Fungous diseases of plants . an infestedtree is free from this general attack. As a matter of fact, the in-fection usually takes place at the time of blossoming and the dis-ease is most abundantly distributed at that time, as will be shownlater. Upon the pear the blight may continue to extend down thetwig or the branch, the branch being entirely killed as it progresses ;and in the course of some months it may have extended into thelarger limbs, or into the main body of the tree (Fig. 31). Watershoots may also be affected both in the case of the pear and theapple (Fig. 32), and direct entrance
Fungous diseases of plants . an infestedtree is free from this general attack. As a matter of fact, the in-fection usually takes place at the time of blossoming and the dis-ease is most abundantly distributed at that time, as will be shownlater. Upon the pear the blight may continue to extend down thetwig or the branch, the branch being entirely killed as it progresses ;and in the course of some months it may have extended into thelarger limbs, or into the main body of the tree (Fig. 31). Watershoots may also be affected both in the case of the pear and theapple (Fig. 32), and direct entrance to the body gained after a 124 FUNGOUS DISEASES OF PLANTS very short period of growth. Nevertheless, under conditionsmore favorable for the host plant the blight may never extendmore than a few inches, resulting merely in a tip pruning. Inthe case of the apple this twig blight is the rule, the diseaseapparently being usually unable to maintain itself in the largerbranches. Young fruits of the apple, an inch in diameter, are. Fig. 32. Water Sprouts of Apple killed by Blight frequently affected; and the copious growth of the organismgorges the fruit with the slime which may be exuded in progress of the disease is ordinarily very clearly indicatedby the appearance of the bark. The growth of the organismwithin the tissues of the soft bark causes a water-soaked appear-ance, and finally a blackening and shriveling. The organismmay, however, extend to a distance of several inches, or evena foot, below the water-soaked area. When the organism ceasesto spread rapidly in the tissues, a sharp line of demarcatioii isnoticeable, separating the dead from the healthy or comparatively SCHIZOMYCETES. BACTERIA 125 healthy tissues. In many instances the bark is broken, due proba-bly to a gelatinizing process set up by the organism in the tissuesof the host; and from these ruptured areas there are exuded beadsof a gelatinous or gummy nature, varying in color from milkywhite to brown o
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