224 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



felt that the following general conclusions in regard to the codling moth 

 and plum curculio are warranted. 



In regions where the codling moth is not especially severe, as in the 

 New England States and other more northern States, dusting controls 

 this insect practically as well or as well as spraying. In regions where the 

 codling moth is more abundant, due to a larger second brood or to 

 subsequent broods of larvae, as in Maryland, Virginia, Illinois, the 

 Ozarks, etc., dusting is not a satisfactory control. In such arid regions 

 as the Grand Valley, Colo., where the codling moth is very prolific and 

 injurious dusting is notably less effective than spraying. 



In the case of the plum curculio on apples, dusting compares favorably 

 with spraying where the insect is not especially abundant. Under 

 conditions of curculio abundance, as is often the case in orchards in sod, 

 dusting is not an effective control for this insect and spraying under these 

 conditijns may n )t furnish the protection desired. 



The results given in the tables on the control of scab, brown-rot, and 

 apple blotch are presented for the consideration of Pathologists inter- 

 ested in the subject. In reference to comparative merits of dusting and 

 spraying in apple disease control. Prof. Waite has recently expressed 

 himself as follows (Annual Report, Bureau of Plant Industry, for the 

 fiscal year ending June 30, 1920, page Gl) : 



Comparative tests of dusting and spraying methods were continued 

 in both peach and apple orchards. In the case of the peach the tests 

 were particularly severe, and neither spray nor dust gave as good 

 control of brown-rot as was expected. The dust was about as efficient 

 as the spray. In the case of the apple, as in previous years scab black- 

 rot, leaf-spot blotch, sooty blotch and bitter rot were not controlled 

 by dusting. To the list of diseases almost entirely prevented by spray- 

 ing but not controlled by dusting was added the New Hampshire 

 fruit-spot, which was especially destructive in the Ozarks, where our 

 experiments were carried on. 



Dusting Versus Spraying of Peaches 



Considerable work has been done in dusting peaches in comparison 

 with spraying for the control of the plirni curculio, scab and brown -rot 

 in different parts of the coimtry, but little of this work has been entirely 

 satisfactory from the experimental standpoint owing to the scarcity 

 in the same orchard of one or more of these troubles. The most con- 

 clusive results obtained com.e from Mississippi and Georgia and indicate 

 that during periods of average abundance and under average weather 

 conditions dusting is about as effective as spraying for these three peach 

 troubles. It should be pointed out however that during the last two 

 seasons in Georgia, where the weather has been unusually hot and rainy. 



