. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. ASCOMYCETES 283 destructive in that state. Under ordinary circumstances the fungus is doubtless a mere saprophyte, and it. is not restricted to the apple or to other members of the apple family. It has in fact been found upon such trees as the following: American elm (Ulmus america?ia), Magnolia sp., Judas tree (Cercis canadensis), and Sorbus sp. Symptoms. The disease is usually found upon the larger limbs or upon the trunk, and the appearance of the canker areas is so characterist
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. ASCOMYCETES 283 destructive in that state. Under ordinary circumstances the fungus is doubtless a mere saprophyte, and it. is not restricted to the apple or to other members of the apple family. It has in fact been found upon such trees as the following: American elm (Ulmus america?ia), Magnolia sp., Judas tree (Cercis canadensis), and Sorbus sp. Symptoms. The disease is usually found upon the larger limbs or upon the trunk, and the appearance of the canker areas is so characteristic that it cannot be mistaken, at least in late stages of the disease, for any of the cankers thus far discussed. At first the infested areas are brown, slightly sunken, and con- sist of small spots of healthy tissue intermingled within the general diseased area. These die later, but there is an irregular and mottled effect which per- sists and is readily observed. The infected area may cover many square inches of surface, and it is sharply delimited from the healthy tissue, due to the drying and cracking. Occa- sionally there is a slight de- velopment of slime during the , . , , Fig. 12^. Blister Canker of Apple early part of the season, but this has not been associated with the action of the parasite. Hasselbring describes the external appearance during the late season as follows: The bark of the older parts becomes much roughened and blackened as if it had been charred. Numerous rifts and cracks appear over the surface of the dead bark, which is very dry and brittle, and falls off in irregular patches, ex- posing the dead wood. The circular stromata are firmly attached to the wood by means of a ring of hard fungous tissue, so that they remain seated on the wood even after the bark has fallen away. The entire blackened area is dotted over with the circular stromata, which form the most pronounced distinguishing feature of this canker. The disease is always easily recognized b
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Keywords: ., bookauthorduggarbe, bookcentury1900, bookdecade1900, bookyear1909
