ANNUAL REPORT, 1941 65 



sulfur 4 pounds, fish oil 1 pint in 100 gallons of water when the fruit was 4/16, 

 5/16, and 6/16 of an inch in diameter, as determined by the measurement of 

 200 apples with calipers. 



Variety 



Wealthy 



Mcintosh 



These records, based on the examination of 57,835 apples, show least injury 

 by the plum curculio to apples sprayed when they measured approximately 

 5/16 of an inch in diameter. This difference is the more significant since the 

 "5/16" trees were located near a stone wall and fence row where much curculio 

 injury has occurred in the past. In the Wealthy apples the curculio injury was 

 1 percent greater on dropped fruit than on picked fruit; but in Mcintosh the 

 dropped fruit showed 3 to 12 percent more injury. 



Biology and Control of the Grape Plume Moth and Grape Cane Girdler. (W. D. 



Whitcomb and Wm. E. Tomlinson, Jr., Waltham) 



Grape Plume Moth. A study of the parasitism of the grape plume moth yielded 

 two new species (undetermined), but the total parasitism in the larvae collected 

 was less than 1 percent. 



The application of dormant sprays on April 10, just before the larvae hatched, 

 showed that dinitro compounds are more effective than oil emulsion. In one 

 experiment the addition of a DNOCHP compound at the rate of 15 ounces 

 in 100 gallons increased the control from 74 to 86 percent over oil emulsion at 

 the rate of 3 percent actual oil; and in another experiment the addition of DNOC 

 (15 ounces-100 gallons) to 3 percent oil emulsion increased control from 60 to 

 82 percent. The best control was obtained with a commercial sodium dinitro 

 cresylate 1 percent which gave 94 percent protection. When this material was 

 used at 3^ percent dilution the infestation was 12 percent or twice that follow- 

 ing the use of the 1 percent dilution. 



Grape Cane Girdler. The first activity of the grape cane girdler was observed 

 on May 22 when the maximum temperature was 89° F. The average life of 26 

 individuals from egg deposition to adult in bagged canes in the vineyard was 

 60.8 days with most of the beetles emerging from August 15 to 25 but continuing 

 until September 22. 



In the vineyard, beetles were reared from 28 percent of the girdled canes under 

 observation and this seemed to be a normal survival under the conditions. 



