14 



BULLETIN 837, U. S. DEPARTMENT OF AGRICULTURE. 



In Table IV are brought together all of the data bearing on the 

 time and number of spray applications, arranged by vineyards and 

 varieties. This table provides for a comparison of the plats within 

 each vineyard by reading from top to bottom, as well as a com- 

 parison of the plats receiving similar spray treatment in the different 

 vineyards, by reading across.. While the comparison between plats 

 within a vineyard is relatively consistent, considerable variations 

 exist between vineyards. A study of the column of averages shows 

 satisfactory commercial control to have been effected in all plats 

 which received either two or three spray applications with the excep- 

 tions of the first two plats. These two plats illustrate the necessity of 

 timeliness of spraying and adhesiveness of spray material, since in 

 1917 the more timely spray treatment, and the use of resin fish-oil 

 soap throughout, reduced the average infestation from 19 per cent 

 in 1916 to 5 per cent in 1917. 



RELATIVE EFFICIENCY OF DIFFERENT TIMES AND NUMBERS OF SPRAY 



APPLICATIONS. 



Table V. — Summarised results from Table IV — relative efficiency of different 

 times and numbers of sprat; applications, 1916, 1917, and 1918 — Arsenicals 

 applied in Bordeaux mixture and soap solution* 





a 



o 

 o 



3 



u 



a> 



ea 

 >. 



03 



s 



•d 



o 



■d 



Dm 

 ft 03 



03 03 

 11 



■eg 









Percentage of grape 



berries infested, aver- 





u 



03 



ft-*? 



03 ?3 



h d 

 a3 



■94 



§1 



03 o 



H 

 fl'Sb 

 oj 03 





03 

 03 



a 



03 



ages 



of all experiments, 1916, 1917, 



L918. 



1 



08 



Catawbas. 



Concords. 



Ives. 



& 

 ft 









8 







03 



o 



o 





-CO 



> 



C"o3 



-d 



> 







O 

 U 



03 



p. 



a 



03 

 ft 



d 



a 



a 



1 



ft 

 ■d 



o 



.a 



H 



-d 



a 



o 

 o 



2 



d © 



1" 



-*-3 



03 

 03 



J5 



a 

 d 



a 



03 

 k> 

 03 

 Eh 



ft 



03 



o 



03 



■d* 



03 

 t>> 

 03 



tH 



ft 



3 



03 



03 



03 



k> 



03 



ft 



03 



o 



03 



-d 



fc 



h 



co 



^ 



<< 



fH 



2; 



£ 



CO 



■"1 



CO 



-«) 



CO 



■""1 



2 



X 



X 





24 



1916,1917 



9 



ii 



11.35 



79.22 



3.04 



48.20 



2.11 



39.67 



2 



X 

 X 



X 



X 



24 



l 1 



1916 

 1917,1918 



3 



11 



4 

 14 



18.99 

 4.67 



83.98 

 64.92 



2.31 



.82 



22.67 

 26.00 







2 



1.53 



16.85 



2 . 



X 



X 

 X 

 X 



X 

 X 



X 

 X 



1-i 

 2| 

 24 



24 

 l| 

 1 



14 



1917,1918 



1916 



1916 

 1917,1918 



5 

 3 

 6 

 5 



6 



4 

 8 

 5 







1.11 

 2.66 

 1.32 

 1.21 



35.64 

 22.67 

 66.26 

 52.96 



2.07 



30.14 



2 



5.78 



6.86 



.41 



79.27 

 79.98 

 42.00 





3 



X 

 X 







3 



1.31 



17.92 



1 





X 





1916,1917 

 1917,1918 



1918 



1918 



6 

 4 

 2 

 2 



7 

 4 

 2 

 2 



16.90 



79.77 



6.21 

 13.30 



31.91 

 26.40 



7.23 



8.75 

 2.08 

 4.20 



39.67 



1. . . 



X 

 X 



9.89 



2. . .. 



X 



X 





7.39 

 25.67 



62.36 



82.82 



6.93 



1. . . 







10.04 



1 









A comparison of the combinations of the first and second sprays 

 with first and third sprays shows little choice between them as far 

 as berry-moth control is concerned. Since the combination of the 

 first and second sprays leaves the fruit practically free of all spray 

 residue at harvest time and since the second spray is more easily ap- 

 plied than the third because of lighter grape foliage, this combina- 

 tion of the first and second application is preferred by the writers. 

 It is important to know, however, that if for any reason the second 

 spray can not be made, the third may be applied and will give about 



