36 BULLETIN 1032, U. S. DEPAETMEjSTT OF AGEIGULTUEE. 



Pbessuee. 



The pressure need not be higher than about 200 or 250 pounds at 

 the tank, depending upon the size and length of pipe or hose through 

 which the liquid has to be forced and the number and kind of noz- 

 zles used. 



Time and Number of Applications. 



For vines which are only lightly infested three applications are 

 recommended. The first of these should come when the new upright 

 growth is from one-half to three-fourths of an inch long; that is,, 



Fig. 15. — A spray boom for holding 10 Vermorel nozzles. Note the unevenness of the 

 spray cone and the necessity of considerable walking and dragging of hose over vines 

 in spraying. Not a good type of outfit to use. 



when large numbers of the young larvse are proceeding to and some 

 working in or near the new unfolding leaves at the tips of the up- 

 rights. The second should be applied shortly after the first blos- 

 soms appear, or, in other words, at the early "hook stage," This 

 may come from 10 days to 3 weeks after the first application, de- 

 pending on the weather; it is designed to kill the next group of 

 larvse before they conceal themselves in the new growth. The third 

 application should be made when the vines are in full bloom, or 

 about 2 weeks after the second application, the object being to keep 

 the young larvse from destroying blossoms and newly forming berries. 



