EXPERIMENT STATION WORK WITH INSECTICIDES. 243 



Tn Illinois the California and Oregon washes, prepared according 

 to various formulas, have been subjected to thorough tests in com- 

 bating San Jose scale and related insects." On account of the fact 

 that the California wash was generally sui)posed to be ineffective in 

 the East by reason of the freciuent rains, the Illinois Station under- 

 took experiments to test the effects of rain on both the California and 

 Oregon washes. During these experiments it was found that fre- 

 quent short rains did not visibly diminish or delay the action of the 

 Oregon wash, even when such rains occur within five days after the 

 apjilication of the insecticide. The California wash in the earlier 

 experiments of the Illinois Station, prepared according to the for- 

 mula 15-15-15-50, appeared to be somewhat less effective than the 

 Oregon wash and more susceptible to the action of rains during the 

 first few days after its application. The conclusion was therefore 

 reached from the first experiments of this station that the California 

 and Oregon washes are no less eflFective in the East than on the 

 Pacific coast, and are very satisfactory insecticides in the hands of 

 ordinary orchardists. These washes were noted as possessing the 

 great advantage of harmlessness to the tree and of Ijeing cheaper 

 than the applications of kerosene. In a further test of sulphur mix- 

 tures by the same station fumigation with whale-oil soap and kero- 

 sene emulsion were compared with the California wash. All proved 

 to be effective destroyers of San Jose scale under favorable conditions, 

 but fumigation was found to be restricted to snuill trees and to mild, 

 quiet weather. The California wash as well as fumigation was 

 found to be perfectly safe to all trees and shrul)s if applied after the 

 leaves had formed, but whale-oil soap and kerosene emulsion were 

 sometimes harmful. Fumigation was the most expensive of the four 

 methods, while the California wash and kerosene emulsion cost least. 

 In point of convenience kerosene enndsion and California wash were 

 given preference. On the whole the California wash was considered 

 the best insecticide for common use against the San Jose scale during 

 the winter. The latest recommendations of the Illinois Station are to 

 the effect that the owners of infested trees and shrubs should spray 

 promptly, using the Oregon wash with a formula calling for 15 

 pounds lime, 15 pounds sulphur, and U pounds copper sulphate 

 per 50 gallons water or with the California wash made in the same 

 manner after substituting 15 j)ounds of salt for the blue vitriol. 

 These washes are never to be applied while the tree is in leaf, i)ut 

 rather late in winter or early spring before the buds open. AVhen 

 usi'd in this manner they have j)i-()ved harndess to trees and shrul)s 

 of all kinds in Illinois. 



1 Illinois Sta. Huls. 71, SO; Circ. 85. 



