Plant Diseases and Insects. 



65 



benefits derived from the use of Paris green upon stone fruits, 

 but he had not made experiments. 



The first publication of a well considered experiment was 

 made by Weed in July, 1888.* Thirty-five Early Richmond 

 cherry trees were sprayed with London purple, and other 

 trees in the orchard received no treatment. Upon eight of 

 the sprayed trees and seven of the unsprayed trees the cher- 

 ries were picked and individually examined. Of 8,000 cher- 

 ries from the sprayed trees, 280 were wormy; while of 7,500 

 from the unsprayed trees, 1,086 were wormy, showing a per- 

 centage of benefit in favor of spraying of 75.8 per cent. His 

 conclusions were as follows : " 1. That three-fourths of the 

 cherries liable to injury by the plum curculio can oe saved by 

 two or three applications of London purple in a water spray 

 made soon after the blossoms fall. 2. That if an interval of a 

 month occurs between the last application and the ripening of 

 the fruit no danger to health need be apprehended from its 

 use. As a precautionary measure, however, I would advise 

 in all cases, and especially when there are few r rains during 

 this interval, that the fruit be thoroughly washed before it is 

 used." In October, 1888, Cook published new experiments."}" 

 A few trees were sprayed three times, June 6th, 12th and 20th. 

 The fruit was unusually free from injury, although "cherry 

 and apple trees near by, not sprayed, suffered seriously." 

 "From these experiments, and those of former years, I con- 

 clude that while one application will not save our plums and 

 cherries and prevent apples from being stung, two or three 

 applications may be of signal advantage." In July, 1889, 

 Forbes recorded valuable experiments in the same direction, j 

 He states that "there can certainly be no further question of 

 the liability of the curculio to poisoning by ver}^ moderate 

 amounts of either London purple or Paris green while feed- 

 ing on the .leaves and fruit of peach or plum." Cook has ex- 

 perimented again during the past season, and he gives a re- 

 view of his experience^ "For six or seven years I have 

 sprayed plum trees once and even twice with no apparent ef- 

 fect. Test trees, close beside the trees sprayed, and that were 

 not treated, were as free from attack as were the trees that 

 were sprayed, and the trees treated were no more exempt from 



*Bull. 4, second series, Ohio Exp. Sta. 

 JInsect Life, ii. 3. 



tBull. 39, Mich. Exp. Sta. 

 gBull. 53, Mich. Exp. Sta. 



