The chestnut bark disease . Fig. 5.—Young tree showing postules on smooth bark, and sprouts. (See alsoFig. 11, page 221.) A closer examination reveals the diseased band near th(base of the affected portion. It is especially conspicuous oismooth bark, causing a reddish brown discoloration and pro-ducing numerous little pustules which break through the barland set free vast numbers of spores. These spore masses areorange colored but vary considerably in appearance accord-ing to climatic conditions. During warm, moist weather the]are especially prominent and sometimes may be seen as longicurly, y
The chestnut bark disease . Fig. 5.—Young tree showing postules on smooth bark, and sprouts. (See alsoFig. 11, page 221.) A closer examination reveals the diseased band near th(base of the affected portion. It is especially conspicuous oismooth bark, causing a reddish brown discoloration and pro-ducing numerous little pustules which break through the barland set free vast numbers of spores. These spore masses areorange colored but vary considerably in appearance accord-ing to climatic conditions. During warm, moist weather the]are especially prominent and sometimes may be seen as longicurly, yellow threads issuing from the pustule (figure 6). March, 1912.] THE CHESTNUT BARK DISEASE. 215. Fig, 6.—-A very close view of a diseased portion. Note the summer sporesissuing in long twisted strings from some of the pustules. 216 W. V. AGR. EXPERIMENT STATION [Bulletin 137 Such threads are composed of countless numbers of sporesheld together by some sticky material. Rains dissolve thisadhesive material and carry the spores to lower portions of thesame tree or to others standing close by. When -a branch is girdled by cutting around it, there is aptto be an enlargement produced just above the wound, and asimilar effect is often noted in limbs attacked by this fact many of the gross symptoms are exactly similar tothose which would be produced by mechanical or insect girdl-ing. If older portions are attacked, the discoloration and pus-tule formation are not so evident, as most of the pustules areproduced in the fissures of the bark. Such bark, when cutthrough, is found to be discolored and breaks up easily likepunk. Tapping upon this bark will usually produce a pecu-li
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