POTATO DISEASES. Until comparatively recent ly the potato blight or rot was believed to be all caused by a single fungus. Two distinct forms are now held accountable, the leaf or early blight, and the late blight or rot. The early blight (Ai ternaria soluni) appears upon the leaves as gray b-h brown spots, which, about the time the tubers are beginning to form, enlarge, and in ten days or two weeks involve half the leaf. In about a month all the foliage may have succumbed. The late blight or rot ( Phytophtbor« infcstans) ap pears in August or September, attacking leave-, stems, and tubers.. The leaves are first to ap pear to be injured. They show brown or black areas, winch soon become soft and foul-smelling. Moisture and a fairly warm. but not hot, temper ature is most favorable to its rapid development, and a few dry, hot days will check its spread. The tubers also become blotched or discolored on the surface and streaked within with brown or black. Since they are likely to rot, the crop is practically worthless. Both of these diseases can he prevented by spraying with Bordeaux mixture, beginning when the plants are 4 to 6 inches high and continuing through the season at intervals of 10 days to 2 weeks. Brown rot, believed to be
caused by Bacillus solanaccarum, is sometimes troublesome in the Southern States. The foliage usually wilts, shrivels. and turns brown or black. Since leaf-eating insects are held accountable for the spread of this trouble, they are combated with insecticides. Rotation of crops is recommended as a means of prevention and care in the selec tion of seed tubers that they do not come from infested regions. Scab appears as rough. (lark patches of varying depth upon the tubers and upon beet roots, rendering them unsightly and de stroying the outer portions. Scabby potatoes and infested soil should he avoided. Many growers soak the 'seed' in a solution of ounces of cor rosive sublimate in 15 gallons of water; or S fluid ounces of formalin, or formaldehyde, in 15 gallons of water, after which the tubers are spread to dry. These are considered preventive measure-:.