of old patches will usually control this pest. It attacks only the staminate varieties but commercial growers select commercial varieties, be they varieties subject to attack or those immune to attack. Tarnished Plant-bug. — This plant-bug breeds in the strawberry patches and the overwintering adults often do serious damage to the crop. They at- tack the blossom buds and young fruits causing them to be imperfect or as the grower terms it "buttoning" of the fruit. CONTROL. — Clean culture in and near the patch during the winter as well as the summer will reduce the number of adults to pass the winter in the patch or nearby and thus reduce early spring injury. Systematic driving of the pest with the wind early in the spring is suggested also as a means of lessening the injury to strawberries the same as in case of budded nursery stock. Sprays and hand gathering is impractical in the commercial field. NURSERY AND ORCHARD INSECT PESTS 35 Crown Borer (Tyloderma fragoriae). — This beetle breeds abundantly in the crowns of older plants doing considerable damage. New plantings and fields reset often do not suffer. Keep down volunteer plants and plow under aban- doned patches. The beetles are unable to fly, so new fields should be set at some distance from old ones using only young plants. Those distributing plants should sell only the young plants which are not infested. White Grubs (Lachnostcrna spp.). — In recent years numerous complaints of white grubs have come from strawberry growers. They attack the roots, weakening or killing the plants. Often where sod is plowed under and straw- berries planted in the ground serious injury may result. Where old fields are not abandoned and new ones set often enough the brown June beetles, the adults of the white grubs, may visit strawberry fields and deposit their eggs thus starting an infestation. Some species of white grubs may feed as grubs for two or three seasons. CONTROL. — Set new fields on uninfested, cultivated soil and replant often enough to prevent this pest becoming abundant and injurious to the crop. In this report no effort has been made to discuss all the thousands of in- sects which may attack the various fruits. Only those, which for the past ten or twenty years have been of most serious injury to nursery stock and the bearing fruit crops, have been included. Fruit growers and nurserymen, there- fore, who have trouble with species not discussed herein, should communicate with the Agricultural Experiment Station, Columbia, Missouri and the pest will be investigated, if a new important one, or information on its control promptly given. Investigations are now being made of a number of the pests discussed herein and when completed the results of these studies will appear in full in future station publications. UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BULLETIN 177 AN INVESTIGATION OF THE DIPPING AND FUMIGATION OF NURSERY STOCK A lot of condemned apple trees COLUMBIA, MISSOURI DECEMBER, 1920 UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE Agricultural Experiment Station BOARD OF CONTROL THE; CURATORS OF THE; UNIVERSITY OF MISSOURI EXECUTIVE BOARD OF THE UNIVERSITY H. J. BLANTON, Paris JOHN H. BRADLEY, Kennett JAS. E. GOODRICH, Kansas City ADVISORY COUNCIL, THE MISSOURI STATE BOARD OF AGRICULTURE OFFICERS OF THE STATION A. ROSS HILL, PH. D., LL. D., PRESIDENT OF THE UNIVERSITY F. B. MUMFORD, M. S., DIRECTOR STATION STAFF DECEMBER, 1920 AGRICULTURAL CHEMISTRY C. R. MOULTON, Ph. D. L. D. HAIGH, Ph. D. W. S. RITCHIE, A. M. E. E. VANATTA* R. M. SMITH, A. M. T. E. FRIEDEMANN, B. S. A. R. HALL, B. S. in Agr. E. G. SIEVEKING, B. S. in Agr. A. B. CULBERTSON, JR., B. S. in Agr. B. W. MANNING, B. S. in Agr. G. W. YORK, B. S, in Agr. AGRICULTURAL ENGINEERING J. C. WOOLEY, B. S. MACK M. JONES, B. S. ANIMAL HUSBANDRY E. A. TROWBRIDGE, B. S. A. L. A. WEAVER, B. S. in Agr. A. G. HOGAN, Ph. D. F. B. MUMFORD, M. S. D. W. CHITTENDEN, B. S. in Agr. PAUL B. BERNARD, B. S. in Agr. A. T. EDINGER, B. S. in Agr. H. D. Fox, B. S. in Agr. BOTANY W. J. ROBBINS, Ph. D. E. F. HOPKINS, Ph. D. DAIRY HUSBANDRY A. C. RAGSDALE, B. S. in Agr. W. W. SWETT, A. M. WM. H. E. REID, A. M. SAM BRODY, M. A. C. W. TURNER, B. S. in Agr. C. H. NELSON, B. S. in Agr. ENTOMOLOGY LEONARD HASEMAN, Ph. D. K. C. SULLIVAN, A. M. S. R. McLANE, B. S. in Agr. FIELD CROPS W. C. ETHERIDGE, Ph. D. C. A. HELM, A. M. L. J. STADLER, A. M. E. O. POLLOCK, B. S. in Agr. O. W. LETSON, B. S. in Agr. B. B. BRANSTETTER, B. S. in Agr. RURAL LIFE O. R. JOHNSON, A. M. S. D. GROMER, A. M. B. H. FRAME, B. S. in Agr. R. C. HALL, A. M. FORESTRY FREDERICK DUNLAP, F. E. HORTICULTURE V. R. GARDNER, M. S. A. H. F. MAJOR, B. S. H. D. HOOKER, JR., Ph. D. J. T. ROSA, JR., M. S. F. C. BRADFORD, M. S. H. G. SWARTWOUT, B. S. POULTRY HUSBANDRY H. L. KEMPSTER, B. S. SOILS M. F. MILLER, M. S. A. H. H. KRUSEKOPF, A. M. W. A. ALBRECHT, Ph. D. F. L. DULEY, A. M. R. R. HUDELSON, A. M. WM. DEYouNG, B. S. in Agr. H. V. JORDAN, B. S. in Agr. RICHARD BRADFIELD, A. B. O. B. PRICE, B. S. in Agr. VETERINARY SCIENCE J. W. CONNAWAY, D. V. S., M. D. L. S. BACKUS, D. V. M. O. S. CRISLER, D. V. M. A. J. DURANT, A. M. H. G. NEWMAN,. A. M. ZOOLOGY GEORGE LEFEVRE, Ph. D. OTHER OFFICERS R. B. PRICE, M. S., Treasurer LESLIE COWAN, Secretary S. B. SHIRKEY, Asst. to Dean O. W. WEAVER, B. S., Agricultural Editor J. F. BARHAM, Photographer Miss BERTHA C. HiTE,1 A. B., Seed Testing Laboratory aln service of U. S. Department of Agriculture. On leave of absence. An Investigation of the Dipping and Fumigation of Nursery Stock K. C. SULLIVAN More than one hundred years ago the first nursery was started in Mis- souri. At that time Missouri was a part of the Great West and was settled mostly along the water courses. The fruit industry at that time was undevel- oped. Today there are in Missouri more than one hundred nurseries. One of the largest, if not the largest, nurseries in the world is located in Mis- souri and the acres of some of the others run well up into the hundreds. The growth of the fruit and nursery industry in Missouri has been remark- able. Also, the increase in the number of injurious insect pests of the fruits has been equally as remarkable; in fact, they have increased so rapidly that in some sections farmers are abandoning the fruit industry and entering some other line of work in which insect pests are not so troublesome. Some of the most injurious insect pests and fungous diseases of fruit trees, that we have to contend with, were first introduced and scattered over the country on nursery stock. The most noted and most injurious one of these is the San Jose scale. This scale is so destructive that every state in the Union and the Federal Government have passed stringent laws regard- ing its distribution and control. Missouri has a law which forbids anyone in the State to distribute or dispose of nursery stock of any sort upon which there is San Jose scale ; nor is anyone from outside the state allowed to ship infested plants into the state. In many states there is a law which requires that all plants badly infested with San Jose scale be destroyed and that those which are not visibly infested be treated with the best known remedies for the destruction of the scale. The San Jose scale has become so widely distributed in Missouri that strong measures have been taken to stop further distribution. It is usually carried from one section of the country to another upon nursery stock. Practically all original infestations in Missouri were started from' scale brought into the community upon nursery stock. Since the San Jose scale is usually carried into a non-infested district upon nursery stock, the logical thing to do is to produce clean stock; that 1 is, nursery stock upon which there is no scale. This is very difficult to do, especially where the scale has once obtained a foothold. From time to time, various remedies have been recommended by which nursery stock can be treated and the scale destroyed. Some of these treaments killed the trees as well as the scale; others did not always kill the scale, and others cost so much that they were not practical, especially with the smaller nurserymen. During the past five years the writer has been constantly in touch 4 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 with all the Missouri nurserymen and it has been his pleasure to make per- sonal visits with practically every nurseryman in the state and, especially with those located in communities where San Jose scale is prevalent. He has worked with them and helped them treat their nursery stock for scale and other injurious insects. While engaged in the work, many problems, confronting the nurserymen, concerning the eradication of San Jose scale from nursery stock, have been brought to his attention. As a result, a number of experiments have been made to test the effect of the different materials commonly used upon infested and non-infested stock, with the object in view of determining which remedy is the most practical from all standpoints, under Missouri conditions. Life cycle of San Jose scale. — 'The mature San Jose scale is yellow with a sac-like body which is covered with a soft, waxy secretion — the scale. This covering serves as a protection for the pest. The insect passes the winter in a half-grown stage, all other stages being killed by winter condi- tions. These half-grown insects are found under a small black scale just visible to the naked eye. About 95 per cent or more of these are male insects, they being greatly in excess. About the first of May, the males pupate and in a short time emerge as delicate two-winged insects. The females at this time have arrived at the stage of impregnation and in a few days the males disappear. The females reach maturity about a month later and begin to give birth to living young. Most of the other scale insects deposit eggs which later hatch, but this is not true of the San Jose scale. The young are developed in a mem- branous sac which corresponds to an egg, but they usually burst out of this before being born. Thus the San Jose scale is usually oviviviparous, but it may be partially oviparous. A single female is capable of giving birth to 600 young in a period of about six weeks. It is doubtful, however, if a female gives birth to more than 100 or 200 insects and many of these are males. Even at this rate of reproduction, from one single female the total number of off-spring at the end of a season reaches into the millions. The newly born insects are very tiny, yellow in color and have six legs. They soon push their way out from under the scale of the mother and crawl around for a day or so finding a suitable place to settle down. On the apple the young scale seem to push out towards the tender growing tips to settle down, while on the peach they stay more on the old wood. It is at this stage, while the young are crawling about, that the pest is likely to be scat- tered from one place to another upon the feet and bodies of birds, beetles and other objects. If the branches of two trees intermingle, the young easily crawl from tree to tree and it is often in this manner that the pest spreads. When a suitable place is found, the young settle down and begin to work the long proboscis, which is three or four times the length of the in- sect's body, into the tissue of the host and begin developing a scale cover- ing. Within two or three days, this covering of cottony and waxy fibers becomes matured into a pale grayish scale which gradually becomes darker. Male and female scales are similar in size, shape and color until the first molt, which takes place in from twelve to fourteen days after the emer- gence of the larva. Up to this time the male and female are indistinguish- DIPPING AND FUMIGATION OF NURSERY STOCK 5 able in appearance, but after the first molt they lose all resemblance to each other. The females lose their eyes, legs and antennae and becorrfe almost circular with indistinct segments. They resemble very much a minute flat- tened, yellowish sac. Springing from beneath the body, near the center, they have a set of long needle-like mouth parts with which they obtain nourishment from the plant. After the first molt, the male insects change in appearance also. They lose their legs and antennae but instead of losing their eyes they develop large purple ones and they become elongated and pyriform in shape. At this time the scale covering of the body of both sexes has a decidedly grayish tint mixed to some extent with yellow. In about eighteen days after birth, the male changes to the pro-pupa or first pupal condition and the scale covering assumes a longer shape which sometimes tends to be curved. At this stage the male begins to look more like an insect. Two or three terminal segments can be seen, the posterior one bearing two short spines. The antennae, legs and wing pads are visi- ble. The purple eyes are set close together. About two days later, or about twenty days from birth, the male insect transforms to the true pupa. The matted skin at this time, instead of form- ing a part of the scale covering as in the preceeding molt, is pushed out from beneath the scale. The last or third molted skin is also pushed from beneath the scale. The male insect becomes mature in twenty-four to twenty-six days from birth and pushes out backward from beneath the scale. In from three to five weeks from the larva, the females molt the sec- ond time. The skin splits around the edge of the body. The upper half adheres to the scale covering and the lower half forms a sort of ventral scale between the insect and the bark. The female insect becomes full grown in from thirty to forty days from birth. The adult male insect appears as a very small, delicate, two-winged fly about 0.6 mm. long and is capable of flying from place to place. The mature female does not develop as the male does, but remains concealed beneath her scale as a small, yellowish, almost circular insect about 0.8 mm. wide and 1 mm. long. No eyes, legs, wings or antennae are developed. The scale covering of the female is almost circular and slightly raised in the center. The exuvia is central or nearly so. In diameter the scale varies from 1 to 2 mm. The color of the scale is gray, excepting the part covering the exuvia, which is a pale or reddish yellow and the ring effects, which are often noted between the center and outer edge of the scale, marks the edges of the molts of the larval scale. The scale covering of the male is darked than that of the female and es- pecially in the winter, when it is black. In shape, it is oblong-oval and just about half as wide as long. It ranges from 0.5 to 1 mm. in length. There is a nipple-like prominence located between the anterior margin and center of the scale which marks the position of the larval scale. In Missouri there are four generations a year and probably five, espe- cially in a favorable season. The generations overlap to a great extent. Owing to the smallness and the color of the scales, the insect is hard to detect by the untrained eye and in many cases the writer has known the lenticles, or small knots on a tree, to be mistaken for the San Jose scale. 6 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 When a plant becomes encrusted with' the insects, it looks grey in color and upon rubbing the hand along the trunk or branches large flakes of the dead scales become loosened and fall off. The tree looks sick and does not leaf out so early in the spring as a normal tree and usually dies within a season or two. Where there is only a scattering of scale on the plant, it can usually be detected by the sunken places in the bark caused by a lack of food material which has been used by the insect instead of by the tree. Also immediately around the scale the bark takes on a reddish tinge, which is supposed to be caused by a toxin which the insect injects into the plant. This red-like blotch is very characteristic of the San Jose scale, especially on the apple and peach. Damage. — It is impossible to estimate the amount of damage done by the San Jose scale in Missouri orchards because at present no one knows exactly how extensively Missouri is infested, but it is a known fact that many large commercial and small orchards have been completely destroyed Some poorly packed nursery 'stock. This stock was also infested with San Jose scale. It was found and condemned thus preventing its dis- tribution by it. However, in the nurseries of Missouri in the past two years, the damage caused by this insect has amounted to the tremendous sum of $20,- OOO.OQ and this is but a drop in the bucket as compared with the damage to the orchards in Missouri. Control in the orchard. — The San Jose scale can be controlled in the orchards if proper precautions are taken. The most successful method practiced today is the use of lime-sulphur as a dormant spray. Certain of the miscible oils are also used to a greater or less extent with good results. Commercial lime-sulphur can be purchased on the market, which, when mixed with water, one gallon of lime-sulphur to seven gallons of water, makes a most efficient spray. A miscible oil makes a good spray when mixed with water at the rate of one gallon of the oil to twelve gallons of water. The lime-sulphur spray is the cheaper spray of the two and is recommended by the United States Department of Agriculture, and by the state experiment stations. DIPPING AND FUMIGATION OF NURSERY STOCK 7 As the San Jose scale is a sucking insect, it is impossible to destroy it by using a poisonous spray, so a contact spray must be used. The spray must be strong enough to either destroy the scale outright, that is, con- sume its body, or have great penetrating power, like the oil emulsions which burn and smother the insects. According to Lodeman, lime-sulphur spray was first used for the Con- trol of insects in 1851, by a Frenchman by the name of Grison, a gardner at Versailles, France. Grison used the following formula at first but later reduced the amount of lime to half. Flowers of sulphur 500 gms. Freshly slaked lime 500 gms. Water ' 3 liters. Boil for ten minutes, draw off the clear liquid and use 1 to 100 parts of water. This mixture was used as a fungicide and is one of the few early spray preparations still in use. Regarding the first use of lime-sulphur washes in America, Lodeman says: "A mixture similar to the following was originally used in California as a sheep dip, but as fruit trees began to drive out the sheep, the applica- tions of the compound were transferred to the trees, and thus it has been very generally used, and has proved to be of value in the orchards as well as on the sheep. It is used against insects and fungi. Lime (unslaked) 25-40 pounds Salt 15 pounds Sulphur 20 pounds Water 60 gallons "To mix the above, take 10 pounds of lime, 20 pounds of sulphur and 20 gallons of water. Boil until the sulphur is thoroly dissolved. Take the remainder, 15 pounds of salt and 15 pounds of lime, slake and add enough water to make the whole 60 gallons. Strain and spray on the trees when milk warm or somewhat warmer. This can be applied when the foliage is off the tree and will have no injurious effect upon the fruit buds or upon the tree itself." Marlatt says "the early experience with lime-sulphur and salt washes for San Jose scale was unfavorable, largely due apparently to the fact that the observations on the trees treated were not continued long enough to note the effect of the late summer results. Good results were obtained with the kerosene emulsions and particularly with the soap washes and the fish- oil soap washes." The formula which is commonly used at the present time in making home made concentrated lime-sulphur solution is as follows: Lump Lime 40 pounds Sulphur 80 pounds Water . 50 gallons About 10 gallons of hot water is added to the sulphur and thoroly stirred. The lime is then added. As the lime slakes hot water is added as necessary to, prevent caking. When the lime has completely slaked enough hot water is added to make 50 gallons and the solution boiled for an hour and kept constantly stirred. Water is added from time to time to keep the liquid up to 50 gallons. This concentrated solution should test about 31 degrees Beaume. It should be stored in tight barrels until ready 8 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 for use. When used it is diluted with water in the same manner as the commercial lime sulphur. Hydrocyanic-acid' gas was also tried in controlling San Jose scale on orchard trees, and at present is used upon citrus trees for controlling citrus scale. Where care was taken this method proved quite successful when used on the deciduous fruit trees, but the cost of fumigating an orchard as compared with spraying was so great that the former method has been abandoned altogether. An air-tight box had to be constructed in such a way that it could be moved from over one tree to another, or a large tent had to be placed over the tree to be treated and the gas generated beneath. Each tree had to be treated for about one hour. The treatment for San Jose scale must be applied while the tree is in a dormant condition for the scale is so difficult to kill that a treatment, to be effective, must be made so strong that it will also kill foliage. While the tree is in a dormannt condition, the insects are easily reached and a strong spray can be applied without any fear of damaging the foliage. Also, as the insects pass the winter in a half-grown state, they are more easily killed during the dormant season. In applying a spray for the scale, thoroness of the application is of the utmost} importance. If twigs here or there are left without a coat of the spray material, the insects which are on them will soon reinfest the tree. At the present time the standard spray for the control of the San Jose scale upon deciduous orchard trees is lime sulphur. Commercial concen- trated lime sulphur has a specific gravity of approximately 1.28. One gal- lon of it is used to seven gallons of water which reduces the specific gravity to 1.04. This solution is then applied with either a barrel or power spraying machine during the dormant season. Besides controlling the San Jose scale with a dormant spray of lime- sulphur, many other pests, such as Forbes scale and aphids are also con- trolled. One of the important reasons why the San Jose scale is difficult to con- trol is the fact that it attacks so many of the deciduous plants including fruits, ornamentals and shade trees. Control on nursery stock. — As has been previously explained it was thru the infestation of nursery stock that the San Jose scale has become so widely distributed and naturally the first place to start in the control of the pest is upon nursery stock. Probably the most important means of controlling the scale upon nursery stock has been the passing of laws requiring that all infested stock be destroyed and the remainder treated under the direction of a competent man. Before 1913 Missouri had no law controlling the growing or trans- portation of infested nursery stock, and as a result much infested stock was sold to Missouri farmers. In 1913 an effective law was passed and has been vigorously enforced. Every state in the Union has a law similar to the Missouri law and they have done much to prevent further spread of San Jose scale and other dan- gerous insect pests and diseases as well. Practically all states require the use of hydrocyanic-acid gas in the DIPPING AND FUMIGATION OF NURSERY STOCK 9 control of the scale on nursery stock and up to the present time it is most widely used. Some nurserymen prefer to dip their trees in a miscible oil rather than fumigate and this method has, to a great extent, been successful. In fumigating with hydrocyanic-acid gas the trees are dug in the fall or early spring, all excessive moisture allowed to dry from the tree and then placed in an air tight box or room. The gas is generated in the room and the trees are left exposed to it for from 45 minutes to one hour. Special preparations must be made, such as building an air tight box or house, in using hydrocyanic-acid gas. The gas is very poisonous, the chemicals are costly and it is easy to make a mistake in mixing them. Under certain conditions the gas is likely to injure the stock, especially the more tender species. This is also true in using liquid dips. Hydrocyanic- acid gas first used. — Hydrocyanic-acid gas has been used in collecting jars for years by entomologists to kill insects, but was first used for the destruction of scale insects by D. W. Coquillett in the orange groves around Los Angeles, Cal. His first work with hydrocyanic- acid gas was in September 1886, and was carried on at this time for the control of the cottony cushion scale on citrus trees. Such means as tobac- co smoke, sulphur fumes, concussion from gun powder, heat, muriatic acid, carbonic acid gas, chloroform, arsenic, bisulphide of carbon and other fumes and gases were tried, but none was so successful as hydrocyanic-acid gas. Dr. F. W. Morse of the University of California also began studying the control of the cottony cushion scale in 1887 and as a result that uni- versity gave to the public, in bulletin 71, the first knowledge of the use of hydrocyanic-acid gas. In doing this first work, a tent was thrown over the tree and the gas generated beneath the tent by putting together in one ves- sel sulphuric acid, water and dry potassium cyanide. All of this work done in California was upon citrus trees, which were in full foliage and a great deal of burning and injury resulted. However, the method of using hydrocyanic-acid gas has been so well perfected that at the present time it is comparatively safe to fumigate citrus trees which are infested with white fly or scale. The California agricultural experiment station, under the direction of Morse, conducted experiments with other gases as insecticides with special reference to the white scale (Icerya purchasi). The following is a summary of the results obtained, as set forth in bulletin 70 of the California agricul- tural experiment station. Chlorine, carbon bisulphide, sulphuretted hydrogen, ammonia, carbon menoxide, aloxic acid, carbolic acid and hydrocyanic-acid gas were tried and it was found that hydrocyanic-acid gas was the only one that produced suf- ficiently fatal effects as to warrant a more thoro determination of the time of exposure and quantities of material which would produce the best results. Hydrocyanic-acid gas was not used upon deciduous trees until 1894, when the San Jose scale was found upon deciduous fruit trees in Charlottes- ville, Va. and Coquillett was detailed by the United States Department of Agriculture to conduct experiments with hydrocyanic-acid gas on these infested trees. The results of the first experiments were so satisfactory that the work was continued. 10 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 It was in 1898 that it was first suggested that hydrocyanic-acid gas could be used in mills, elevators and warehouses for the destruction of in- jurious insects. Use up to the present time. — Since the discovery of hydrocyanic-acid gas as an insecticide it has been used in a number of different ways. 1. To fumigate citrus trees infested with all sorts of scale insects. 2. To fumigate deciduous fruit trees, including nursery stock, for the destruction of San Jose scale. 2. To fumigate deciduous fruit trees, including nursery stock, for the destruction of San Jose scale. 3. To fumigate greenhouses for the destruction of white fly, red spider and other pests on greenhouse plants. 4. To fumigate warehouses, elevators, mills and other buildings for the destruction of various insect pests. Apparatus for fumigating car load lots: A tight oil canvas is placed over the frames. The hydrocyanic acid gas is generated in a tank and con- ducted through a pipe to the enclosure 5. To fumigate dwelling houses, railroad coaches, street cars, hotels and similar places for the destruction of lice, bedbugs, clothes moths and household pests. The use of hydrocyanic-acid gas as a fumigating material is becoming more extensive and the United States Department of Agriculture and all of the state experiment stations recommend it. Method of using. — The most general method practiced at the present time in using hydrocyanic-acid gas is as follows: One fluid ounce of sulphuric acid having a specific gravity of at least 1.83 is poured into an earthenware crock, wooden bucket or tub, containing 3 fluid ounces of water. Into this mixture 1 ounce, by weight, of fused cyanide of potassium, 98-99 per cent pure, is added. The above amounts are used for every 100 cubic feet of space. In fumigating tender growing plants, the above formula is too strong and has to be weakened. For dor- mant trees, mills, elevators and the like the 1-1-3 formula is recommended by both the United States Department of Agriculture and practically all of the state experiment stations. In fumigating nursery stock an air tight box or house is necessary. DIPPING AND FUMIGATION OF NURSERY STOCK 11 The trees are placed in the box or house. The water and sulphuric acid are mixed in an earthen jar and the jar placed in the box or house. The potassium cyanide is then dropped in and the box or house closed just as quickly as possible. The hydrocyanic-acid gas which is generated is deadly poisonous and the person doing the fumigating must be very careful not to breathe any of it. It requires about 45 minutes to fumigate nursery stock, altho some authorities say that better results can be obtained by letting the stock remain an hour. At the end of this time the fumigating box or house is opened and the gas allowed to escape and in from 15 to 20 minutes the trees can be safely removed. It is never advisible to fumigate trees while they are damp or wet. It is claimed that under such conditions the gas is more likely to injure the stock. However, the writer's experiments to date fail to corroborate this, though they do show that less scale is killed under those conditions. Some states require by law that all nursery stock grown within its borders or shipped in from outside nurseries be fumigated and,, as a result, all of the larger nurseries in the United States have constructed special fumigating houses or boxes. Chemical composition of hydrocyanic-acid gas. — In fumigating work hydrocyanic-acid gas is generated, as has already been explained, by placing together potassium cyanide (KCN) sulphuric acid (H2SO4) and water (H20). The sulphuric acid, which is sold commercially, has a strength known as 66° Baume which corresponds to the 96 per cent pure sulphuric acid. Commercial sulphuric acid, however, contains some impurities and is seldom more than 93 or 94 per cent pure. The potassium cyanide which is purchased on the market runs about 98 per cent pure. When the sulphuric acid and the potassium cyanide are brought to- gether, the chemical reaction that takes place is as follows: 2 KCN + H.SCX = K2SO4 + 2 HCN In the above reaction, 1 ounce (avoirdupois) of potassium cyanide (100 per cent pure) requires 0.75 ounce (avoirdupois) sulphuric acid or .81 ounce of commercial sulphuric acid containing 93 per cent sulphuric acid which would be equal to 0.42 fluid ounces. Under conditions met with in fumigating work, the above reaction can- not be obtained and result in the best yield of hydrocyanic-acid gas. More sulphuric acid must be used and this causes acid potassium sulphate to be formed as is shown in the following equation: KCN + H2S04 = KHSO. + HCN In this reaction 0.84 fluid ounce of 93 per cent sulphuric acid is required for each ounce (avoidupois) of potassium cyanide. This amount in round numbers equals 1 part cyanide to 1 part acid which gives the best results in field work. In order to get the best yield of hydrocyanic-acid gas only two parts of water should be used, but in field practice when only two parts of water are used, the residue in the generating jar often solidifies and in order to prevent this, three parts of water are used. Thus the 1-1-3 formula is used in fumigating nursery stock. 12 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 RESULTS OF EXPERIMENTS WITH HYDROCYANIC-ACID GAS Because of the large amount of damage being done in Missouri by the San Jose scale, and in order to help the fruit grower and nurserymen to better control the scale and thus lessen the danger of further dissemination of the pest, the writer began a series of experiments in the fall of 1915 with reference to the control of the scale upon nursery stock. Some of the nursery stock in the state which was found to be infested with San Jose scale was brought to Columbia where the experiments were conducted. . ' The primary object of the investigation was to determine if possible the most practical, efficient and cheapest method to use in controlling the scale on nursery stock with the least injury to the trees or plants. In Missouri there are a number of nurserymen who grow nursery stock on a small scale and do not care to go to the expense of building an ex- pensive fumigating house or box and besides many object to using hydro- cyanic-acid gas because of its very poisonous nature. Several of these nurserymen have asked repeatedly about the possibilities of dipping nurs- ery stock in a lime-sulphur wash or a miscible oil for the control of San Jose scale. Some of the nursery stock which was used in the experimental work at the Missouri Agri- cultural Experiment Station Method of procedure. — First, during the fall of 1915 the following number of fruit trees and plants were obtained: Apple, 356 trees; peach, 164; pear, 52, and plum, 52. All of the fruit trees were two years old. Of the apple trees obtained, 260 were heavily infested with San Jose scale and 86 of the peach trees were also heavily infested. The trees were dug in the fall after the leaves hati fallen and shipped to Columbia. Most of the scale-infested trees showed marked weakness caused by the ravages of the pest; otherwise all of them were in good condition. The trees were heeled in the fall and left until March 21 and 22, 1916, when they were given the different treatments. None of the trees died during the winter. The work was continued during 1917. On April 5, 1917, the following two-year-old trees were obtained, all of which were heavily infested with DIPPING AND FUMIGATION OF NURSERY STOCK 13 San Jose scale: Apple, 58 trees; peach, 58, and plum, 5. These trees had just been dug from the nursery row. They showed weakness from the effects of the scale, but were otherwise in excellent condition. A part of these trees were treated with hydrocyanic-acid gas on April 10, 1917. In the spring of 1918 a small nursery was started on the experimental grounds at Columbia for the purpose of obtaining trees to continue scale control investigations. Both peaches and apples were grown and in the summer of 1919 scale infested trees were placed with them and by fall the stock was all heavily infested. In March 1920 these trees were used in fumigating and dipping experiments. As has already been explained, one fluid ounce 66° Baume sulphuric acid, 1 ounce potassium cyanide and three fluid ounces of water for 100 cubic Fumigating Box used at the Missouri Agricultural Experiment Station. Notice the cleats against which the lid fits. These cleats are covered with felt to prevent the escape of gas. feet is most commonly used in fumigating nursery stock. Some of the nurserymen of Missouri had complained of severe burning of the stock when used this strong so two strengths of hydrocyanic-acid gas were used in the work in 1916. The regular 1-1-3 formula was tried and a formula just half as strong (%-%-!%) was also tried. A fumigating box was constructed from 1 inch cypress lumber. The box was made 7 feet long, 3 feet wide and 2 feet deep, havirtg a total capacity of 42 cubic feet. The top of the box was hinged on so as to form 14 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 a lid. Cleats were nailed on to the lid so as to fit tightly against the inside of the box when closed and these cleats were covered with felt so as to make the box just as nearly air tight as possible. The number of plants to be treated dry with the 1-1-3 formula were dug, the dirt removed from the roots and placecl in the box. The sulphuric acid was weighed out and placed in an earthen jar, then the required amount of water was added slowly so as to prevent sputtering. The jar was then placed in the bottom of the fumigating box in such a way as not to come in contact with the nursery stock. The potassium cyanide, 98 per cent pure, which had been broken up into small pieces, was then added to the mixture and the lid quickly closed and clamped down. The stock was allowed to fumigate for 45 minutes, when the box was opened, the gas allowed to escape, which took about 10 to 15 minutes. The plants were then removed and set about two feet apart in rows 3 feet apart. The residue left in the jar is very poisonous so it was removed and buried to prevent anything from getting hold of it. Just as soon as the set of trees were removed from the fumigating box, a second set containing the same number of plants was taken. This set of plants was treated in exactly the same way as the above set with the ex- ception that they were thoroly dampened, both roots and tops, before being placed in the box. The object in fumigating this set of wet plants was to find out exactly if possible to what extent the plants would be injured and also if the effect upon the scale would be the same as upon the scale on the dry plants. The third set of plants was treated exactly the same as the first except the yz-Vz-^Vz formula was used. A fourth set of plants, which were wet, was also treated with the %-%-!•% formula. Effect of hydrocyanic-acid gas upon San Jose scale. — As is shown by the following table, eighty apple trees with scale, were treated with hydro- cyanic-acid gas in 1916. TABLE 1. — APPLES TREATED IN 1916 Date Treatment Condi- tion of trees Length of treat- ment, No. trees treat- ed Per cent scale dead Per trees cent dead 1916 mm. 5/14/16 5/26/164/4/17 March 21 HCN 1-1-3 wet 45 20 77.8 10 40 HCN 1-1-3 dry 45 20 100 10 30 HCN %-%-!% wet 45 20 72.6 10 30 HCN y2-y2-ii/2 dry 45 20 97.5 25 55 Check 20 38.9 0 60 On May 14, 1916, a count was made to determine the effectiveness of the hydrocyanic-acid gas. In making the counts on these trees, several heavily infested twigs were collected from several of the different trees. The twigs were placed under a high power binocular and the numbers of DIPPING AND FUMIGATION OF NURSERY STOCK 15 dead and live insects counted. From these numbers, the percentage of live insects was determined. On May 25, 1916, additional counts were made and on May 26, 1916, the number of trees which were dead was counted. The results obtained show clearly that hydrocyanic-acid gas used at the strength of 1-1-3 and •%-%-!% will kill San Jose scale on dry plants better than on moist plants. Also the dry plants suffered more from the treatment than the wet ones. The hydrocyanic acid gas gave best results when used at the rate of 1-1-3 upon dry trees. Upon the other three sets live scales were found, the larger percentage being upon the trees treated while damp. All of these trees were heavily infested with the scale at the time of treating and their vitality had been weakened a great deal and this is undoubtedly the reason why such a large percentage died. The normal mortality of scale on the check trees was 38.9 per cent and the high mor- tality of the trees was undoubtedly due to the effects of the pest. On April 9, 1917, the following trees were treated with hydrocyanic acid gas, 1-1-3. TABLE 2. — APPLES TREATED IN 1917 Date Treatment Condition Length of No. trees Per cent of trees treatment, treated scale dead 1917 min. 4/20/17 April 9 HCN 1-1-3 wet 45 8 100 HCN 1-1-3 dry 45 8 100 Check .... 4 75 This test in 1917 was made in order to check or substantiate the results obtained in 1916. On April 20, 1917, the trees were thoroly examined for scale and no live scale whatsoever could be found on either the trees wet or dry. In comparing the above treatments with the check it is clearly shown that good results were obtained with hydrocyanic-acid gas used at the rate of 1-1-3. On March 22, 1920, additional experiments were performed with HCN as is shown by the following table. TABLE 3.— APPLES TREATED IN 1920 Date Treatment Condition of trees Length of treat- min. No. of trees treated Per cent scale dead Per cent trees dead 1920 5/20/20 11/8/20 March 23 HCN 1-1-3 wet 50 34 100 44.1 March 22 HCN 1-1-3 dry 50 34 100 50.5 March 27 HCX 2-2-6 wet 50 34 100 70,5 March 26 HCN 2-2-6 dry 50 34 100 73.5 March 29 HCN* 1-1V2-3 wet 50 34 100 70.5 March 29 HCN* l-lV2-3 dry 50 34 100 50.0 Check 68 76 94.2 this treatment Sodium cyanide (NaCN') was used. 16 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 As the table shows in 1920 potassium cyanide was used twice as strong as is recommended. Also sodium cyanide (NaCn) was used. Sodium cyanide, which is stronger than potassium cyanide and which is ordinarily used at the strength of one ounce sodium syanide, one and one-half ounces sul- phuric acid and three ounces water. Every treatment of cyanide used in 1920 killed 100 per cent of the scale. As to the effect of the treatments upon the trees the HCN used at the rate of 1-1-3 it seems causd less injury both upon wet and dry trees. Effect of hydrocyanic-acid gas upon scale on peaches* — Somewhat bet- ter results were obtained on peaches. From counts made on May 25, as is shown by the table, three of the treatments gave perfect results so far as controlling the scale was concerned. TABLE 4. — PEACHES TREATED IN 1916 Date Treatment Condi- Length No. Per Per cent .' tion of trees cent trees dead of treat- treat- scale trees ment, ed dead 1916 min. 5/14/16 5/26/16 4/4/17 March 21 HCN 1/2-1/2-11/2 wet 45 8 95.4 37.5 87.5 HCN 1/2-1/2-11/2 dry 45 8 100 37.5 62.5 HCN 1-1-3 wet 45 8 100 12.5 50 HCN 1-1-3 dry 45 8 100 87.5 875 Check .... 8 100 25 62.5 Hydrocyanic-acid gas used at the rate of 1/2-1/2-1% on damp trees gave the poorest results. A larger number of the trees treated dry were dead May 26 than was the case with those treated wet. TABLE 5. — PEACHES TREATED IN 1917 Date Treatment Condition Length of No. trees Per ceni of trees treatment, treated scale dead 1917 min. 4/20/17 April 9 HCN-1-1-3 wet 45 4 100 HCN-1-1-3 dry 45 4 100 Check .... 6 50 In 1917 hydrocyanic-acid gas proved to be effective in killing the scale on peaches upon both wet and dry trees. Fifty per cent of the scale on the check trees had passed the winter in safety. DIPPING AND FUMIGATION OF NURSERY STOCK 17 TABLE 6.— PEACHES TREATED IN 1920 Date Treatment Condi- tion of trees Length of treat- ment, No. of trees treated Per cent scale dead Per cent trees dead 1920 • min. 5/26/20 11/8/2C March 29 HCN 1-1-3 wet 50 5 100 20 March 22 HCN 1-1-3 • dry 50 5 100 20 March 27 HCN 2-2-6 wet 50 5 100 100 March 26 HCN 2-2-6 dry 50 5 100 0 March 29 HCN* l-lV2-3 wet 50 5 100 80 March 29 HCN* 1-11/2-3 dry 50 5 100 60 Check 10 85 67 100 *In this treatment Sodium cyanide (NaCN) was used. One hundred per cent of all the scale was killed in every case in 1920. Effect of hydrocyanic-acid gas upon San Jose scale on pear.— TABLE 7.— PEARS TREATED IN 1920 Date Treatment Condi- tion of trees Length of treat- ment, -No. of trees treated Per cent scale dead Per cent trees dead 1920 min. 5/26/20 11/8/20 March 23 HCN 1-1-3 wet 50 2 100 50 March 22 HCN 1-1-3 dry 50 2 100 0 March 27 HCN 2-2-6 wet 50 2 100 50 March 26 HCN 2-2-6 dry 50 2 100 100 March 29 HCN* 1-11/2-3 wet 50 2 100 50 March 29 HCN* 1-1V2-3 dry 50 2 100 0 Check •--- 4 74.68 0 *In this treatment Sodium cyanide (NaCN) was used. Practically the same results were obtained upon pear as upon peaches and apples. Effect of hydrocyanic-acid gas upon San Jose scale on plum. — TABLE 8.— PLUMS TREATED IN 1917 Date Treatment Condition Length of No. trees Per cent of trees treatment, treated scale dead 1917 m:n. 4/20/17 April 9 HCN 1-1-3 wet 45 1 100 HCN 1-1-3 dry 45 1 100 Check 1 57 18 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 As to the effectiveness of hydrocyanic-acid gas upon San Jose scale, the above tables show that it might not in every case kill all of the scale, es- pecially when used at a strength weaker than 1-1-3. When used at a weaker strength it will kill a large percentage of the insects but not enough to recommend its use. From the summary it is readily seen that more of the trees died when treated with the stronger hydrocyanic-acid gas than with the weaker. It is a known fact that plants treated with a high strength of hydrocyanic-acid gas will be injured and if the hydrocyanic-acid gas is too strong it will kill the trees. Whether or not it takes the gas longer than a month to effect a tree enough to kill it, is not known but it stands to reason that if the gas does injure a plant,, the 1-1-3 strength would cause more injury than the 1/2-1/2-l;i/2 strength. As has been shown, the greater strength gave better results in con- trolling the scale than the weaker and as far as killing the trees is con- cerned, there is not enough difference in the two strengths to amount to a great deal. Since the control of the scale is of the most importance, it is undoubtedly advisable to use the 1-1-3 formula when fumigating nursery stock. Another very important thing that was brought out in this work is the effect of hydrocyanic-acid gas upon wet and dry plants. It is the general belief among nurserymen that if plants are treated with hydrocyanic-acid gas while wet, or damp, the moisture on the plant will absorb a large quantity of the gas, which in turn, will cause a great deal of burning and injury to the plant. It will be noticed that in this work, a larger percentage of those plants treated dry died than those treated wet which is contra- dictory to the general belief of nurserymen and experiment station workers. In treating plants with ether to stimulate growth, a larger dose of ether must be used if plants are damp or the exposure must be longer if the same results are derived as would be ob- tained if the plants were dry. This may also be true of hydrocyanic-acid gas and as the re- sults obtained indicate, a larger dose of hydro- cyanic-acid gas must be used on damp plants to obtain the same results as on dry plants with a smaller dose. Also, fewer scale were killed upon the damp trees than on the dry, which indicates that possibly the same thing holds true in regard to animals as to plants. Since the scale was killed better on stock treated dry than on stock treated wet, and as the destruction of scale is of prime importance, nursery stock should not be fumigated with hydrocyanic-acid gas when wet, even tho the injury to the plants may be greater when treat- ed dry. A well constructed fumigating house. It is built of tongue and grooved lumber and cleats cover the joints on the outside DIPPING AND FUMIGATION OF NURSERY STOCK 19 CARBON BISULPHIDE FIRST USED Carbon bisulphide was first used as an insecticide by Louis Doyere, a former professor of Agriculture at the Institute of Versailles, in 1856 and 1857. He used small amounts of the liquid on grain to destroy the weevils and their eggs. He also demonstrated that carbon bisulphide would not injure the grain. In 1876, Cornu and Moulleferet, both French investigators, demonstrated that carbon bisulphide could be successfully used upon grape phylloxera, caterpillars, butterflies, cicadas, wasps and plant lice. Use up to present time.— After 1876 the popularity of carbon bisulphide as an insecticide became great and many experiments were carried on with it. It was found to be an effective and cheap insecticide and easy to use. Today carbon bisulphide is widely used for the following: 1. To kill grape phylloxera on the roots of the grape. 2. Root maggot of different sorts on the roots of different plants. 3. For destruction of ants. •4. To kill grubs and mole crickets. 5. For the destruction of burrowing animals, such as moles, prairie dogs, gophers, etc. 6. For the destruction of sucking insects upon small plants. 7. For fumigating buildings containing stored cereals to destroy the insect pests. 8. For destroying household pests, museum pests and similar pests. In fact carbon bisulphide is the most extensively used fumigant today for destroying the more easily killed insects. Methods of using. — Carbon bisulphide is easy to obtain and easy to use. Any one who is willing to take a few precautions can use carbon bi- sulphide with perfect safety. Carbon bisulphide is put up in tight tin cans or steel drums and can be purchased in small quantities. It is very volatile and diffuses through the air rapidly. The gas is heavier than air and this factor is taken advantage of when using carbon bisulphide. In fumigating bins containing cereals or similar places, shallow pans are usually employed. The pans are set on top of the grain or on anything near the ceiling. Better results are obtained if the place to be fumigated is made air tight and the temperature is 70° F. or above. The carbon bisulphide is poured in the pans, the doors closed and the cracks stopped so as to prevent the gas from escaping from the building. Different authorities vary as to the rate at which carbon bisulphide should be used. In Kansas the following amounts have been recommended and other stations report similar amounts: At 90° F. 1 Ib. CS2 is sufficient for every 500 cu. ft. At 80°F. 1 Ib. CSi> is sufficient for every 400 cu. ft. At 70° F. 1 Ib. CS2 is sufficient for every 300 cu. ft. If used in an open bin, the above amounts should be greatly increased At a temperature below 60°F. it is not advisable to fumigate with carbon bisulphide at all for it does not evaporate sufficiently fast below this temperature. 20 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 The bin or building should be allowed to fumigate for from 36 to 48 hours. For fumigating seeds with carbon bisulphide, from 1 to iy2 pounds should be used to every 1000 cubic feet. Carbon bisulphide has been tried a number of times upon nursery stock for destroying scale insects, but up to the present time has proven unsatis- factory. Chemical composition of carbon bisulphide. — According to W. E. Hinds, of the United State sDepartment of Agriculture, Farmers' Bulletin 145, "the chemical symbol of carbon bisulphide is CS2. Its molecules consist of one atom of carbon united with two atoms of sulphur. The specific gravity of the liquid is 1.29. The vapor is 2.63 times as heavy as atmospheric air. The pure article volatilizes rapidly and completely when exposed to the air. The liquid boils at 115°F. "The vapor takes fire in air at about 300° F. and burns with a faint blue flame, scarcely visible in daylight, but evolving considerable heat and de- composing the carbon bisulphide into carbon dioxide (CO2) and sulphur dioxide (SO2). The latter is the familiar gas given off by the burning of sulphur matches and is a strongly poisonous suffocating gas, which should not be inhaled. Carbon bisulphide vapor mixed with three times its volume of oxygen, or an amount of air containing that amount of oxygen, forms a mixture which is very highly explosive upon ignition. As 21 per cent of the air is oxygen, one volume of liquid carbon bisulphide evaporated in 5,357 volumes of air would form such a mixture. An atmosphere composed of one volume of carbon bisulphide vapor to approximately 14.3 volumes of air is liable to violent explosion in the presence of fire of any kind whatever, or a temperature of about 300° F. without flame. This is about the maxi- mum danger point from explosion in the use of carbon bisulphide." The higher the temperature, the more carbon bisulphide will be taken up by the air. RESULTS OF EXPERIMENTS WITH CARBON BISULPHIDE As has already been pointed out, carbon bisulphide is probably the most generally used insecticide for fumigating, especially for such insects as grain weevil. It has been tried to some extent upon nursery stock for the -control of San Jose scale, but so far satisfactory results have not been re- ported. Carbon bisulphide is cheaper than hydrocyanic-acid gas, easier to handle and, used as a poison,, does not act in an effective way so quickly Avhich makes it less dangerous for the person handling it. Object. — The idea in using carbon bisulphide was to determine if possi- ble, whether or not it could be used at 'all for destroying San Jose scale upon live plants without injury to the plants. Owing to its cheapness and the ease with which it can be used as compared with hydrocyanic-acid gas, carbon bisulphide would be a great deal more desirable provided the same results could be obtained. Procedure. — The same fumigating box was used with the carbon bisul- DIPPING AND FUMIGATION OF NURSERY STOCK 21 phide as with the hydrocyanic-acid gas and, as shown by the following table, the same number of trees were used. The first dry and the first, wet set of trees were treated for an hour with carbon bisulphide at the rate of 1 pound of the insecticide to 100 cubic feet of space. Sets No. 3 and 4 were treated for an hour also, but the carbon bisulphide was used at the rate of iy2 pounds to the 100 cubic feet. In treating the trees, each set was placed in the fumigating box -sep- arately, as with the hydrocyanic-acid gas. Near the top of the box a shelf was constructed upon which a shallow pan was placed. The nursery stock was placed in the box, the required amount of carbon bisulphide poured into the pan and the lid closed. Eighty apple trees heavily infested with San Jose scale were treated with carbon bisulphide as is shown by the following table. TABLE 9. — APPLES TREATED IN 1916 Date Treatment Condi- tion of trees Length of treat- ment, No. trees treat- ed Per cent scale dead Per trees cent dead 1916 min. 5/25/16 5/26/164/4/17 March 21 CS2 1-100 dry 60 20 92.3 30.5 70 March 21 CS2 1-100 wet 60 20 88.2 15 50 March 21 CS2 1V2-100 dry 60 20 77.1 10 45 March 21 CS2 iy2-ioo wet 60 20 83.9 10 40 Check .... 20 38.9 0 60 As is shown, counts made May 14 and 25 definitely show that carbon bisulphide used at a strength of either 1 to 100 or 1% to 100 will not control scale. As compared with the check,, however, it is evident that a number of the insects were killed but not enough to warrant its use. On April 9, 1917, the following trees were treated with carbon bisul- phide, 11/2 to 100. TABLE 10.— APPLES TREATED IN 1917 Date Treatment Condition Length of No. trees Per cent of trees treatment, treated scale dead 1917 min. 4/20/17 April 9 CS2 li/2-lOO wet 60 8 96.6 CS2 li/2-lOO dry 60 8 94.6 Check 4 75.0 The results obtained in 1917 are practically the same as those obtained in 1916 and they also show that carbon bisulphide used at the rate of ll/2 to 100 will not control San Jose scale. 22 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 TABLE 11. — PEACHES TREATED IN 1916 Date Treatment Condi- Length No. Per Per cent tion of trees cent trees dead of treat- treat- scale trees ment, ed dead 1916 min. 5/25/16 5/26/164/4/17 March 21 CS2 1-100 wet 60 8 100 62.5 75 CS2 1-100 wet 60 8 100 62.5 87 5 CS2 1V2-100 wet 60 8 100 37.5 75 CS2 1%-100 dry 60 8 94.8 30 87.5 Check .... 8 100 25 62.5 The results obtained on the peach also show that carbon bisulphide will not entirely control San Jose scale when used at the rate of 1% to 100. However, these results are much better than those obtained upon the apple which is probably due to the fact that most of the heavily infested peach trees died, which made it impossible to get as good a count. The peaches that lived were not so heavily infested. TABLE 12.— PEACHES TREATED IN 1917 Date Treatment Condition Length of No. trees Per cent of trees treatment, treated scale dead 1917 min. 4/20/17 April 9 CS2 1^-100 wet 60 4 100 CS2 11/2-100 dry 60 4 100 Check .... 6 50 No live scale could be found upon the peach trees treated which was probably due to the fact that as a result of the treatment practically all of the young tender growth, which was the most heavily infested part of the trees, had died. It will also be noticed that a larger per cent of the plants treated wet died, both at the end of the second month and at the end of the first year. However, the difference was not very great. With hydrocyanic-acid gas more of the plants treated dry died. It may be that carbon bisulphide has an altogether different physiological effect upon the plant, especially in the presence of moisture. A larger percentage of the scale on the trees treated wet were killed which seems to further indicate that carbon bisulphide used in the presence of moisture is more active. Owing to the fact that carbon bisulphide did not in any case completely control the San Jose scale upon apple trees, and in only five out of six cases upon the peach, and since the percentage of injury to the plants was very great, its use as a fumigating material upon nursery stock should be discouraged. DIPPING AND FUMIGATION OF NURSERY STOCK 23 LIME-SULPHUR FIRST USED On page six, under "Control in the Orchard," a discussion of the first use of lime-sulphur for the control of insects is given. F. A. Sirrine of New York Agricultural Experiment Station was prob- ably the first to dip nursery stock for the control of San Jose scale. He dipped some nursery stock in 1894 on Long Island with a whale-oil soap preparation. Lime-sulphur was probably first used as a dip for nursery stock for the control of the scale by Professor C. V. Close of the Deleware Experiment Station in 1903. Used up to present time. — Since 1894 a large number of experiments have been made with lime-sulphur as a tree dip for the control of San Jose scale but none have been, on the whole, entirely successful. In some cases the scale was controlled but the most serious objection to using it was the fact that in nearly every case the plants were injured to a greater or less extent. Although lime-sulphur is used almost altogether for controlling San Jose scale on old trees, it has never proven to be a practical success for dipping nursery stock. Methods for using. — When lime-sulphur is used upon nursery stock as a spray for the control of San Jose scale, it is during the dormant season while the trees are still in the nursery row. It is applied at the usual rate, the same as recommended for mature trees, 1 to 7, and is put on with a spraying machine, either hand or power. Most large nurseries have espe- cially constructed spraying machines which are built so as to be easily gotten between nursery rows. When lime-sulphur or any other material is used for dipping nursery stock a vat is constructed or a trough made which is large enough to hold sufficient liquid to immerse an entire tree. Chemical composition of lime-sulphur. — Lime-sulphur is made by boil- ing in water slaked rock lime containing not less than 95 per cent calcium oxide and flowers of sulphur. A very complicated chemical reaction takes place when lime and sulphur are boiled together in water. The sulphur (S) combines with the calcium (Ca) in the lime (CaO), in varying amounts, with the result that two compounds are formed — calcium tetrasulphide (CaSO, containing 76 per cent of sulphur. Also a small quantity of thiosulphate (CaSsOs) is formed. These compounds formed are soluble in water and it is to them that the insecticidal value of the mixture is due. The higher the oercentage of pentasulphide, the more effective is the mixture. In making the lime-sulphur solution it is necessary to boil it for an hour in order to form a complete chemical union of the lime and sulphur. Two parts of sul- phur combine with one part of lime and in making the solution, twice as much sulphur as lime should be used. RESULTS OF EXPERIMENTS WITH LIME-SULPHUR As the lime-sulphur wash has become the most standard spray for the control of San Jose scale on infested fruit trees, the writer saw no reason why it should not be used to dip infested nursery stock. 24 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 Object. — The object in using lime-sulphur was to determine definitely, if possible, its exact efficiency for killing scale on nursery stock and its in- jurious effects, if any, upon the plants. L/ime-sulphur is the cheapest ma- terial used in the control of San Jose scale and as no fumes are produced, it is less dangerous to use than hydrocyanic-acid gas or carbon bisulphide. Procedure. — First a water tight wooden V-shaped trough was made, 9 feet long and 8 inches deep. This trough held with ease 8 gallons of the solution. The number of trees to be dipped were divided into four sets. In the first set the tops and trunk, down to the roots only, were dipped and those trees dipped in 1916 and 1920 were immersed and immediately removed, while those dipped in 1917 were left immersed for five minutes. With the second set of trees the tops and roots both were dipped. With the first two sets lime-sulphur was used at the rate of 1 gallon to 9 gallons of water. The third and fourth sets were treated exactly as the first two except the lime sulphur was used at the rate of 1 gallon' to 7 gallons of water. After the trees had been dipped they were allowed to drain for a few minutes, then set out. Effect of lime-sulphur upon San Jose scale. — As shown by the following table, forty apple trees, heavily infested with San Jose scale, were dipped in the lime-sulphur solution. TABLE 13. — APPLES TREATED IN 1916 Date Insect- icide Parts treated trees Length of treat- ment, No. trees treat- ed Per cent scale dead Per trees cent > dead 1916 min. 5/25/16 5/26/16 4/4/17 March 21 L. S. 1-9 tops inst. 10 100 20 50 L. S. 1-9 t. & r* inst. 10 100 30 70 L. S. 1-7 tops inst. 10 99.6 10 70 L. S. 1-7 t. & r.* inst. 10 93.6 30 50 Check 20 38.9 0 60 *Both tops and roots dipped. These results show that lime-sulphur will, to a very large extent, con- trol San Jose scale on nursery stock but that the control may not be com- plete. Every tree was thoroly dipped, care being taken that every branch and twig was completely wet to the top, and the writer is convinced that none of the insects escaped immersion. Also a count of the scale was made from every tree and as shown by the results a very small percentage was alive a month after treatment. So far as the strength of the solution is concerned, the weaker gave the best results; however, there is very little difference in the strength of the two solutions used and the fact that the weaker solution gave the better results if of little significance. DIPPING AND FUMIGATION OF NURSERY STOCK 25 In order to verify the above results, the following trees were treated in 1917 with lime-sulphur at a strength of 1-7. . TABLE 14. — APPLES TREATED IN 1917 Date Insect- Parts Length of Xo. trees Per cent icide treated treatment, treated scale dead 1917 min. 4/20/1917 April 9 L. S. 1-7 tops 5 6 100 L. S. 1-7 t. & r. 5 6 100 Check 5 4 75 In 1920 besides using commercial lime-sulphur in which to dip the trees, soluable sulphur, dry lime-sulphur and barium tetrichloride sulphide were used. The last three named compounds have been placed on the market and are sold as scale remedies. The following table shows the results obtained in 1920 with these different materials on scaly apple trees. TABLE 15.— APPLES TREATED IN 1920 Date Treatment Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment, treated dead dead 1920 3/20/20 11/18/20 March 27 1 gal. lime- t. & r. inst. 34 96.62 91.1 sulphur to 9 gal. H2O March 27 1 gal. lime tops inst. 34 99.66 44.1 sulphur to 9 gal. H2O March 27 1 Ib. soluble tops inst. 34 97.34 52.9 sulphur to 4 gal. HSO March 24 12 Ibs. dry tops inst. 34 100 50 lime sulphur to 50 gal. H2O March 25 14 Ib. Barium tops inst. 34 98.53 67.6 tetrichloride sulphide to 50 gal. H2O Check 68 76 94.2 Of the above materials used dry lime-sulphur used at the rate of 12 pounds to 50 gallons of water gave the best results. 26 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 TABLE 16. — PEACHES TREATED IN 1916 Date Insect- icide Parts treated of trees Length of treat- ment No. trees treat- ed Per cent scale dead Per trees cent dead 1916 min. 5/4/16 5/26/16 4/4/17 March 21 L. S. 1-9 tops inst. 4 100 25 25 L. S. 1-9 t. & r. inst. 4 100 25 25 L. S. 1-7 tops inst. 4 94.3 12.5 100 L. S. 1-7 t. & r. inst. 4 100 12.5 100 Check 8 100 25 62 5 Practically the same results were obtained upon the peach in 1916 as upon apple. TABLE 17.— PEACHES TREATED IN 1917 Date Insect- Parts Length of No. -trees Per cent icide treated treatment, treated scale dead 1917 min. 4/20/17 May 4 L. S. 1-7 tops 5 9 100 L. S. 1-7 t. & r. 5 9 100 Check 6 50 As with the apple, no live scale could be found. TABLE 18.— PEACHES TREATED IN 1920 Date Treatment Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 1920 3/20/20 11/15/20 March 27 1 gal. lime- t. & r. inst. 34 99.66 44.1 sulphur to 9 gal. H2O March 27 1 gal. lime- tops inst. 5 100 0 sulphur to 9 gal. H2O March 27 1 Ib. soluble tops inst. 5 100 100 sulphur to 4 gal. H2O March 24 12 Ibs. dry tops inst. 5 100 100 lime-surphur to 50 gal. H2O March 25 14 Ibs. barium tops inst. 5 100 80 tetrichloride sulphide to 5 gal. H2O Check 10 86.67 100 DIPPING AND FUMIGATION OF NURSERY STOCK 27 Each treatment killed 100 per cent of the scale, except the first which killed 99.66 per cent. TABLE 19.— PEARS TREATED IN 1920 Date 1920 Treatment Parts treated Length of treat- ment Xo. of trees treated Per cent scale dead 3/20/20 Per cent trees dead 11/15/20 March 27 1 gal. lime- t. & r. inst. 2 100 100 sulphur to 9 gal. H2O March 27 1 gal. lime- 9 tops inst. 2 100 0 sulphur to 9 gal. H2O March 27 1 Ib. soluble tops inst. 2 100 0 sulphur to 9 gal. H2O March 24 12 Ibs. dry lime- tops inst. 2 100 100 sulphur to 50 gal. H2O March 25 14 Ibs. barium tops inst. 2 90 0 tetrichloride sulphide to 50 gal. H2O Check 4 74.68 0 All gave good results except the barium tetrichloride sulphide which killed only 90 per cent of the scale. TABLE 20.— PLUMS TREATED IN 1917 Date Insect- Parts Length of No. trees Per cent icide treated treatment, treated scale dead 1917 min. 4/20/17 April 4 L. S. 1-7 tops 5 1 100 L. S. 1-7 t. & r. 5 1 100 Check 1 100 The scale on the treated trees were all dead.. The lime-sulphur solution used at both strengths caused considerable injury. There was not a great deal of difference in the strength of the two solutions used and some authorities claim that lime-sulphur used at the rate of 1 gallon lime-sulphur to 9 gallons of water will give as good results as 1 gallon lime-sulphur to 7 gallons of water. At the end of the first two months and also at the end of the first year, a larger percentage of stock treated with the weaker, or 1-9 solution, was dead, which seems to indicate 28 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 that nursery stock can stand a solution of lime-sulphur a little stronger than 1-9 without any additional injury. Neither did the lime-sulphur have any effect upon the roots of the plants which were treated in 1915, for in only one case, the 1-9 solution where both roots and tops were dipped, was the percentage of dead plants greater than when tops only were dipped. Of these plants treated with the 1-7 solution, the percentage of dead was greater in the set treated tops only. In 1920 the results were different and the plants that were dipped both tops and roots suffered a much higher mortality than those dipped tops only. All of the plants trea-ted with both the lime-sulphur and miscible oil were dipped instantaneously. If the plants had been allowed to remain in the solution for 5 or 10 minutes or longer there would have probably been a greater difference in the results obtained. The 1-9 solution gave better results in Controlling the scale than the 1-7 solution, so taking everything into consideration it seems that just as good results could be obtained by using a 1-9 solution upon nursery stock for the control of scale, as a 1-7 solution. However, owing to the fact that none of the sulphur compounds killed all the scale and that considerable injury may result from their use upon young plants it seems advisable according to these experiments, to discourage the use of them as a dip. MISCIBLE OIL FIRST USED In a paper which appeared in Marseilles, France in 1763, petroleum, turpentine and other oils were recommended for killing plant lice. In this country turpentine mixed with earth and water was used to destroy worms in trees as early as 1835 and in 1865 kerosene was recommended for destroy- ing scale on orange trees and was successfully applied to oleander, sago- palm, acacia and lemon trees. The oil was applied by means of a feather. In June 1866 kerosene was recommended, in Gardener's Monthly, for de- stroying all insect life. Later it was found that kerosene and other oils mixed better with water if a soap was added and the material could be applied with a syringe. It is not definitely known who made the first kero- sene emulsion but about 1875 kerosene mixed with soap was first used. Use up to present time. — Since 1875 many different mixtures containing miscible oils have been recommended for the destruction of both chewing and sucking insects, particularly the latter. Petroleum oils and soap form the basis of many patented miscible oil solutions which can be purchased on the market today. The miscible oils kill the insect by contact. The oil has great penetrating ability and probably kills the insect by preventing the assimilation of oxygen in the tissues. The following are some of the most common and most widely used of the miscible oil insecticides. Kerosene 2 gallons Soap Vz pound Water 1 gallon Dissolve the soap in hot water, remove from fire and while still hot add the kerosene. Th emixture is thoroly agitated for five or ten minutes or until it becomes a creamy mass. Crude oil can be substituted for the DIPPING AND FUMIGATION OF NURSERY STOCK 29 kerosene. For a dormant spray one part of mixture is used to five or seven parts of water. DISTILATE EMULSION Distillate (28° Baume) 20 gallons Whale oil soap 20 pounds Water 12 gallons Dissolve the whale oil soap in the water, which should be heated to the boiling point, add the distillate and agitate thoroly while the solution is hot. For dormant use, add 20 gallons of water to each gallon of stock emulsion. Method of using. — The miscible oils may be used upon all types of sucking insects and also upon the chewing Insects where it is desirable to kill them with a contact spray. The best results are obtained by using a spraying machine when treating trees in the field, either a power or hand pump, and give the trees a thoro spraying. When used for scale insects it must be applied during the dormant season. It may be used as a dor- mant spray upon nursery stock, but more generally when nursery stock is treated for scale with a miscible oil, a tank is constructed, the tank filled with the oil at the desired strength, and the trees dipped. It is the general belief that the oil is not good for the roots of a plant and the tops only are dipped. Chemical composition of miscible oil. — The alkali in the soap or other emulsifier reacts upon the oil in such a way as to cause it to break up and become miscible in water. The commercial preparations are presumably composed of different types of oils treated in different ways and are pro- tected by United States patents. RESULTS OF EXPERIMENTS WITH MISCIBLE OIL Owing to the fact that miscible oils are used to some extent in con- trolling San Jose scale 'upon fruit trees and, that in some states nursery- men are allowed to use it instead of hydrocyanic-acid gas upon nursery stock, an effort was made to determine its efficiency for controlling the scale, Some of the nurserymen who use a miscible oil to dip their stock say that it controls the scale just as well, if not better, than hydrocyanic- acid gas; that it is not so costly, and that there is less danger of injury to the tree. Also, like lime-sulphur, it is non-poisonous. Procedure. — The larger nurserymen who make a practice of dipping their stock, usually construct a large cistern-shaped vat of concrete or use a large tank which they fill with the solution and in which very large trees can be dipped. In this work the same trough was used as with the lime- sulphur and in every detail the methods of procedure were the same with the exception of the solution. With the first two sets of trees treated, 1 gallon of oil was used to 15 gallons of water; with the third and fourth sets, 1 gallon of oil to 13 gallons of water was used. Effect of miscible oil upon San Jose scale on apple. — The following 30 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 table shows the results obtained by using miscible oil upon San Jose scale on apple trees, at the strength of 1 gallon to 15 gallons of water, and 1 gallon to 13 gallons of water. TABLE 21. — APPLES TREATED IN 1916 Date Insect- icide Parts treated Length of treat- ment No. trees treat- ed Per cent scale dead Per trees cent i dead 1916 min. 5/14-25/16 5/26/16 4/4/17 March 21 Mis. Oil 1-15 top inst. 10 100 10 50 Mis. Oil 1-15 t. & r. inst. 10 100 0 40 Mis. Oil 1-13 top inst. 10 100 10 50 Mis. Oil 1-13 t. & r. inst: 10 100 20 50 Check 20 38 9 o 60 Each tree was very carefully examined and no live scale whatever could be found, and the control seemed to be complete. TABLE 22.— APPLES TREATED' IN 1917 Date Insect- Parts Length of No. trees Per cent icide treated treatment, treated scale dead 1917 min. 4/20/17 April 9 Mis. Oil 1-12 top 5 5 100 Mis. Oil 1-12 t. & r. 5 5 100 Check 4 75 No live scale could be found when examined. TABLE 23.— APPLES TREATED IN 1920 Date Insecticide Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 1920 3/20/20 11/15/20 March 26 1 gal. Mis. Oil t. & r. inst. 34 100 88.2 to 15 gal. H2O March 26 1 gal. Mis. Oil tops inst. 34 100 73.5 to 15 gal. H2O March 27 1/2 pt. Lemon tops inst. 34 84.20 76.4 Oil, &y4 gal. H2O and V2 Ib. soap Check 68 76 94.2 DIPPING AND FUMIGATION OF NURSERY STOCK 31 The lemon oil gave very poor results. TABLE 24.— PEARS TREATED IN 1920 Date Insecticide Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 3/20/20 11/15/20 March 26 1 gal. Mis. Oil t. & r. inst. 2 100 100 to 15 gal. H2O March 26 1 gal. Mis. Oil tops inst. 2 100 100 to 15 gal. H2O March 27 y2 pt. Lemon tops inst. 2 100 50 Oil, 6V2 gal. H2O and V2 lb. soap Check 4 74.68 0 All treatments gave good results. TABLE 25.— PEACHES TREATED IN 1916 Date Insect- icide Parts treated Length of treat- ment No. trees treat- ed Per cent scale dead Per trees cent dead 1916 min. 5/14-25/16 5/26/164/4/17 March 21 Mis. Oil 1-15 top inst. 4 100 0 0 Mis. Oil 1-15 t. & r. inst. 4 100 37.5 37.5 Mis. Oil 1-12 top inst. 4 99.3 25 25 Mis. Oil 1-12 t. & r. inst. 4 100 25 62.5 Check 8 100 25 62.5 All of the above treatments proved effective with the exception of one, the 1-12, tops only, and the control in this case was 99.3 per cent. How- ever, this is enough to reinfest the tree. TABLE 26.— PEACHES TREATED IN 1917 Date Insect- Parts Length of No. trees Per cent icide treated treatment, treated scale dead 1917 min. 4/20/17 April 9 Mis. Oil 1-12 top 5 9 100 Mis. Oil 1-12 t. & r. 5 9 100 Check 6 60 32 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 No live scale could be found. TABLE 27.— PEACHES TREATED IN 1920 Date Insecticide Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment, treated dead dead 1920 min. 3/20/20 11/15/20 March 26 1 gal. Mis. Oil t. & r. 5 5 100 60 to 15 gal. H2O March 26 1 gal. Mis. Oil tops 5 5 100 40 to 15 gal. H2O March 27 y2 pt. Lemon tops 5 5 60 80 Oil, 6J4 gal. H2O and % Ib. soap Check 10 85.67 100 The foregoing tables show that miscible oil does not injure nursery stock to any great extent; however, as compared with the check, some in- jury results from its use. Probably some time is required before the injury shows up to any great extent. At the end of the first two months the per cent of dead plants was not so great where the tops only were treated, as in. the case of the checks. At the end of a year, however, there was about three times as many of the plants, which were treated tops only, dead as in the case of the check. Those plants which were dipped both tops and roots showed a higher percentage of death than those dipped tops only. So it seems that it is not advisable to dip the roots of plants in miscible oil. In comparing the two strengths of miscible oil used, the 1 gallon to 12 gallons of water, caused a much greater percentage of injury than the weaker strength of 1 gallon of the oil to 15 gallons of water. As to the control of San Jose scale, the miscible oil gave excellent results. Both strengths controlled the scale upon the apples. Upon the peach the results were as good with the exception of those treated, tops only, with the 1-12 strength and in this case 99.3 per cent of the scale was killed. Taken as a whole, the miscible oil injured the plants less and controlled the San Jose scale better than any of the other materials used. As the tables show the lemon oil which was used in 1920 gave very poor results. Lemon oil is used to some extent by florists to spray green house plants which are infested with scale insects, however it seems to be of little value in controlling San Jose scale. NICOTINE SULPHATE AS A SPRAY In addition to all of the other materials used in 1920 nicotine sulphate, a tobacco extract, was tried. It is a sulphate of nicotine and therefore an acid material. It contains 40 per cent nioctine and is used as a contact DIPPING AND FUMIGATION OF NURSERY STOCK 33 spray for soft bodied insects like the plant lice. It is usually used at the rate of one gallon of nicotine sulphate to about 800 gallons of water. In using it as a dip for San Jose scale on dormant trees it was used at the rate of one gallon of nicotine sulphate to 100 gallons of water. The following tables show the results obtained. TABLE 28.— APPLES TREATED IN 1920 Date Treatment Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 1920 min. 3/20/20 11/15/20 March 27 1 gal. Nicotine tops inst. 34 64.74 91.1 sulphate to Check 68 76 94.2 TABLE 29.— PEACHE s TREATED IN 1920 Date Treatment Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 1920 min. 3/20/20 11/15/20 March 27 1 gal. Nicotine tops inst. 5 100 80 sulphate to 100 gal. H20 Check 10 85.67 100 TABLE 30.— PEARS TREATED i N 1920 Date Treatment Parts Length No. Per Per treated of of cent cent treat- trees scale trees ment treated dead dead 1920 min. 3/20/20 11/15/20 March 27 1 gal. Nicotine tops inst. 2 100 100 sulphate to 100 gal. H2O Check 4 74.68 0 Nicotine sulphate seemed to have killed all the scale on the peach and pear but on the apples it gave very poor results. It also caused con- siderable injury to the plants treated. Evidently it should not be used as a dip in controlling San Jose scale on nursery stock. 34 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 SUMMARY 1. Hydrocyanic-acid gas did not in every case completely control the San Jose scale. However, the gas used at a strength of 1-1-3 gave better results than the weaker strength of %-%-!%. The 1-1-3 strength gave as good results as the 2-2-6 strength. Sodium cyanide used at the strength of 1-1M.-3 killed 100 per cent of the scale. 2. Hydrocyanic-acid gas was more effective when used upon dry plants than upon wet. A larger percentage of the scale was killed. 3. All strengths of the hydrocyanic-acid gas caused more or less Injury to the plants. The stronger it was used, the more injury it caused. 4. The 1-1-3 formula should always be used in fumigating nursery stock, and the stock should be dry. There may be greater danger of in- jury to the plants, but the scale will be more completely controlled, and this is the most important factor. 5. Carbon bisulphide did not control the scale and it caused a very high percentage of injury. Its use as a fumigating material for the control of San Jose scale on nursery stock should 'be discouraged. 6. Lime-sulphur used at 1-9 and 1-7 strengths gave fairly good results in controlling the scale. The 1-9 solution gave perfect results on pears and plums. 7. The sulphur dips injured the plants to some extent. The plants dipped both tops and roots showed more injury than those dipped tops only. 8. The miscible oil gave the best results, 100 per cent of the scale being controlled in every case but one and in this case the control exceeded 99 per cent. 9. Miscible oil caused some injury to the plants. Those dipped tops and roots were injured most. When treating nursery stock with miscible oil the roots should not be dipped. 10. Lemon oil or nicotine sulphate should not be used as dips for con- trolling scale on nursery stock. 11. None of the materials used completely controlled the San Jose scale. 12. All scale-infested nursery stock should be burned or destroyed in some other way. • 13. Nursery stock which has been subjected to infestation, but is not infested should be treated before being placed on the market. 14. The best results should be expected by treating the stock with hydrocyanic-acid gas 1-1-3, or with miscible oil at the strength of 1-12 or 1-15, tops only. DIPPING AND FUMIGATION OF NURSERY STOCK 3.S BIBLIOGRAPHY (1) COMSTOCK, J. H. 1916. Report on Scale Insects. Cornell Bui. No. 372. (2) CORDLY, A. B. 1910. Insecticides and Fungicides. Oregon Agr. Exp. Sta. Bui. 108. (3) DEAN, GEORGE A. Mill and Stored Grain Insects. Kan. Exp. Sta. Bui. 189. (4) FAUROT, F. W. 1906. Preliminary Experiments in Dipping Nursery Stock. Mo. Fruit Exp. Sta. Bui. 14. (5) FELT, E. P. Petroleum and Petroleum Products as Insecticides. N. Y. State Ed. Dept., Albany. (6) GARMAN, H. Nursery Inspection and San Jose Scale. Kentucky Sta. Bui. 110. (7) — Diseases of Nursery Stock. Ky. Sta. Bui. 93. (8) GIRAULT, A. A. 1912 . Insects Injurious to Stored Grains and Grain Products. 111. Exp. Sta. Bui. 156. (9) HASEMAN, L. 1915. Control of an Jose Scale in Missouri. Mo. Agr. Exp. Sta. Bui. 132. (10) HINDS, W. E. Carbon Bisulphide as an Insecticide. Farmer's Bui. 145. (11) HOWARD, L. O. Hydrocyanic-acid Gas Against Household Insects. U. S. D. A. Cir. 46, 2d. ser. (12) JOHNSON, W. G. 1902 Fumigation Methods. (13) LODEMAN, E. G. Spraying of Plants. Macmillan Company. (14) LOWE, V. H. Inspection and Treatment of Infested Nursery Stock. N. Y. Exp. Sta. Bui. 136. (15) LOWE, V. H. and PARROTT, P. J. 1901. San Jose Scale Investigations 111. N. Y. Exp. Sta. Bui. 202. (16) MARLATT, C. L. 1906. The San Jose or Chinese Scale. B. O. E. Bui. 62. (17) MORSE, F. W. 1887. The Use of Gases Against Scale Insects. Cal. Exp. ta. Bui. 71. 36 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 (18) MCDONNEU,, C. D. 111. Chemistry of Fumigating With Hydrocyanic-acid Gas. U. S. D.-A. B. O. E. Bui. 90. (19) PARROTT, P. J., HODGKISS, H. E., and SCHOENE, W. J. 1908. Dipping of Nursery Stock in Lime-Sulphur Wash. N. Y. Exp. Sta. Bui. 302. (20) PEARIS, L. M., and MERRIU,, J. H. 1916. San Jose Scale. Kan. Exp. Sta. Bui. 214. (21) SCHOENE, W. J. 1913. The Influence of Temperature and Moisture in Fumigating. N. Y. Exp. Sta. Tech. Bui. 30. (22) - 1914. Analysis of Materials as insecticides and Fungicides. N. Y. Exp. Sta. Bui. 384. (23) SHAEERM, GEO. D. 1915. How Contact Insectides Kill. Mich. Agr. Exp. Sta. Tech. Bui. 21. (24) SIRRINE, F. A. 1901. Treatment of San Jose Scale in Orchards. N. Y. Exp. Sta. Bui. 209. (25) 1895. N. Y. Exp. Sta. Ann. Rpt. (26) SUNGERLAND and CROSBY Manual of Fruit Insects. (27) STEADMAN, J. N. 1898. San Jose Scale in Missouri. Mo. Exp. Sta. Cir. 3. (28) — 1898. San Jose scale in Missouri. Mo. Exp. Sta. Bui. 41. (29) WOODSWORTH, C. W. School of Fumigating. Univ. of Calif., Pomona, Calif. (30) — 1909. Fumigating the Apple for San Jose scale. U. S. Ent. Bui. 84. (31) 1910. U. S. Census Report. (32) Missouri Nursery Inspection Law. Mo. Exp. Sta. Cir. 63. (33) Cw>SE, C. V. 1903-1906. Del. Sta. Ann. Rpts. 15:137; 16, 17, and 18:48. UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION COLUMBIA, MISSOURI CIRCULAR 101 DECEMBER, 1920 PLANT INSPECTION IN MISSOURI • K. C. SULLIVAN Plant inspection work has been carried on in a systematic manner in Missouri since 1913, and it is the object of this report to give a brief sum- mary of the work done since that time and the results accomplished. The inspection of nurseries in particular has a direct bearing upon the fruit industry, for it is thru the distribution of nursery stock that our most dangerous insect pests and plant diseases have been scattered from one fruit-growing community to another. Unfortunately, it has been only dur- ing the last few years that the full value of a systematic annual inspection of nurseries and orchards has been appreciated, with the result that prior to 1913 only those nurseries, which shipped stock, received annual inspec- tion. In the meantime many very serious insect pests and plant diseases have been introduced into the fruit-growing sections of the state. Many of these pests and diseases like the San Jose Scale, crown gall and hairy Fig. I. — A good grape nursery in southwest Missouri 2 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 root first gained their admission to Missouri on nursery stock. The tax paid to insect pests and diseases by the Missouri fruit growers in the last fifty years has amounted to hundreds of millions of dollars. Much of this loss could have been prevented had the real value of inspection work and the control of insects and diseases been realized sooner. Several of the more prominent nurserymen and fruit growers of Mis- souri did realize the value of inspection work and for a number of years before Missouri had an inspection service they secured the assistance of the entomologists of the Agricultural Experiment Station and had their nurs- eries and orchards inspected annually. However, due to the expense, only the larger and more prosperous nurserymen and orchardists felt that they could afford to have their premises inspected each year. The need of a good inspection service for Missouri, which would be state wide, and which would reach out to; the little nursery men and or-* chardists as well as the large ones, became so apparent that in 1913 the State Legislature passed a Nursery Inspection Law providing for the in- spection of plants by the Missouri Agricultural Experiment Station. This law was approved by the Governor March 27, 1913. The purpose of the Law is to prevent the further introduction of San Jose scale and other dangerously injurious insects and plant diseases, and to suppress as far as possible those pests which may have secured a foot- hold in this state. This Law also provides fully for the most careful in- spection of suspected plants and for the destruction of badly diseased plants, the distribution of which might result in serious consequences to the farm- ers and fruit growers of Missouri. The Nursery Inspection Law further provides that it shall be the duty of the Agricultural Experiment Station at Columbia to seek out, suppress and eradicate San Jose scale and other dangerous insect pests and plant diseases affecting the agricultural and horticultural interests of the State of Missouri. The Agricultural Experiment Station shall make necessary regu- lations and shall be vested with all the powers necessary to carry into effect the provisions of this Act. Section 2 of the Law authorizes the official inspectors to enter any grounds or other premises for inspection and eradication of insects and diseases. It further authorizes the Agricultural Experiment Station to carry on demonstrations and experiments dealing with insect control and to give information on the control of insects and plant diseases by lectures and printed literature. Section 3 of the Law gives the Agricultural Experiment Station au- thority to inspect from time to time nurseries, orchards, fruit plantations or other property and if dangerous insect pests or plant diseases are found it shall recommend the method of treatment. Section 4 of the Law provides that each person or corporation in the state engaged in growing nursery stock for distribution shall notify the office of the Plant Inspection Service on or before the first day of July of each year and make application for the inspection of their nursery stock. The Plant Inspection Service must inspect the stock before September 15. Each individual or corporation importing nursery stock from a foreign PLANT INSPECTION IN MISSOURI 3 country must notify the Plant Inspection Service upon the arrival of the stock. The Plant Inspection Service shall issue to each nurseryman a certifi- cate of inspection providing the stock has been found free of dangerous insect pests and plant diseases. The certificate is good for one year provid- ing a fee of $5 has been received for the certificate plus the actual necessary expenses incurred in making the inspection. All shipments of nursery stock originating in Missouri must have attached to it a certificate of inspection from the Plant Inspection Service of Missouri. All shipments of nursery stock originating outside and coming into Missouri must have attached to it a certificate of inspection satisfactory to the Missouri Plant Inspection Service. Annually every nursery or firm outside Missouri shipping nursery stock into Missouri must file with the Missouri Plant Inspection Service a valid certificate of inspection issued by a state or government inspector showing that said stock has been inspected and found free from all danger- ous insect pests and plant diseases, together with a statement under oath that no stock will be shipped into Missouri that has not been inspected and certified. Annually every agent or authorized representative of any nursery or dealer must file with the Missouri Plant Inspection Service a statement under oath that he will offer for sale no stock which has not been duly inspected and certified, together with a copy of the certificate of and proper credentials from the nurseryman or dealer represented. Annually, each dealer, person or firm engaged in the sale and delivery of nursery stock in Missouri and who is not the authorized representative of any nurseryman must file in the office of the Missouri Plant Inspection Service a statement under oath that he will handle only stock which has been officially inspected and certified. The statement must contain the names of the nurserymen or firms from which stock is obtained. He must also obtain a dealer's certificate from the Plant Inspection Service for which a fee of $5 must be paid and which is good for one year beginning July 1 of each year. This certificate may be attached to shipments of nursery stock. Section 5 requires that all shipments of nursery stock must be plainly labeled on the outside with the name of the consignor and consignee and a brief statement of the contents and a valid certificate of inspection. It is unlawful to deliver shipments of nursery stock in Missouri that are not so labeled. Section 6 provides that any owner of an orchard or fruit plantation or dealer in plant products can request the Plant Inspection Service to in- spect the same, and as soon as convenient the Plant Inspection Service must make the inspection and issue a certificate to the facts disclosed by the inspection. Section 7 provides the penalty for violating the Nursery Inspection Act. The penalty of violating the Nursery Inspection Act is a fine of not less than $25 nor more than $100 for each offense, together with the cost of procedure. The prosecuting attorney shall prosecute violators of the act. Section 8 defines the terms "nursery stock," "dangerous insect pests" and "plant diseases." 4 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 Section 9 provides for the enforcement of the Nursery Inspection Act which is placed under the supervision of the director of the Agricultural Experiment Station and he is empowered to appoint a chief inspector and such additional assistants as may be necessary to execute the provisions of the Act. Under the provision of the Nursery Inspection L/aw, Dr. Leonard Haseman, Entomologist of the Agricultural Experiment Station, was ap- pointed Chief Inspector and since 1913 the provisions of the law have been carried out under his direction. Every state in the Union maintains a nursery inspection service of some type and the nursery inspection service of Missouri closely cooperates with the officials of the different states especially as regards the shipping of nursery stock to and from those states and Missouri. The Federal Government also maintains a large inspection service Fig. 2. — Inspecting evergreens in a Missouri nursery which is under the control of the Federal Horticultural Board. The Fed- eral Board regulates the importation of all kinds of plants, seeds, etc., in- cluding nursery stock from foreign countries, and also makes rules and regulations when necessary regarding interstate shipping of nursery stock, etc. The Missouri Plant Inspection Service cooperates in every way possi- ble with the Federal Board in furthering the eradication of dangerous in- sect pests and plant diseases and in preventing the introduction of new ones. Every year, Missouri nurserymen and florists import large quantities of nursery stock from foreign countries, especially France, Belgium and Hol- land. The Federal Horticultural Board requires that all imported stock be inspected upon arriving at its point of destination. Officials of the Mis- souri Plant Inspection Service inspect all of this foreign stock which comes into Missouri. PLANT INSPECTION IN MISSOURI 5 PLANT INSPECTION, 1913 As soon as the Plant Inspection Law was passed and approved by the Governor, the director of the Agricultural Experiment Station appointed the Chief Inspector and plans were at once begun for carrying out the requirements of the Law. Most of the inspection for 1913 was made during July and August by Dr. Leonard Haseman, Chief Inspector, and T. J. Talbert, Assistant in Entomology, and B. Szymoniak, Assistant in Horticulture, who had been deputized to assist with the work. During the months July, August and September, 1913, 125 nurseries were inspected, of which 114 were certified as being free from injurious insect pests and plant diseases. Twenty-three nurseries were found to be infested with San Jose scale. A total of 3,000 acres of nursery stock was FIG, 3. — Good two-year-old apples of which hundreds of acres are grown in Missouri every year inspected; located in 44 different counties. Also during the year 500 cases of imported stock containing over 500,000 plants were inspected. Inspection Certificates to the number of 114 were issued by the Plant Inspection Service and 78 certificates were issued to dealers in nursery stock. One hundred and nineteen permits were issued to growers in other states who desired to ship nursery stock into Missouri and 377 permits were issued to agents or representatives of nurseries who desired to sell stock in Missouri. As previously stated, twenty-three nurseries were found infested with San Jose scale and steps were immediately taken to clean up these infesta- tions. Also, in connection with the nursery inspection work, a considera- ble acreage of orchard was inspected. Every attempt possible was made to determine whether or not the San Jose scale was present in orchards dangerously near nurseries. In many cases it was found near the nursery blocks and when in dangerous proximity the nurseryman was required to 6 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 take due precaution in preventing the spread from the orchards to his nursery stock. Owners of such orchards were given orders to clean them up and in most cases steps were taken at once to destroy infested trees and shrubs. Due to the fact that 23 nurseries and a large number of orchards were found infested with San Jose scale an educational campaign, as provided for in the Nursery Inspection Law, was inaugurated in the fall of 1913. Where a nursery was found infested with scale the nurseryman was re- quired to destroy all infested plants including trees and shrubs and to treat all stock subject to infestation with hydrocyanic-acid gas. Also scale-infested orchards were selected at Sikeston, Boonville, Wil- lard, Pierce City, Jackson, Hannibal and Alexandria and during the fall of 1913 and early spring of 1914 spraying demonstrations were held at these places for the control of the scale. In this work no effort was made to spray large orchards in each locality but only a portion of an orchard. Just enough spraying was done to show the fruit growers who were not familiar with scale control just how it should be done. At these spraying demonstrations, meetings were held at which methods of controlling in- sects and diseases were described. Also the best methods of planting, pruning, cultivating, selecting the site and other practical subjects of or- chard management were given consideration. The results obtained from these demonstrations were quite satisfactory and led to the purchase by many fruit growers of sprayers and spraying material and the production of cleaner and better fruit. The results of this work are given in detail in Missouri Experiment Station Bulletin 132, "The Control of San Jose Scale in Missouri." The results of the first year's work of nursery and orchard inspection showed clearlv that a number of the nurserymen and many fruit growers faced the problem of eradicating that most serious of nursery and orchard pests, the San Jose scale, and also that the Plant Inspection Service had a big task before it in heloine^ in this work of keeping Missouri orchards free from injurious pests and diseases in the future. PLANT INSPECTION 1914-1915 During the year 1914-15 the inspection work was done by Dr. Leonard Haseman, Chief Inspector and Mr. T. J. Talbert, Deputy Inspector. A total of 135 nurseries were inspected of which 113 were certified. The acreage of nursery stock in Missouri in 1914-15 was 2551 located in 44 dif- ferent counties. Five hundred and forty-nine cases of foreign stock re- ceived in 13 different counties were inspected. These 549 cases contained nearly 600,000 plants. One hundred and thirteen certificates of nursery in- spection were issued; sixty-four dealers certificates, ninety-four growers permits and 249 agents permits. Eleven more nurseries were inspected in 1914 than in 1913. These nurseries existed in 1913 but due to the fact that 1913 was the first time that a systematic inspection was ever attempted it was almost impossible to locate every nursery in the State. These nurseries which were located and inspected for the first time in 1914 were small ones and not widely known. PLANT INSPECTION IN MISSOURI Also some of them were infested with San Jose scale. A total of twenty- three nurseries were found to be infested in 1913 while in 1914 the number infested was twenty-seven. Many of the nurseries which were found in- fested in 1913 had been thoroughly cleaned up but as a large percentage of the nurseries inspected for the first time in 1914 were found infested the total number of infested nurseries was higher than in 1913. As in 1913 the amount of foreign stock received in 1914-15 was large and a great deal of time was spent in inspecting it. The results of the nursery inspection work in 1914-15 showed that the problem of eradicating the San Jose scale from the infested nurseries was indeed a great one and plans were made to push with increased vigor the work of eradication. PLANT INSPECTION 1915-16 During the summer of 1915 the inspection work was done by A. H. Hollinger, Assistant in Entomology who was appointed to fill the vacancy caused by the resignation of Mr. Talbert, and by K. C. Sullivan and J. H. Shepherd who were appointed deputy inspectors for the summer. All these were under the direction of Dr. Haseman, chief inspector. The scope of the work was greatly enlarged in 1915 and a large acreage of orchards were inspected in practically every county of the state. Of the 173 nurseries inspected in 1915-16, 161 were certified. Two thousand six hundred and two acres of nursery stock was inspected in forty-six different counties and 489 cases containing 325,106 foreign plants were inspected in fourteen different counties. One hundred and sixteen nursery inspection certificattes; eighty-seven dealers certificates; 125 growers permits and 300 agents permits were is- sued by the Plant Inspection Service in 1915-16. It will be noticed that in 1915-16, 173 nurseries were inspected as corn- pared to 135 in 1914-15. This increase was due to the fact that many of the strawberry growers in Southwest Missou- ri who had exceedingly fine beds wished to ___^^^___^^—-—_ sell and ship plants and in order to meet the requirements of the different states had their plant beds inspected. Twenty-four nurseries of the 173 inspect- ed were found to be infested with San Jose scale while in 1914 twenty-seven nurseries out of 136 inspected were infested. This reduc- tion of scale-infested nurseries was due large- ly to the efforts of the Inspection Service and its ability to cooperate with the nurserymen in a just and fair manner. Altho the nursery and orchard inspection service has police power, at no time was it necessary to use this power in connection with the San Jose scale clean up work. The scale clean up work was conducted as an educational project and in every case the nurseryman was glad to do his FIG. 4. — Looking down the row «/f a block of seedling peach- es. These are peaches ready to bud 8 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 part. Where a nursery was found to be infested with San Jose scale or any other dangerous pests or diseases, the owner was immediately told of the existing conditions and given instructions as how to proceed in order to bring about their eradication. Usually the nursery was visited the sec- ond time in the digging period and all infested stock was condemned and burned and the remainder treated either with hydrocyanic acid or a mis- cible oil dip, and as is shown, this work was very effective. In addition to the regular nursery inspection work the Plant Inspection Service in 1915-16 for the first time did a large amount of orchard inspec- tion. The inspection of permanent orchards is one of the most important proj- ects of the Plant Inspection Service and until this time no definite information had ever been obtained as to the prevailance of dangerous insect pests and diseases in the orchards of Missouri. This was especially true with ref- FIG. 5. — A lot of scale-infested nursery stjck which was condemned by the Plant Inspection Service erence to the San Jose scale. Before this time the San Jose scale had been found in a number of commercial orchards but no one knew just how generally it was scattered over the state. The object in making an in- spection of the orchards in all sections of the state was to find out defi- nitely just how great a foothold the more serious insect pests, especially San Jose scale, and plant diseases had obtained in Missouri. Therefore, during the year 1915-16, 118 orchards composing a total of 1,967 acres lo- cated in sixty-nine counties were visited by inspectors from the Plant In- spection Service and carefully examined. Thirty-nine or practically a third of the orchards inspected were found to be infested with San Jose scale, some very bad, others very slightly. Whenever an orchard was found to be infested with San Jose scale or any other pest or disease, instructions were given regarding the eradication of the pest or diseases. It is a well known fact that an old orchard is an ideal place for such pests as the San Jose scale to breed from year to year PLANT INSPECTION IN MISSOURI 9 and unless it is thoroughly cleaned up will serve as a source of infesta- tion for an entire community and in the long run may cause a loss of thou- sands of dollars. In case an infested orchard was found near a nursery, additional emphasis was placed upon the necessity of cleaning up the prem- ises. It is gratifying to state that in practically every case the fruit grow- ers were more than willing to cooperate with the Plant Inspection Service in every way in order to get rid of dangerous pests and diseases. That most dangerous of orchard pests, the San Jose scale, is widely distributed over Missouri and the Plant Inspection Service has a gigantic task before it in cleaning up and preventing a further spread of this pest. A task which will require both a great deal of time and a great deal of money, but which in the end will amount to very little as compared to the returns which can be obtained from a clean and healthy orchard. The results of the inspection work in 1915-16 showed very conclusively that the Missouri Plant Inspection Service was rendering a great service to the nurserymen and fruit growers of the State by locating and helping clean up infestations of dangerous insect pests and diseases. PLANT INSPECTION 1916-17 During the year of 1916-17 the nursery inspection work was carried on by Dr. Leonard Haseman, chief inspector and C. V. Vinson and K. C. Sullivan, deputies. The work was conducted in the same manner as the year before, except very little orchard inspection work was done due to in- sufficient funds necessary for carrying on such work. One hundred thirty nurseries were inspected located in forty-seven different counties of which 107 were certified. The total acreage of nursery stock growing in Missouri in 1916-17 was 2,860. Three hundred eighty- nine cases of imported stock containing 570,766 plants were inspected in eleven different counties. One hundred seven certificates of nursery in- spection; sixty-seven dealers certificates; 101 growers permits and 182 agents permits were issued in 1916-17. Twenty-two nurseries were found to be infested with San Jose scale, being two less than in 1915-16. The report for 1916-17 shows that the numbers of scale infested nurs- eries was gradually being decreased. The clean up work in 1916-17 was carried on as in 1915-16. PLANT INSPECTION 1917-18 The work of the Plant Inspection Service was carried on in 1917-18 by Dr. Leonard Haseman, chief inspector and A. H. Hollinger and K. C. Sullivan, deputies. One hundred twenty-three nurseries were inspected and 103 were cer- tified. The nurseries inspected were located in forty-five different coun- ties and included a total of 2,035 acres. Forty-four cases of imported stock containing 425,849 plants received in seven different counties were inspected. Fifteen nurseries were found infested with San Jose scale as compared to twenty-two in 1916-17. This noticeable decrease in scale-infested nurseries was due largely to the untiring efforts of the Plant Inspection Service. 10 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 Another noticeable fact was the decrease in acreage which was due largely to the war which caused a decrease in demand for nursery stock. When the demand became less the nurserymen naturally planted a smaller acreage. Also many of the Missouri nurserymen for patriotic reasons lessened their acreage of nursery stock and grew a large acreage of wheat and corn which was badly needed at that time. PLANT INSPECTION 1918-19 During the year 1918-19 all of the nursery inspection work was done by Dr. Leonard Haseman and K. C. Sullivan with some assistance by T. J. Rosa, Jr., Help was very scarce and also the number of nurseries to be inspected was less than ever before, due largely to the war. Ninety-six nurseries were inspected, of which number ninety were cer- tified. A total of 1,313 acres located in forty different counties were in- spected. One hundred twenty-seven cases of imported stock containing 314,631 plants were inspected in nine different counties. Ninety certifi- cates of nursery inspection, thirty-five dealers certificates; 111 growers permits and ninety-two agents permits were issued. The report of 1918-19 shows very conclusively the effect of the war upon the nursery business in Missouri in both the number of nurseries and the total acreage of stock. Due to the decrease in the demand for nursery stock and the scarcity of labor, many of the smaller nurseries closed down altogether and the larger ones cut down the acreage. In 1918-19 only two nurseries were found to be infested with San Jose scale and those but slightly. In 1913 when the Missouri Plant Inspection Service began to function, twenty-three nurseries were found to be in- fested. Taking into consideration the fact that San Jose scale is about the hardest insect known to eradicate, the Inspection Service really feels it had accomplished a great deal of good in the short time which it had been working. Up to this time the Missouri Plant Inspection Service had been main- tained entirely by fees paid by the nurserymen. This source of income could be relied upon, but it was entirely inadequate to carry on the work of nursery and orchard inspection properly in the state. In 1917 the State Legislature, realizing the importance of the nursery and orchard inspec- tion work, made an appropriation of $5,000 to be used in furthering the work. This appropriation, however, was not made available. In 1919 the State Legislature again made an appropriation for the Plant Inspection Service. This time the amount was $10,000 of which $2,000 was made avail- able in 1919, thus partially placing the Plant Inspection Service on state support. PLANT INSPECTION 1919-20 During the year 1919-20 the nursery and orchard inspection work was done by Dr. Leonard Haseman, chief inspector and K. C. Sullivan and S. R. McLane, deputies. Also a small amount of work was done by R. S. Springate. As was stated before $2,000 of the appropriation made by the State Legislature was made available for the work during 1919-20 with PLANT INSPECTION IN MISSOURI 11 the result that a great deal more good was accomplished than ever before. Ninety-three nurseries, located in forty different counties, were in- spected, eighty of which were certified. A total of 1,469 acres of nursery stock was growing in 1919-20. Sixty-seven cases of foreign stock con- taining 442,000 plants were received in six different counties and inspected. Eighty nursery inspection certificates; twenty-three dealers certificates; 157 growers permits and 121 agents permits were issued. During the year 1919-20 eight nurseries were found to be slightly in- fested with San Jose scale. In every case the nursery infested was in close proximity to a heavily infested orchard and as the season in 1919-20 was favorable for the growth and spread of the scale some of the near-by nurseries had become infested to some extent, but none seriously. As in previous years every precaution was taken to prevent its further spread and to eradicate it from the nurseries and the near-by orchards. The method most generally used in eradicating and preventing the spread of San Jose scale on nursery stock and the one recommended by the Plant Inspection Service is to destroy all visibly infested stock and treat all other stock, subject to infestation, by either hydrocyanic acid gas or by dipping it in a miscible oil. The hydrocyanic acid gas treatment is more commonly used than the latter. In using this gas this method is followed: One fluid ounce of sulphuric acid having a specific gravity of at least 1.83 is placed in an earthernware crock, wooden bucket, or tub; then 3 fluid ounces of water are added. In this mixture 1 ounce, by weight, of fused cyanide of potassium, 98-99 percent pure, is added. The above amounts are used for every 100 cubic feet of space. In fumigating tender growing plants, the above formula is too strong and has to be weakened. For dormant trees, mills, elevators and the like the 1-1-3 formula is recom- mended by both the United States Department of Agriculture and prac- tically all of the state experiment stations. In fumigating nursery stock an air tight box or house is necessary. The trees are placed in the box or house. The water and sulphuric acid are mixed in an earthern jar and the jar placed in the box or house. The potassium cyanide is then dropped in and the box or house closed just as quickly as possible. The hydrocyanic acid gas which is generated is deadly poisonous and the person doing the fumigating must be very careful not to breathe any of it. It requires about 45 minutes to fumigate nursery stock, although some authorities say that better results can be obtained by let- ting the stock remain an hour. At the end of this time the fumigating box or house is opened and the gas allowed to escape and in from 15 to 20 minutes the trees can be safely removed. It is never advisible to fumigate trees while they are damp or wet. It is claimed that under such conditions the gas is more likely to injure the stock. However, the writer's experiments to date fail to corroborate this, though they do show that less scale is killed under those conditions. Some states require by law that all nursery stock grown within its borders or shipped in from outside nurseries be fumigated, and, as a result, all of the larger nurseries in the United States have constructed special fumigating houses or boxes. 12 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 At the present time a form of sodium cyanide which is stronger than potassium cyanide is being substituted for the latter. Due "to the fact that the sodium cyanide is stronger than the potassium cyanide a slight change has to be made in the formula, otherwise the method of using it is exactly the same. The formula recommended when using sodium cyanide is one ounce of sodium cyanide, 1^ ounces sulphuric acid and two ounces of water. Sodium cyanide is much cheaper than potassium cyanide and gives just as good results and is therefore coming into general use. As previously stated, the use of a miscible oil for treating nursery stock which has been subject to infestation by San Jose scale is practiced to some extent by some nurserymen and good results have been obtained. In case a miscible oil is used, a tank or vat is constructed large enough to allow the dipping or complete emersion of the top of the trees to be treated. The oil is used at a strength of one gallon of the oil to twelve or fifteen gallons of water and the stock to be treated is completely emersed except the roots, immediately removed and allowed to drain and dry. In 1915 a number of experiments were started at the Missouri Agri- cultural Experiment Station to determine the most practical, efficient and cheapest method to use in controlling scale on nursery stock with the least possible injury to the plants. The results of this work will appear in a separate publication. Unfortunately only $2000 of the $10,000 appropriation made by the State Legislature was made available for use in 1919-20 and this was not made available until very late in the year. However, this sum made it possible for the inspection service to carry on its work to a much greater extent than would otherwise have been possible. Due to the increase in price of railroad fares, hotel accommodations, labor etc., it costs the Inspection Service just about twice as much to do the same amount of work as it did four years ago. Thus it would have been practically impossible for the inspection service to have carried on its work without this additional help. PLANT INSPECTION 1920 During the year 1920 the inspection work was done by Dr. Leonard Haseman, chief inspector and K. C. Sullivan, S. R. McLane and G. A. Tumbleson, deputies. Due to the fact that $5000 of the $10,000 state appro- priation was made available the work of the Plant Inspection Service was enlarged. A very important phase of the work which is being carried on in addition to the nursery and orchard inspection is the inspection for the European Corn-borer, which will be discussed later. The following 100 nurseries were inspected during the summer of 1920: NURSERIES INSPECTED 1920-21 Aroma Plant Company. Seligman Chapman, W. C., Higbee Bennet. B. F,, Seymour Clever Nursery Company, Clever Bellefontaine Cemetery, St. Louis Crotsenburg, C. N., Carthage Birch, F. A., Neosho Davis, E., Seligman Crumly Brothers, Monett De Soto Nursery Co., De Soto Calvary Cemetery, St. Louis Dobbs, Earl S., Anderson Cameron Nursery, Cameron Elk Horn Nurseries, Noel Case Nursery, Case Ely, H. S. & Company, Neosho PLANT INSPECTION IN MISSOURI 13 KM st ridge and Landis, Neosho Ellisville Nursery, Ellisville Fanners Nursery, Chillieothe F;iirview Nursery, Bethany Fort, J. T. Nursery Co., Kansas City Flowers, F. A., Carthage Gibson's Ozark Nursery, Springfield Golden City Nursery Co., Golden City Howell County Nursery, West Plains Hatzfeld, L. H., Goodman Halava Nursery, Hillsborough Hall, W. S., Hannibal Hardy-Field Nursery & Seed Co., Kan- sas City Hendricks J. O., Seligrnan Hermann Grape Nursery, Hermann, Jablonsky, A., Ovillete Jones, Elva A., Anderson Jenkins, H. W., Boonville Kansas City Peony Gardens, Kansas City Kaupp Floral Company, Nevada Kelsey Nurseries, St. Joseph Lamberth, O. H., Sarcoxie Linn, F. B., Louisiana Litson Nursery, Nevada Ludwig, Henry, Pochontas Luke's Nursery, Lowry City Model Nursery, Poplar Bluff May Brothers Nursery, Sedalia McCurdy, J. F., Marshall McCartney, E. W., Neosho Morris, Miss Mary, Neosho Murray Nurseries, Oregon Norton, A. L., Clarksville Neosho Nursery Co., Neosho New Haven Nurseries, New Haven Old Reliable Nursery, Kansas City Ozark Nursery Co., Seligman Osage County Nursery, Aud OronoRO Flower Garden, Carterville Park Floral Co., St. Joseph Pasteau Nursery, St. Louis Peyton Nursery, Boonville Piedmont Nursery,, Piedmont Pinehurst Floral Co., Pleasant Hill Polster Nursery, Warrenton Rausch, Charles, Monett Ragau, O. P., Ridgeway Rau Floral Co., St Joseph Rhoeder Nurseries, Osceola Reed, Homer, Louisiana St. Louis Park Dept., St. Louis St. Louis Water Dept., St. Louis Sanders Nursery Co., St. Louis Schnell, Henry, Glasgow Schreier, A., Neosho Seligman Plant Co., Seligman Sedan & Mt. Grove Nursery Co., Mt. Grove Swope Park Nurseries, Kansas City Sommers Nursery, St. Joseph Stanley Nursery, Campbell Stark Bros. Nursery & Orchard Co., Louisiana Southwest Golden Nurseries, Bolivar Sunny Slope Seed Farm, Independence Taiclett, F. A., Neosho Teas Nursery, Carthage Taos Nursery, Taos Thuli, J. A. & Sous, Chamois Vallenweider, C., Seymour Valhalla Cemetery, St. Louis Wiseman Nursery, Springfield Wallace, R. F., Logan Waldbart, A. & Sons, St. Louis Westport Nursery Co., Kansas City Watson, J. G., Seligman Wallace Nursery, Farmington Walker, Rolla, Neosho Wayrnan, H. S. & Son Nursery, Prince- ton Weber, H. J. & Sons Nur. Co., Nursery Westover Nursery Co., St. Louis Wild, Gilbert Nursery, Sarcoxie Wild Bros. Nursery Co., Sarcoxie Wilson John L., Anderson Young C. & Sons Co., St. Louis, Mo. Of the above list of nurseries nine were found to be slightly infested with San Jose Scale. The year 1919-20 was one of the most favorable years known in Missouri for the propogation and spread of San Jose Scale and in some of the nurseries it was found for the first time in 1920. Every nursery found infested is being reinspected at the time the stock is dug and every effort is being made to completely eradicate the San Jose scale from every nursery in Missouri. In 1920-21 there was a total of 1681 acres of nursery stock growing in nurseries in forty-two different counties. The counties having the largest acreage were Newton, Lawrence, St. Louis, Pike, Buchanan and Franklin. There was practically 200 acres more of nursery stock growing in 1920-21 than in 1919-20. This seems to indicate that like a great many other indus- tries the nursery and orchard industry in Missouri has entered upon a period of prosperity and that in the future a still larger amount of nursery stock will be growrn and a greater acreage of fertile Missouri soil will be planted to orchards. REPORT OF THE EUROPEAN CORN BORER INSPECTION WORK During the summer of 1920 a careful search was made for the Eu- ropean Corn borer in Missouri under the direction of the Missouri Plant Inspection Service. The work was done by K. C. Sullivan, S. R. McLane 14 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 and G. A. Tumbleson, deputies, under the direction of Dr. L. Haseman, chief inspector. The European Corn borer, a pest of European origin has gained a foothold in Massachusetts and New York and is causing very serious damage. Besides attacking corn it is also a pest of over 100 other plants including many which are classed as nursery and green house plants. Its favorite food plant however, is corn and should it gain a foothold in the middle western states in the corn belt it would practically revolutionize ag- ricutlure. Just recently this pest was found in Eastern Ontario, Canada and a little later a large area in Western Ontario was found to be infested. This brings it within a short distance of Detroit, Michigan and danger- ously near the corn belt. In one field in Ontario it caused a commercial loss of twenty or twenty-five percent and should it continue to spread down into the corn growing states where the seasons are longer it would un- doubtedly cause a much greater loss. This pest was probably brought to the United States in 1909 on Hungarian broom corn and as a quantity of this imported broom corn was shipped to and used in Missouri broom factories it is possible that this destructive pest may already be present in Missouri. One of the first acts of the Missouri Plant Inspection Service in 1920 was to promulgate a quarantine prohibiting the shipping into Mis- souri any plants or plant parts from the known infested areas in the east upon which the pest might gain entrance. This was done in order to pre- vent if possible any future introduction of the European Corn borer into Missouri. In addition to this a large amount of inspection work was and is being done especially in the vicinity of broom factories. If the European Corn borer has already found its way into Missouri, which is not at all improbable, it is necessary that it be found and eradicated as quickly as possible. As some of the broom corn imported from Hungary was used by Missouri broom factories in 1909-10 one of the first things that the Plant Inspection Service did was to locate and get in touch with these broom factories and later an inspector was sent to each factory and a thorough inspection was made of corn fields and especially sweet corn fields, in the vicinity of the factories. Also some inspection work was done in the vicinity of some Corn Cob Pipe factories. The corn-cob pipe fac- tories obtain corn cobs from widely separated communities in the state and it was not at all unlikely that the pest might be brought to the factory in corn cobs and later escape to the corn fields near the factory. For this reason inspections were made in some of the communities near pipe fac- tories. Inspections were made at the following places: Jefferson City, Wash- ington, St. Charles, St. Louis, Ste. Genevieve, Bland, Windsor, Canton, and Chillicothe. At the above named places thorough inspections were made in many cases requiring several days. Whenever possible the inspector called upon the proprietor or manager of the broom factory and in every case the broom factory officials were more than glad to do everything in their power to help in the work. Besides the inspection work done at the above named places many corn fields were inspected in other parts of the state at different times during the summer. At no place was the European Corn borer found and the Missouri In- PLANT INSPECTION IN MISSOURI 15 spection Service feels that up to the present time it has not made its way to Missouri. However, as the European Corn borer is a new pest in the United States and as it was probably present in Massachusetts and New York about ten years before it was found it is still possible that it may be present in Missouri. For this reason the Missouri inspection service is doing everything possible to find it if it is present and during the summer of 1921 still further inspection will be made. The European Corn borer is a medium sized moth the male of which has a wing expansion of about one inch, the female a little more. The front wings of the male are reddish brown while the hind wings have a greyish tinge. The front wings of the female are of a dull yellowish color streaked more or less with brown while the hind wings are grayish brown in color. Under Missouri conditions the adult would probably appear early in May. Soon after eggs would be deposited upon corn and other host plants and in June the greenish colored caterpillars would appear. When the caterpillar becomes full grown it is brownish or pinkish in color, from one fifth to an inch long with dark spots and tubercles on its body and has a brown shiny head. It is the caterpillar or larvae stage of the insect that causes the injury. It is a boring insect and burrows within the roots stalk, ear and tassel of the corn plant causing a weak, sickly plant and poor pol- lination. The pest and its work is easiest to detect just after the tassels appear. It passes the winter as a full grown caterpillar within its burrow in the host plant. The present known method of control consists of de- stroying the plant in which the pest is wintering or by utilizing it in some manner. Where corn is used for ensilage or the fodder is shredded the caterpillars are destroyed. Clean culture also helps to keep the pest down. In Massachusetts and New York where the insect is bad, large sums of money have been spent in collecting corn stalks, weeds and etc., during the fall and winter and burning them in order to destroy the caterpillar. The Missouri Plant Inspection Service is doing everything in its power to keep this destructive pest out of Missouri. SWEET POTATO INSPECTION During the past few years the Sweet Potato weevil has become a verv serious pest in some of the Southern States also some fungus diseases such as black rot, foot rot, and dry rot have caused a large amount of damage to sweet potatoes with the result that many of the Southern States have promulgated rules and regulations governing the inspection and transpor- tation of both seed sweet potatoes and sweet potato plants. The sweet potato weevil is not present in Missouri and the Plant Inspection Service intends to keep it out, however, some of the sweet potato diseases have been found in certain sections of Missouri to some extent but not serious. Some of the states of the south on account of the sweet potato weevil and the sweet potato diseases will not allow either seed sweet potatoes or sweet potato slips to enter their state without first being inspected. Every k^ear hundreds of bushels of Missouri grown seed potatoes and thousands of Missouri grown slips are shipped south and for the past two years the Plant Inspection Service has been called upon to inspect these seed pota- 16 MISSOURI AGRICULTURAL EXPERIMENT STATION CIRCULAR 101 toes and slips. The sweet potato industry in Missouri is growing rapidly each year and it is just as important that this industry be protected from the attack of dangerous insect pests and plant diseases as any other. The Plant Inspection Service is performing a real service to the sweet potato industry of the state by inspecting large quantities of both seed and slips. Certificates were issued to the following sweet potato growers during the year 1919-20: Bushman Company, Poplar Bluff Schilser, Fred, Poplar Bluff Davis, Silas, Poplar Bluff Shull, C. A., Neosho Davis, W. D., Poplar Bluff West, W. G., Poplar Bluff Ely & Company, H. S., Neosho Walker, W. A., Neosho Peterson, H. W., Poplar Bluff OTHER IMPORTANT INSECT PESTS AND PLANT DISEASES Some of the dangerous insect pests and plant diseases which the Mis- souri Plant Inspection Service is watching closely and which have not as yet been introduced into Missouri are the Gypsy moth, the Brown tail moth, the Bean Lady beetle, the Cotton Boll weevil, the Pink Cotton Boll worm; the white pine blister rust, chestnut blight and others. The Gypsy moth and Brown tail moth are insects of European origin which have caused millions of dollars of damage to fruit and forest trees in the New England States and during the past year new outbreaks of the Gypsy moth have been discovered in New Jersey and Pennsylvania. Both of these pests are very common in Europe and have in recent years been sent to the United States in shipments of nursery stock. During the spring of 1920 a shipment of apple seedlings from France arriving in Missouri was found to harbor nests of the Brown tail moth. In inspecting the stock the nests were found and destroyed and the shipment fumigated thus possibly preventing an outbreak of the insect in Missouri. The Bean Lady beetle is a dangerous insect which is very common m the Western States. It feeds upon beans and related plants. Recently it was accidently introduced into Alabama where it has rapidly spread over a large area of the state and caused serious losses. The Cotton Boll weevil has spread from Mexico over practically the entire cotton growing region of the United States but has not as yet gained1 access into Missouri. The Pink Cotton Boll worm just recently has been found in Texas and Louisiana where it is causing very serious damage and large sums of money are being spent in an effort to eradicate it. It was introduced from Mexico and is the most serious cotton pest known. Both the white pine blister rust and the chestnut blight have caused very serious losses in the eastern part of the United States and on account of these diseases it is unlawful to ship certain kinds of nursery stock sub- ject to infection from the infected regions. The Missouri Plant Inspection Service is watching closely these and other dangerous insect pests and plant diseases with the object in view of keeping them out of Missouri, and is working towards the control and eradication of those pests and diseases that are present. Forest Planting in Southern Michigan' BY L. J. YOUNG, Associate Professor of Forestry, University of Michigan The text of this paper is hardly so broad as its subject, since it is confined to the planting done by the Forestry Department of the University of Michigan in the vicinity of Ann Arbor. Plantations were started within a year after the establishment of the department to increase the facilities for instruction, to afford opportunities for research later on and to serve as demonstration areas to the public. Since the university is located in a strictly hardwood region, the only way in which readily accessible stands of conifers could be had was by planting, so this sort of work was pressed rapidly during the early years. Hardwoods, however, have not been neglected but have received equally as much attention as the conifers. In addition to lands owned by the university, much larger areas, belonging to the local power company, have been restocked with a variety of species. Sowing methods have been employed only with a few of the nut trees and not even atttempted with conifers, since all early experi- ments along this line resulted in absolute failure. The climate of this locality is not one that is conducive to an easy life for the young forest tree of any species when set out in the open amid unnatural surroundings. A mean annual precipitation of twenty- eight inches furnishes no great margin of safety, and when combined with an erratic distribution, that margin becomes still less. There is a tendency toward dry and rather hot summers. Little droughs of two or three weeks that are apt to come in May and early June are often especially provoking. In 1917, for example, there was no rain worthy of the name from the completion of planting in the middle of April until late in September. Long and severe winters occur every two or three years, often without a great deal of snow, so that the soil is frozen deeply. The change from winter to spring is usually a prolonged process with much alteration of cold nights and warm 1 Read before the annual meeting of the Society of American Foresters, at New York, N. Y., December 20, 1919. days, thus causing a great deal of frost heaving on wet and heavy soils. The soil shows all the usual variability of glacial drift, from sand and gravel to the heaviest clay, with hardpans often occurring within a foot or two of the surface. On all of the better soils, a very heavy, tough sod soon forms, serving to increase costs and add to the difficulties of the trees in getting established. The only enemies that have been at all serious are mice, rabbits and a few insects. Mice have caused a varying amount of damage, con- fined chiefly to red oak, sugar maple, chestnut, basswood, hickory, black locust, yellow poplar, Scotch pine, Douglas fir, Norway spruce, and western yellow pine. The only species that have been entirely free from this sort of damage are white elm and white pine. By 1917, mice had become such a pest that all areas of hardwoods and yellow pines were poisoned. In the beginning, rabbits were a negligible quantity, but since the prohibition of hunting a few years ago, have steadily become more numerous, so that special measures of control are now necessary. Snaring in the winter has proven very effective. Among the insects, the locust borer, the oyster shell scale on white ash, the larvae of the June bug, and certain defoliators have caused the most damage. During the first few years after planting, the borer threatened to ruin the stands of black locust, but within the last five years, the appar- ent damage from this source has decreased decidedly, and a good stand still remains. Oyster shell scale became so bad on white ash as to force the clear cutting of all stands as a precaution against its spread to others of its numerous host species in adjoining stands. The June bug did little damage in early plantings that followed closely upon the use of the land for agriculture. In recent plantings, however, they have in several cases caused the death of as much as three-fourths of the trees in the first summer. Box elder, basswood, and white elm have suffered from time to time most severely from attacks of defoliators, though sugar maple, white ash, black walnut, and chestnut have also been damaged enough in this way to deserve mention. A few small spots of white pine have been stripped of foliage on three occasions by the sawfly. Tamarack has not been planted in stands, because of the prevalence of the sawfly. The white pine is now infested to quite an extent with Chermes, though no damage is apparent, as the enemies of Chermes seem to be holding it pretty well in check. In addition to the scale, white ash has been badly damaged by a twig borer. Climatic factors also have contributed their share to the quota of damage. A severe hail storm in 1916 caught the leaders of white pine, Douglas fir, western yellow pine and Norway spruce just at the period of rapid elongation and broke off from 10 to 15 per cent. A sleet storm in the following year caused heavy damage to white pine leaders, but very little in the case of other conifers. Late frosts have killed back all new shoots at intervals of three to four years on Douglas fir, Norway spruce, catalpa, Russian mulberry, black locust, red oak, and white cak. The same frosts have killed the newest leaves on yellow poplar, white ash, and black walnut but without damage to the stems. Severe winter killing has occurred only with catalpa, osage orange, and chestnut. Catalpa trees 14 years old were killed back to the ground during the winter of 1917-18. Windfall damage has been limited to Scotch and Austrian pines, caused by a wind of unusual strength in November of last year. All of the first plantings were established by first plowing and culti- vating the areas thoroughly and then placing the trees in a slit made and closed with a spade. With one exception, these were highly suc- cessful, resulting in a catch of over 95 per cent. On a few areas, squares of sod were stripped off with a grub hoe and the trees set in a slit made and closed with a spade. The soil was a heavy clay, and subsequent growth has been slow, though the catch was over eighty per cent. On all the heavier soils, cultivation of the area has resulted in a dense stand of weeds for several years after planting, which not only interferes with the development of the young plants but incurs the hostility of neighboring farmers. As a result, all of the more recent work has been done with the grub hoe, stripping the sod from a six- teen-inch square and digging a hole, not a slit, for the plants. The catch with this method has varied from 50 to 95 per cent, the poorer ones being due, in most cases, to unfavorable site conditions and poor stock rather than to the planting method. Sowing has been done in drills and seedspots. Drill sowing, pre- ceded by cultivation of strips has been very successful with red oak. Seed spots with reel oak and black walnut have given good results, but with hickory have practically failed. It might be mentioned, however, that planting hickory has not been any more satisfactory on the sites where it has been tried. In the first plantings of conifers, where the soil was cultivated, 2-0 stock was used throughout, but where the grub hoe method is used, stronger stock has been found necessary, especially on the heavier soils. The main trouble in these latter cases seems to have been the encroachment of the sod, resulting in a much lower catch and slower growth in the early years. As a result of our experience, the present practice is to use 2-2 stock with white pine, Norway spruce, and Douglas fir and 1-2 stock with Norway, Scotch, and western yellow pines. Unfortunately, the parallel plantings made with different ages of stock of the same species were placed upon privately owned lands and were allowed to run for a short time only. One case will illustrate the general trend of results obtained. Two plantings of white pine were established side by side on level ground with all conditions the same, except that one was started as 2-0 stock and the other as 2-2. At the end of two years, the 2-0 stock showed a catch of 52 per cent, the other 95 per cent ; the average height of the 2-0 stock was five inches, of the other 18 inches. All hardwoods have been started as one-year seedlings, except cotton- wood, which was established by cuttings. Spacings used have been 3x3, 2x4, 4^x4*4 5x5, 6x6, 7^x7^, 10x10. The 2x4 spacing was used only in seed-spot work ; the 10x10 only with cottonwood. In a few cases parallel plantings have been made with the same species, using two or three different spacings. The results of these are already instructive. Three areas of black locust were set in 1906 with spacings of 3x3, 4^x4*4 and 6x6. Measurement of all the trees on these plots last year showed the growth to have been as follows : Spacing Average d. b. h. Average height Maximum d. b. h. Maximum height Basal area per acre 3x3 3.1 28.2 6.2 39.5 66.67 4^x4//2 3.4 28.8 6.3 39.5 58.65 6x6 3.7 28.4 6.5 36.2 37.8 These figures represent the growth during 14 years after planting. The present stand per acre in each case is as follows : Spacing No. trees per acre 1 er cent of loss Basal area per acre 3x3 6x6 1,222 925 508 75 57 58 66.67 58.65 37.8 Since the per cent of trees dropping out has been modified very con- siderably by the work of the borer, these figures can not be considered as normal. A better example of the effects of spacing is furnished by two plots of white pine planted in 1(J04 with spacings of 3x3 and Based on measurements made in the fall of 1920, the results have been as follows : Spacing Average d. b. h. Average height Maximum d. b. h. Maximum height Basal area per acre 3x3 2.7 20.8 5.3 30.3 141.34 4^x4^ 3.3 21.8 6.2 33.8 118.74 The present stand per acre follows : Spacing No. trees per acre Per cent of loss 3x3 4^x4^ 3,377 1,945 30.3 9.6 The relative condition of the stands in the fall of 1916 is shown in the following table : Spacing Average d.b. h. Average Maximum height d. b. h. Maximum height Basal area per were 3x3 2.3 17 0 3.6 20.9 99.67 4^x4>* 2.5 16.0 4.8 21.8 75.00 The 1920 figures, showing the results of 17 years of growth, indicate clearly that most of the advantages lie with the wrider spacing. The cost of establishment was about one-half that of the 3x3 ; the average height and diameter are now greater ; the stand closed over only about two years later; and the individual trees have the branches shaded out within one or two feet of the height to which they are killed in the more closely spaced stand; the loss of trees through suppression has been less than a third as great. So far, the stand with wider spacing has failed to equal the basal area of the other, but this difference will probably continue to grow smaller rather more rapidly than it has in the past, though, during the past four years, the stand with 4J/^-foot spacing has gained only two square feet over the other. The race between them from now on will be an interesting thing to watch. tn~view of the fact that these stands are growing south of the natural range of white pine in this part of the state, it was to be expected that their development would fall below that of those found well within its original habitat. However, a comparison with the yield table for Quality I white pine in New Hampshire, given on page 21 of the bulletin, "White Pine Under Forest Management," by E. H. Froth- ingham, shows that such has not been the case, especially with the 4^- foot spacing. If values for the age of 17 years are computed by inter- polation from Frothingham's figures, they run as follows: New Hampshire stand Michigan stand Average height 18.5 feet 21 8 feet Average diameter 3.34 inches 3 3 inches Basal area per acre No trees per acre 86.8 square feet 1,441 118.7 square feet 1 945 The figures for average height are not exactly comparable, since those for New Hampshire are the average for dominant trees only, while those for Michigan are for all the trees in the stand. The character of the soil in this case makes these results even more sur- prising, since it is composed largely of sand and had been badly worn out by a long period of wasteful agricultural use. Its one virtue lies in its generous depth. In all cases up to the present stage of development, the conifers planted, intolerant as well as tolerant, have demonstrated their ability to produce and maintain good forest conditions in pure stands. Ground cover of all sorts disappeared as soon as the stands became closed, and a good forest floor has been formed. These conifers include the Scotch, white, Austrian, and western yellow pines, Douglas fir (Rocky Mountain form), and Norway spruce. (All attempts to grow stock from Pacific Coast seed of Douglas fir have failed because of winter killing, even in winters that are unusually mild for this locality.) On the other hand, all of the intolerant hardwoods planted have lacked this ability. With the exception of black locust stands during a short period immediately after their closing, stands of these species have a heavy ground cover of grass, and, consequently, no forest floor. These species include white ash, white elm, white oak, catalpa, and Russian mulberry. Stands of other intolerants, red oak, osage orange, hickory, chestnut, black walnut, and cottonwood have not yet closed, so no positive statement concerning them in this respect can be made, though a small part of one sowing of black walnut on exceptionally good soil shows the ground cover entirely driven out. This condition will probably be temporary, as it was with black locust. Yellow poplar has been planted only in mixture with white pine, so we have no demonstration of what a pure stand would do. Bass^rood, a medium tolerant here, will probably make a better showing when the stand closes. After making a very promising beginning, considerable portions of pure stands of white elm and white ash seem to have stagnated. Throughout a strip immediately adjacent to a stand of black locust, box elder has made excellent growth and has succeeded in eliminating ground cover, though no forest floor has accumulated. This particular stand furnishes a striking illustration of the beneficial effect of black locust upon soil. Sugar maple is the only hardwood of high tolerance planted and has run true to form in maintaining an excellent soil con- dition. Catalpa, chestnut, and osage orange have shown conclusively that they have no real place here. Russian mulberry has developed into nothing more than a lot of scrubby brushes. Better soil or a mixture with other species might make something out of it. In addition to those already listed, other species in small groups that have made thrifty growth are jack and Norway pine, blue and white spruce, eastern balsam, concolor fir, hemlock, honey locust, horse chest- nut, buckeye, cucumber, arbor vitse, tamarack, European larch, Euro- pean alder, sycamore, silver maple, white birch, and coffee tree. On the basis of average annual growth in height and diameter, Scotch pine still leads all of the conifers with white and Austrian pine a close second and Douglas fir, western yellow pine, and Norway spruce in the order named. The relatively poor showing of Norway spruce is largely due to its location on a poor spruce site. Among the hardwoods, cottonwood ranks first with sugar maple second and the other species in the following order : Box elder, white elm, yellow poplar, red oak, catalpa, white ash, white oak, black walnut, Russian mulberry, basswood, osage orange, chestnut, and hickory. However, a large part of the differences in growth is undoubtedly due to soil variations rather than to inherent differences of the species themselves. In determining the above order, the growth made by the best stand of each species was used. Red oak furnishes an illustration of the variability in soils. Several stands of this species of nearly the same age are located on various parts of the area. In these stands, the average annual height growth for the whole life of each one ranges from 0.43 of a foot to 0.92. The details of the growth made by each stand up to the time of the last measurement (complete measurements are made at five-year inter- vals) are shown in the following table: Species Scotch pine Scotch pine White pine White pine Austrian pine Douglas fir W. yellow pine.. . W. yellow pine... Norway spruce . . Cottonwood Sugar maple Sugar maple Box elder Box elder White elm Yellow poplar. .. Red oak Red oak Red oak Red oak Red oak Red oak Red oak Red oak Red oak Catalpa Catalpa ... Catalpa . . White ash White ash White ash White oak White oak White oak Black walnut Black walnut Black walnut Russian malberry Basswood Osage orange Chestnut Hickory 17 14 17 17 14 14 11 14 15 5 12 12 12 12 12 14 14 12 12 12 12 12 13 13 12 14 13 15 12 14 13 13 11 14 11 14 8 13 13 15 14 10 No. trees per acre Original spacing, feet S-i g«g «<-d~ |J! Maximum d b. h.. inches Maximum height, feet -S£ • rt «j o£ liss rt ft ,0 Average annual growth D.b.h.. inches Height, feet 1,800 4x4 irreg. 3x3 4^x4^ 4x4 4x4 6x6 irreg. 3x3 10x10 4x4 5x5 6x6 4x4 5x5 4x4 4x4 5x5 6x6 5x5 5x5 6x6 6x6 6x6 6x6 4x4 4x4 4x4 6x6 4x4 6x6 4x4 5x5 5X5 5x5 5x5 2x4 4x4 4x4 4x4 6x6 4x4 3.6 2.5 2.7 3.3 2.9 1.3 1.3 1.6 25.7 21.1 20.8 21.8 17.9 11.1 7.6 10.9 6.5 9.7 14.0 13.9 11.4 13.2 12.8 15.0 8.4 6.6 5 2 7.7 5.9 5.3 6.2 5.2 2.8 3.1 4.8 "i!7 2.6 3.5 3.2 4.0 3.8 3.0 2.6 t 41.5 33.0 30.3 33.8 24.7 17.2 13.9 18.7 21.1 15.2 21.8 20.6 22.0 26.8 24.0 22.4 17.9 16.7 13.7 127.8 0.21 0.18 0.16 0.19 0.20 0.09 0.12 0.11 1.51 1.51 1.22 1.28 1.28 0.79* 0.69 0.78 0.43 1.94 1.16 1.16 0.95 1.10 1.07, 1.07b 0.60 0.55 0.43 0.71= 0.76d 0.71e 0.62. 0.55f 0.92 0.83« 0.89 0.70 0.59 0.83 0.87 0.62 0.44 0.26 0.55. 0.41P 0.601 0.60 0.55 0.42 0.35 0.26 3,377 1,945 2,244 1,138 825 3,188 ' 207 2.750 1.555 1,081 2,203 ' 928 ' 1.026 1,019 308 573 680 522 980 829 526 1 884 2,780 2,218 1,200 2,500 1,100 1,717 839 671 606 2,085 550 1,887 1,701 2,205 128 120 141.3 118.7 104.9 9.321 8.258 0.8 1.3 1.4 1.2 1.2 1.4 1.5 0.8 .621 25.98 17.04 0.55 18.66 "l2.10 3.96 0.16 0.11 0.11 0.10 0.10 0.12 0.11 0.057 0.8 0.9 0.7 0.8 0.6 0.9 1.5 1.4 1.3 8.6 9.1 8.6 8.1 7.1 11.1 11.7 ll.6 10.5 7 1 2.3 3.0 2.1 2.2 2.8 2.4 6.7 3.6 4.1 15.4 19.6 16.2 17.2 16.4 17.6 31.1 18.6 22.5 15.9 19.0 22.3 15 5 3.822 6.170 9.31 3.712 2.261 2.456 24.16 30.58 31.096 " 17. 500 9.700 0.066 0.075 0.06 0.06 0.05 0.075 0.11 0.11 0.09 1.1 1.3 11.7 11.4 8 1 2.3 3.3 0.08 0.10 0.2 '"b'.4" 4.8 3.7 6.1 5 8 0.7 i!i 9.4 11.2 10.1 11 9 0.168 ' .545 0.018 '6'.036 4 7 8.1 7 8 17 7 0.8 7.2 6.3 4.9 2.6 3.1 16.3 20 3 5.920 0.06 ...... 9.3 6.0 a Now mixed with P. ponderosa. b Mixed with white pine, c Seed spot in fall, d Seed spot in spring, e Seed spot in spring, f Seed spot in spring, g Mixed with Scotch pine, b Seed spot in fall, i Seed spot in spring. HYPERTROPHIED LENTICELS ON THE ROOTS OF CONI- FERS AND THEIR RELATION TO MOISTURE AND AERATION By GLENN G. HAHN, Scientific Assistant, CARL HARTLEY, Pathologist, and ARTHUR S. RnoADS,1 Assistant in Forest Pathology, Investigations in Forest Pathology, Bureau of Plant Industry, United States Department of Agriculture INTRODUCTION At the Bessey Nursery of the United States Forest Service at Halsey, Nebr., warty excrescences were observed upon the roots of coniferous seedling stock during the shipping season of 1915. Such excrescences occurred on all pine species grown there. They were so abundant on western yellow pine (Pinus ponderosa) 2 that the possibility of a parasite as the causal agent was suggested, and the forest officers properly ques- tioned^the advisability of shipping the stock to other regions. Attempts were made by the writers to obtain evidence of a pathogenic organism, but always with negative results. This experimentation con- sisted of (a) incubation in moist chambers of portions of roots beating excrescences, (b) insertion of the interior portion of the excrescences, removed with aseptic precautions, into nutrient agar, and (c) inocu- lation of portions of the excrescences into roots of healthy 2-year-old and 4-year-old Pinus ponderosa stock. After the failure to obtain evidence of a pathologic organism, a histo- logical examination was made, which showed that the excrescences had the structure of the hypertrophied lenticels (PI. 44) so commonly seen in many dicotyledonous plants. DESCRIPTION The hypertrophied lenticles are found both upon the main tap root (PI. 45, B) and upon the lateral roots, not only close to the ground level and upon the stems proper but also on the tap roots as far as 14 inches (36 cm.) below the surface of the soil.3 On the stems of conifers the hypertrophied lenticles usually occur only on the basal portions of trees growing in abnormally wet situations (PI. 45, A) or on parts otherwise submerged. In exceptionally humid situations they may occur occa- sionally on parts of the stems above the soil surface. 1 The writers wish to acknowledge helpful suggestions from Dr. B. E. Livingston, of the Johns Hopkins University, and Dr. T. H. Goodspeed, of the University of California. 8 All the western yellow pine referred to in this paper was the type sometimes referred to as Pinus pon- derosa var. scopulorum, from eastern Rocky Mountain seed. 3 In all probability hypertrophied lenticels will be found at much greater soil depths on the roots of older trees. Journal of Agricultural Research, Vol. XX, No. 4 Washington, D. C. Nov. 15, 1920 vl Key No. 0-207 (253) 254 Journal of Agricultural Research vol. xx, NO. 4 On the small roots the hypertrophied lenticels occur most commonly, but not always, at the junction of a lateral root or rootlet with its parent root, usually originating immediately above the point of origin but also subtending, at the sides or immediately below, the root or rootlet in question. This agrees with the findings of De Vaux (5)1 on normal lenti- cels, who reports that primary lenticels on roots are always at the bases of root branches, though secondary lenticels are sometimes formed later at other points. It was this coincidence of lenticels and root branches that caused some botanists during the early part of the nineteenth century to believe lenticels equivalent to buds, a doctrine attributed to De Candolle (7; ij, Vorwort) and overthrown by Majer (13), 2 Unger (22), Terras (19), and others. The excrescences vary greatly in size and shape, from minute circular areas 0.5 mm. in diameter to bands nearly encircling the larger rolots in cases where two or more lenticels have become laterally confluent. Around the root crowns and the bases of the submerged stems large, wartlike patches may occur, 5 to 8 mm. in diameter and projecting i to 3 mm. above the surface of the bark. Examination with a dissecting microscope shows these excrescences to be made up of a very loosely piled mound of pale yellowish tissue. As a general rule these mounds of loosely piled cells split in a stellate manner, the segments recurving out- ward, occasionally leaving a few filamentous columns standing by them- selves in the center. Such structure is evident only when the young trees have been removed from the ground with great care, for the slightest touch upon these loose-lying columns causes them to crumble instantly to a flat, powdery mass, especially when they are dry. On the bases of still older stems i to 2 inches (2.5 to 5 cm.) in diameter that stand for a large part of the growing season in water or poorly drained soil, the bark, which is here considerably thickened, exfoliates in patches of varying size, revealing irregularly connected flattened masses of cells, or, more rarely, unbroken areas of such cells i inch (2.5 cm.) broad. On some pines these excrescences frequently become so abundant that con- siderable areas of the lower stem and the tap root are covered by them (PI. 46, B). After the cessation of growth in the lenticels, these excre- scences become dark root-brown and gradually slough off. The lenticellular excrescences vary in different conifers from loosely connected, more or less divergent, columnar masses crumbling at the slightest touch, common in the pines, to fairly compact, corky masses usually seen in the trees of other coniferous genera. Histological examination of the excrescences at once proves the white, spongy tissue to consist of more or less loosely connected masses of cells developed from the phellogen. Plate 44 illustrates a cross section of 1 Reference is made by number (italic) to " Literature cited," p. 264-265. 3 This seems to be the 1836 paper attributed to Mohl by Haberland (7). Mohl apparently directed the work of Majer and wrote a preface for the dissertation, but Majer was the author of the paper itself. NOV. 15, 1920 Hypertrophied Lenticels on the Roots of Conifers 255 one of these hypertrophied lenticels on a root of Pinus rigida. The out- growths consist of homogeneous parenchymatous elements, more or less radially elongated, sometimes very much so. The individual cells are thin-walled with a thin layer of cytoplasm. SPECIES AFFECTED Stahl (18) states that all trees which have lenticels on the stems also have them on the roots. De Vaux (5) reports the presence of lenticels on the roots of a large number of tree species, including a number of conifers. For one species of Ephedra he states that lenticels are found only on the roots. He states that especially in Pinus maritima the lenticels on the roots are larger than those on the stems. This author was able to find or to produce lenticel hypertrophy on some part of the plant in 60 per cent of the 155 plant species considered but was unable to secure any hypertrophy on the representatives of the several conif- erou: genera which he studied. On roots less than 3 mm. in diameter he found the normal lenticels so small that the microscope was usually necessary in demonstrating them. Tubeuf (20) lists a small number of species, of which he was able to secure lenticel hypertrophy on some part of 12 nonconifers. He, however, failed to get this hypertrophy on species of Sequoia, Thuja, and Taxus, or on Gingko biloba and 14 other nonconiferous species. Zach (23) later secured hypertrophy of lenticels on stems of G. biloba under certain conditions. However, a rather careful search in the earlier literature appears to justify the statement by the reviewer of Zack's paper (16) that no hypertrophy of lenticels had been up to that time reported on conifers. The present writers have found hypertrophied lenticels on the roots of the following conifers : Pinus ponderosa, Pinus coulteri, Pinus rigida, Pinus resinosa, Pinus banksiana, Pinus mrginiana, Pinus syhestris, Pinus cari- baea, Pinus strobus, Pinus monticola, Pinus excelsa, Picea canadensis, Picea rubens, Picea mariana,1 Picea pungens, Abies balsamea,2 Tsuga canaden- sis, Larix laricina, Taxus cuspidata, Taxus brevifolia, and Araucaria bidwellii. Several of the species of Pinus on which the hypertrophy was found were growing in the greenhouse of the United States Department of Agriculture at Washington, D. C. It was noteworthy that plants of Juniperus mrginiana under the same conditions in the same greenhouse apparently were free from such growths so far as could be determined. In a swamp in which the hypertrophied lenticels were found on Abies balsamea, Picea rubens, and Tsuga canadensis none could be discovered on Taxus canadensis. Among the pines the hypertrophied lenticels were frequent mainly on the 3-needled species, Pinus ponderosa and Pinus 1 Material furnished by Dr. H. P. Brown, of The New York State College of Forestry at Syracuse University. 2 Dr. James R. Weir advises the writers that he has frequently found hypertrophied lenticels on the roots of Abies grandis in the Northwest. 256 Journal of Agricultural Research voi.xx,No.4 rigida, while on the strictly 2-needled Pinus mrginiana, Pinus banksiana, and Pinus resinosa they were very difficult to find. Klebahn (io,p. 582, 586) states that up to the time of his publication he had not been able to find lenticels on Pinus sylvestris, nor had he satisfactorily demonstrated a substitution for lenticels. Excrescences like those just described on the conifers are common and widespread occurrence on a number of dicotyledonous plants, particularly upon swamp plants such as Sambucus canadensis , Rhus copallina, Decodon verticillatus , and Cephalanthus occidentalis . Such excrescences on dicotyledonous plants have long been known under the term ' ' water lenticels. " CONDITIONS UNDER WHICH HYPERTROPHY HAS BEEN FOUND The lenticel hypertrophy observed on roots has been generally limited to plants growing in wet soil. Affected hemlock, balsam fir, red spruce, and black spruce have already been noted as growing under swamp conditions. All the pitch pines found with hypertrophied lenticels in the vicinity of Washington were in heavy, wet soil. There hypertrophy was very frequent on Pinus rigida and P. mrginiana growing in swampy locations. The pines found so affected in the greenhouse at Washington were all growing in soil very much wetter than that in which they are usually found. The only Scotch pines found with hypertrophied lenticels were growing at the edge of an irrigation ditch in especially wet soil at a Michigan nursery. The same has been true in the most striking cases of hypertrophy at the Bessey Nursery. In a bed, a portion of which was repeatedly flooded from a leaking irrigation ditch, approxi- mately 20 per cent of the plants showed marked cases of hypertrophy, while less than i^ per cent of the plants showed hypertrophy in parts of the neighboring beds which were not affected by the leakage. Infor- mation has been received from Mr. W. H. Schrader that at the Monu- ment Nursery of the United States Forest Service in Colorado the only conspicuous occurrence of root lenticel hypertrophy was during an unusually wet season. The hypertrophy here considered has been found both in heavy and in very sandy soils; in the latter case there was ap- parently more hypertrophy in parts of the beds to which clay had been added. The youngest seedling observed with lenticel hypertrophy was one of Pinus ponderosa which was raised from the seed with its roots in a 2-ounce bottle of tap water in the laboratory. This water was not changed during the entire period of growth. The bottle was stoppered but was not absolutely sealed at the point of passage of the stem through the stopper. At the end of approximately five months the plant, which still seemed fairly vigorous, had developed a single root, which, after reaching the bottom of the bottle, had coiled itself around two or three times close to the peripheral limit of the bottle. On this tap root were a NOV. 15, 1920 Hypertrophied Lenticels on the Roots of Conifers 257 number of conspicuous, glistening, mound-shaped excrescences, as is shown, slightly magnified, in Plate 46, C. A microscopic examination of sectional preparations of these excrescences (PL 46, A) showed clearly their lenticellular structure. The outgrowths were so loose and delicate that the outer portions were necessarily lost in sectioning, but the figure shows enough of the bases to indicate the type of structure. In general, root-lenticel hypertrophy has been found especially frequent not only on species like western yellow pine, which are somewhat inclined to lack fine fiberous roots, but also on individuals of other species when a strong tap root has been developed with relatively little development of laterals. Whether or not the larger lenticels are of advantage to such plants in fulfilling part of the functions that the missing laterals might have performed is of course uncertain. In this connection it is of some interest to note the finding of root-lenticel hypertrophy in Michigan on white* and Colorado blue spruce (Picea canadensis and P. pungens) whose roots had been injured by May beetle larvae. It is also especially interesting that nursery trees that have not been transplanted or that are in their second season in the transplant beds show decidedly less hypertrophy than recently transplanted stock. The recently trans- planted trees have, of course, lost most of their absorbing roots, while the trees transplanted the preceding season have had a chance to develop normal root system again after transplanting. IRRIGATION EXPERIMENTS Trees of Pinus ponderosa in their third year in the nursery, and two months following transplanting, were given river water from the irri- gating ditch frequently during a three months' period, beginning July u, 1917. All the tests considered in this and the following section were conducted at the Bessey Nursery in cooperation with Forest Supervisor Jay Higgins and his assistants. The water added at each irrigation was approximately equivalent to 2.2 inches (5.6 cm.) of rainfall. A bed which received 31 such irrigations during these three months showed at the end of the period 31 per cent of the trees with 8 or more distinctly hypertrophied lenticels each and a total of 57 per cent with some evi- dence of hypertrophy. The figures are based on an examination of 255 trees. This amount of watering was sufficient to cause more or less chlorosis, especially of the shoots which arose after the watering began. Another bed in the same section, on which the frequent watering was not started until a month later and which received during the entire three months a total of 17 irrigations, showed at the end of the period eight or more enlarged lenticels each on approximately 13 per cent of the plants examined. Other beds used as controls received the usual amount of water given at this nursery, involving six irrigations in addi- tion to the 7.7 inches (20 cm.) rainfall during the period of three months. 258 Journal of Agricultural Research Vol. XX, No. 4 These showed less than i >£ per cent of the plants with abundant hyper- trophied lenticels and a total of less than 13 per cent showing any evi- dence of hypertrophy. The results in the most heavily watered bed and in the controls are given in Table I. The results with the pruned trees shown in the table lead to the same conclusions as the results cited above orj the unpruned trees — namely, that heavy watering increased the amount of lenticel hypertrophy. TABLE I. — Effect of watering and top pruning on root-knticel hypertrophy of third-year western yellow pine at Bessey Nursery, Halsey, Nebr., pruned in early July and examined September 10 to 15 Plot. Part removed by pruning. Number of trees examined. Percentage of trees with hypertrophy. Percentage of trees with strong hyper- trophy.0 Heav- ily watered series. Nor- mally watered series. Heav- ily watered series. Nor- mally watered series. Heav- ily watered series. 3 2 0 19 !7 33 24 Nor- mally watered series. O O O O 0 3 c B A E D F All the secondary needles & ... 185 182 32 108 58 206 49 42 47 51 48 o 72 71 8 9 6 4i 31 58 51 7 2 0 17 II 13 All the secondary needles & and tip of third season terminal shoot. All the secondary needles ° and entire third-season shoot Third season terminal shoot only . . . Half the secondary needles only6. Unpruned Additional unpruned rows scat- tered among the different series. . Heavily pruned . . ABC DE 399 1 66 255 140 48 143 9 37 57 2.9 *7 12 2-3 18 3i 0 o 1.4 Lightly pruned . . Unpruned ° Having 8 or more noticeably hypertrophied root lenticels per tree. b Including the needles that had appeared on the third-season shoot as well as those produced in earlier years. Cut back to sheath but portion of needle remaining in the sheath left intact. PRUNING EXPERIMENTS Pruning experiments were conducted in an effort to throw a little more light on the factors controlling the lenticel hypertrophy. The tops of a number of rows of western yellow pine transplants at the Bessey Nursery were pruned with different degrees of severity during the first week in July, 1917. This is about the middle of the season of vigorous growth at this nursery. The results of a root examination three months later appear in Table I. The most heavily pruned plants showed the least lenticel hypertrophy, with the exception of plot E in the normally watered series. The percentage in this case is based on only 48 trees, only one- third as many as furnished the basis for each of the other figures in the three lower lines of the table. The pruning did not so injure the plants as to prevent growth entirely, for even those most heavily pruned reacted by sending out new shoots. NOV. is, 1920 Hypertrophied Lenticels on the Roots of Conifers 259 CAUSES OF LENTICEL HYPERTROPHY Schenck (15) attributed lenticel growth on roots to oxygen hunger. However, the association which has been observed between moist condi- tions and abnormal lenticel growths, as well as experience in artifically producing lenticel hypertrophy by placing cuttings in water or moist air, have led more recent writers to suppose that for dicotyledonous plants the hypertrophies are directly due to the presence of an unusual amount of water (5; n, p. 72-80; 17). It is reasoned, in the first place, that water or constantly moist atmosphere on the outside of the lenticels allows the steady growth of the lenticels, while dry or intermittently dry air tends to dry out the superficial cells of the lenticels or to increase their solute concentration, with resultant chemical changes, including cork and lignin formation. According to this idea the growth of the lenticel tissue is controlled by transpiration through the lenticels; with intense trans- piration the tissues become dried and the hypertrophy is checked. The suberized or lignified layers thus formed are supposed to restrain mechan- ically further proliferation on the part of the cells beneath them from which the lenticel structures arise. So far this supposition seems logical, though there is as yet no basis for a quantitative estimation of the im- portance of tissue drying in the phenomenon. DeVaux has advanced another theory, based on the fact that the sup- plying of abundant water to the absorbing surfaces and the reduction of transpiration have both been found to be followed by lenticel hypertrophy in experiments with dicotyledons. This writer supposes that both these treatments result in increased sap pressure in the plant as a whole and exert their influence entirely through increased sap pressure. He does not apparently give sufficient weight to the possibility that both decrease in transpiring surface and increase in soil moisture may involve decreased oxygen supply as well as increased sap pressure. The limited aeration of wet soils is a matter on which there is general agreement. The necessity of soil oxygen for the normal development of mesophytic plants, as indicated by common observation, has been recently confirmed by direct experiments by Cannon and Free (j) and by Livingston and Free (12). It is by no means certain that over- wet soil results in in- creased sap pressure in mesophytic plants, especially since the last-named authors find that a deficiency of oxygen in the soil results in some cases in decreased water absorption. The association between swampy soil and lenticel hypertrophy is at least as easily explained on the basis of oxygen hunger as by DeVaux's " hyperhydrose " doctrine. The argument which Tubeuf (20, 21) seems to consider strongest against oxygen hunger as the stimulus for lentical enlargement is the fact that enlargement can be produced in cuttings in a moist chamber. By placing cuttings with paraffined ends in moist chambers he secured lenticel overgrowth, even in cases in which an atmosphere of oxygen was 260 Journal of Agricultural Research vol. xx, NO. 4 provided. This seems at first glance to dispose of the oxygen-hunger hypothesis quite effectively. However, an atmosphere of oxygen would not necessarily insure an oxygen supply to the interior of a woody stem unless the lenticels were already open at the time the cutting was placed in the chamber. A section of stem removed from the plant and therefore deprived of the oxygen that it would normally get from the leaves and perhaps also from the roots, if its lenticels were closed, might easily by oxidation of stored food materials develop abnormal partial pressures of carbon dioxid in its interior tissues which would not be relieved till the lenticels were opened by the stimulated growth which Tubeuf de- scribes. The experience reported in his later paper, in which he records interesting cases -of lenticel stimulation secured by covering bark with impervious materials, and observation of lenticel hypertrophy on the swelling above a heat lesion lead him to consider the stimulation lenticel growth too complicated to be explained by any single factor so simple as humidity. He still appears to consider oxygen hunger as excluded from further consideration. However, his observation of numerous lenticels on the stem of a heart-rotted spruce is the only refer- ence that has been found concerning abnormal lenticel growth on any part of a coniferous tree. The intumescences produced by Atkinson on tomato (i) and by Douglas on potato (6) were clearly related in some way to excessive general sap pressure. They are not analogous cases to the root lenticels here con- sidered, since the hypertrophy in the intumescences was, so far as can be judged from the illustrations given, mainly due to the stretching of soft tissue cells already present rather than to the formation of large masses of new cells. It may be of some interest to note in passing that Cowles (4, p. 553-554) expresses himself as inclined to regard lacunar tissue in submerged parts of water plants to be a response to lack of transpiration rather than to oxygen deficiency. The present writers' findings bearing on the factors causing hypertro- phy of subterranean lenticels on young conifers are as follows: 1 . Hypertrophy is apparently limited to trees with their roots in water or very wet soil. This may indicate either increased sap pressure or decreased aeration as among the effective stimuli. It seems rather improbable that there should be a significantly greater sap pressure in a mesophyte like Pinus rigida or a semixerophyte like P. ponderosa (Rocky Mountain type) in an excessively wet soil than in a plant in more normal condition. This seems especially improbable in view of the slow water absorption by the mesophytes in soil deficient in oxygen in the experiments already referred to (12). 2. While lenticel hypertrophy seems to be most common in soils con- taining clay, it has been frequently found in one nursery (at Halsey, NOV. 15. 1920 Hypertrophied Lenticels on the Roots of Conifers 261 Nebr.) having a very sandy, well-drained soil, with a wilting coefficient1 in the neighborhood of 3.4 per cent for the nursery as a whole, and an unusually high proportion of the soil (79 per cent) in particles between 0.25 and 0.05 mm. in diameter. The results of a mechanical analysis of this soil have already been published (8, p. 2). This, at first thought, indicates sap pressure rather than deficient aeration as the cause of hypertrophy. It is worthy of note, however, that in this case there was frequent artificial watering in addition to considerable rainfall, and it is therefore entirely possible that even in this case aeration was insufficient. Buckingham (2} found that both diffusion and molar movement of gas were slower in a wet sand than in any of the other soils, wet or dry, with which he experimented. 3. Reduction of the transpiring surface by removal of a large part of the needles, or of the terminal growth, or both, resulted in distinctly reducing the tendency to lenticel hypertrophy. (Table I.) The un- pruned plants presumably had, at least part of the time, a lower general sap pressure than the pruned. The result of the experiment therefore tends to diminish the probability that there is any important causal relation between general excessive sap pressure and the hypertrophy in question. 4. The rinding of the most abundant hypertrophy on roots which are deficient in fibrous laterals or whose absorbing surface has been greatly reduced by insect injury or by transplanting also tends to weaken the hypothesis that excessive general sap pressure throughout the plant is the chief cause of the hypertrophy. It is possible that roots which have little absorbing surface will take less oxygen from the soil than would better-developed root systems. An indication that this is the case is seen in the experience of Livingston and Free (12, p. 185) with the oxygen requirements of roots with different amounts of surface area. This association between deficient root surface and lenticel hypertrophy may therefore be an indication of a relation between oxygen deficiency and lenticel production. The fact that lenticel hypertrophy was actually less in plants whose leaf surfaces had been reduced by pruning not only tends to decrease the probability of the ' ' hyperhydrose " explanation; it is suggested that it is perhaps a further support for an oxygen-hunger (or carbon-dioxid excess) hypothesis. Plants with their leaf surfaces reduced during the latter part of the summer will of necessity produce less carbohydrate. The smaller amount of carbohydrate reaching the roots in consequence of the pruning might conceivably result in less respiration in the root tissues and therefore in a decreased need for oxygen. If this were the case the decreased oxygen hunger might furnish a partial explanation of the slight lenticel growth in the pruned plants. 1 Determined by the Office of Biophysical Investigations, Bureau of Plant Industry. 262 Journal of Agricultural Research vol. xx, NO. 4 Another possible connection between leaf pruning and oxygen hunger of root and stem is suggested by Prof. Livingston in a personal communi- cation to one of the writers. A reduction of the transpiring surface by pruning should result in less absorption by the roots. If it be supposed that oxygen dissolved in water absorbed from the soil is important as a source of oxygen supply for the root tissues, a decrease in the amount of water absorbed might result in oxygen deficiency in the root tissues. This suggestion might help to explain the earlier reports of the stimulated growth of lenticels on stems of dicotyledons whose transpiration has been experimentally reduced. It obviously complicates any attempt to explain on an oxygen-hunger basis the effects of pruning on lenticel growth described in the present paper. Of course it does not seem likely that any part of a plant accustomed to the presence of free oxygen would be likely to make much growth in the entire absence of oxygen. However, the condition existing in the soil in which the hypertrophies occurred certainly did not involve the entire absence of oxygen. Pfeffer concludes (14, p. 115), in spite of some conflicting evidence, that experiments have shown that reduction of the proportion of oxygen, at least in some cases, acts as an accelerating stimulus to growth. It is of course true that any strong local growth is probably dependent on high local sap pressure. However, it is well known that such local high pressures are not necessarily dependent on excessive turgidity of the plant as a whole. Unusual chemical conditions, such as might conceiv- ably result from local oxygen hunger, might easily cause them. The writers do not consider that oxygen hunger is established as the main cause of the lenticel hypertrophy found. They can not, however, agree with De Vaux in attributing the effect of increased soil moisture on lenticel growth entirely to increased water supply, excluding oxygen hunger as a possible factor in stimulating lenticel growth. Experiments in which the oxygen, carbon-dioxid, and water supplies in the soil are independently controlled, as by the technic of Livingston and Free (12), and perhaps also with temperature control, will be needed to make a beginning on determining the relative importance of these various environmental factors in causing hypertrophy of root lenticels. Since conifers are rather difficult to handle in experimental work, poplar would perhaps be a better subject for preliminary experimentation. It seems likely, as has been suggested for hypertrophied lenticels in general by Tubeuf (21) and for intumescences by Hasselbring (9), that these unusual lenticel enlargements on the roots of conifers depend on a complex of conditions rather than on any one simple stimulus, and that with different species the conditions which call forth lenticel hypertrophy may be found to differ in relative importance. NOV. is. 1920 Hypertrophied Lenticels on the Roots of Conifers 263 RELATION BETWEEN LENTICEL HYPERTROPHY AND HEALTH OF PLANTS Sorauer (17, p. 210-219) nas used the name "tan disease" for lenticel hypertrophy on roots and stems of fruit trees. His use of the term "disease" appears justified in view of the association in many cases between the lenticel hypertrophy and a general pathological condition of the trees. The large lenticels described in the foregoing paragraphs as occurring on conifers are undoubtedly abnormal and in that sense are pathological. Since they occur only in abnormally wet situations, it is to be expected that in many cases the pines on which they have been found are unused to very moist surroundings and under the unfavorable conditions are subnormal in general vigor. The hypertrophies were first noted in a part of a nursery in which general vigor was unsatisfactory. Comparisons of the less vigorous and more vigorous plants in the section in which the hypertrophy was common showed lenticel hypertrophy present in both the weaker and stronger plants. The first examina- tion, made by Hartley on about 200 3-year-old transplants of Pinus ponder osa, showed lenticel hypertrophy on a larger proportion of the weak trees than of the stronger trees. Later examinations made by Hahn on about 2,000 plants showed, particularly on P. ponder osa, that the greatest number of hypertrophied lenticels were associated with vigorous growth, This was true of plants in which the terminal root was rapidly advancing and the roots were large and stocky but correspondingly undeveloped as to lateral root surface. In one particular instance, however, where 2 -year- old transplants of P. ponder osa had been badly affected by yellowing due to excessive irrigation, 50 per cent of 95 vigorous plants examined showed light occurrence of lenticel formation, while of no weakened and dying plants 80 per cent were found to exhibit light occurrence, and 10 per cent showed pronounced occurrence. This same bed examined a month later showed that the majority of the weak plants had died, while the vigorous plants, or those beginning to show renewed terminal growth, were alone showing freshly proliferating lenticels, those upon the dying plants becoming darkened and sloughing off. It therefore appears that lenticel hypertrophy is found on both weak and strong plants and that the conditions which bring on their formation may, if sufficiently pro- longed, eventually cause the weakening and death of the plant. There is, however, so little direct connection between lenticel hypertrophy and the pathology of the conifers that it seems logical to recommend that any further investigation of the factors stimulating lenticel growth should be made from the point of view of physiology rather than from that of pathology. 264 Journal of Agricultural Research vol. xx, NO. 4 SUMMARY (1) Unusual excrescences on the roots of a number of different pines, spruces, and other conifers are found to have the structure of lenticels, much enlarged. They are produced in various kinds of soil in the pres- ence of excessive moisture. Hypertrophy may occur on either weak or vigorous plants. Hypertrophy was decreased by top pruning and was increased by root injury. Such overgrowths have apparently not been previously reported on conifers. (2) Conclusions of certain writers, based on work with dicotyledons, that excessive soil moisture stimulates lenticel hypertrophy mainly by increasing general sap pressure and that oxygen hunger is of no impor- tance as a stimulus are not supported by the experience here set forth with conifers. Experiments in which the oxygen supply t6 the roots is varied without varying the water supply are believed necessary to settle the relative importance of these two factors. LITERATURE CITED ' (i) ATKINSON, G. F. 1893. OEDEMA OP THE TOMATO. N. Y. Cornell Agr. Exp. Sta. Bui. 53, p. 77-108, 8 pi. Also in N. Y. Cornell Agr. Exp. Sta. 6th Ann. Rpt. 1893, p 99-128. 1894. (2) BUCKINGHAM, Edgar. 1904. CONTRIBUTIONS TO OUR KNOWLEDGE OP THE AERATION OF SOILS. U. S. Dept: Agr. Bur. Soils Bui. 25, 52 p. (3) CANNON, W. A., and FREE, E. E. 1917. THE ECOLOGICAL SIGNIFICANCE OP SOIL AERATION. In Science n. s. v. 45, no. 1156, p. 178-180. (4) COULTER, John Merle, BARNES, Charles Reid, and COWLES, Henry Chandler. 1911. A TEXTBOOK OP BOTANY ... v. 2. New York, Cincinnati. (5) DEVAUX, Henri. .1900. RECHERCHES SUR LES LENTICELLES. In Ann. Sci. Nat. Bot., s. 2, t. 12, p. 1-240, pi. 1-6. (6) DOUGLAS, Gertrude E. 1907. THE FORMATION OF INTUMESCENCES ON POTATO PLANTS. In Bot. Gaz., v. 43, no. 4, p. 233-250. (7) HABERLANDT, Gottlieb. 1875. BEITRAGE ZUR KENNTNISS DER LENTICELLEN. In Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Kl., Bd. 72, Abt. i, p. 175-203. (8) HARTLEY, Carl. 1915. INJURY BY DISINFECTANTS TO SEEDS AND ROOTS IN SANDY SOIL. U. S. Dept. Agr. Bui. 169, 35 p., pi. (9) HASSELBRING, H. 1905. [REVIEW OF PAPERS ON INTUMESCENCES.] In Bot. Gaz., v. 40, no. 5, p. 390-391. (10) KLEBAHN, H. 1884. DIE RINDENPOREN . . . In Jenaische Ztschr. Naturw., Bd. 17 (n. F. Bd. 10), p. 537-592, pi. 12. (n) KusTER, Ernst. 1903. PATHOLOGICAL PLANT ANATOMY. Translation by France? Dorrance. 258 p. [n. p.] Multigraphed. NOV. 15, 1920 Hypertrophied Lenticels on the Roots of Conifers 265 (12) LIVINGSTON, B. E., and FREE, E. E. 1917. THE EFFECT OF DEFICIENT SOIL OXYGEN ON THE ROOTS OF HIGHER PL ANTS. In Johns Hopkins Univ. Circ. 293 (n. s. 3), p. 182-185. (13) MAJER, Carl Eduard. 1836. UNTERSUCHUNGEN UBER DIE LENTicELLEN. 19 p. Tiibingen. Inaug. Diss., Hugo von Mohl, praeses. (14) PFEFFER, W. 1900-06. THE PHYSIOLOGY OP PLANTS ... ed. 2, rev., transl. and ed. by Alfred J. Ewart ... 3 v., illus. Oxford. (15) SCHENCK, H. 1889. UEBER DAS AERENCHYM, EIN DEM KORK HOMOLOGES GEWEBE BEI SUMPFPFLANZEN. In Jahrb. Wiss. [Pringsheim], Bd. 20, p. 526-574, pi. 23-28. (16) SIMON. 1912. [REVIEW OF] ZACH, FR. ZUR KENNTNIS HYPERHYDRISCHER GEWEBE. In Just's Bot. Jahresber., Jahrg. 37 (1909), Abt. i, Heft 5, p. 832. (17) SORAUER, P. 1914-17. MANUAL OF PLANTS DISEASES, ed. 3, transl. by Frances Dorrance, v. i, p. 1-8. Wilkes-Barre, Penn. (18) STAHL, E. 1873. ENTWICKELUNGSGESCHICHTE UNO ANATOMIE DER LENTICELLEN. In Bot. Ztg., Jahrg, 31, No. 35, p. 565-567; No. 37, p. 577-586; No. 38, p. 593-601; No. 39, p. 600-617. pi. 5-6. (19) TERRAS, James A. 7900. THE RELATION BETWEEN THE LENTICELS AND ADVENTITIOUS ROOTS OF SOLANUM DULCAMARA. In Trans. Bot. Soc. Edinburgh, v. 21, pt. 4, p. 341-353' 2 pl- Literature referred to, p. 352-353. (20) TUBEUF, K. von 1898. UEBER LENTIZ ELLEN- WUCHERUNGEN (AERENCHYM) AN HOLZGEWACHSEN. In Forstl. Naturw. Ztschr., Bd. 7, p. 405-414, illus. (21) 1914. ERKRANKUNGEN DURCH LUFTABSCHLUSS UND UBERHITZUNG. In Naturw. Ztschr. Forst u. Landw., Jahrg. 12, Heft 2, p. 67-88, 2 fig.; Heft 4, p. 161-169. (22) UNGER. 1836. UEBER DIE BEDEUTUNG DER LENTICELLEN. In Flora, Jahrg. 19, Bd. 2, p. 577-606. (23) ZACH, Fr. 1908. ZUR KENNTNIS HYPERHYDRISCHER GEWEBE. In OsteiT. Bot. Ztschr., Jahrg. 58, No. 7/8, p. 278-284, 2 fig. PLATE 44 Section through a hypertrophied lenticel on root of Pinus rigida growing in swampy situation. Approximately X 59. (266) Hypertrophied Lenticels on the Roots of Conifers PLATE 44 Journal of Agricultural Research Vol. XX, No. 4 Hypertrophied Lenticels on the Roots of Conifers PLATE 45 Journal of Agricultural Research Vol. XX, No. 4 PLATE 45 A. — Hypertrophied lenticels on the basal part of layering stem of Picea mariana, which had been covered with sphagnum. Approximately X iK- B. — Tap root of a Pinus ponder osa transplant, bearing an unusually large number of hypertrophied lenticels. Approximately X i^« PLATE 46 A. — Cross section of the stem through one of the hypertrophied lenticels shown in C. In embedding and sectioning most of the loose outer tissues are unavoidably lost. Approximately X 112. B. — Large patches of excrescences upon the tap root near the root crown, on Pinus rigida. Approximately X iK- C. — Hypertrophied lenticels on root of 5-months-old Pinus ponderosa, grown in a loosely stoppered 2-ounce bottle, in tap water which had not been changed since the germination of the seed. The entire structure of the lenticel, which is too delicate to recover in digging roots from the soil, is here preserved. Approximately X iK« Hypertrophied Lenticels on the Roots of Conifers PLATE 46 B Journal of Agricultural Research Vol. XX, No. 4 A CHLOROSIS OF CONIFERS CORRECTED BY SPRAY- ING WITH FERROUS SULPHATE By CLARENCE F. KORSTIAN, Forest Examiner, CARL HARTLEY, Pathologist, LYLE F. WATTS, Forest Examiner, and GLENN G. HAHN, Scientific Assistant, Forest Service and Bureau of Plant Industry, United States Department of Agriculture * INTRODUCTION In plants the term "chlorosis" is commonly applied to any abnormal condition whose most conspicuous symptom is a deficiency of green pigment. An exception to this general statement is perhaps the albin- ism of seedlings of oak, pine, and other plants which are from the first entirely lacking in chlorophyll, or, as sometimes happens in the conifers, have green cotyledons but no green in the leaves formed later. While such plants have always, so far as the writers' experience goes, died in the seedling stage, and the phenomenon must therefore be regarded as strictly pathological, the condition is not ordinarily spoken of as chlo- rosis. The inherited tendency on the part of healthy plants of horti- cultural varieties to grow leaves or parts of leaves lacking in chlorophyll is not usually considered pathological, and is better known as "varie- gation" than as chlorosis. True chlorosis may be due to a number of causes, such as low temperature, which hinders the formation of pigment, or lack of nitrates, which, according to Crocker (2)? at least in one of the algae, is associated with a rapid decomposition of chlorophyll. Plants in full sunlight are often less green than those less exposed, probably because of the rapid disintegration of the pigment in strong light. High temperatures very likely have the same effect (Black- man's "time factor"). Plants with deficient water supply are, on the other hand, liable to chlorosis caused by difficulty in pigment synthesis. Much study has been given to the chlorosis of plants on calcareous soils, especially in connection w^th grapes in Europe. Roux (18) lists a large amount of literature on this subject. Recent papers by Maze", Ruot, Lemoigne (jj), and Gile (6) are well worth attention. The favor- able effect of iron on plants affected with certain types of chlorosis was discovered before the middle of the last century, spraying a solution of an iron salt on chlorotic leaves having resulted in correcting the chlorotic appearance (24). Molisch (74) discusses many of the earlier experiments with iron. In a recent interesting paper, Johnson (12) states that spraying with iron salts is helpful for a chlorosis associated with extremely high 1 The writers wish to acknowledge helpful suggestions from Dr. C. B. Lipman and Dr. Howard E. Pulling. 2 Reference is made by number (italic) to "Literature cited," p. 170-171. Journal of Agricultural Research. Vol. XXI, No. 3 Washington, D. C. May 2, 1921 xp Key No. F-s (153) 154 Journal of Agricultural Research vol. xxi, NO. 3 manganese content of the soil. Dement jew (4) discusses the question of whether chloroses corrected by iron are really cases of iron hunger. The literature on the chlorosis of conifers is relatively small. Sorauer (23) has reported chlorosis in Thuja occidentalis in Europe, and Schmuzi- ger (21) and Dafert and Kornauth (j) have noted chlorosis in spruce, without attempting to connect it with causal factors. Schmuziger re- ports, as do other observers on angiosperms, that the chlorotic leaves con- tained plastids which became green when the leaves recovered. Neger (16) has described in more detail a chlorosis of spruce in a cold autumn in which the yellow leaves or parts of them were found to contain much more starch than the green leaves or their green bases with yellow tips. He rather vaguely connects both current low temperature and the drouth of the preceding winter with the various phenomena observed. Contejean (j) lists Scotch pine (Pinus sylvestris) as somewhat calcifuge, and makes the general statement that excess lime accompanied by lack of iron, or "encore plus" lack of potassium, results in chlorosis of calcifuge plants. He, however, makes no specific mention of chlorosis in any conifer. Fliche and Grandeau (5) attribute the calcifuge tendencies of P. sylvestris to the physical rather than the chemical qualities of lime soils. They find Austrian pine (P. austriaca), P. halepensis, and Abies pectinata doing well on strongly calcareous soils, but they find P. pinaster making a poor growth in plantations on calcareous soil in all cases ob- served and entirely refusing to grow in some cases. Deficiency in starch and chlorophyll are noted for this pine on the lime soils, and also to a very slight extent for the Austrian pine on soils with extremely high calcium-carbonate content. The chloroplasts of the chlorotic plants are said to be small. The poor condition is attributed to potash hunger, and no mention is made of iron hunger as a possible cause. Ash analyses showed the following conditions : On good soil, Pinus pinaster, potash 16 per cent, iron oxid 3.8 per cent, linie 40 per cent. On excessively calcareous soil, Pinus pinaster, potash 5 per cent, iron oxid 2.1 per cent, lime 56 per cent. Pinus austriaca, potash 14 per cent, iron oxid 3.3 per cent, lime 49 per cent. Sachs (20) reports chlorosis in young trees of Abies balsamea, A. apollonis, and A. bicolor and says that entirely chlorotic new growth becomes green more or less promptly after considerable quantities of solid iron sulphate are placed in ditches in the soil near the roots. No controls are mentioned, but the promptness with which the younger trees are reported to have responded to the treatment supports his con- clusion that the recovery was due to the iron added, despite the fact that fast-growing chlorotic shoots, according to his own statement, Maya, 1921 Effect of Ferrous Sulphate on Chlorosis of Conifers 155 usually improve in color toward the end of the season without any special treatment. An interesting American report is that on chlorosis of Sequoia sempervirens by Peirce (17). CHLOROSIS OF CONIFER NURSERY STOCK IN THE UNITED STATES At several of the nurseries of the United States Forest Service in Nebraska and farther west, conifers are occasionally somewhat chlorotic The condition has become a matter of importance, however, only in the Morton Nursery, in northwestern Nebraska, and the Pocatello Nursery, in southern Idaho. Chlorosis has also been noted in conifers at the Great Basin Experiment Station in central Utah, especially in lodgepole pine (Pinus contorta) seedlings and transplants grown two years in the seed bed and one year in the transplant bed. At the latter locality native aspen (Populus tremuloides) was also chlorotic in places. ANALYSES OF SOIL AND WATER At all the points at which chlorosis was found, analysis (by courtesy of the United States Bureau of Soils for the nursery soils, and of Dr. J. E. Greaves, of the Utah Agricultural Experiment Station, for the Great Basin Experiment Station soils, showed the presence of carbonates as indicated by carbon-dioxid evolution. Carbon dioxid was, however, reported from sites near the Great Basin Experiment Station on which no chlorosis had been observed in either aspen or conifers, and from a nursery at which chlorosis had never been serious. In some cases the amount reported from soils on which the trees were green was greater than from those where the trees were chlorotic. The acid-digestion analyses showed for all the soils on which chlorosis was observed a con- siderable amount of calcium, much greater than that ordinarily found in the humid region of the United States, and in every case greater than the average of the 570 soils of the arid region reported by Hilgard (10, p. 377) . However, there is little apparent correlation between the amount of chlo- rosis and the amount of calcium reported. The Utah soil on which coni- fers were not chlorotic yielded over 17 per cent of lime (as CaO) and 12% per cent of carbon dioxid. The Pocatello nursery soil on which chlorosis was serious yielded more than twice as much calcium (2.9 to 4.7 per cent CaO) as Hilgard 's average for arid soils. It was not an excessively calcareous soil, however, as compared with some of the soils reported in connection with chlorosis in Europe and Porto Rico, with the chalk soils reported by Somerville (22) on which healthy Douglas fir was growing, or with the Utah soil just mentioned as supporting normally green coni- fers. The phosphorus (as P2O5) for the Pocatello soil was reported as approximately 0.7 per cent for all the samples, an unusually high figure. This at once suggests a possible relationship, in view of the slight 156 Journal of A gricultural Research vol. xxi, NO. 3 solubility of ferric phosphate. The other soils on which chlorosis occurred, however, did not give any such high phosphorus analysis. The fact that the solubility of ferric phosphate is sufficient to make it a good source of iron in water-culture experiments prevents any probability of a relation between the amount of phosphorous found by analysis and the availability of iron. All the analyses indicated normal quantities of iron. The results are in agreement with the general experience that acid-digestion soil analyses yield little information of value from the plant physiological or patho- logical standpoint. Petrographic examination by the United States Bureau of Soils of the Pocatello soil and of the nursery soil which con- tained carbonates without chlorosis gave no clue to the difference be- tween the plants on them. Acidity determinations by Dr. L. J. Gillespie, of the Bureau of Plant Industry, showed a PH of 7.8 for the Pocatello soil and 8.4 for the nursery at which there were carbonates but no serious chlorosis. The main facts to be drawn from the examination of the soils of the different stations was that all the soils on which chlorosis occurred contained carbonates and that two of them were underlaid with lime- stone. Analysis by the United States Bureau of Chemistry of the water supply showed 320 mgm. of bicarbonic acid (HCO3) per liter of water at the Pocatello Nursery, and practically no other anions, while at the nursery at which there were soil carbonates but no chlorosis there were reported 1 80 mgm. of bicarbonic acid per liter, as against 450 mgm. of sulphate (SO4) per liter. This is of some interest in connection with the difference in the amount of chlorosis at the two places, as the arid conditions made necessary the application of considerable amounts of water to the nursery beds during warm weather. The soil solutions during the periods of greatest growth must, therefore, have been influenced to a considerable extent by the character of this water. It was noted at the Pocatello Nursery that the chlorosis was more prevalent in beds which had been under nursery management for several years than in beds which had just been included in the nursery area and had therefore received less of the water. KIND AND EXTENT OF INJURY At the Pocatello Nursery there was so much chlorosis and the growth of affected stock was so unstisfactory that a detailed study of it was undertaken. The nursery is at an elevation of 5*200 feet, well below the lower limit of natural coniferous forest growth in this region. Precipita- tion for the period during which the nursery is usually free from snow (April to October, inclusive) averaged but 11.2 inches for the years 1909 to 1917, inclusive. The days are warm and the nights cool during the growing season, only 2^ months being entirely free from killing frost. The soil is a rather heavy black silt loam; composite samples from 8 to 10 May 2, X9» Effect of FeYYous Sulphate on ChloYosis of ConifeYS 157 points each show for three different parts of the nursery wilting coeffi- cients of 11.7, 12.6, and 14.3 per cent, respectively.1 The species in which the chlorosis has been noted are western yellow pine (Pinus ponder osa), Jeffrey pine (Pinus jeffreyi), Corsican pine (Pinus laricio corsicana], and Douglas fir (Pseudotsuga taxifolia). Of the two most important species grown here, western yellow pine and Douglas fir, the former is the more susceptible, especially during its first year. During the second year, Douglas fir is also considerably affected. The yellowing first becomes evident in the leaves of most recent growth, as reported by Sachs (20) for firs and broad-leaved plants. The entire foliage may be affected. In serious cases, the leaves are short, inclined to curl, and are less turgid than normal leaves (as a consequence of lack of sugars and therefore low osmotic pressure) . The terminal bud either fails to develop or is dwarfed and usually abnormally light in color. The height and diameter of the stem, the length of the roots, and especially the ability to form fibrous lateral roots also appear to suffer in typical cases of chlorosis. The disease may occur in patches, or isolated yellow plants may occur. In severe cases death ensues, the parts first discolored being the first to die. The greater part of the injury develops after height growth has mainly ceased for the season. A marked functional disturbance is indicated in the apparent inability of chlorotic plants to harden properly for the winter. Chlorotic first-, second-, and third-year seedlings of both Douglas fir and western yellow pine, though not growing with the vigor of green seedlings, continue growth later in the season and are more susceptible to injury by early fall frosts. This recalls the frost susceptibility of chlorotic redwood shoots reported by Peirce (77) and further suggests a relation between chlorosis and low osmotic pressure due to failure to make sugar, as in wilting. Decreased winter loss as a result of a treat- ment which controlled the chlorosis is shown by the data in Table I. Seedlings chlorotic during their first or second year start growth tardily or not at all the following season. The number of dwarfed chlorotic plants which die during the summer is increasingly great during the second and third years in the seed bed. In transplanting, chlorotic seedlings are discarded. 1 Determined by the indirect method of Briggs and Shantz in the Laboratory of Biophysical Investiga- tions, Bureau of Plant Industry, United States Department of Agriculture- 158 Journal of Agricultural Research Vol. XXI, No. 3 TABLE I. — Effect of iron-sulphate spraying on mortality of western yellow pine seedlings 1 'reatments . D« ad seedlin gs. Num- Age of ber of Series and plot. during treat- ment period. seed- lings per square foot. Dates. Strength of solution (grams per Amount FeS04 per square foot of Sept. 3 to Oct. 22, 1917- Oct. 22, 1917, to Apr. 23, 1918. (winter- Sept. 3, 1917, to Apr. 23, 1918. TOO CC.). bed. killed). Months. 1917. Gm. Per cent. Per cent. Per cent. Aug. 2, I treated 1 4 to 18 1 08 24,Sept. 2 ° o- 95 o 4 II, treated ..do.... 75 3. 12, 22, I 0.47 5 0 5 Oct. 2. do... IJ5 3 8 II do go 15 19 Ill, treated... 2 to 5 . 52 Sept. 3 2 °-9S 13 0 13 Do do 58 o .47 14 o 14 Do ..do.... 63 and . 5 0.24 14 II 24 Oct. 2. III control do. 76 14 9 32 a o.i pint of solution per square foot, equivalent to 0.02 inch of rain, applied to each treatment. The prevalence of chlorosis in the Pocatello Nursery during Septem- ber, 1917, was determined by examining several thousand plants of the different age classes of western yellow pine and Douglas fir. Of the first- and second-year western yellow pine seedlings 82 and 62 per cent, re- spectively, were chlorotic; while 74 per cent of the transplants grown two years in the seed bed and one year in the transplant bed were chlorotic. First-, second-, and third-year seedlings of Douglas fir were chlorotic to the extent of 6, 65, and 26 per cent, respectively; while 15 and 62 per cent of the transplants grown three years in the seed bed and one and two years, respectively, in the transplant bed were chlo- rotic. OF WATERING It was at first thought that too heavy watering might have been responsible for tihe chlorosis at the Pocatello Nursery. While an exam- ination of the condition of the soil did not indicate water-logging, varia- tions in the amount of artificial watering were tested. Four plots of Douglas fir seedlings approximately 2 months old were given varying amounts of water throughout a period of slightly over two months. The results appear in Table II. The artificial watering was at first given approximately once a week and amounted to the equivalent of 0.55 inch of rain on plot D, the most heavily watered plot. Plot C received two-thirds of this amount, plot B one-third, and plot A none. After the first month the amount of water added at each watering was decreased because of the difficulty of avoiding run-off, and the frequency of application was increased. The plots in this experiment were free from chlorosis at the beginning of the period, and all of them later exhibited more or less yellowing. The amount of water applied arti- ficially, combined with the natural precipitation, did not total an ex- Maya, 1921 Effect of Ferrous Sulphate on Chlorosis of Conifers 159 cessive amount, except possibly in plot D. This experiment was carried on in a section of the nursery in which the disease did not prove to be prevalent, and little chlorosis occurred in any of the plots. The entire number of yellow seedlings shows an increase with increased watering through all four plots for the last three counts and a somewhat less marked but similar relation for the earlier counts. The magnitude of the difference is, however, not sufficient to permit positive conclusions. Whether the apparent effect of the watering in increasing chlorosis was mostly due to the solutes in the excess water, to cooling the soil, or to hindering aeration, it is not possible to say. That the entire effect of the watering should have been due to disturbance of aeration, or tem- perature, seems scarcely possible in the cases of plots B and C, which received relatively little artificial watering. These plots did not seem excessively wet, but the soil of plot D was sufficiently wet to permit the development of moss — abnormally wet for this nursery. II. — Effects of different amounts of artificial "watering on chlorosis in 4- to 5- month-old Douglas fir seedlings Plot A, un- watered. *> Plot B, lightly watered. & Plot C, moderately watered. b PlotD heavily watered. & 1917. Rainfall and artificial watering (in inches): First half of August Traces. 0.25 (3) 1.07 (6) .71(2) 0.54 3) .34 4) 1-34 7) 1.07 6} .18(2) 1-11(3) • 43 (4) i. 61 (7) 1-43(6) .36(2) 1.65 •53 1.91 1.83 •56 •i 6) 2) Last half of August. First half of September Last half of September . First half of October Total Aug. 2 to Oct. 6 2.03 (n) 3-47 (22) 4.94(22) 6.48(22) Percentage of seedlings found chlorotic: « Sept. i 7.8 6.1 i-7 •4 •4 ii. 8 7-5 4-3 2. 2 2. 2 10.7 7.0 5- i 2-9 2.6 17.9 14.7 8.4 4.8 4.0 Sept 13 Sept. 22 Oct. 2 Oct. 22 a Two square feet counted in each plot. Number of seedlings per square foot at beginning of test: Plot A, 241; B, 244; C, 363; D, 278. & Figures in parenthesis indicate total number of days on which rain or artificial watering occurred. A pathologic condition may be encountered in certain conifers growing in wet situations. This condition would be unfavorable and therefore would result in subnormal vigor and growth of the plants subjected to such abnormal conditions. In studying hypertrophied lenticels at the Bessey Nursery, near Halsey, Nebr., one of the writers (8) conducted an experiment in heavy watering, in which irrigations approximately equiva- lent to 2.2 inches of rainfall were repeated 17 times during a period of three months on western yellow pine transplants grown two years in the seed bed and one year in the transplant bed. Considerable chlorosis appeared in the heavily watered beds, the plants of which were originally thrifty and free of chlorosis, while the controls remained nonchlorotic. There is also a possibility of a lack of proper aeration of the soil and of i6o Journal of Agricultural Research Vol. XXI, No. 3 oxygen hunger as a very probable and effective stimulus in inducing chlorosis in a mesophyte like Douglas fir in an excessively wet soil. SPRAYING WITH FERROUS SULPHATE Spraying with ferrous sulphate was tested on western yellow pine and Douglas fir. The first tests were on seedlings of the former species approximately 14 months old. Plots 4 by 10 feet were laid out, series I in beds in which chlorosis was not serious, and series II in beds in which it was very prevalent. The two plots in each were adjacent and parallel. Care was taken to choose plots as nearly as possible identical in vigor, number of seedlings per square foot, and amount of chlorosis. One of the plots in each series was sprayed with iron-sulphate solution at the rate of 2 gm. of sulphate per 100 cc. of water, and the other was given an £0 70 90 27O //O /3O /SO /7O J9O &O 23O 25Q &/A/CE F/RST ffrtY/NG ON fiVG. 2J917. FIG. i.— Graph showing the effect of a ferrous sulphate spray treatment on chlorosis in seedlings of western yellow pine 14 to 18 months old. equal quantity of water only and was used as a control. The spraying was done with a hand-spray pump and was begun on August 2, 1917. In each case the plot selected for the treatment appeared slightly more chlorotic than the control at the time of the first treatment. On August 24, after two sprayings, it was evident that chlorosis had been decreased but that chemical injury to the youngest growth had resulted from the treatment. This injury is somewhat surprising, in view of the successful use of 8 per cent solutions on pineapple (12). The difference in results may, of course, be due to difference in the localization of the solution on Maya, i92 1 Effect of Ferrous Sulphate on Chlorosis of Conifers 161 the surfaces of the two plants. Conifers are very difficult to coat evenly with a spray. Also the fact that there had been practically no rain from the first treatment to the time the injury was observed may have been responsible for the degree of injury by the 2 per cent solution. In a region of heavier rainfall this solution, or even a stronger one, might be entirely harmless to conifers. The treatments were continued, but with a i per cent solution at the rate of only o. i of a pint, containing approxi- mately 0.47 gm. of ferrous sulphate per square foot of seed bed. Spray- ings with this weaker solution were made on August 24, September 3, September 12, September 22, and October 2;- and the seedlings on sample areas were counted and classified as to the degree of chlorosis on different dates in September and October, and again in April of the following year. /9/>fi/L /$/& 22 OCT.I9/Z 3 12 '2 22 /60 ISO gOO ttO g*O FlG. 2. — Graph showing the effect of a ferrous sulphate spray treatment on chlorosis in seedlings of western yellow pine 2 to 5 months old. The results are shown graphically in figure i. Decided inprovement in the color of the sprayed plots during the period covered by the counts is indicated by the data. The undiminished persistence of the good effect through the winter, a total of 6X months after the last spraying, and the smaller percentage of winterkilled seedlings in the sprayed plots (Table I) are worthy of note. At the time the first counts were made on the older seedlings (September 3) plots of the same size were also laid out in beds of both western yellow pine and Douglas fir of the current year's sowing and were therefore 1 62 Journal of Agricultural Research Vol. XXI, No. 3 about 3 months old. The results with the young western yellow pine (fig. 2) are more striking than those with the older stock. Autumn losses, presumably due to late damping-off, were not affected by the treatments; but winterkilling was entirely prevented (Table I). The heaviest treatment seemed to give better results than the lighter ones, so far as correcting chlorosis was concerned, both at the fall and the succeeding spring examinations, but resulted after the third treatment in the blackening of some of the leaves. The chemical injury was even more marked at the time of the spring examination, when practically every seedling in all the western yellow pine plots treated with the 2 per cent solution showed chemical injury, whereas the plots treated with the weaker solution showed none. With young Douglas fir (fig. 3) the amount of chlorosis initially present was less, and the untreated seedlings as well as the treated improved in color during the course of the experiment. In so far as chlorosis is corrected, the results are similar to those secured with western yellow OCT. £2,1917: FIG. 3.— Graph showing the effect of a ferrous sulphate spray treatment on chlorosis in seedlings of Douglas fir 2 to 5 months old. pine. On Douglas fir, however, the heaviest treatment was no more effective against chlorosis than the lightest; the intermediate gave the best results. In view of this and the injury to western yellow pine from the strongest solution, it appears that only the intermediate strength (i per cent) should be used on conifers, at least if repeated spraying is practiced. Though the total area counted in all the spraying experiments with first-year seedlings was small — 12 square feet in the treated plots and 6 square feet in the controls — the data obtained from the counts show on the whole such consistent and decided improvement in the sprayed plots as to leave no reasonable doubt about the therapeutic value of the treatment for western yellow pine. Observations on the entire area of the western yellow pine experimental plots (200 square feet treated and 120 square feet in the controls) indicate that the sample areas on which the counts were made were reasonably representative of the entire plots. Maya, i93 1 Effect of Ferrous Sulphate on Chlorosis of Conifers 163 The contrast between the treated and untreated plots of western yellow pine at the close of the experiments was very strong throughout. No attempt was made to exclude the ferrous sulphate from the roots. In view of the high absorptive capacity for iron sulphate of the cal- careous soil with which Sachs worked (19, 20) and the prompt reaction (fig. 2) following the small amount of the sulphate added by the writers in the i per cent solution treatments on the younger western yellow pine seedlings (fig. 2 and Table I), it is believed that the effect of the iron- sulphate spraying was due to the entrance of traces of iron into the leaves, presumably mostly through the stomata, though Molisch (14) reports it as entering through the cuticle. Forest officers report that i per cent ferrous sulphate sprayings begun in April at the Morton Nursery corrected chlorosis in 2 -year-old seedlings of both jack pine (Pinus banksiana) and western yellow pine by June. Scotch pine did not show chlorosis ; jack pine showed it most. The con- trol of the yellowing was not absolute but was practically complete by the end of July. The iron-sulphate spray treatment is considered so successful that it has now been put into general use on all the jack pine and western yellow pine seed beds at the Morton Nursery. VALUE OF THE EXPERIMENTS It appears from the literature cited in the introduction that on soils containing considerable calcium carbonate there often occurs a chlorosis which can be corrected by the addition of iron in soluble form to either the roots or the leaves. The trouble-making capacity of the calcium carbonate, though not always in evidence, appears to be more or less specific. Other calcium salts and other carbonates do not seem equally effective as causes of chlorosis. It is reasonable to suppose, in view, among other things, of the precipitation of iron in alkaline solutions, the apparent substitution of iron for calcium in soil (75), and the nonavail- ability of colloidal iron (7, jj) that the trouble was chiefly due to the lack of dissolved iron in the water of certain calcareous soils. However, in the lime soil it might conceivably be that the balance of the solution for plants which are not distinctly calciphile is so disturbed as to make more than the usual amount of iron necessary to maintain the plants in normal health on such soils. A further complication is the fact that the distribu- tion of chlorosis in different parts of the same plant is sometimes such as to indicate that at least part of the difficulty may be due to derangements in conduction instead of or in addition to absorption failures. Further- more, physiologists are not all ready to agree that the lack of green is really a symptom of a specific iron hunger, even in cases in which the remedial value of iron addition is demonstrated. The writers' results have made no addition to the knowledge of the immediate cause of the chlorosis or the way in which the addition of iron works in correcting it. These complications are mentioned merely to show that fundamental 164 Journal of Agricultural Research voi.xxi,No.3 work on chlorosis lies in the domain of the biochemist rather than of the pathologist or the forester. The immediately practical applications are fortunately simpler. The writers have added three gymnosperms to the considerable list of angio- sperms in which chlorosis can be relieved by spraying ferrous sulphate on the surfaces of the leaves. While the best way to avoid chlorosis in co- niferous nurseries is probably to avoid soils containing any considerable quantities of calcium carbonate, an entirely practicable method of treat- ment is offered by which chlorosis can apparently be relieved in coniferous nurseries on lime soils. At the rate at which the experimental spraying was done, using the i per cent solution, which on the whole gave the best results, i pound of the relatively cheap ferrous sulphate is sufficient for over 900 square feet of bed. While with larger stock more material would be required, the process would still be relatively cheap. Johnson (jo), using a solution eight times as strong, reported the total cost of spraying pineapples as $0.60 per acre for each spraying. In a business as intensive as that of raising coniferous nursery stock such a cost item would be almost negligible. RELATION BETWEEN CHLOROSIS AND GROWTH Observations through several seasons at the Pocatello Nursery have indicated a relation between chlorosis and poor growth. In order to secure data on this relationship the seedlings in the control plots whose counts are given in figure i were classified by their apparent vigor of growth as well as according to their chlorotic condition. The counts showed for the first series that 23 per cent of the seedlings classed as vig- orous were chlorotic, while 42 per cent of the weak seedlings were in the chlorotic class. For the second series the difference was about the same, 46 per cent of the vigorous seedlings being chlorotic against the very high proportion of 73 per cent among the seedlings classed as weak. In an effort to put this relationship on a more exact basis, specimens were selected from each class and subclass of seedlings of which a sufficient number were available to give a reasonable numerical basis, and measure- ments of roots, stems, and leaves were made. METHODS OF SECURING MEASUREMENTS The seedlings taken were selected by a process of mechanical elimina- tion, every fifth seedling being chosen in most of the cases, so that they are believed to be representative of the groups from which they came. The leaf surface values were obtained by a method which does not pre- tend to give the absolute surface accurately, but which is believed to give sufficiently accurate relative values to permit a comparison of the different groups of plants. The surfaces of the primary and secondary leaves of western yellow pine were determined separately on account of their different shapes. May 2,i93i Effect of Ferrous Sulphate on Chlorosis of Conifers 165 FIG. 4. — Cross-sectional shape of fascicle of three secondary leaves of western yellow pine. The primary leaves are approximately semicircular in cross section, and for the purpose of obtaining a comparative surface value were considered as halves of cylinders having a radius equal to the thickness of the leaf midway between the base and the tip, with the length equal to the length of the leaf. The perimeter of the cross section at this point was taken as xR + 2R — that is, the sum of the lengths of the curved and the flat margins of the cross section. The surface of the leaf was taken as S = L(7rR+2R), in which L, equals the length of the leaf. A sufficient number of primary and secondary leaves from each plant were measured to allow averaging (usually from 25 to 100, depending on the number per plant) . The total primary leaf surface for the plant was obtained by multiplying the surface of the average leaf by the entire number of primary leaves. The secondary leaves were in most cases in fascicles of three, and their cross-sectional shape may be diagrammed as in figure 4. The same assumptions were made in this case as in the case of the primary leaves, the leaf being taken as an exact third of a cylinder with the radius equal to the thickness of the leaf midway between the base and the tip, and the surface calculated by the formula S = I/ - - 4- 2R a paraboloid formula, and it is believed that it offers a better basis for comparing the leaf surface of one group of plants with that of another than would be given by statements of the average number, length, breadth, and thickness of the leaves. INTERPRETATION OP THE MEASUREMENTS From Tables III and IV it appears that the height and the weight of the tops, the length and the weight of the roots, the diameter of the stems at the root collar, the length and thickness of the secondary leaves, and the average total leaf surface of the plants was less for chlorotic plants than for green seedlings of the same vigor class and that terminal bud formation was most common and most pronounced in the most vigorous plants. The data indicate that the failure to form buds is related to a general lack of vigor, which in many cases is associated with chlorosis. The adverse effects of chlorosis on terminal bud forma- tion and development is significant in connection with the high winter mortality of the strongly chlorotic seedlings. The small size of the different parts of the plants in the chlorotic seedlings, as compared with the green seedlings, is, on the whole, fairly uniform. Two exceptions to this are, however, noteworthy. In Table III it appears that the roots of the chlorotic plants are nearly as long This formula appears to be more nearly correct than 1 66 Journal of A gricultural Research vol. xxi, NO. 3 as those of the green plants. However, the weight of the roots was decidedly less in the chlorotic than in the green plants. This agrees with the field observations, indicating an association between chlorosis and a deficiency of fibrous lateral roots. It will be noted that the strongly chlorotic plants in the vigorous class had a root weight con- siderably less than that of the green plants in the weaker class. While the roots of these plants were also somewhat shorter, the weight differ- ence was distinctly greater. The other lack of parallelism between increased chlorosis and de- creased growth is in the primary leaves. These were nearly as well de- veloped in the chlorotic plants as in the green plants. This is considered significant as indicating that the plants which were decidedly chlorotic and lacking in vigor during the second season were not originally very different in their growth rate from the others. This relationship is most easily seen in the three columns under "Relative leaf surface " in Table IV. TABLE III. — Root, top, and terminal bud development of the different type classes of 2-year-old seedlings UNTREATED WESTERN YEtLOW PINE a Tops. Roots. Terminal buds. Aver- Aver- Type classes. Num- Der of seed- lings. age diame- ter of stem at root collar. Aver- age length. Aver- age weight. Aver- age length. Aver- age weight. age total weight of seed- lings. Per- centage of seed- lings forming termi- Aver- age length. Aver- age diame- eter. nal buds. Inches. Inches. Cm. Inches. Gm. Gm. Inches. Inches. Vigorous, green Vigorous, slightly 100 0.075 2. 2 1.40 11.7 0.5? 1.97 9 0.33 o. 16 chlorotic .065 i. 7 . 77 9. 7 . 33 i. n 2 .23 . 14 Vigorous, strongly .062 1.6 8.6 . 72 O 060 z 6 o 6 . 26 .80 o Weak, slightly chlo- .0*8 .18 o Weak, strongly chlo- 100 • 045 I. 2 . 22 9.6 . 12 •34 0 UNTREATED DOUGLAS FIR ° Green 2.8 9-6 . IJ > SO IOO . 15 .08 Chlorotic 50 .038 2-3 . 22 8.2 .08 •3° 86 . 10 .04 o The number of chlorotic plants in the treated plots at the end of the season was insufficient to serve as a basis for measurement. Maya, 1921 Effect of Ferrous Sulphate on Chlorosis of Conifers 167 § I °°3 ** $*" . I I as . 00 VTVO M M