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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
which commend their use especially with dormant sprays, but incom¬ 
patibility with sulfur and bordeaux compounds, as well as with arsenicals, 
is an important barrier to their practical use. 
Although further experimental evidence is needed on the point, there 
can be no doubt that rain and wind exert a great influence in reducing the 
efficiency of sprays. By combining suitable adhesive qualities in the 
spreader, it is possible not only to overcome to a considerable extent the 
deleterious effects of rain and wind in removing the spray material, but 
also, by lengthening in this manner the period over which a spray 
application will give protection, to reduce the number of applications 
necessary to control certain pests. Hence, the adhesive qualities of a 
spreader becomes of much importance. The casein type of spreader 
has shown superior adhesiveness in comparison with saponin, soaps, oils 
and gum arabic. 
A consideration of the more important factors involved leaves little 
room for doubt that a suitable spreader is efficacious in giving increased 
control of those insect and fungous pests which in general are amenable 
to the spraying method of control. However, adequate orchard, field 
and garden spraying experiments to determine this point with accuracy, 
have not yet been consummated. Carefully conducted orchard and 
insect ary tests, made by the writer in Idaho during the years of 1920 
and 1921, gave results which indicated very positively that calcium 
caseinate, used with arsenate of lead, is capable of giving improved 
control of codling moth. These tests also showed clearly that the 
addition of calcium caseinate to the combined spray of arsenate of lead 
and nicotine sulfate, gave much better control of green apple aphis 
{Aphis pomi DeG.) and woolly apple aphis (Eriosoma lanigera Hausm.) 
than did the same spray materials when used without the spreader. 
Furthermore, the experiments indicated that with the spreader, appar¬ 
ently due to its adhesive qualities, it would be possible under Idaho 
conditions to omit the second cover spray for codling moth without 
impairing the effectiveness of control. 
The rather general use of a commercial calcium caseinate spreader 
during the past year in practically every fruit growing section of America, 
shows with reasonable conclusiveness, if we assume that the orchardist 
himself is capable of judging correctly that this type of spreader possesses 
decided merit in increasing spraying efficiency and giving improved 
control of various pests for which sprays are applied. 
