. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 302 FUNGOUS DISEASES OF PLANTS encouraged by certain weakening influences, such as the age of the leaf, the presence of flea-beetle injuries, etc. When large spots near the margins of the leaves become confluent, such ex- tensive areas are affected that there may result a rolling up of the edge, which might be mistaken for the tip burn, a disease gener- ally due to climatic conditions. The injury from the early blight results, therefore, in an early death of the leaves, as a result
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. 302 FUNGOUS DISEASES OF PLANTS encouraged by certain weakening influences, such as the age of the leaf, the presence of flea-beetle injuries, etc. When large spots near the margins of the leaves become confluent, such ex- tensive areas are affected that there may result a rolling up of the edge, which might be mistaken for the tip burn, a disease gener- ally due to climatic conditions. The injury from the early blight results, therefore, in an early death of the leaves, as a result of which the vines dry up and the losses to the growing crop are often very considerable, amounting to as much as 50 per cent. The disease is said to be more likely to begin at the time of flowering and while the work of the plant is directed toward the development of tubers. This fungus produces no rot directly. This Macrosporium is found not only upon the potato but also upon tomatoes and upon the jimson weed, {Datura Stramonium). There is also a very considerable difference in the susceptibility of the different varieties of potato, but at present no wholly resistant sorts are known, although the general question of the resistance of potatoes to diseases is receiving special attention in the chief potato-growing regions of the world. The fungus. Within the tissues the mycelium is light brown to olivaceous, and the conidiophores arise through stomates or push up between the collapsed epidermal cells as erect or assurgent fruiting hyphae 50-90 x 8-9 /*. They are septate, slightly curved, and, as is characteristic of this genus, the conidia are produced singly, so far as observed, upon the host. The conidia have been described as "obclavate, brown, 145-370 x 16-18/*, terminating in a very long, hyaline, septate beak (apical cells) equalling fully one-half the length of the spore (often exceeding this) ; body of spore with 5 to 10 transverse septa, longitudinal septa few o
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Keywords: ., bookauthorduggarbe, bookcentury1900, bookdecade1900, bookyear1909
