270 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 17 
obtained in the experiments during 1923 are briefly summarized as 
follows: 
Effect of Spray and Dust Mixtures on Fruits 
All the spray and dust mixtures affected to some degree the surfaces of 
apple fruits. The most conspicuous type of injury was “sun scald” 
or “spray burn” characterized by the occurrence of somewhat circular 
brownish or brownish-black spots on the sides of the apples. These 
were most conspicuous on the south side of the tree where there was 
apparently the greatest exposure to sunshine, and were common in all of 
the plants receiving applications of sulfur either as lime-sulfur solution or 
flowers of sulfur or sulfur flour applied as a dust. (See Table 1). This 
type of injury was most abundant in the plats sprayed with lime-sulfur 
solution. In considering the number of apples affected with “spray 
burn” in relation to the total yield, it will be observed that the amount of 
injured fruit is not large, but, small as it is, it must be admitted that the 
size and color of the blemished areas are such as to produce in the mind of 
the one examining the trees that the damage is much greater than the 
actual counts indicate. Associated with “spray burn” there was 
russeting of the fruits, which was also noticeable in all the plats receiving 
applications of sulfur, both spray and dust. Judging from the number 
of apples affected and the effect of the discoloration on the general 
appearance of the yield, russeting was really more important than sprav 
burn. 
Russeting varied in intensity with the different treatments. In 
certain plats a small percentage of the apples were distinctly russeted so 
that the natural green color of the fruits over more or less extensive 
areas was largely or completely obscured. With the majority of the 
apples the discoloration appeared as streaks or netting in varying grada¬ 
tions. Even tho barely discernible, and therefore not conspicuous 
enough to be considered important, it is an interesting fact that a small 
amount of injury detracts from the appearance of the apples, as they 
lack to some extent the finish and luster of normal fruits. 
In the plats sprayed with lime-sulfur russeting of apples was general, 
involving perhaps 80 or 90 percent of the fruits. It was especially 
noticeable about the calyx end, altho it was by no means confined to this 
region. The addition of calcium caseinate to lime-sulfur (1 lb. to 100 
gals.), caused an appreciable reduction in the number of affected apples 
as well as in the severity of russeting, while 2 lbs., of the spreader to the 
