CONTROL OF THE GRAPE-BERRY MOTH. 35 



applied at this time is especially apt to collect at these places again, 

 at which point it may be most effective later. It also covers the 

 berry, and since there is comparatively little growth following this, 

 it remains over the larger part of the surface until it is weathered off, 

 or for about two months. Thus it remains effective during the period 

 when the greater part of the second-brood larvae hatch. As shown 

 by the single-spray applications in 1916, this second spraying is prac- 

 tically as effective against the second-brood larvae as is one applied 

 three weeks later, just as they are beginning to hatch. 



Larvae which succeed in entering the first berry may be poisoned 

 upon moving to a second. Larger larvae seldom consume enough 

 poison to prevent their entering the grape berry, but may be found 

 dead in the berry a day or two later, whereas those that have reached 

 the fourth stage are seldom susceptible to poison in the amounts in 

 which it is to be found, after weathering, on sprayed grapes. 



If this schedule is followed closely, the places on the grape berry 

 at which the majority of the larvae would normally enter should be 

 well covered with poison, and the surface of the berry as a whole will 

 be covered for a longer time than by two sprayings applied at any 

 other time. If the first application were made earlier, before the 

 falling of the grape blossoms, most of the poison would be lost with 

 the shedding of the floral parts, and the application would be com- 

 paratively ineffective. If the second application were made earlier, 

 while the berries were still growing rapidly, it could not cover the 

 surface of the berries permanently nor could it collect at the points 

 where the berries would touch, and while it might destroy more of 

 the first brood, it would be almost entirely ineffective against the 

 second. Hence no variation in the time of these two applications is 

 advisable. 



Relation of Different Grapevine Training Systems to Spraying. 



The system of pruning and training a vineyard must be largely 

 determined by horticultural considerations. Nevertheless the dif- 

 ferent systems greatly affect the facility with which the grapes may 

 be sprayed and in other ways are related directly to the control of 

 insect pests. To determine the relation to grape-berry moth con- 

 trol of five of the more important systems, a small block in Mr. A. P. 

 Bartlett's vineyard was used in 1916. In all of the other spraying 

 experiments the vines had been trained according to the Chautauqua 

 system. This block was trained by the owner especially for this 

 experiment according to the Four-cane Kniffin, Munson, Umbrella, 

 High-renewal, and Chautauqua systems. 



As there may be many who are not familiar with all of these vine- 

 training systems the following brief descriptions have been compiled 

 from the papers of Husmann (15) and Gladwin (14). 



