. Manual of fruit diseases . Fruit. PLUM DISEASES 381 Before wilting, diseased trees may be located by the scorched appearance of their leaves. This is particularly noticeable in dry weather in late summer. The edges of the leaves become dry. This, however, is not a specific sign of the wilt disease inasmuch as this appearance may be induced by any factor which cuts off the water-supply. Trees growing in a dry, hard soil as well as those with diseased roots are very liable to ex- hibit symptoms similar to those of the early stages of wilt. From those wilted trees which die in the early sum- me
. Manual of fruit diseases . Fruit. PLUM DISEASES 381 Before wilting, diseased trees may be located by the scorched appearance of their leaves. This is particularly noticeable in dry weather in late summer. The edges of the leaves become dry. This, however, is not a specific sign of the wilt disease inasmuch as this appearance may be induced by any factor which cuts off the water-supply. Trees growing in a dry, hard soil as well as those with diseased roots are very liable to ex- hibit symptoms similar to those of the early stages of wilt. From those wilted trees which die in the early sum- mer, gum is exuded. Later beetles bore holes in the bark through which gum flows freely. Death of the tree follows in the fall and winter, and no leaves are put out the next spring. Old trees are said to suffer more than young ones. Cause. Recent investigations have shown conclusively Fig. iii. âPlum-wilt, that plum-wilt is due to the fungus â Lasiodiplodia Triflorw. The pathogene gains entrance into the tree by means of wounds. Observations show that at least 33 per cent of the infections occur through borer wounds. Borers prefer Japanese varieties, probably be- cause they are budded on peach stock in which the borers make their attack. Wounds made by the black-spot pathogene, Bacterium Pruni, are also very common points of entrance for th0 plum-wilt fungus. In this connection it is to be noted that. 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 Hesler, L. R. (Lexemuel Ray); Whetzel, Herbert Hice, 1877-1944. New York : Macmillan
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