Metcalf: The Chestnut Bark Disease 



11 



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SECOND STAGE OF THE DISEASE. 



One after another, the limbs are invaded by the parasitic spores, and quickly succumb. A 

 peculiar ragged appearance in the tree is produced, due to the fact that many branches 

 have not yet been girdled by the fungus, and therefore retain their normal foliage. When 

 the canker begins in the trunk, it rapidly extends until it girdles the whole tree, and death 

 quickly results. (Figure 3.) 



in the fonn of long, irregularly twisted 

 strings or horns (fig. 6), which are at 

 first bright yellow to greenish yellow, or 

 even bufi^, becoming darker with age. 

 If the canker is on the trunk or a large 

 limb with very thick bark there is no 

 obvious change in the external ap- 

 pearance of the bark itself, but the 

 pustules show in the cracks (fig. 7), and 

 the bark often sounds hollow when 

 tapped. After the limbs or trunks are 

 girdled the fungus continues to grow 

 extensively through the dead bark, 

 sometimes, if conditions of moisture are 

 favorable, covering the entire surface 

 with the reddish brown pustules (fig. 7). 

 These pustules produce mostly the type 

 of spores called ascospores. If the 

 proper conditions of moisture are present 

 the fungus may grow on the bark of 



chestnut logs and even upon bare wood. 

 When a branch or trunk is girdled the 

 leaves beyond change color and sooner 

 or later wither (figs. 2, 3, 4, and 8). 

 These prematurely killed leaves often 

 remain on the branches, forming, to- 

 gether with the persistent burs, the 

 most conspicuous winter symptom of the 

 disease (fig. 8). Suspicion has been 

 recently aroused in some quarters that 

 the dwarfed and abortive nuts in these 

 burs may under some circumstances be 

 unwholesome, or even poisonous, when 

 eaten. So far, however, the evidence 

 on this point is wholly inconclusive. 



CONSPICUOUS SYMPTOMS. 



The most conspicuous symptom at 

 all times of the year is the occurrence of 

 sprouts at the base of the tree, on the 



