Veg a ie ery ge b 8 v / 3 SB 818 C578 ENT Issued August 12, 1910. US: DEPARTMENT, OF AGRICUELURE, BUREAU OF ENTOMOLOGY—CIRCULAR No. 124. L. O. HOWARD, Entomologist and Chief of Bureau. THE SAN JOSE SCALE AND ITS CONTROL. BY A. L. QUAINTANCE, In Charge of Deciduous Fruit Insect Investigations. Uv] { 48873°—10 WASHINGTON : GOVERNMENT PRINTING OFFICE : 1910 “a\sonlan instit, ~~ cx? ; ey \ AUG 29 210 } Noy. nua —‘Onal Muse” BUREAU OF ENTOMOLOG Y. L. O. Howarp, Entomologist and Chief of Bureau. ©. L. Martarr, Assistant Entomologist and Acting Chief in Absence of Chief. R.S. Currron, Executive Assistant. W. F. Taster, Chief Clerk. F. H. CuirrenneENn, in charge of truck crop and stored product insect investigations. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. Wesster, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. E. F. Pures, in charge of bee culture. D. M. Roaers, in charge of preventing spread of moths, field work. Rouiia P. Currte, in charge of editorial work. Mase Co.icorp, librarian. Decipuous Fruit Insect INVESTIGATIONS. A. L. QUAINTANCE, in charge. FreED. JoHNson, S. W. Foster, E. L. JEnnE, P. R. Jones, A. G. Hammar, R. W. Braucuer, ©. W. Hooker, J. R. Horton, W. Postirr, J. B. Grit, agents and experts. E. W. Scorr, C. H. Gaste, J. F. Zeer, entomological assistants. [Cir. 124] (11) ey D> mal de CIRCULAR No. 124. Issued August 12, 1910. United States Department of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD, Entomologist and Chief of Bureau. THE SAN JOSE SCALE AND ITS CONTROL.¢ 3y A. L. QUAINTANCE, In Charge of Deciduous Fruit Insect Investigations. CHARACTER OF INJURY. The San Jose or Chinese scale (Aspidiotus perniciosus Comstock) infests practically all portions of its host plants that are above ground—the trunk, limbs, and branches—and when abundant it may occur on the leaves and fruit. Injury results from the extraction, by the scale insects, of the juices of the plant. At first this merely checks growth, but as the insects increase in number the speedy kill- ing of the branches and twigs follows, resulting finally in the death of the plants. In addition to the extraction, by the scales, of sap as food, the puncturing of the bark by the slender sucking mouth-parts results in a diseased and often pitted condition; the inner bark, or cambium, showing a reddish discoloration, as exposed in cutting with a knife, and the bark itself may crack, in stone fruits exuding drops or masses of gum. A reddening effect is also much in evi- dence as red rings around the scales on the bark, especially of the apple and pear, and on the fruits of these plants, though not charac- teristic of any one scale species. On peach the scales have a tendency to infest to a greater extent the older limbs and branches than the newer growth, as the wood 1 year old. On apple and pear, the terminal twigs are quite gen- erally infested, and many of the young may find their way to the fruit, settlmg principally in the calyx and stem cavities. Most varieties of fruit trees and plants infested from the nursery, in the absence of treatment, perhaps never reach fruiting condition. a An extended recent account of this insect will be found in Bulletin 62 of this Bureau, “The San Jose or Chinese Scale,’’ by C. L. Marlatt, which may be obtained of the Superintendent of Documents, Government Printing Office, Washington, D. C., for 25 cents. Foreign applicants should send 4 cents additional to cover postage. [Cir. 124] (1) 2 Peach trees will usually be killed in two or three seasons, while pear or apple trees will maintain a feeble existence much longer. This insect, on account of its great similarity to certain other species of scale insects, may not be positively determined except by specialists. The occurrence of diseased and dying branches showing severe scale infestation furnishes strong presumptive evidence of the presence of this pest, but specimens of infested twigs should be promptly submitted to a qualified person for examination. The appearance of a 3-year-old peach tree, presumably infested from the nursery, is shown in figure 1. The principal limbs have Fig. 1.—Appearance of 3-year-old peach tree badly injured by the San Jose scale (As pidiotus perniciosus) the larger branches having been killed. (Original.) already been killed, although new shoots have developed. . s Ase es ae es ene eee eee pounds... 20 Sulphur (houmorflowers)= == ee eer eee ee eee eee doze aly Wiaiter:to:makeso. 22 2.35. ee ene eerie gallons.. 50 Heat in a cooking barrel or vessel about one-third of the total quantity of water required. When the water is hot add all the lime and at once add all the sulphur, which previously should have been made into a thick paste with water. After the lime has slaked, about another third of the water should be added, preferably hot, and the cooking should be continued for one hour, when the final dilution may be made, using either hot or cold water, as is most convenient. The boiling due to the slaking of the lime thoroughly mixes the ingredients at the start, but subsequent stirring is necessary if the wash is cooked by direct heat in kettles. If cooked by steam, no [Cir. 124] 13 stirring will be necessary. After the wash has been prepared it must be well strained as it is being run into the spray pump or tank. The wash may be cooked in large kettles or, preferably, by steam in bar- rels or tanks. This wash has proved entirely effective in controlling the insect on all plants, so far as preserving their life is concerned, and has been especially satisfactory for stone fruits. For the apple, however, it has not in all cases been so satisfactory, as difficulty is experienced, especially in the case of large trees, in making the application suffi- ciently thorough to kill all the scales. The spotting of the fruit by the progeny of those that escape renders it unsightly for market pur- poses, though its intrinsic value is but little reduced. The presence of the scale is furthermore very objectionable for the reason that cer- tain foreign governments and certain States in this country rigidly quarantine against fruits showing the presence of this insect. Con- siderable loss on fruit exported thus results to orchardists and dealers.¢ Some apple growers rely principally upon the oil sprays, or use them at least every other year, alternating with the lime-sulphur wash, and in this way keep the scale well in check. CONCENTRATED LIME-SULPHUR SOLUTIONS. The inconvenience experienced in preparing the lime-sulphur wash by cooking with steam or in open kettles at home has been one of the principal objections to this spray. Certain manufacturers have therefore put on the market concentrated solutions of lime-sulphur wash, which have only to be diluted with water for use. These com- mercial washes have proved to be about as effective in controlling the scale as the well-cooked lime-sulphur wash, and, although some- what more expensive, have been adopted by many commercial orchardists in preference to the home-prepared spray. They are especially useful for the smaller orchardist, whose interests do not warrant the construction of a cooking plant. In other ways, too, they possess advantages; for instance, those using the commercial washes may have always on hand a stock solution, so that the spray may be quickly prepared and advantage taken of favorable weather conditions. HOMEMADE CONCENTRATED LIME-SULPHUR SOLUTIONS. The question of the preparation at home of concentrated lime-sul- phur solutions which will not crystallize upon cooling, thus duplicat- ing essentially the commercial product, has been the subject of inves- « Experiments made by the Bureau of Entomology indicate the practicability of successfully fumigating scale-infested apples intended for export or other trade. (See Bul. 84, Bur. Ent., U.S. Dept. Agr., 1909.) [Cir, 124] 14 tigation by several entomologists, notably by Cordley in Oregon, Stewart “in Pennsylvania, and Parrott ®in New York State. These gentlemen have demonstrated that it is practicable for orchardists to prepare concentrated stock solutions of lime-sulphur wash for immediate or later use. Several orchardists have already adopted this plan, and it will doubtless come into more general use in the future. The details of the preparation of concentrated lime-sulphur solutions can not properly be given in the scope of this circular, but those interested should secure, if possible, copies of reports on the work from the directors of the respective experiment stations. SELF-BOILED LIME-SULPHUR WASH, In the earlier experiments with the lime-sulphur wash in the East many efforts were made to avoid the necessity of cooking the wash by utilizing, to dissolve the sulphur, the heat generated by the slak- ing of the lime, or supplementing this by the addition of a quantity of caustic soda or potash. This preparation, formerly designated as self-boiled lime-sulphur wash, has now largely, if not entirely, fallen into disuse, and the spray under consideration is essentially a differ- ent preparation and was developed primarily as a fungicide. Experiments made by the Bureau of Entomology in the vicinity of Washington in 1908, however, have shown that this self-boiled wash, by destroying the young insects and interfering with their establishment, is an excellent summer treatment for the San Jose scale. It is also effective in destroying aphides and, in addition, as stated, will prevent numerous fungous diseases, as established by Prof. W. M. Scott, of the Bureau of Plant Industry. Its use is espe- cially recommended for scale-infested fruit trees which should receive applications of a fungicide and which may be more or less affected with aphides. By the addition of arsenate of lead, at the rate of 2 pounds to 50 gallons of spray, the wash also becomes effective against biting insects, such as the codling moth and plum curculio, and this furnishes as nearly an all-around spray as anything at present known. It is possible that the commercial concentrated lime-sulphur wash, previously referred to, used at the rate of 14 gallons to 50 gallons of water, would destroy many of the young San Jose scales. It has been shown to be an excellent fungicide, and at this strength not injurious to the foliage. Arsenate of lead may also be added, as in the case of the self-boiled wash. In using the self-boiled lime-sulphur wash as a scale treatment, however, especial pains should be taken to coat the limbs and branches a Bul. 99, Pa. State Coll. Agr. Exp. Sta. (State College, Pa.), 1910. 6 Bul. 320, N. Y. Agr. Exp. Sta. (Geneva, N. Y.), 1909. [ Cir. 124] 15 of the infested trees, and, on account of the presence of the leaves, careful work will be necessary to accomplish this. This wash is made as follows: Sling: INVA Foes cae Soe Ee REE todo GnoRe Aaa ae Keene pounds... 8 Siutlonur dlourortlowers) assess as. 6 eee eee ee =e dol. 8 NVTtetaCOMIlal ke sects os BEES yy s Sent gs i Ree ine Ree ae 5 re gvallons.. 50 The lime should be placed in a barrel and enough water poured on to almost cover it. As soon as the lime begins to slake the sulphur should be added, after first running it through a sieve to break up the lumps. The mixture should be constantly stirred and more water added as needed to form a thick paste at first and then grad- ually a thin paste. The lime will supply enough heat to boil the mixture several minutes. As soon as it is well slaked water should be added to cool the mixture and prevent further cooking. It is then ready to be strained into the spray tank, diluted, and applied. The stage at which cold water should be poured on to stop the cooking varies with different grades of lime. Some limes are so slug- gish in slaking that it is difficult to obtain enough heat from them to cook the mixture at all, while other limes become intensely hot on slaking, and care must be taken not to allow the boiling to proceed too far. If the mixture is allowed to remain hot fifteen or twenty minutes after the slaking is completed the sulphur gradually goes into solution, combining with the lime to form sulphids, which are injurious to peach foliage. It is therefore very important, especially with hot lime, to cool the mixture quickly by adding a few buckets of water as soon as the lumps of lime have slaked down. The intense heat, violent boiling, and constant stirring result in a uniform mix- ture of finely-divided sulphur and lime, with only a very small per- centage of the sulphur in solution. It should be strained to take out the coarse particles of lime, but the sulphur should be carefully worked through a strainer. The mixture can be prepared in larger quantities if desirable, say enough for 200 gallons at a time, making the formula 32 pounds of lime and 32 pounds of sulphur to be cooked with a small quantity of water (8 or 10 gallons), and then diluted to 200 gallons. The first application should be given when the young scale insects are beginning to crawl, which time will vary according to locality. In the neighborhood of Washington this will be about the middle of May, earlier in the South, and later in the North. This one treat- ment, if thoroughly applied, will do much to check the increase of the insect and to protect the trees from serious damage until the more thorough winter application can be made. A subsequent appli- cation should be given, if practicable, in the course of five or six weeks in order to destroy the young scales of the second generation. [Cir. 124] 16 PETROLEUM-OIL SERIES. Under the heading ‘‘ Petroleum-oil series’’ are to be included kero- sene and crude petroleum, either pure or in emulsion, and the so- called miscible oils. Pure kerosene treatment.—Pure kerosene has been more or less recommended for spraying trees badly infested with the scale, but it has never been very generally employed. There is no question of the efficiency of such an application in the destruction of the insects, but the great danger of injury to the plants precludes its general application. Treatments of pure kerosene should be made only dur- ing bright days and should be applied through a nozzle with a very fine aperture. Only the minimum amount of kerosene necessary to cover the trees should be given, and care is necessary that the liquid does not puddle around the roots of the trees. Pure crude petroleum treatment.—Pure crude petroleum is used in identically the same manner as pure kerosene, and the same cautions as to its use should be remembered. The crude oil employed in the East is known as “‘‘insecticide oil’’ and has a specific gravity of 43 to 45 degrees on the Beaumé scale. Kerosene emulsion (stock solution 66 per cent oil).—Kerosene emul- sion is made after the following formula: Kerosene (coal oil, Jami oil): 2ssc- 22 : io Seer gallons.. 2 Whale-oil soap or laundry soap (or 1 quart of soft soap)....- pound... 4 WVgibe rcs 232 io! = Lek Se eed 5 Oe iP ee gallon: oI Dissolve the soap in boiling water; then remove vessel from the fire. Immediately add the kerosene, and thoroughly agitate the mixture until a creamy solution results. The stock emulsion may be more conveniently made by pouring the mixture into the tank of a spray pump and pumping the liquid through the nozzle back into the tank for some minutes. The stock solution, if well made, will keep for some months, and is to be diluted before using. In order to make a 10 per cent spray (the strength for trees in foliage), add to each 1 gallon of the stock solution about 53 gallons of water. For 20 and 25 per cent emulsions (for use on dormant trees and plants), use, respectively, about 24 gallons and 13 gallons of water for each 1 gallon of stock emulsion. Agitate the mixture in all cases after adding the water. The preparation of the emulsion will be simplified by the use of a naphtha soap. No heat will be required, as the kero- sene will combine readily with the naphtha soap in water when thor- oughly agitated. Of naphtha soap, however, double the quantity given in the above formula will be required, and soft or rain water should be used in making the emulsion. In regions where the water is ‘‘hard”’ this should first be broken with a little caustic potash or soda, such as common lye, before use for dilution, to prevent the soap from combining with the lime or magnesia present, thus liberat- ing some of the kerosene; or rain water may be employed. [Cir. 124] aN Crude petroleum emulsion.—Crude petroleum emulsion may be pre- pared in identically the same way as described for kerosene emulsion, substituting crude petroleum for kerosene. The same dilutions for winter and summer spraying should be made as prescribed for kero- sene emulsion, but it should be noted that for summer treatments of trees in foliage the kerosene emulsion is preferable, as it is less likely to cause injury, Miscible oils —Under the heading “ Miscible oils” are to be desig- nated several proprietary preparations which are essentially petro- leum oils with the addition of a vegetable oil and an alkali, to secure ready saponification with water. These come in concentrated solu- tions and the spray is prepared by adding a specified amount of water. In point of convenience they leave little to be desired. Miscible oils are coming into increased use in place of kerosene or crude petro- leum, either pure or in emulsions, and have a distinct usefulness as winter sprays about the same as have the concentrated lime-sulphur solutions. As has been indicated, the petroleum oils are at times the cause of injury to twigs and fruit buds, and it is a question of judg- ment whether, under conditions of severe scale infestation, the petro- leum oils or the sulphur solutions should be used. The petroleum oils, on the whole, are more effective and the danger of injury from them is less to pome than to stone fruits. The practicability of making miscible oils at home has been inves- tigated by Prof. C. L. Penny,® and he has shown it to be entirely feasible, as detailed in the publications cited below. SOAP WASHES. Practically the only soap wash which has come into extended use against the San Jose scale is that made from whale-oil soap. . This is used mostly on dormant trees, the soap being employed at the rate of 2 pounds to the gallon of water. A potash whale-oil soap is prefer- able and should contain not more than 30 per cent of water. Soda soaps, while perhaps cheaper, will be likely to solidify on cooling when used at the strength above indicated, and are hence forced through the spray-pump nozzle with difficulty. For spraying trees in foliage the soap should be used at the rate of 1 pound to 3 or 4 gallons of water, or somewhat weaker. SPRAYING APPARATUS. The washes as above described are applied by means of some form of spray pump, the size and character depending upon the size of the plants to be treated. For small plants, such as ornamentals, hedges, etc., a bucket pump (fig. 8) or knapsack pump (fig. 9) will be satis- factory. The barrel form of pump, however (fig. 10), will permit of more thorough work and will be suitable for orchards of some size. @ Bul. 75, Del. Coll. Agr. Exp. Sta. (1906). Bul. 85, Pa. State Coll. Agr. Exp. Sta. (1908). State College, Pa, (Cir. 124] STITUTION LIBRARIES wv HE It may be placed in a wagon or cart or mounted on a sled. For large commercial orchards the hand-power tank or gasoline outfits are better. It is quite practicable, however, in case but two or three trees in a yard are to be treated, to apply the wash to the limbs and branches Fic. 8.— Bucket spray pump suitable for use in yards. (Author’s illustration. ) Fic. 9.—Knapsack sprayer suitable for spraying Fic. 10.—A barrel sprayer, suitable for orchard low-growing plants. (Author’s illustration.) or similar large-scale work. (Author's illus- tration. ) by means of old cloths or brushes. Whale-oil soap is excellent for this purpose. Severe pruning of the trees is usually desirable in such cases. Approved: JAMES WILSON, Secretary of Agriculture. Wasuineton, D. C., May 27, 1910. [ Cir. 124] O