. [Fruit culture]. spots that bear spore cases, and as the disease progresses thegrapes wither, turn black, and become hard and shriveled,sometimes clinging to the vine until the following 41 shows the effect of black rot on grapes. Growing shootsare attacked as well as the leaves and fruit. During winterand spring the resting spores are formed, usually on theshriveled berries. Treatment.—The treatment for black rot consists of destroy-ing, as far as possible, all diseased fruit, old leaves, prunings,and rubbish, and spraying the vines thoroughly with Bor-deaux mixture. The spray s
. [Fruit culture]. spots that bear spore cases, and as the disease progresses thegrapes wither, turn black, and become hard and shriveled,sometimes clinging to the vine until the following 41 shows the effect of black rot on grapes. Growing shootsare attacked as well as the leaves and fruit. During winterand spring the resting spores are formed, usually on theshriveled berries. Treatment.—The treatment for black rot consists of destroy-ing, as far as possible, all diseased fruit, old leaves, prunings,and rubbish, and spraying the vines thoroughly with Bor-deaux mixture. The spray should be put on at the followingperiods: 1. Just as the pink tips of the first leaves appear. 2. From 10 days to 2 weeks after the first spraying. 3. Just after the blossoming. 4. From 10 days to 2 weeks after the third spraying. 5. From 10 days to 2 weeks after the fourth spraying. In regions where the disease is not virulent and in seasonsunfavorable to its spread, the fourth and fifth treatments maybe § 13 GRAPE CULTURE 59 74. Do\^Tiy Mildew.—^When first known, downy mildew,which is an American fungus, was confined to the MississippiValley and the Middle Atlantic States. This mildew is nowto be found, like black rot, in all of the grape-growing regionsof America, except those of the Pacific slope, but it is not nearlyas troublesome in some regions as in others. It is found onpractically all grapes, wild or cultivated, and there are fewvarieties that are very resistant under all conditions. Fortu-nately, this trouble is relatively easy to control by spraying. Description.—Downy mildew attacks all of the tender grow-ing parts of the grape. It does much damage to the leaves, onthe upper siirface of which it produces greenish-yellow spotsof irregular outline, and on the under surface a loose, downy,white growth. This white growth consists of short filamentsthat bear spores, the summer spores, which are carried by theelements to other growing parts of the plant,
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