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Show PROMISING NEW TREATMENT FOR ERADICATION OF SAN JOSE SCALE Br A. L. QUAINTANCE, Entomologist In Charge Fruit Insect Investigations, United States Department of Agriculture. The San Jose scale Is Just now exceedingly ex-ceedingly abundant and destructive In many orchards in the Bentonville, (Ark,) section, and growers state they are unable to adequately control the pest with the usual dormant tree treatments treat-ments with lime-sulphur spray. While the bureau of entomology believes that thorough spraying with dormant tree strength of lime sulphur will control con-trol the San Jose scale, yet to meet the desire of orchardlsts for other than lime-Bulphur treatments, a number of experiments with sprays were undertaken. under-taken. The purpose of the present article Is to call attention to results secured In the treatment of the scale by the use of a spray containing 2 per cent of lubricating or engine oil emulsified with potash Ash-oil soap. Remarkably Effective Spray. The careful experiments In Florida by W. W. Yothers with various sprays for the control of citrus scale Insects and the orange white fly, as published In Farmers' Bulletin 033, resulted in a formula of engine-oil spray which has been found remarkably effective in view of the small amount of oil used, treatment containing 2 per cent of oil. In order to render the treatment available to orchardlsts who may wish to test it on a small scale, the following follow-ing directions for making the stock emulsion are given : Formula for Stock Emulsion. Red Engine Oil, or oil of similar grade gallon 1 Water do.. Potash Fish-Oil Soap pound 1 The oil, water and soap are placed In a kettle or other receptacle and heated until the contents come to a boll. A brown scum appears on the surface of the mixture as It first begins be-gins to boll. After boiling for a few minutes the brown scum begins to disappear dis-appear and at this stage the kettle Is removed from the fire and the entire mixture Is pumped twice under pressure pres-sure of about 60 pounds while still very hot A proper emulsion cannot be made by stirring nor should the mixture mix-ture be allowed to cool before It Is pumped. Too much pumping will often break up the emulsion. During pumping, pump-ing, ordinary pump packing is burnt up rather quickly by the hot oil mixture. mix-ture. For making the stock emulsion on a large scale an all-metal pump would be necessary. f San Jose Scale With Larvae and Adult Beetles Feeding on Them A, Adult Beetle; B, Larvae; C, Pupa; All Enlarged. namely, 1 per cent, emulsified with potash flsh-oll soap. Mr. Yothers found that any one of several oils of the lubricating type, when thoroughly emulsified and used at the dilution indicated, in-dicated, was quite effective against these scale insects and the white fly, and these sprays have now come -Into large commercial use In Florida. the surprising efficiency of a spray containing such a low per cent of oil suggested the desirability of testing sprays of this character against the San Jose scale. The abundance and destructlveness of the scale In the Bentonville section of Arkansas and the desire of growers for other than lime sulphur sprays, has offered excellent ex-cellent opportunity for testing various dilutions of engine oil sprays against this pest The experiments were 'carried 'car-ried out by A. J. Ackerman, of the office of deciduous fruit Insect Investigations, Inves-tigations, and have included tests of lubricating oils of a strength of from one-half per cent to 4 per cent or 5 per cent, thoroughly emulsified with potash flsh-oll soap. The results showed practically complete killing of the scale by one thorough application of the spray of a strength as low as 2 per cent of oil. Injury by Oil Spray. A point yet to be established In connection con-nection with the present experiments Is the possibly injury from oil spray which may result to the trees, twigs, or fruit buds, and several seasons' experience ex-perience will be necessary before a final decision on this question can b( reached. In view of the experience In Florida In spraying citrus trees In foliage with 1 per cent of oil, it Is felt that dormant deciduous trees will probably prob-ably stand without Injury one annual The stock emulsion contains 00 2-3 per cent of oil. To make a 2 per cent emulsion for use in a 200-gallon spray tank It Is necessary to use 6 gallons of the stock emulsion. Precaution should be taken to prevent pre-vent the stock emulsion from freezing, which occurs at a temperature of about 15 degrees F. above zero. Use Soft Water. In case difficulty is experienced In making a proper emulsion, due to hardness of the water, the water used should be softened by the addition of 1 pound of caustic soda or lye per 100 gallons of diluted spray. The caustic soda should be dissolved in 2 or 3 gallons of water and then added to the spray tank and thoroughly stirred, after which the proper quantity of stock emulsion can be added. Any one of the following, or similar oils, may be used, some one or more of which can doubtless be obtained In most parts of the country: Diamond Paraffin OIL 180 Red Neutral. Jr. Red Engine Oil. Nabob Oil. An oil which has given excellent results re-sults In the experiments herewith reported re-ported has approximately the following characteristics : Sp. gravity (20 C.) 914 Flash Point 173 C. Fire point X C. Viscosity (20 C.) (Engler, H,O100) 17.31 Volatility (loss at 106s C i hrs.) 3.3 per cent. Acid or corroding substances None. Distillation 300370" C 48 per cent by volume. Above 370 C 52 per cent by volume. |