30 



BULLETIN 805, U. 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 first-hrood nymphs of the apple leaf- 

 hopper, West Chester, Pa., 1916. 



Plat 

 No. 



Spray material. 



Strength. 



Date of 

 applica- 

 tion. 



Number 

 of trees 

 treated. 



Nymphs 

 killed. 



1 



40 per cent nicotin sulphate and fish-oil soap 



1-1,000 

 2-50 



1-1,400 

 2-50 



1-1,400 



1-1,500 

 1^50 



June 12 



...do.... 



...do.... 

 ...do.... 



300 



300 



300 

 300 



Per cent. 

 S9 



2 



40 per cent nicotin sulphate and fish-oil soap 



98 



3 



40 per cent nicotin sulphate 



94 



4 

 5 



40 per cent nicotin sulphate Ume-sulphur solution 



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 

 sHghtly 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 27year-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-brood nymphs of the apple leaf- 

 hopper. West Chester, Pa., 1916. 



Plat 

 No. 



Spray material. 



Strength. 



Date of 

 applica- 

 tion. 



Number 



trees 

 treated. 



Nymphs 

 MUed. 



40 per cent nicotin sulphate. 



do 



do 



40 per cent nicotin sulphate and fi.sh-on soap. 



Fish-oil soap 



Kerosene emulsion 



Check, unsprayed 



1-1,400 

 1-1, 500 

 1-1, 600 

 1-1, 500 



2-50 



l-i 



June 15 



...do 



...do 



}june 16 



do.... 



5 per centi 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 Httle 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, 



