70 MASS. EXPERIMENT STATION BULLETIN 378 



The most effective sprays on Gravenstein, Mcintosh and Baldwin were 

 applied when the apples were approximately 5/16 of an inch in diameter 

 and on Wealthy at the 4/16 inch size. It is also evident that the most 

 effective spray was applied June 3 at which time the maximum temper- 

 ature and greatest curculio activity of the period occurred, and that the 

 high temperature stimulated both curculio activity and growth of apples. 

 One timely spray during the critical period is satisfactory on Mcintosh, 

 Baldwin, and Wealthy but not on Gravenstein. On Gravenstein and 

 Baldwin the percentage of curculio-stung apples was from 50 to 100 per- 

 cent greater on the dropped apples than on the harvested apples, but on 

 Mcintosh and Wealthy the injury was 5 to 10 percent greater on the 

 harvested fruit. 



A growth of 1/16 of an inch in diameter of an apple represents an in- 

 crease in surface area of 156 percent, and since this growth may occur in 

 24 hours, timeliness in the application of a spray is important. 



Biology and Control of the Grape Plume Moth and Grape Cane Girdler. 

 (W. D. Whitcomb and W. E. Tomlinson, Jr., Waltham.) 



Grape Plume Moth. Life history studies of the grape plume moth showed 

 that larvae hatched from 57.89 percent of the eggs which were over- 

 wintered on potted grape vines, and that all hatching occurred in tlie 

 three-day period. May 14—16. The feeding period of larvae averaged 39.2 

 days and the pupation period 16.37 days, making a developmental period 

 from hatching to adult of approximately eight weeks. Because of cool 

 weather, this period was about two weeks longer than in 1939. 



On heavily infested vines the number of overwintering eggs averaged 

 3.36 per foot of cane, or 3.18 eggs per node. Since each node ordinarily 

 produces a shoot, this infestation is equivalent to about 3 insects for each 

 growing shoot. 



Laboratory experiments with commercial dormant spray materials gave 

 complete mortality of eggs with lubricating oil emulsions containing 3 

 or 4 percent actual oil, and 90 percent mortality or higher with 1 or 2 

 percent actual oil in the diluted spray. Lime sulfur 1-8 gave 80 percent 

 mortality of the eggs. Sodium dinitro cresylate was effective when 

 diluted to 1 and \% percent, but at dilutions of Yi and 54 percent only 

 48 percent mortality resulted. On unsprayed canes, 63 percent of the 

 larvae hatched. 



Field experiments in home vineyards showed 80.4 percent protec- 

 tion where lubricating oil emulsion diluted to contain 3 percent actual 

 oil was used, and 72.86 percent where 3^ percent sodium dinitro cresylate 

 was used. On unsprayed vines 84.12 percent of the tips were infested. 

 In another experiment where 58 percent of the tips on unsprayed vines 

 were infested, treatment with y2 percent sodium dinitro cresylate gave 

 92 percent protection, and lime sulfur 1-8 gave 11 percent protection. 



Spraying on May 1 when the buds were breaking and about one week 

 before the larvae hatched, using lead arsenate and fish oil and lead arsenate 

 combined with Bordeaux mixture, failed to give protection. 



Grape Cane Girdler. Emergence of the grape cane girdler beetles from 

 hibernation and their appearance in the vines occurred when the new 

 canes were about 6 inches long. They also appeared to be stinuilated by 

 high temperatures to the same degree as the plum curculi(j. Mating 

 occurs soon after the beetles leave hibernation and the first girdled canes 

 were observed June 2. 



