14 BULLETIN 554, U. S. DEPARTMENT OF AGRICULTURE. 



The fertilizers listed in Table VI have been of no avail in repelling 

 the girdlers; in fact, these plats in 1916 showed serious injury, as 

 evidenced by the considerable areas of girdled vines found on them. 

 In general, it may be said that the use of fertilizers tends to make 

 conditions more favorable for girdler infestation by increasing the 

 amount of vine and foliage production and thus in direct propor- 

 tion increasing the trash on the ground beneath the vines. This, 

 however, should not deter anyone from using fertilizers on cranberry 

 bogs where the vines need stimulation, but should be taken as a cau- 

 tion that girdler infestation is likely to follow a heavy production of 

 vines, particularly on well-drained land. 



In a test to determine the repellent value of certain materials a 

 lumpy and granular residue, said to be a by-product of a gasworks, 

 was applied to an infested piece of land by broadcasting at the rate 

 of 650 pounds per acre. The larva? were not repelled and were as 

 abundant at the time of cocooning on the treated plat as on the 

 adjacent untreated plats. 



BURNING. 



Burning infested areas has been recommended in the past and occa- 

 sionally has been resorted to by growers. When a bog is burned over 

 (PI. VII), a large quantity of the trash remains unconsumed on the 

 bog floor, but it is probable that the heat generated is great enough 

 to kill the larves, naked or in cocoons, that may have been buried in 

 this debris. Other methods of controlling the girdler have, been 

 devised which do not entail destruction of the vines by burning, and 

 the practice therefore is not recommended. 



TRAP LIGHTS. 



Capturing the moths by trapping with lights was tried for two 

 seasons with very unsatisfactory results. On one occasion four 

 moths were captured at a stationary light in the course of a night. 

 The tests with lights were made in the height of the flying season, 

 and the results showed conclusively that the moths are not attracted 

 to lights in sufficient numbers to warrant employing this method of 

 capture. 



LATE HOLDING OF THE WINTER FLOWAGE. 



By late holding of the winter flowage is meant maintaining the 

 winter head of water over the vines from the time it is applied in 

 December or thereabouts until some time between July 1 and August 

 1. Holding the flowage until July 1 does not always satisfactorily 

 destroy girdler infestations, but if the head is maintained until 

 July 15 much better results are obtained. Occasionally a grower is 

 met who has kept the water on the bog until August 1. and. while 



