. Chestnut blight. Chestnut blight; Chestnut. 10 The Journal of HerEdtty. AMERICAN CHESTNUT ATTACKED. This and the four following figures, showing stages in the progress of the bark disease, were taken by Professor J. F. Collins at various points on Long Island. This photograph shows where the disease has seeured a foothold on some of the smaller limbs, which are quickly killed. When the infection is on the smaller limbs, however, the rest of the tree may survive for several years. (Figure 2.) parasite have been considered as pos- sible retarding agents, but as these same insects appear to als
. Chestnut blight. Chestnut blight; Chestnut. 10 The Journal of HerEdtty. AMERICAN CHESTNUT ATTACKED. This and the four following figures, showing stages in the progress of the bark disease, were taken by Professor J. F. Collins at various points on Long Island. This photograph shows where the disease has seeured a foothold on some of the smaller limbs, which are quickly killed. When the infection is on the smaller limbs, however, the rest of the tree may survive for several years. (Figure 2.) parasite have been considered as pos- sible retarding agents, but as these same insects appear to also distribute the spores, their controlhng influence is not hlvcly to prove important. MANNER OF INFECTION AVhen, in the Chinese chestnut, any spores of the parasitic ftingus gain entrance into a wound on any i.\art of tlic trunk' or Hmbs, the)' give rise to a canker wliich persists on the tree, be- coming deeper year by year as healthy wood is formed around it. In the American chestnut, however, the canker rapidly enlarges until it girdles the tree. If the |)art attacked happens to be the trunk, the whole tree is killed, some- times in as short a time as a single season. If tju- smaller liranches are attacked, only those portions bej'ond the point of attack are killed, and the remainder of the tree may survive for scA'cral years. Ultimately, however, all American chestnut trees that are at- tacked, die completely (fig. 5). Figures 2, 3, and 4 show the typicaUy ragged appearance of such trees, due to the fact that some branches are not yet girdled and still have nonnal foliage, while others are dead. Limbs and trunks with smooth bark soon show cankers in the fomi of dead, discolored, sttnken areas, which con- tinue to enlarge and become covered more or less thickly with the yellow, orange, or reddish brown pustules of the fruiting ftmgus (figs. 6 and 7). From these pustules masses of minute spores (conidia) are commonh'extruded. Please note that these images are extracted from s
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