APPLE BLOTCH 
This disease is generally known as apple blotch, but it is sometimes 
called black scab, fruit-blotch, and star-fungus. 
It should be clearly borne in mind that apple blotch is entirely distinct 
from sooty blotch and apple scab, in spite of the common names applied. 
This disease, like bitter rot, is confined largely to the central and southern 
states, and in the southern half of the apple-belt it is more destructive, 
taken year by year, than bitter rot and apple scab combined. 
SYMPTOMS 
The fruit, bark and foliage are all affected by this disease. 
On the fruit. The lesions vary somewhat with the variety. Using 
available affected fruits, and Pl. Ind. Bur. Bul. 144, pl. I, II, IV, V and 
VI, study the symptoms and oBSERVE :— 
1. That the first evidence of the disease is a very small in- 
conspicuous, light-brown speck, which, under slight magnification, has the 
appearance of a stellate collection of brown fibers just beneath the epider- 
mis. On account of this stellate character of the spot this disease is at 
times confused with apple scab. On young apples, the lesions are at 
first water-soaked, and in wet weather there may be a yellowish gummy 
exudate therefrom. 
2. That spots enlarge radially, attaining a diameter of from 
3-10 or more millimeters, becoming darker in color. On light-colored 
varieties the spots are green, later becoming brown, while on red varieties 
the spots are at first red, then changing to black. The advancing margin 
is irregular and jagged and has a fringed appearance. 
, 3. That sometimes the spots are sunken and may or may not 
show this fringed margin, or they may be raised; gradations between the 
fringed smooth spot and the umbonate spot (raised and strongly projecting 
in the center). Where the spots are numerous, they may coalesce, forming 
large lesions involving a major portion of the fruit. On some varieties at 
least, like the Ben Davis, the skin ultimately cracks. The crevices, 
although usually about a half an inch long, may girdle the fruit and extend 
to the core. Often these cracks intersect, forming a cross. 
4. That within a few days after the spots become visible, black 
pimples (the fruiting bodies of the pathogene) develop thereon. 
Make a series of SKETCHES to bring out points observed in 1, 2, 3, and 4. 
On the bark. The disease affects the fruit-spurs, twigs and rapidly 
growing shoots, producing characteristic cankers. Larger limbs and trunks 
are not usually affected. On the material provided, oBSERVE:— 
5. That on the fruit-spurs, the spots are at first purplish or 
blackish. The center turns brown with age, the margin remaining pur- 
plish. The resulting lesion is small but rather conspicuous, with a crack 
along the margin. : 
6. That on water-sprouts and on other rapidly growing shoots, 
the cankers have much the same appearance as that just described, but 
are larger, sometimes measuring an inch or more in length and often 
girdling the stem. Longitudinal cracks appear not only along the edge 
but also through the cankered tissue, eventually giving the surface a rough 
appearance. This character is noticable on cankers two or three years 
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