66 



Annals of Horticulture. 



attack than others. * * * * In 1888 I studied this mat- 

 ter very closely, and concluded that as the plum is a smooth 

 fruit, with no calyx cup like that of the apple in which the 

 poison ma}^ lodge, and as the curculio lays its egg anywhere 

 on the smooth rind, the poison would be very easily washed 

 off, or even blown off by the wind. I thus concluded that 

 my want of success was very likely due to a want of thorough- 

 ness. In 1888 I sprayed certain trees three times, at intervals 

 of eight days, and omitted to treat other trees close along 

 side. The benefit from spraying was very marked. * * * 

 The arsenites * * will protect against the plum curculio if 

 they can be kept on the tree or fruit. But in the case of very 

 frequent rains the jarring method will not only be cheaper, 

 but much more effective." 



Weed's second experiments were published* September, 

 1889. Of 24,000 cherries examined from sprayed trees, 360 

 were wormy; while of 24,000 from unsprayed trees, 1,483 

 were wormy, showing a benefit from the use of London purple 

 of 75.6 per cent, of those fruits liable to injury. The con- 

 clusions which he draws from his critical experiments are as 

 follows : 



' ' This series of experiments, carried on through two seasons upon two vari- 

 eties of cherry trees and four varieties of plum trees, during which a grand 

 total of 65,500 cherries have been individually examined, seems to me to 

 confirm the conclusions provisionally announced one year ago, which may 

 now be put in the following form : (1) That about three-fourths of the 

 cherries liable to injury by the plum curculio can be saved by two or three 

 applications of London purple in a water spray, in the proportion of one 

 ounce to ten gallons water. (2) That a sufficiently large proportion of the 

 plum crop can be saved by the same treatment to insure a good yield when 

 a fair amount of fruit is set. (3) That if an interval of a month or more 

 occurs between the last applicatiou and the ripening of the fruit, no danger 

 to health need be apprehended from its use. (4) That spraying with the 

 arsenites is cheaper and more practical than any other known method of 

 preventing the injuries of this insect." 



The report of the United States Entomologist for 1888, re- 

 cently received, records two tests, which were made under 

 his direction. In 1887 Alwood experimented upon Green 

 Gage plums, spraying the trees twice with Paris green. The 

 record shows that considerable benefit was derived from the 

 use of the poison. Osborn, of Iowa, made experiments in 

 1888 upon several varieties of native plums. He finds that 



*Bull. 6, vo 1 . ii. Ohio Exp. Sta. 



