October, '21] penny: oil sprays for leaf roller 429 



Oil spraying for leaf -roller control in the apple orchards of the Pajaro 

 Valley during the past few years has been, at best, only partially suc- 

 cessful. The more or less unsatisfactory' results obtained were undoubt- 

 edly due to several factors, one of which, and in the writer's opinion, by 

 far the m.ost important, has been the use of oils not especially adapted 

 to leaf-roller control. 



Various workers along these lines have recommended, at different 

 times, kerosene emulsion and miscible oil spra}'S. Indeed the splendid 

 results obtained by Gillette and Weldon^ in Colorado, by Leroy Childs* 

 in Oregon and by B . B . Fulton^ in Oregon would seem, to indicate that the 

 problem of leaf-roller control has been solved. In the Watsonville 

 section, however, oil sprays that might be classified under the names of 

 kerosene emulsion or m.iscible oils have given practically no control. 

 It occured to the writer that the generally negative results obtained with 

 these types of m_aterials might possibly be due to the fact that the oils 

 used m.ay have been of the Western, or asphaltum, type rather than the 

 Eastern or paraffin type. Air. George M. List'' in reporting the results of 

 the season's spraying in the Canyon City and Penrose districts of 

 Colorado in 1919 states that a considerable difference was found between 

 the killing qualities of a miscible oil prepared from a heavy paraffin base 

 oil and a m.iscible oil prepared from an asphaltum. base oil. With the 

 idea of this difference in mind several tests of a few sam.ples of both of 

 these oils were conducted by the writer during the winter of 1920-1921 

 and it is with the results of these experiments that this paper chiefly deals. 



The several .oils used in the tests included a 42° Baume crude oil direct 

 from the wells of Pennsylvania, Gas oil, a distillate of 34° Baume 

 from the Pennsylvania crude oil and sold by the Standard Oil Company 

 of New Jersey, a 24° Baume California crude oil. Western Shell distillate 

 of 38° Batune, Calol Diesiel engine oil of 24° Baume sold by the Standard 

 Oil Company of California. In addition to these oils two com.mercially 

 prepared emulsions were tested. These were Ortho Crude Oil Emulsion 

 manufactured by the California Spray Chemical Company and Spra- 

 mulsion sold by the Sherwin-Williams Company. Also included in the 



^Gillette, C. P. and Weldon, Geo. P. 1912. The Fruit Tree Leaf-Roller in Colorado. 

 Circular 5. Office of State Entomologist of Colorado. October 1912. 



^Childs, Leroy. Entomological Investigations 1915. Report of the Hood River 

 Branch for 1914-1915. Oregon Agricultural E.xperiment Station. 



Tulton, B. B., 1921. The Fruit Tree Leaf-Roller. Report on Progress of In- 

 vestigations. Third Crop Pest and Horticultural Report, 1915-1920. Oregon 

 -Agricultural College Experiment Station, Jan. 1921. 



*List, Geo. AI., 1920. Fruit Tree Leaf-Roller, Archips argyro-spila Walker. 

 Circular 2S. Eleventh Annual Report of the State Entomologist of Colorado for the 

 year 1919-Aug. 1920. 



