APPLE DISEASES 5 
The losses are greatest in epiphytotic years, but these occur 
with sufficient frequency to make apple-growing unprofitable 
unless preventive measures are taken. The nature of the 
losses may be indicated as follows: (1) Reduction in or destrw@@ — 
tion of the set of fruit. Heavy losses of fruit, in some cases 
total, are incurred under conditions favorable to scab at blossom- 
ing-time. (2) Impairing the efficiency of the foliage. Affected 
leaves are often smaller than normal ones and they may fall 
prematurely. (3) Reduction in size of the f@t. Scabby 
apples are almost always smaller than healthy orles. (4) Re- 
duction in quality of the fruit. This is usually regarded as the 
chief consideration, but obviously other types of losses are nearly 
of equal importance. (5) The keeping qualities of the fruit 
are diminished. Pink-rot and other storage troubles com- 
monly follow scab on stored apples. (6) The number of wind- 
falls is increased just before picking time. Scabby fruit does 
not cling well to the trees. 
Symptoms. 
The disease affects the leaves, flowers and fruit. On cer- 
tain varieties, such as the Lady, scab is found on the twigs; 
but this form of the disease is rare in America. 
On the leaves the disease usually makes its first appearance 
in the spring on the lower surface, since that side is first ex- 
posed as the leaf emerges from the bud. These hypophyllous 
spots are as a rule smaller and less prominent than those on the 
upper surface. The former lesions are brownish or olivaceous, 
of a webby appearance, with margins indefinite, fimbriate, and 
commonly tending to follow the veins of the leaf (Fig. 1). The 
spots on the upper surface (Fig. 1) are similar to those below, 
but are more definite in outline, darker, more velvety and larger. 
When a great number of lesions occur on a leaf, each spot is 
smaller than where fewer lesions prevail. The spots on the 
upper surface often cause the affected area to become convex 
above and concave below. Near the end of the season the 
