70 The Spraying of Plants. 



sible to poison some of them, but the benefit to be derived from 

 such is as yet unsettled." 1 



In 1888 Weed made the first report of an experiment planned 

 upon a large scale, in which the method could be apparently 

 well tested. 2 London purple, used at the rate of one-half pound 

 to fifty gallons of water, was applied to seventy-five Early Rich- 

 mond cherry trees. Three applications were made. As a re- 

 sult, " it was found that 14.5 per cent of the unsprayed fruit 

 gave evidence of curculio attack, while 3.5 per cent of the 

 sprayed fruit was injured. There was consequently a percen- 

 tage of benefit of 75.8." The same year similar experiments 

 were made upon plums and pears, but, as stated in the record 

 (Seventh Ann. Rept. Ohio Agric. Exp. Sta. 134-150), the oppor- 

 tunities for a satisfactory test were not so good as with the 

 cherries, so that although the fruit was saved, less stress w r as 

 laid upon the result. 3 



Professor Herbert Osborn, of Iowa, also tried to solve the 

 problem during this year. There was a trifling difference be- 

 tween the sprayed and unsprayed plots in favor of the former, 

 but it seems that two species of insects were at work, so that no 

 definite conclusions can be drawn regarding the value of the 

 treatment against the plum curculio alone. 4 



The experiments made by Professor Cook during 1888 were 

 somewhat more extended than those of preceding years, but- 

 still rather limited. The trees, cherries and plums, were 

 sprayed three times, June 0, 12, and 20, and the results obtained 

 appeared to warrant the following conclusions : " From these 

 experiments, and those of former years, I conclude that while 

 one application will not save our plums and cherries, and pre- 

 vent apples from being stung, two or three applications may be 

 of signal advantage. 6 



In 1889, Cook repeated his former experiments. At the 

 close of the work his opinion was decidedly against the appli- 

 cation of arsenites. He says : " All the trees were severely 

 attacked and all the plums were lost. . . . The arsenites will 



1 Ann. Rept. U. S. Com. of Agric. 1888, 70. This is the first published state- 

 ment of his work. 



2 Ohio Agric. Exp. Sta. Bull. 4, second series, 39. 



3 Weed, American Naturalist, 1891, Jan. 70. 



* Ann. Kept. U. S. Com. of Agric. 18SS, 72-75. 

 Mich. Agric. Exp. Sta. Bull. 39, 9. 



