168 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 7 



equally effective whether applied one pound of sulphur to three 

 gallons, or one pound to six gallons. I noted the same in some tests 

 at Clarkston in 1908, but discovered that here and there on certain 

 branches were individuals that were still alive a month after spraying, 

 although as well covered by the spray as the others. This experiment 

 was repeated in 1910 at Walla Walla, Washington, with the same 

 results, except that a considerable number of the scales, averaging 

 more than 10 per cent, was still alive. 



For several years the San Jose scale has been increasingly prevalent 

 in the Clarkston Valley. The growers have erected a local sulphur- 

 lime factory in the effort to control faulty preparation of the spray; 

 they have drenched their trees by power spraying in the endeavor 

 to overcome faulty application, and yet the scale has uncontrollably 

 spread. Some branches I examined in 1912, that had been given 

 three appHcations, at intervals of about two weeks, using a hot sulphur- 

 lime of the .30:40:100 formula, showed 50 per cent, of the scales still 

 alive under the crust of dried spray. 



This led us last spring at the Washington Station to try identical 

 solutions in a number of localities, and then to make bi-weekly counts 

 of the proportion of living and dead scales, — an experiment we were 

 able to carry on through the help of the Adams Fund. Clarkston, 

 Walla Walla, Kennewick, Prosser, Sunnyside, North Yakima and 

 Wenatchee were the localities selected, comprising an air-line circuit 

 of four hundred miles, and at each place materials from the same stock 

 were used. In the course of the bi-weekly visits made to these places 

 upwards of 350,000 scales were individually examined under the 

 binocular microscopes, by my assistant, M. A. Yothers and myself. 



Percentage of Living Scales 



1. Sulphur-lime 5° 



2. Sulphur-lime 3° 



3. Sulphur-lime 2° 



4. Sulphur-lime, l:j:5 



5. Sulphur-Ume, 1:2:5 



6. Spramulsion 



7. Orchard Brand Oil Spray 



8. Fuel oil emulsion 



8 

 13 



17 

 4 

 8 



12 

 

 



For the sake of brevity the accompanying table shows the results 

 obtained at but three of the places, North Yakima, Sunnyside and 

 True's orchard, Clarkston, selected because the conditions for the 



