. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 212 FUNGOUS DISEASES OF PLANTS outset as to cause manifest loss in the final crop. Again, diseased plants may entirely recover. The surfaces of diseased roots may be roughened and browned by the presence of the fungus, but the tissues within are usually, in the case of violets, peas, etc., tinted red or pink. Ordinarily the fungus penetrates all parts of the rootlet, but as is common with plants which are not vigorous or obligate parasites, there are no abnormal cell divisions of t
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 212 FUNGOUS DISEASES OF PLANTS outset as to cause manifest loss in the final crop. Again, diseased plants may entirely recover. The surfaces of diseased roots may be roughened and browned by the presence of the fungus, but the tissues within are usually, in the case of violets, peas, etc., tinted red or pink. Ordinarily the fungus penetrates all parts of the rootlet, but as is common with plants which are not vigorous or obligate parasites, there are no abnormal cell divisions of the host. Morphology of the fungus. The mycelium is intercellular, abundantly septate, and at first hyaline. The threads are narrow, and the branches are cut off by a septum at a slight distance from the main hypha, somewhat as in Rhizoctonia {Corticium vagum). Three kinds of spores have been commonly found, namely, (i) endosporous conidia; (2) thick- walled conidia, or chlamydo- spores; and (3) ascospores. 1. The endospores are an interesting type of spores formed in chains in terminal branches or clusters of branches (Fig. 83, a). These spores are formed by basi- petal septation as short cylindrical cells within the branch. The tip of the branch is finally broken and they are pushed out by os- motic force, the branch assuming the part of a spore case. The endospores are distinctly hyaline, and as produced in artificial cul- tures, they may remain united in short threads, or cohere laterally as small rafts. Individuals measure about 10-20 x 4-5 p. 2. The chlamydospores are thick walled, more or less cy- lindrical, brown spores, borne in chains, the early stages of for- mation differing apparently only in size from the endospores. At maturity, however, the short chains, or rather the colored spore cells of these, break up, as shown in Fig. 83, b, measuring about 12/u. in Fig. 83. Conidia and Chlamydo spores of thielavia. Please note that these images are extracted from s
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Keywords: ., bookauthorduggarbe, bookcentury1900, bookdecade1900, bookyear1909
