CONTROL, OF GRAPE-BERRY MOTH. 15 



equally as good control. When the third application is made the 

 fruit will usually be unfit for basket market because of excessive 

 spray residue. 



Where a third application is added to the first and second, control 

 is slightly better, 6.8 per cent infestation as compared with 11.3 per 

 cent in 1916 and 0.4 per cent as compared with 4.6 per cent, an aver- 

 age for 1917 and 1918. These differences, however, were not suffi- 

 cient to justify the expense of the third application. 



ONE-SPRAY METHOD. 



One spray application by the trailer method at the time the 

 grapes fi^st touched in the clusters gave an average control of 83 per 

 cent on Catawbas and 94 per cent on Concords as compared with 89 

 per cent control on Catawbas and 97 per cent on Concords when both 

 the first and second sprays were given. This is a good showing for a 

 " one-spray " schedule and this treatment might be the most efficient 

 under some conditions. All results indicate that this one spray may 

 be depended upon to save the crop from ruin by the berry moth. 



In an effort to eliminate entirely the factor of spray residue on 

 fruit for the basket market the spray application directly after 

 grape bloom was tried alone. Data are insufficient on this treat- 

 ment but indicate a marked effect on the final infestation. This 

 treatment has the advantages of being the most important one for 

 rootworm beetle control and of being timely to prevent black-rot in- 

 fection of the young grapes. It may develop that this method will 

 be practical after the infestation of the moth has been reduced by the 

 use of the two-spray schedule for one or more years. Experiments 

 on this point were conducted in several vineyards in 1918 but ad- 

 jacent checks failed to show sufficient infestation to make results 

 conclusive. 



CONCLUSIONS FROM EXPERIMENTS. 



The combinations of the first spray treatment with the second and 

 of the first with the third gave satisfactory control. The third spray 

 added to the first and second increased the effectiveness, but not 

 enough to justify the expense of making the application. The second 

 application alone averaged 83 per cent control and in all cases saved 

 the commercial crop. The first application alone reduced the final 

 infestation appreciably but needs further testing. 



MATERIALS USED IN SPRAYS. 



Arsenicals. 

 arsenate of lead, commercial powder. 



Arsenate of lead in powder form was used throughout this work. 

 Since previous infestation had been extremely heavy in the experi- 

 mental vineyards, the powder was used in 1916 at the rate of 2£ 



