THE PLUM CURCULIO IN APPLES 41 



CONTROL 



Cultural Practices 



Destruction oj Beetles in Hibernating Quarters 

 By burning the leaves and trash which have accumulated along fences, 

 walls, brush heaps, undergrowth, and adjacent woods, many beetles are 

 killed in their hibernating quarters. Burning may be done at any time 

 in the winter or early spring but is most effective when the trash is dry 

 enough to make a hot fire close to the ground. Burning about 300 yards 

 into woods adjoining orchards is recommended where possible. Ample fire- 

 fighting apparatus, such as fire extinguishers, a power sprayer, rakes and 

 brushes should be available to keep the fire under control. Experiments show- 

 ing the effect of burning have not been made in Massachusetts, but an 

 idea of the results which may be expected can be obtained from an experi- 

 ment in North Carolina (8) which is summarized in Table IL 



Table IL — Comparison of Number of Beetles Jarred from Three Blocks of 

 Peach Trees Adjacent to Woods and Field 

 Aberdeen, N. C. 1922 

 Location of j.rees Dates Jarred 



Opposite unburned woods Mar. 14 to May 9 

 Opposite burned woods Mar. 14 to May 9 



Next to field Mar. 14 to May 9 



Destruction of Larvae in Dropped Apples 



All apples infested with living plum curcuho larvae fall to the ground and 

 the larvae remain in the apples approximately ten days after they fall. 

 From an entomological viewpoint the destruction of the grubs in the dropped 

 apples is a perfect method of controlling this insect even to the point of 

 elimination, but from the standpoint of the fruit grower the labor and 

 expense of picking up all of the infested apples at the proper time gives 

 this operation a decidedly unpractical aspect. However, the positive destruc- 

 tion of the insect and the knowledge that for a certain period about July 

 1 the dropped apples under a heavily infested tree contain an average of 

 more than one larva per apple (See Table 12) gives this operation great 

 value even from a practical standpoint. 



Cutting grass under the tree, clean cultivation, and a liberal hay mulch aid 

 greatly in reducing the cost of picking up apples. In 1928 one progressive 

 fruit grower in eastern Massachusetts picked up an average of three bushels 

 per Yellow Transparent tree, capable of bearing twenty bushels of mature 

 apples, at an average cost of $1.00 per tree without preparation for the 

 work. The estimated damage by the plum curculio on these trees exceeded 

 $5.00 per tree. By cutting the grass and better organizing the work, he 

 plans to reduce the cost greatly in the future. 



As shown in Table 12, more apples fall before June 28 than after, and 

 from these apples the largest number of larvae emerge. However, the apples 

 which fall during the next ten days contain the greatest number of larvae 

 per apple and consequently should be picked up very carefully. In late 

 June and early July the first larvae emerge about six days after the apples 

 fall, and about four days, later they are leaving the fruit in large numbers 

 so that gathering them after this time has little value. Three collections 

 of "drops" are usually sufficient to destroy the majority of the grubs in 



