THE GRAPE-BERRY MOTH. 



55 



The variations in the formulas were made to ascertain, if possible, 

 the value of arsenate of lead as against arsenite of lime in the control 

 of this insect. The resin-nsh-oil was added on some plats and with- 

 held on others to determine its value as an adhesive in making the 

 spray stick to the grape berries. The variation in number of appli- 

 cations was made to ascertain if applications made before the blossom- 

 ing of the grape were of greater value than those made after blossom- 

 ing. The application on June 19 was made when the blossom clusters 

 were well developed, but a few 

 days before actual blossoming 

 (see fig. 20). The application on 

 July 8 was made after blossoming 

 when the berries were about the 

 size of buckshot (PI. V, fig. 1). 

 At this stage of development the 

 berries stand some distance apart 

 and the spray can be forced 

 through the cluster, so as to cover 

 all of the berries. The application 

 July 27 was made for the purpose 

 of covering the berries to protect 

 them from the entrance of larvse 

 of the second brood. 



In all of these applications 

 the work was quite thorough, and 

 with the exception of the third 

 application most of the clusters 

 were well covered by the spray. 



When the third application Was FlG - 20 -- s t a g e of development of grape blossom clus- 



iii ter at which poison-spray application should be made 



made the foliage had become against early hatching larvae of the grape-berry moth 



rather dense, making it more dif- wMc * infest the blossom clusters - (° ri s ina1 -) 

 ficult to reach the clusters, and at the same time the berries had 

 increased in size, forming a somewhat compact cluster. These con- 

 ditions made it increasingly difficult to force the spray in among the 

 berries. Furthermore, too much poison forced into the clusters in 

 this condition is undesirable, since some of it is likely to be present 

 in the cluster when the fruit is ripe and thus render it undesirable for 

 table use. 



During the season four counts were made of infested berries on 25 

 vines in all of the plats. Table XXIII shows the increase in infestation: 



