. Manual of fruit diseases . Fruit. 216 MANUAL OF FRUIT DISEASES cultivated currants and gooseberries; this stage is known as Cronartium Rihicola, the name now used to apply to any and all stages of the fungus on whatever host it is found. The fungus lives from year to year ill the bark of living pines (Fig. 57) _, finally fruiting and developing a crop of eeeiospores which blow to Ribes (currant and goose- berries) near by. In pines the organism may be shipped thousands of miles. It is not known whether the fungus hibernates on the Ribes or not, although there is some evidence that such is th
. Manual of fruit diseases . Fruit. 216 MANUAL OF FRUIT DISEASES cultivated currants and gooseberries; this stage is known as Cronartium Rihicola, the name now used to apply to any and all stages of the fungus on whatever host it is found. The fungus lives from year to year ill the bark of living pines (Fig. 57) _, finally fruiting and developing a crop of eeeiospores which blow to Ribes (currant and goose- berries) near by. In pines the organism may be shipped thousands of miles. It is not known whether the fungus hibernates on the Ribes or not, although there is some evidence that such is the case. In the spring from early April to June (chiefly in May), the seciospores are blown to young Ribes leaves. These spores are produced over a period of about two weeks. They apparently are never carried more than a few hundred feet. ShoiJd any of these spores fall on pines, infection will not re- sult ; the fungus cannot pass from pine to pine; it must first go to the currant or goose- berry, if it is to grow. In the presence of moisture the seciospores germinate and infect the Ribes leaves. Cold weather inhibits the rapid progress of the fungus in the currant leaves. With a favorable tem- perature the fungus soon establishes itself, and after two weeks a new crop of spores is produced. These are always produced on the lower surface of the Ribes leaf. They are distinct from the seciospores which come from the white pine, and are known as uredospores. The uredospores are capable of infecting other currants and goose- berries. This stage is sometimes called the summer or repeat- ing stage (Fig. 55). This repetition may proceed throughout. Fig. 57. — Euro- pean currant-rust; secia on white Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hesler, L. R. (Lexemuel Ray); Whetzel, Herbert Hice, 1877-194
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