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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
cated by the development of brown spots in the leaves and browning of 
the margins. Subsequently a large proportion of the foliage dropped. 
The same material applied as a dust produced quite similar results, 
altho the injury was not so extensive. 
Dehydrated copper sulfate and copper arsenite dusts exerted, on the 
whole, no injurious effects; at least not to any important degree, altho 
all the trees receiving heavy applications of copper dusts displayed 
characteristic brown spots which were diagnosed by various workers as 
frog eye (Sphaeropsis malorum). As these were observed only in the 
plats treated with the copper dusts, it is difficult to draw any other 
conclusion than that the spotting was primarily due to the treatment. 
Conclusions 
The standardization of apple grades and the growing discrimination 
against imperfect fruits in commercial packages have directed attention 
to the importance of spray injuries, revealing a need of safer spraying 
mixtures as well as improved methods of handling standard insecticides 
and fungicides to reduce danger of injury to fruit and foliage. 
Of common spraying mixtures, none are quite as satisfactory as lime- 
sulfur for the treatment of apples. The chief defect of this spray is that 
it may cause burning of leaves as well as “spray burn” and russeting of 
the apples, injuries which vary in degree apparently with different sorts 
of apple and according to seasonal conditions. No methods have been 
devised by which these injuries may be entirely prevented or largely 
controlled. The addition of calcium caseinate caused an appreciable 
reduction in the amount of “spray burn” and russeting, but still both 
types of injury were conspicuous. Glue, apparently, was not as 
effective as calcium caseinate. Lime hydrate reduced burning of foliage 
to an appreciable extent, but did not prevent important damage in some 
instances. Since calcium caseinate as revealed by analyses 1 prevents 
any important reaction between lime-sulfur and lead arsenate and lime 
hydrate neutralizes the soluble arsenic developing from this combination, 
it would appear that sulfur is largely responsible for the damage to 
apple foliage and fruit and that sulfur contained in sulfides is more in¬ 
jurious than ground sulfur or sublimed flowers of sulfur applied as 
dusts or in suspensions. 
Sulfur suspensions, known as “wettable sulfur” or “dry mix” sprays, 
were tested as possible substituted for lime-sulfur. They produced 
noticeable russeting as well as “spray burn” of apples, but the damage 
Unpublished analyses by Dr. R. W. Thatcher and L. R. Streeter. 
