ANNUAL REPORT, 1945-46 29 



THE CRANBERRY STATION 



East Wareham, Massachusetts 



H. J. Franklin in Charge 



Injurious and Beneficial Insects Affecting the Cranberry. (H. J. Franklin.) 

 DDT. This insecticide was advocated as a control for gypsy moth caterpillars 

 in the annual Cranberry Insect and Disease Control Chart in the spring of 1946, 

 and it was used widely and freely both on bogs and on the surrounding uplands, 

 especially in Plymouth County, with entirely satisfactory results. In spraying, 

 complete kills were obtained with 2 pounds of the 50 percent wettable powder in 

 100 gallons of water, 400 gallons to an acre; and with 3 pounds in 100 gallons, 

 250 gallons per acre. In dusting, 50 pounds of the 5 percent dust to the acre was 

 used. No injury to cranberry vines from the DDT appeared. 



DDT was used considerably as a spray and as a dust treatment for the first 

 brood of the black- headed fireworm in May and early June, 1946, in the amounts 

 found effective against gypsy moth caterpillars, and the control appeared to be 

 satisfactory in all cases. Its further use against first-brood fireworms seems ad- 

 visable. It probably should not be used on second-brood fireworms or on blunt- 

 nosed leafhoppers till more is known about its effects on bees. 



Ftreworm Flooding. Flooding for as short a period as 10 hours to kill the less- 

 than-one-third-grown black-headed fireworms of the first brood was tried very 

 successfully in 1945 and was advocated in the 1946 Cranberry Insect and Disease 

 Control Chart. Various cranberry growers tried this treatment in the spring of 

 1946, some of them with excellent results. It was found that, to be entirely suc- 

 cessful, it has to be repeated once or twice at intervals of a week to 10 days. The 

 success of this treatment seems to be based on the following facts: 



(a) It is especially important to kill the leaders of the first brood of worms, 

 for their moths lay most of the eggs which produce the second-brood worms of 

 this only partially two-brooded insect. 



(b) A short flooding kills the smaller worms more easily and completely 

 than the larger ones. 



(c) Short floodings are less likely to harm cranberry vines than the longer 

 ones heretofore employed. 



Dusting by Airplane. Extensive tests of dusting by airplane were conducted 

 by the A. D. Makepeace Company in the spring of 1946. Observations of the 

 results indicated that this method of treatment is practicable on cranberry bogs 

 when properly applied. It probably will come to be used widely in treating the 

 gypsy moth and the black-headed fireworm. 



Prevalence of Cranberry Insects in the season of 1945: 



1. Gypsy moth infestation moderate, but heavy in some sections. 



2. Leafhoppers (Ophiola) not very plentiful. 



3. Fruit worm infestation lighter than for many years, in very striking con- 

 trast to the severe infestation of 1944. 



4. Black-headed fireworm less troublesome than usual. 



5. Practically no fire beetles {Cryptocephalus) found. 



6. Very few spotted fireworms (Cacoecia) found. 



7. Ladybugs normally abundant. 



8. Spanworms in general not troublesome. 



9. False armyworm (Xylena) infestation normal. 



10. Black cutworm (Eiixoa) infestation medium, mostly on bogs flowed for 

 control of root grub (Amphicoma). 



