CONTROL OF GRAPE-BEERY MOTH. 7 



CONTROL EXPERIMENTS. 



STATUS OF SPRAY PRACTICE FOR GRAPE-BERRY MOTH CONTROL. 



When these investigations were undertaken the following prin- 

 cipal facts were known about spraying for the control of the grape- 

 berry moth: First, satisfactory control had not been effected by the 

 use of any system of set-nozzle spraying, particularly in thrifty 

 vineyards where foliage growth was heavy. Second, satisfactory 

 control had been effected in Ohio 1 by using the trailer method of 

 spraying at. the time of the hatchings of second-brood larvae, usually 

 in early August. This practice, however, left a heavy residue of 

 spray material on the fruit at harvest time, which tended to exclude 

 such fruit from a basket market. Third,, two spray applications by 

 the trailer method, the last when the grapes first touched in the 

 clusters, had given satisfactory control on the Concord variety in 

 the Chautauqua-Erie belt in 1915. This practice was to be 

 thoroughly tried in northern Ohio on Concords and Catawbas. 



SCOPE OF EXPERIMENTS. 



From this summary of the knowledge available it appeared that 

 the investigations should deal with three main points: (1) Time and 

 number of spray applications, (2) chemicals used in spray materials, 

 (3) spray residues left at harvest time. 



In studying these factors spraying experiments were conducted 

 by the writers in 6 vineyards in 1916, in 9 in 1917, and in 15 in 1918, 

 a total of 30 vineyards. These vineyards were selected for the op- 

 portunity they offered for the advantageous study of any one or 

 more of the important features enumerated above. Since little would 

 be gained by considering each vineyard separately it has seemed 

 desirable to assemble in Tables I, II, and III the data relating to the 

 different vineyards and to bring together in similar form in Table 

 IV the results of the experiments. 



TIME OF SPRAY APPLICATIONS. 



Former experiments 2 indicated that a spray application directly 

 after grape blooming was important for the control of both grape 

 rootworm beetles and grape-berry moth larvae. In the Sandusky and 

 island sections of Ohio a spray application following grape bloom is 

 usually made for the control of downy mildew, Plasmophora viticola, 

 particularly on Catawba and Delaware varieties. This application 

 directly following grape bloom was considered as the first spray in 

 all of the experiments in which it was included. The second spray 



1 Goodwin, W. H., op. cit. 



2 Goodwin, W. H., op. cit. Johnson, Fred, and Hammer, A. G., op. cit. Isely, Dwight, 

 op. cit. 



