CONTEOL OF THE GRAPE-BEERY MOTH. 



37 



The umbrella system with the canes bent down from the upper 

 wire to the lower presented a difficulty in spraying similar to that of 

 the Chautauqua system, although it seemed slightly easier to spray. 



The high-renewal system was much more difficult to spray owing 

 to the tendency of the rods to catch in the numerous upright shoots. 



Summary of Important Factors in Spraying Practice. 



The most important factors in spray practice to control the grape- 

 berry moth, shown by the final counts in 28 of the 49 experimental 

 plats of three years, are summarized briefly in Table 24. Factors of 

 minor importance such as a complete comparison of adhesives and 

 value of nicotine sulphate are omitted. In addition, the plats in the 

 experiment in the Phillips vineyard, 1914, because of the erratic 

 infestation, and the plats in the Miller and Carlburg vineyard, 1915, 

 which were affected by rain, are excluded. 



Table 24. — Relative efficiency of spraying measures tried. 



Spray mixture, method of application, and spray schedule fol- 

 lowed. 



Years 

 tried. 



Number 



of 



sprayed 



plats. 



Infested fruit. 



sprayed 

 plats. 



Average 

 in adja- 

 cent un- 

 sprayed 

 checks. 



I. Arsenate of lead, paste, 3 pounds, or powder, 1J pounds; 

 laundry soap. 1 pound; Bordeaux mixture, 3-3-50. Ap- 

 plied with "trailers" immediately after blossoms had 

 fallen and again when grape berries were just touch- 

 ing (or about 2 weeks later) 



II. Same as I except arsenate of lead omitted 



III. Same as I except adhesive omitted 



IV. Same as I except Bordeaux mixture omitted 



V. Same as I except arsenate of lead increased to 5 pounds 



(paste) or 2J pounds (powder) 



VI. Same as I except resin fish-oil soap used instead of laun- 

 dry soap, 1 pound 



VII. Same as I except fish-oil soap (without resin) used in- 

 stead of laundry soap, 2 pounds 



VIII. Same as I with addition of a third application 5 weeks 



after first : 



IX. Same as I (including only the plat adjacent to VI) 



X. Same as I except first application omitted 



XI. Sameaslexcept "set nozzles" used in first application 



instead of " trailers " 



XII. Same as I except "set nozzles" used in both applica- 

 tions instead of "trailers" 



XIII. Same as I except adhesive omitted and "set nozzles" 

 used in both applications instead of "trailers" 



1915,1916 

 1915 

 1915 

 1916 



1915, 1916 



1916 



1915, 1916 



1916 

 1916 

 1916 



1916 



1915 



1914 



Per cent. 



4.12 

 33.31 

 21. 05 



4.01 



3.34 



2.14 



3.95 



.68 

 1.57 

 18.71 



12.87 



20.41 



26.70 



Per cent. 

 50.03 

 28.80 

 28.80 

 88.74 



54.90 



55.53 



42.84 



67.52 



79.72 

 51.29 



52.04 



28.80 



31.80 



This table shows that both arsenate of lead and soap are essential 

 factors in the spray mixture, while Bordeaux mixture is of little 

 importance. An increase in the amount of arsenate of lead is usually 

 of little value, and variation among the three kinds of soap used is not 

 an essential consideration. Two applications effect a practically 

 satisfactory control so that the advantage of a third application is 

 insignificant. The omission of the first application, or making it 



