30 



BULLETIN 805, IT. S. DEPARTMENT OF AGRICULTURE. 



being so placed that it was possible to spray the undersides of the 

 leaves of two rows of trees from both sides. It was necessary to 

 use eight nozzles on this machine and consequently the pressure was 

 greatly reduced. 



Table XX indicates the results obtained with the compressed-air 

 sprayer against the first-brood nymphs: 



Table XX. — Spraying experiments against the Jlrst-brood nymphs of the apple leaf- 

 hopper, West Chester, Pa., 1916. 



Plat 

 No. 



Spray material. 



40 per cent nicotin sulphate and fish-oil soap . 

 40 per cent nicotin sulphate and fish-oil soap. . 



40 per cent nicotin sulphate 



40 per cent nicotin sulphate lime-sulphur solution. 



Check; unsprayed 



Strength, 



Date of 

 applica- 

 tion. 



1-1,000 

 2-50 



1-1,400 

 2-50 



1-1,400 



1-1,500 

 1J-50 



June 12 

 ...do..., 



.do. . . 



..do... 



Number 

 of trees 

 treated. 



300 

 300 



300 

 300 



Nvmphs 

 killed. 



Per cent. 

 99 



It will be noted that good results were obtained on all plats of this 

 experiment from the use of 40 per cent nicotin sulphate, though 

 slightly better control was obtained when soap was added as a 

 spreader. 



The hand-power outfit with "set nozzles" was used in an experi- 

 ment on several thousand 2-year-old trees which were heavily in- 

 fested with first-brood nymphs. 



The results are shown in Table XXIV. 



Table XXI. — Spraying experiments against the first-broo d nymphs of the apple leaf- 

 hopper, West Chester, Pa., 1916. 



Plat 

 No. 



Spray material. 



Strength. 



Date of 

 applica- 

 tion. 



Number 



trees 

 treated. 



Nvmphs 

 killed. 



40 per cent nicotin sulphate. 



do 



do 



40 per cent nicotin sulphate and fish-oil soap. 



Fish-oil soap 



Kerosene emulsion 



Check, unsprayed 



1-1, 400 

 1-1, 500 

 1-1, 600 

 1-1, 500 



\ 2-50 

 1-8 

 5 per cent 



June 15 



...do 



...do 



June 16 



...do.... 

 ...do.... 



4,000 



10,000 



4,000 



13,000 



4,000 

 4,000 



Per cent. 

 92 

 91 

 89 



97 



50 

 45 

 



As will be noted, the best results in Table XXI were obtained on 

 plat 4 where 40 per cent nicotin sulphate at a strength of 1-1,500 

 was combined with soap. The nicotin solution when used alone 

 proved a little less effective than when the soap was added to the 

 mixture as shown in plats 1, 2, and 3. A potash fish-oil soap solu- 

 tion at a strength of 1 pound of soap to 8 gallons of water (plat 5) 

 gave poor results and was but little more valuable than a 5 per cent 

 kerosene emulsion which was tried on plat 6. 



