. Textbook of botany. Botany. Fig. 214. â A potato leaf at- tacked by the late blight. This fungus can be fairly well controlled by spraying the grape plants with the well-known Bor- deaux mixture.^ 384. Late Blight and Rot of Potato. âThis, commonly called the " potato disease," is at times very destructive and has been responsible for the " potato famines" of history. Because of its destructiveness it has been extensively studied and was one of the first plant diseases against ,which governments waged a real warfare. The fungus that causes the disease is very com- mon in
. Textbook of botany. Botany. Fig. 214. â A potato leaf at- tacked by the late blight. This fungus can be fairly well controlled by spraying the grape plants with the well-known Bor- deaux mixture.^ 384. Late Blight and Rot of Potato. âThis, commonly called the " potato disease," is at times very destructive and has been responsible for the " potato famines" of history. Because of its destructiveness it has been extensively studied and was one of the first plant diseases against ,which governments waged a real warfare. The fungus that causes the disease is very com- mon in some of the northern United States, and- its spread raay at any time when conditions are favorable become a serious problem. It seems to prefer the colder climates and wet, heavy soil. The fungus first attacks the potato leaves, causing spots which are purplish in color when wet, but brown when dry. The disease may be confined to the leaf; but it may spread to the stem and finally to the tubers, causing a dry rot of the latter if they are growing in dry soil or a wet rot if the soil is heavy and wet. The diseased tubers are very likely to decay in storage because many of their. ' Bordeaux mixture. This is probably the most im- portant and most commonly used of fungicides. The formula usually regarded as standard is the following, known as the "5â5â50" formula: Copper sulphate, 5 pounds. Stone lime, 5 pounds. Water, 50 gallons. Fig. 215. â â .\ few cells of a potato leaf on which spores of the late blight fungus have landed; «, a spore; 6, a germinating spore; c, a germinated spore, the germ tube from which is entering an air-pore of the leaf. After 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 Allen, Charles E. (Charles Elmer), b. 1872; Gilbert, Edward Martinius, joint author. Bos
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