CRANBERRY GROWING 



31 



The fruit worm (Fig. 24) lias taken an estimated third of tlie whole 

 Cape crop in some years. It may be checked by holding the winter flow- 

 age till late May or by spraying or dusting late in the blossoming period 

 and again 10 days later with derris or cryolite. 



The black-headed fireworm (Fig. 25 A) seldom harms strictly dry bogs 

 much. It was formerly treated largely by flooding in late May or early 

 June. This is usually effective for the time being, but its usual long-range 

 effect is to promote the continuance of the infestation. Dusting with 

 pyretlirum or with dusts containing rotenone is very effective. 



Small patches infested with root grubs (Fig. 26) are treated with a solu- 

 tion of 6 ounces of sodium cyanide in 100 gallons of water, a gallon to a 

 square foot (Fig. 27). This is fairly effective but must be repeated in 10 

 years. A much more permanent treatment is to let the winter flowage off 

 earh' in April, reflood about May 12, and hold the water till July 10. This 

 usually cleans out grubs of all kinds thoroughly, but at the cost of the 

 crop. 



The gyi)sy motli (Fig. 25 B) may be controlled by holding the winter 

 flowage till May 25, by reflooding about May 25 for 36 hours, or by spray- 

 ing w-ith 3 pounds of dry lead arsenate in 50 gallons of water about May 

 20. Fooding for 12 hours kills the worms after they are a third grown. 

 High grade pyrethrum dust, 100 pounds to an acre, or a spray of 15 

 pounds of derris (4 percent rotenone) and 2 pounds of soap in 100 gallons 

 of water, 400 gallons to an acre, destroys the maturing worms. The 

 maturing worms must be kept from getting on a bog by removing all 

 deciduous trees for some distance from the margin and by keeping the 

 marginal ditch cleaned out and jxirtly full of water, with a film of fuel 

 oil on the water. 



Fig. 28. Spraying to Control Cranberry Insect Pests. 



Note the long line of hose handled by the men. The spraying machine is always on the 



upland near the bog margin. 



