CONTROL OF THE GRAPE-BERRY MOTH. 



19 



Table 9.— Percentage of infestation in experimental plats, Miller and Carlburg vineyard, 



North East, Pa., 1915. 





First brood. 



Second brood. 



Plat No. 



Num- 

 ber of 

 vines. 



Num- 

 ber of 

 clus- 

 ters. 



Total 

 berries. 



Infest- 

 ed ber- 

 ries. 



Infesta- 

 tion. 



Num- 

 ber of 

 vines. 



Num- 

 ber of 

 clus- 

 ters. 



Total 

 berries. 



Infest- 

 ed ber- 

 ries. 



Infesta- 

 tion. 



I 



25 



25 

 25 

 25 

 25 

 25 

 25 

 25 

 25 

 25 

 25 

 25 



601 

 544 

 492 

 460 

 575 

 796 

 712 

 661 

 561 

 716 

 695 

 792 



14,028 

 12,550 

 11,235 

 13,692 

 13, 705 

 19,544 

 22, 736 

 18, 508 

 16, 269 

 21,480 

 20, 850 

 23,882 



450 



414 



519 



343 



289 



479 



1,264 



795 



901 



1,024 



1,013 



3,533 



Per ct. 

 3.21 

 3.29 

 4.53 

 2.51 

 2.11 

 2.45 

 5.99 

 4.18 

 5.53 

 4.53 

 4.86 

 14.87 



20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 20 

 10 



481 

 435 

 397 

 368 

 460 

 637 

 570 

 529 

 459 

 513 

 556 

 634 

 340 



10, 822 

 9,640 

 9,088 

 10, 956 

 10, 960 

 15, 625 

 16, 587 

 14, 783 

 13, 005 

 15,441 

 14,430 

 19,135 

 9,380 



847 



951 



2,887 



432 



967 



1,188 



5, 523 



2,793 



2,738 



3,152 



3,958 



11, 803 



4,710 



Per ct. 

 7 91 



II 



9 86 



Ill 



31 77 



IV 



3 94 



V 



9 56 



VI 



7 60 



VII 



33 31 



VIII 



18 89 



IX 



21 05 



X 



20 41 



Check A 



28 80 



Check B *...'. 



61 67 



Check C 



50 21 

















In spite of the exceedingly adverse weather conditions at the time 

 of spraying, all plats but one on which arsenate of lead with soap had 

 been applied twice with "trailers" (Plats I, II, IV, V, and VI) showed 

 a satisfactory reduction of the grape-berry moth from a commercial 

 standpoint. In one plat where rain followed immediately after the 

 second spray application (Plat III) the results must be disregarded. 

 The rain also probably reduced the efficiency of control in Plat II, 

 which was sprayed just before Plat III, and to a less degree may have 

 affected others; but the results showed that when the spray had 

 time to dry on the grape berries before rain, a fairly satisfactory con- 

 trol could be secured. Failure to control resulted in plats where 

 spray was applied with "set nozzles" instead of "trailers" (Plat X), 

 where the soap was omitted from the spray mixture (Plat IX), and 

 where flour paste was used as adhesive instead of soap (Plat VIII). 

 Bordeaux mixture and soap were used without arsenate of lead (Plat 

 VII) and no effect, repellent or insecticidal, was noted. Nicotine 

 sulphate appeared to add nothing to the effectiveness of the solution 

 (Plats V and VI). Laundry soap (Plats I, IV, and VI) and fish-oil 

 soap (Plats II and V) were both used apparently without distinct 

 advantage for either. The plat sprayed with 5 pounds of arsenate 

 of lead (paste) to 50 gallons of liquid (Plat II) was much more heavily 

 infested than the plat sprayed with only 3 pounds of arsenate of 

 lead (paste) to 50 gallons (Plat IV), but as the second application of 

 spray on Plat II was closely followed by rain the infestation in this 

 plat was probably also somewhat heavier naturally. (Compare check 

 plats B and C with A.) 



