50 PEACH LEAF CURL: ITS NATURE AND TREATMENT. 



It will be seen by the preceding outline that strong fungicidal spra^^s 

 were in general winter use upon peach trees throughout much of Cali- 

 fornia in the j^ears 1880 to 1885, during which time the peach or- 

 chards of many portions of the State were badly affected Ijy curl. In a 

 report by Mr. W. G. Klee, who inspected the orchards in many counties 

 of California from July to September, 1886, it is stated that in Alameda 

 County the cultivation of peaches must be confined to such varieties as 

 are very little subject to leaf curl; in Santa Cruz County, that "peaches, 

 of course, are subject to curly leaf, and can not, as a general thing, be 

 considered profitable;" and that in the Santa Rosa Valley the peach is 

 "of course subject to curly leaf."^ 



As peach leaf curl was quite prevalent throughout California in 

 1880-85, and as a large number of peach growers treated their dor- 

 mant trees with fungicidal sprays during that period, it is not strange 

 that they soon learned that the winter sprays prevented curl. Mr. I. H. 

 Thomas, of Visalia, informed the writer' that it was about the year 

 1885 that he noticed that the orchards sprayed with the lime, sulphur, 

 and salt solution were entirely free from leaf curl, while orchards con- 

 tiguous were affected so badly that all the foliage fell off'. 



In 1886 Mr. W. G. Klee said,'' when speaking of an inspection he 

 made of the orchard of Mr. A. Block, of Santa Clara, Cal. : "A treat- 

 ment of peaches affected with curly leaf attracted my attention. Trees 

 not subjected to this treatment were in very poor condition, while the 

 others, favored with it, were in fine, health}- bearing." Mr. Block saj's 

 respecting this work* that he was making experiments for the destruc- 

 tion of scale insects when he detected a perceptible- difference in the 

 amount of curl on the treated and the untreated trees. He thinks 

 this was one or two years before Mr. Klee had seen his trees in 1886. 

 After having noticed the action of the sprays applied for scale in the 

 prevention of curl, he went to work to ascertain what particular 

 ingredient caused the prevention of the fungous disease. These direct 

 experiments, Mr. Block states, were carried out on a row of 23 ti'ees 

 in his orchard. Among the chemicals tested were caustic soda, caustic 

 potash, carbolic acid, tobacco, and sal soda, all more or less combined 

 with whale oil. Among the numerous sprays used, Mr. Block thinks 

 that a strong solution of caustic soda gave the best results. All these 

 sprays were applied while the trees were dormant.^ The stronger 



^Klee, W. G., Eeports and Papers by the Inspector of Fruit Pests, read at Sacra- 

 mento, November, 1886, Kept. Cal. State Bd. Hort., 1885-86, pp. 344, 347, 349, 350. 



^Letter dated Yisalia, Cal., Sept. 6, 1899. 



»L. c, p. 347. 



* Letters dated Santa Clara, Cal., Sept. 1 and 10, 1899. 



^ It may be noted that whale oil soaji was thus used Ijy 3Ir. Block with success 

 against curl in 1885 and 1886. Prof. L. R. Taft, in a letter dated Agricultural College, 

 Mich., Aug. 31, 1899, says that he had good results in the treatment of curl with 

 limewater, lye, and whale oil soap. (See also records of experiments by the writer 

 with milk of lime, etc.) Mr. F. M. Webster reports satisfactory results with whale 



