10 



but the high cost of machinery and labor has made the expense 

 of such measures increasingly prohibitive. Very recently grow- 

 ers have begun to look with hope to dusting as a means of 

 meeting the situation, but for the great mass of our fruit 

 growers a lack of understanding or appreciation of the factor 

 of timeliness constitutes the chief cause of failure to control 

 diseases and pests where spraying is carried out. 



Dusting to Replace Spraying. 



Of the many problems pressing us for further study and in- 

 vestigation, none is more urgent than that of dusting. Prior 

 to the war we carried out in New York State an extensive 

 series of investigations on the relative efficiency of dusting in 

 comparison with spraying for the control of apple scab and 

 codling moth. Our results showed dusting to be equally effec- 

 tive against these two pests. Experiments since that time in 

 other ap'ple-growing regions, notably Michigan, Illinois and 

 Nova Scotia, have given results in general accord with the 

 results we obtained. But dusting, as a general practice, has 

 made slow progress, due to certain limitations which, .however, 

 promise early solution. Among the chief drawbacks to its 

 general adoption by our fruit growers has been the lack of an 

 effective contact dust for sucking insects, like aphis, psylla and 

 red bug. Preliminary experiments, especially in California and 

 Nova Scotia, promise an effective nicotine dust in the near 

 future. Improvements in dusting machinery, cheapening of 

 dusting materials, and a better understanding of the factors 

 conditioning effective application are pressing for attention. 



Replying to a questionnaire sent last November to duster 

 owners in New York State, 73 replied that they had dusted 

 apples last season. Of these, 49 reported as good or better con- 

 trol of scab by dusting than by spraying; 51 reported codling 

 moth as well or better controlled; and 68 (over 93 per cent) 

 report that they will dust apples again next season. Even 

 larger percentages replied in favor of dusting .peaches and 

 cherries. 



The results obtained this past season in Nova Scotia, both 

 in the experimental plots and in commercial orchards, were so 



