28 



BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 



the Southwick vineyard, 1916 (Plats I and II), the results in the 

 plat sprayed with the higher amount appeared so much better in the 

 final counts that the result could hardly be accounted for by variable 

 infestation. Moreover, checks on either side showed that very little 

 variation existed. In this vineyard at one end, although not through- 

 out the vineyard, the checks showed an infestation very near to 

 total, and probably enough moths had emerged to have totally 

 infested a crop several times as heavy. Under such conditions of 

 extremely heavy infestation the higher amount of poison was more 

 effective. As previously stated in the discussion of results in the 

 Southwick vineyard, the two amounts of poison were apparently 

 equally effective when the first counts were made, but the higher 

 amount withstood the weathering better and was more effectivea gainst 

 the late second brood. 



ADHESIVES. 



The necessity of adding adhesives to the spray mixture became 

 apparent to the writer in the experiments in 1914. It was readily 

 observed that the spray solutions from which an adhesive was absent 

 did not adhere to the waxy skin of the grape berries, and this was 

 undoubtedly one of the chief reasons for the failure to control the 

 grape-berry moth during that season. The solutions to which soap 

 was added appeared to adhere much better, but since this was used 

 only in the last application a definite contrast in the final count was 

 not shown. The counts in plats where soap had been added to the 

 spray solution and applied with "trailers," however, when compared 

 with counts in the nearest checks are consistently better than the 

 others. 



The effect of applying a spray mixture without adhesives was 

 specifically demonstrated in 1915 by a comparison of the results in 

 Plats V and IX in the Miller and Carlburg vineyard, pages 18-19. 



Table 21. — Relative effectiveness of spray mixtures with various adhesives and without 



adhesive. 



(Treatments common to all plats: Arsenate of lead, 3 pounds of paste or U pounds of powder; Bordeaux 

 mixture (3-3-50 formula) applied twice with "trailers.") 





Years 

 tried. 



Num- 

 ber of 

 vine- 

 yards. 



Num- 

 ber of 

 plats. 



Infested grape berries. 



Kind of adhesive used. 



Best 

 plat. 



Adja- 

 cent 

 check. 



Poor- 

 est 

 plat. 



Adja- 

 cent 

 check. 



Aver- 

 age 

 of all 

 plats. 



Aver- 

 age of 

 all ad- 

 jacent 

 checks. 



Resin fish-oil soap 



Kish-oil soap (without 

 resin). 

 Do 



1916 

 1916 only. 



1915, 1916 

 1916 only. 

 1915, 1916 



1916 



1915 



1915 



1 

 2 



3 

 4 



7 

 1 

 1 

 1 



1 

 2 



3 

 4 

 7 

 1 

 1 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 

 2.14 

 1.97 



3.95 

 4.14 

 4.12 

 19.60 

 18.89 

 21.05 



Per ct. 

 55.53 











31.29 



0.47 



25.76 



7.91 



65.94 



42.84 





61.79 



Do 



.89 



50.43 



8.43 



75.10 



50.03 





33.99 













28.80 





1 











28.80 















