26 



BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 



rery poor adhesive. Arsenate of lead at the rate of 2£ pounds 

 (powder) to 50 gallons of liquid (Plat II) appeared to be little more 

 effective at the increased strength than when used at the rate of 1 J 

 pounds to 50 gallons (Plat I). 



Plats where the first application was made with "set nozzles" 

 (Plat IV) and where it was omitted altogether (Plat V) showed a 

 fairly satisfactory reduction of infestation. It should be noted that 

 the infestation in the checks in these two plats was not as heavy as 



that in the checks adjacent to 

 Plats I, II, and III. 



EXPERIMENT IN THE PHILLIPS VINEYARD, 

 NORTH EAST, PA., 1916. 



A/0/P7V? 



*f£-^r 



£XST 



>SOCT/Y 



Fig. 9. — Diagram, showing the arrangement of ex- 

 perimental plats in the vineyard of Mr. M. D. 

 Phillips, North East, Pa., 1916. The sprayed plats 

 are marked with Roman numerals and the check 

 plats with letters. (Original.) 



infestation unsprayed checks were 

 The arrangement of plats is shown 



This vineyard consisted of Ni- 

 agara grapes, whereas in all other 

 vineyards in which experimental 

 spraying was done the grapes were 

 Concords. It covered about two 

 acres, irregular in shape, and was 

 divided into two plats. To guard 

 against natural irregularities of 

 left in each of the three corners, 

 in the diagram (fig. 9). 



Table 18. — Spray mixtures used and methods and dates of application, Phillips vine- 

 yard, North East, Pa., 1916. 





Dates sprayed. 



Arsenate 

 oflead 

 (paste). 



Bordeaux mixture. 



Laundry 

 soap. 



Water. 



Method of 

 application. 



Plat No. 



Lime. 



Copper 

 sulphate. 



1 



I ' July 5 and 22.. 



II i July 5 and 22.. 



Pounds. 

 5 

 3 



Pounds. 

 3 

 3 



Pounds. 

 3 

 3 



Pounds. 

 1 

 1 



Gallons. 

 50 

 50 



"Trailers." 

 Do. 



Table 19. — Percentage of infestation in experimental plats, Phillips vineyard, North 



East, Pa., 1916. 





Number 



of 

 clusters. 



Total 

 berries. 



First brood. 



Second brood. 



Plat No. 



Infested 

 berries. 



Infesta- 

 tion. 



Infested 

 berries. 



Infesta- 

 tion. 



i 



400 

 400 

 200 

 200 

 200 



15, 200 

 16,000 

 7,200 

 7,600 

 8,000 



436 

 107 

 423 

 1,186 

 289 



Per cent. 

 2.87 

 .67 

 5.88 

 15.61 

 3.11 



479 



142 



5,135 



6,114 



4,034 



Per cent. 

 3.15 



II 



.89 



Check A 



71.32 



Check B 



80.45 



Check C 



50.43 







