52 PEACH LEAF CURL! ITS NATURE AND TREATMENT. 



As early as 1890 the etfectiveness of lime, .sulphur, and salt against 

 curl appears to have been observed in Oregon. Mr. J. D. Whitman, 

 of Medford, Oreg., who was horticultural commissioner for the third 

 district of that State, wrote under date of January 27, 1894, that four 

 years' observation as commissioner had demonstrated beyond a doul^t 

 that a spray of lime, sulphur, and salt is an effectual remedy for leaf 

 curl. He states that the application in every instance was made for 

 the purpose of destroying the San Jose or pernicious scale, and gener- 

 ally on only a portion of the orchard, the other portion showing the 

 curl as usual. 



The first practical (experiments with copper sprays on dormant trees 

 for the control of curl, after the sprays applied by Mr. Sol. Runyon 

 in 1886 and 1887, were conducted, so far as learned, in the year 1890. 

 The sunnner use of these sprays had been tested in Australia, and 

 pr(>bal)ly elsewhere, for several years, but with slight success in the 

 control of curl. 



About the 1st of December, 1889, Mr. L. E. Benton, then of Berke- 

 ley, Cal. , wrote to the United States Department of Agriculture for 

 information relative to the nature and treatment of curl. .These inqui- 

 ries were answered at length, the literature on Exoascus deformans 

 being quite fully cited. No method of controlling this disease was 

 then known at Washington, and as winter spraying had not yet reached 

 its present importance, the recommendations for treatment were nec- 

 essarily inadequate, and were based upon the then accepted views 

 respecting the strict perennial nature of the mycelium of the fungus, 

 and the consequent difficulty of controlling the parasite by sprays. 



After gathering such information as he desired, Mr. Benton insti- 

 tuted a series of spraying experiments in the university orchard at 

 Berkeley in the spring of 1890. The work done by Mr. Benton, 

 although limited in extent, was of the utmost practical importance, as 

 well as of great theoretical interest. A summary of his results was 

 published in August,- 1890.^ Three copper sprays were tested, the 

 ammoniacal copper carbonate, basic copper acetate solution, and Bor- 

 deaux mixture. The ammoniacal copper carbonate was applied on 

 February 28, 1890, before the opening of the buds. All three of the 

 spra3^s mentioned were also tested soon after the leaves started. The 

 results demonstrated that winter treatment of the trees with the salts 

 of copper will effectivel}^ control the disease, but that summer treat- 

 ment will not control it, and also that infection of the spring growth 

 b}^ perennial mycelium was the exception and not the rule with this 

 disease — facts of the utmost practical importance for the orchardist. 

 Mr. Benton's studies likewise led him to the view that the mycelium, 

 passing from infected leaves to the stem, is able to infect new foliage 



1 Pacific Rural Press, Aug. 2, 1890. 



