. Bulletin. Natural history; Natural history. November lQ3b FARRAR: EFFECT OF PETROLEU M-Ol L SPRAYS 17 The technical white oils, properl}- emulsi- fied, may be applied with relative safety at any time of the year except in extremely hot weather. Care should be taken in ap- plying oil sprays to blue spruce, compact arbor vitae and all new plantings. Drench- ing of conifer foliage with oil sprays should be avoided. Pines and junipers will toler- ate one or more applications of 1—2 per cent oil emulsion; spruce, arbor vitae and similar tender species from one-half to 1 per cent oil emulsion. One
. Bulletin. Natural history; Natural history. November lQ3b FARRAR: EFFECT OF PETROLEU M-Ol L SPRAYS 17 The technical white oils, properl}- emulsi- fied, may be applied with relative safety at any time of the year except in extremely hot weather. Care should be taken in ap- plying oil sprays to blue spruce, compact arbor vitae and all new plantings. Drench- ing of conifer foliage with oil sprays should be avoided. Pines and junipers will toler- ate one or more applications of 1—2 per cent oil emulsion; spruce, arbor vitae and similar tender species from one-half to 1 per cent oil emulsion. One, or at most two, applications of the proper oil emulsion have given excellent protection for the season against the common red spiders attacking evergreens. ON RASPBERRIES Oil emulsions have been tested on rasp- berries for two seasons. In these tests one mite, Phyllocoptee oleivorus Ashm., by the use of oil sprays. San Jose Scale Aspidiolus perniiiosHs Com. For control of San Jose scale, the most efficient emul- sions contained relatively large oil droplets associated with high wetting and quick breaking properties. Oil emulsions have been used against scale since about 1878. Because of the wide distribution of San Jose scale it has received much attention in the development of control measures. Great impetus was given to the study of oil emulsions for this insect following the complete destruction of many orchards by this scale from 1919 to 1922, according to Ackerman (1923), Davis (1924) and Chandler, Flint & Huber (1926).. Fig. S.—Soluble oil 16. X490. to three applications of stock oil 200 at 1 per cent concentration gave excellent con- trol of red spider without injury to the foli- age. The sprays were applied with a power sprayer at a pressure of 200 pounds. For satisfactory results it was necessary to use care to wet tlie under surfaces of all leaves. For this purpose a short rod carrying three fine nozzles turned upward permitted ex- cellent spraying from the
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