. Diseases of economic plants . Plant diseases. 104 DISEASES OF ECONOMIC PLANTS. Fig. 43.—The blight showing exudate from bark, much enlarged. This teems with the causal bacteria. After Whetzel. With the flow of sap in the spring these infested linibs become centers of reproduction. From these a milky fluid teeming with the bacteria exudes. This attracts insects which then carry the infection to other twigs and to flowers. Two additional forms of this disease, according to the part affected, are recognized: (1) flower blight, (2) body blight and canker. Neither of these differs essentially fro
. Diseases of economic plants . Plant diseases. 104 DISEASES OF ECONOMIC PLANTS. Fig. 43.—The blight showing exudate from bark, much enlarged. This teems with the causal bacteria. After Whetzel. With the flow of sap in the spring these infested linibs become centers of reproduction. From these a milky fluid teeming with the bacteria exudes. This attracts insects which then carry the infection to other twigs and to flowers. Two additional forms of this disease, according to the part affected, are recognized: (1) flower blight, (2) body blight and canker. Neither of these differs essentially from the twig blight, though the body blight or canker is es- pecially worthy of men- tion »)n account of its peciMar destructiveness. Thiaform occurs where the disease is led by a spur, shoot, or ^cker into the cam- bium under the bark of the body or main limbs of the tree, or where primary infection occurs thrAigh a woimd so as to lead to disease in such parts. Thl result of such in- fection is a diseased area more or less cffcular, which may even girdle the tree or branch, and which in any event causes serious injury. The susceptibility of the tree is largely influenced by external conditions. In general, anything which leads to rapid growth, resulting in tender shoots, favors the devel- opment of the disease. There is also much difference in resistance offered by different varieties. The Anjou, Kieffer, Angouleme, and Seckel possess more resistance than the Bartlett, Clapp, or Flemish Beauty^ Based on the facts as stated above, the following direc-. 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 Stevens, Frank Lincoln, 1871-1934; Hall, John Galentine, 1870-. New York : Macmillan
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Keywords: ., bookauthorstevensf, bookcentury1900, bookdecade1910, bookyear1910
