Treatment 



WINTER FLOOD 



Experiments have shown that the worms in their cocoons generally cannot endure 

 submergence longer than two weeks in water with a temperature above 60° F. Bog 

 experience confirms this, for if the winter flood is held till after May 20, fruitworm 

 trouble is usually much less than on bogs from which the flowage has been let off 

 early. Bogs vary greatly in their tendency to become severely infested, owing 

 probably to differences in their surroundings. Holding the winter flowage late 

 every other year is a good control with some, but others need treatment nearly 

 every year. 



SPRING REFLOW 



If the winter flood is let off early in April, it is often good practice to reflow 

 a bog from about April 20 to about May 24 to curtail the fruitworm, false army 

 worm, and gypsy moth. 



AUGUST FLOOD 



Bogs are sometimes flooded in August to stop the work of fruitworms. 

 This is effective, but it is an extreme measure and is rarely advisable, 

 for the water usually will spoil a considerable part of the crop. Cool weather 

 should be selected for this and the water held for about twenty-four hours. 



INSECTICIDES 



Insecticides are used very effectively to kill the worms as they hatch, two 

 and sometimes three applications, ten days apart, being necessary, the first made as 

 soon as the vines are half out of bloom. Counts of fruitworm eggs on berry 

 samples gathered from scattered locations on the bog should always be made to 

 determine whether such a treatment is advisable. Such examinations should be 

 repeated every few days until after the first of August. Treatment is always 

 advisable when more than four eggs that are unhatched and not turned black 

 by Tricho gramma parasitism (figs. S, T, and 42) are found on a hundred berries. 49 

 Two or three unhatched eggs on a hundred berries justify helicopter dusting, 

 especially where there are prospects of a heavy crop or high prices for berries. 



1. Diist with 40 pounds of cryolite or 70 pounds of activated derris (2 per- 

 cent rotenone) dust to the acre. 



2. Spray with 6 pounds of cryolite or 7 pounds of derris (4 or 5 percent 

 rotenone) and 2 pounds of soap in 100 gallons of water, 400 to 500 gallons to 

 the acre, according to the vine growth. The derris spray is an excellent blanket 

 treatment for fruitworms and second-brood blackheaded fireworms, as is also 

 a spray of 3 pounds of 50 percent wettable DDT in 100 gallons of water, 

 400 or 500 gallons to an acre. 



As fruitworm infestations are commonly more severe along the margins than 

 on the interiors of cranberry bogs, it often is best to confine attention to the 

 former when using insecticides to control them. 



Cranberry Weevil ^o 



This insect worl's on dry bogs and bogs that are flowed for the winter but are not 

 reflooded much. It has been a minor pest, doing serious harm only on small areas 

 here and there, but it has become more troublesome in recent years. When it 

 establishes a considerable infestation it usually stays for years unless it is treated. 



Distribution and Food Plants 

 This beetle ranges from Ontario and New England to the Rocky Mountains and 



*» Such a count indicates a potential loss of at least 25 percent of the crop. The 

 examining is best done with a hand lens magnifying about X14. 



BO Anthonomus musculus Say. — determined by W. S. Blatchley and H. C. Fall. The 

 name A. suturalis LeC. has been tied to this species erroneously in cranberry literature. 



[56] 



