GRAPE PESTS 



It is apparent that the removal of only 72 percent of the eggs on a vine does 

 riot provide effective control of the insect nor does it prevent a light or moderate 

 infestation the following season. However, it is conceivable that the destruction 

 of 72 percent or more of the eggs each year for several years will reduce the in- 

 festation to a minimum and aid greatly in preventing the plume moth from be- 

 coming abundant. 



Arsenical Sprays 



In spite of references (p. 7) to the contrar>-, the writers have never seen satis- 

 factory control of the grape plume moth in backyard vineyards by spraying with 

 arsenicals. To be sure, most of the treatments observed were made according to 

 recommendations for controlling other pests and were not applied at an effective 

 time for combating the plume moth, but the control was always noticeably un- 

 successful. 



In 1940 several backyard grapevines were sprayed with lead arsenate and 

 bordeaux mixture. The application was made on May 1 when the buds were 

 beginning to swell and just before the larvae of the grape plume moth began to 

 hatch. The spray was applied very thoroughly at 250 pounds pressure. The 

 results were unsatisfactory as shown in Table 5. 



Table 5. — Control of Grape Plume Moth by Spraying 

 With Arsenicals. 



Treatment Tips Infested — Percent 



None 48 



Lead arsenate 4 pounds - 100 gallons 51 



Lead arsenate 4 pounds - 100 gallons f 



Bordeaux mixture 8-8-100 \ 40 



Fish oil 1 quart - 100 gallons I 



In this experiment, the newly hatched larvae entered the swelling buds with- 

 out feeding on outer bud leaves where the spray was deposited. After they 

 have entered the bud, they are protected by the webbed leaves of their nest 

 and are not susceptible to arsenical sprays. 



In commercial vineyards the first application for combating the grape berry 

 moth, the rose chafer, and the common grape diseases is, not made until the 

 blossom buds have developed, at which time the larvae of the grape plume moth 

 are well established in their webbed nests. 



Dormant Sprays 



Soon after it was discovered that the grape plume moth hibernated as an egg 

 on the canes, the writers began experimenting with dormant spray mixtures as 

 ovicides. 



