. Diseases of fruits and nuts. Fruit; Nuts. Diseases of Fruits and Nuts 117 Rust.—-TJiis rust, which also attacks tlie jicach, ajn^icot, and almond, is seen on plums and prunes mainly in the black-rust stage. Late in fall, the undersides of the leaves become covered with dark-brown or black spore pustules of the fungus Tranzschelia pruni-spinosae. The attack comes so late that little or no damasre is done and no treatment is neces-. Fig. 64.—Thrips mark on prunes, often mistaken for a fungus disease. sary. The alternate stage of this rust on anemone is seen occasionally in California but seems
. Diseases of fruits and nuts. Fruit; Nuts. Diseases of Fruits and Nuts 117 Rust.—-TJiis rust, which also attacks tlie jicach, ajn^icot, and almond, is seen on plums and prunes mainly in the black-rust stage. Late in fall, the undersides of the leaves become covered with dark-brown or black spore pustules of the fungus Tranzschelia pruni-spinosae. The attack comes so late that little or no damasre is done and no treatment is neces-. Fig. 64.—Thrips mark on prunes, often mistaken for a fungus disease. sary. The alternate stage of this rust on anemone is seen occasionally in California but seems to be of no importance in the perpetuation of the fungus. Shrivels, Drought Spot.—Before maturity, one side or the lower end of the fruit sometimes becomes shriveled and dark-colored in depressed spots where the flesh is dead and sticks to the pit. This may be due to sunburn or drought. Kelsey spot (p. 114) seems to be of a similar nature. Sour Sap.—Trees sometimes die or fail to develop in spring, with a discoloration and fermentation of the inner bark. Young trees are more commonly affected, occasionally in very large numbers. Single branches or whole trees may show the trouble. Sour sap may be due to bacterial canker, phytophthora canker, excess of soil water, or other causes. Many other kinds of fruit trees are affected. See this disease under "Apri- cot" (p. 39). Thrips Effect.—The affected fruit, especially of prunes, is marked with scabby spots and lines and is much disfigured and deformed ( 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 Smith, Ralph E. (Ralph Eliot), 1874-1953. Berkeley, Calif. : The College of Agriculture, University of California
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