2 BULLETIN 543, U. S. DEPARTMENT OF AGRICULTURE. 
DESCRIPTION OF THE DISEASE. 
Leaves, fruit, and twigs are affected, but the injury to the leaves 
usually is the most serious phase of the disease. 
The first indication of injury to the foliage is the appearance of 
small, nearly transparent, water-soaked areas. These are par- 
ticularly noticeable when a leaf is held between the observer's eyes 
and the sun. Later, the spots enlarge, turn darker, and at length 
become dry and brittle. Then, as a final stage, they crack away 
from the living tissues and often fall out entirely, giving the leaf 
the so-called shot-hole appearance (PI. I, figs. 3 and 4) . Sometimes 
a number of spots, especially those near the margin of the leaf, will 
coalesce, giving the leaf a burned or blighted appearance. Later, 
these dead areas, composed of several spots which have run together, 
may break away and fall to the ground, giving the leaf a peculiar, 
ragged appearance. Infections may be so numerous as to injure 
every leaf on the tree, they may be localized so as to affect seriously 
only the foliage of certain limbs, or the infection may be mild all 
over the tree, so mild at times as not to be especially important. 
Though the disease in its later stages on the leaves is difficult to 
distinguish from spray injury, damage by shot-hole fungi, and some 
other diseases, when it appears on the fruit, especially after it has 
passed the first stage of its development, it is not easily so confused. 
Minute spots, scarcely darker than the skin of the young fruit, denote 
the first appearance of the disease. These spots soon become some- 
what enlarged and gradually become darker in color. Later, as the 
fruit enlarges, small cracks appear in the diseased areas (PI. I, figs. 8 
and 9). Beginning with this stage, the disease is most characteristic 
and is not easily confused with any other type of injury. Later, with 
further growth of the fruit, the cracks are extended, and finally several 
may run together, making long irregular fissures (PI. I, figs. 1 and 2). 
The flesh of the fruit is protected by the formation of a corky layer 
in these cracks, but nevertheless the fruit itself presents a ragged and 
irregularly cracked surface which, except in mild cases, renders it 
unfit for market. 
A grayish water-soaked spot is the first indication of the disease 
on the twigs of the current season. This soon becomes dark and later 
is sunken. If there are a number of infections close together they 
may coalesce, forming a rather large canker, which may persist, with 
rather abundant flow of gum. Plate I, figures 5, 6, and 7, shows 
advanced stages of the disease on twigs. 
Usually in the Ozarks the first infections on leaves, twigs, and fruit 
occur in May, or sometimes even earlier. The disease does not 
become conspicuous, however, until much later; in the Ozarks 
about the middle of June in the case of leaves and twigs and about 
