THE EUROPEAN ELM SCALE IN THE WEST. 



CONTROL EXPERIMENTS. 



Table 1. — Experiments performed upon the European elm scale. 



13 



No. 



Date. 



Spray material. 



Dilution. 



Trees. 



Scales 

 killed. 



Remarks. 



1 



Apr. 15 

 Apr. 19 

 Apr. 26 



May 14 



Dec. 3, 

 Mar. 5, 



do.. 



do.. 



do.. 



Apr. 12 



Jan. 19 



do.. 



do.. 



Apr. 12 



do.. 



Dec. 3, 



Mar. 5, 



Jan. 19, 

 do.. 



Mar. 4, 



do.. 



do.. 



do.. 



Apr. 19 



do.. 



do.. 



1918 

 1918 

 1918 



1919 



1918 

 1919 



Water 



100 to 160 pounds 



pressure. 

 50 pounds pressure. 



.do 



191 

 2 

 1 



2 



3 

 3 

 8 

 3 

 1 

 3 



4 

 3 

 3 



3 



3 



5 

 3 

 4 

 2 

 4 

 3 

 3 

 4 

 2 

 2 

 1 



Per 

 cent. 

 85 



95 



80 



97 



60 

 60 

 60 

 25 

 65 

 60 



60 

 20 

 20 



5 



20 



10 

 99 

 98 

 100 

 30 

 20 

 97 

 99 

 40 

 95 

 C8 



Used file engine and 



2 



do 



hose, large trees. 

 Used garden hose and 



3 



do 



nozzle, small trees. 



Used garden hose, ex- 

 tension rod, and 12- 

 foot platform, medi- 

 um-sized tree. 



Used garden hose, 

 small tree. 



Hibernating larvae. 



4 



do 





5 



Distillate emulsion 



Crude-oi 1 emulsion 



Distillate emulsion 



Kerosene emulsion 



Distillate emulsion 



do 



lto5 



6 

 7 



lto4 



Do. 

 Do. 



8 





lto4.5 



Do. 



9 





lto4. ... 



Do. 



10 



1919 

 1920 



.do 



Trees in leaf, slight 



11 



Crude-oil emulsion 



Distillate emulsion. . 

 .....do 



1 to5 



burning. 

 Hibernating larvae. 



12 



1 to 4... 



Do. 



13 





1 to3 . 



Do. 



14 



1919 



Fish-oil soap 



1 pound to 7 gal- 

 lons. 

 1 to 9 . 



Trees in leaf, no burn- 



15 



Lime-sulphur . . . 



ing, young females. 

 Do. 



16 



1918 

 1919 

 1920 



Miscibleoil,33°... 

 Miscibleoil,28°.._ 

 do 



ltol2 



Hibernating larvae. 



17 



1 to 7 



Do. 



18 



do . 



Do. 



19 



do 



1 to9 



Do. 



20 



1920 



Miscibleoil,33°... 



. .do 



Do. 



21 



do 



1 tol2 



Do. 



22 





Miscibleoil,28° 



.do 



lto9 



Do. 



23 





It0l2 



Do. 



24 



1920 



do 



.do 



ltol5 



Young females. 



25 



.do 



Do. 



?6 





.do 



1 to 12 



Do. 













In experiment No. 1 the trees were large, in No. 3 the tree was 

 medium-sized, and in all the others the trees were small and could 

 be sprayed from the ground with an ordinary bucket pump. This 

 was the apparatus used, except in the first four experiments, where 

 water was applied. All but one of the experiments were performed 

 at San Jose, Calif., upon the elms growing on the normal school 

 grounds. 



WASHING EXPERIMENTS. 



Washing the scale from the elm trees with a solid stream of water 

 was experimented with, since fairly good results had been obtained 

 in this manner by Prof. S. B. Doten, of Nevada (<?, 4-)- In fact, his 

 results seemed more satisfactory than spraying with a lime-sulphur 

 solution or kerosene emulsion. 



In preliminary experiments, it was found that the best nozzle 

 that could be obtained for the usual pressure of 50 pounds to the 

 square inch on the garden hose was one with a 3/16-inch outlet and 

 a long taper. 



