310 CONTROLLING INSECTS AND DISEASES 



tance in those sections where burning frequently results from use of 

 concentrated lime-sulfur or Bordeaux mixture. Dusted fruit in such 

 sections often possesses a brighter finish than sprayed fruit. 



7. The investment per acre or per number of trees is less with a duster 

 than with a sprayer. A good dusting outfit with a small first cost will 

 care for a quantity several times greater than an equally good sprayer. 

 This materially reduces the overhead costs. 



8. The removal of spray residues from fruit when applications late 

 in the season have been necessary is becoming a problem of consider- 

 able importance. Dusting materials may on the whole be removed 

 more easily from the fruit than the materials applied in liquid form. 



9. Tor home fruit gardens, the small hand duster is much more con- 

 venient and usually less expensive than a small sprayer. 



Other considerations not favorable to dusting at the present 

 time are: 



1. Materials for dusting are at present more expensive than for 

 spraying. The difference is considerable and usually offsets the labor- 

 saving factor in dusting. 



2. Dusts to compare favorably in effectiveness with the spray mate- 

 rials for dormant applications have not yet been perfected. For in- 

 stance, dusts are not effective against San Jose scale at the present 

 time. Likewise, aphis, largely controlled during the early part of the 

 growing season by nicotine sprays, cannot be controlled satisfactorily 

 at present by nicotine or other dusts. 



3. Authorities and growers in various sections disagree sharply con- 

 cerning the effectiveness of dusts as compared with sprays, chiefly for 

 apple scab. There is considerable agreement that apple insects, with 

 the exception of the various scales and aphis, may be controlled effec- 

 tively by dusts, during the growing season. There is quite general 

 agreement that dusts are effective for the control of insects and diseases 

 of the peach during normal growing seasons. 



In New York, Massachusetts, Nova Scotia, Michigan, 

 Pennsylvania, Minnesota, Virginia, and some other states, 

 experiments favorable to dusting for summer applications have 

 been reported. In New York and elsewhere, some large 

 growers are relying upon dusts exclusively for scab control. 



In some of these sections, as well as in Indiana, Connecti- 

 cut, and New Jersey, other tests have given results in favor of 

 spraying. 



