. Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . FIG. 3. DISEASED POTATO LEAF. brownish spots upon the leaves. As the disease pro-gresses these spots gradually enlarge, finally involvingthe whole leaf, w^hich turns dark brown or neighboring leaves become affected, and the wholeplant eventually wilts and dies. PARASITIC FUNGI 7 If one looks closely at the under surface of the leafbeneath the brown spots, he will see, in case this fungusis present, a w^hitish velvety mold. By making a thincr
. Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . FIG. 3. DISEASED POTATO LEAF. brownish spots upon the leaves. As the disease pro-gresses these spots gradually enlarge, finally involvingthe whole leaf, w^hich turns dark brown or neighboring leaves become affected, and the wholeplant eventually wilts and dies. PARASITIC FUNGI 7 If one looks closely at the under surface of the leafbeneath the brown spots, he will see, in case this fungusis present, a w^hitish velvety mold. By making a thincross-section of the leaf at this point, and putting itunder the microscope, an appearance similar to Fig. 4will be seen. At -the right is one of the long pointedhairs which grow naturally upon the under surface ofthe healthy leaf; next to this toward the left is anotherpeculiar leaf-hair v/ith a club-like tip; and beyond this. FIG. 4. SECTION OF POTATO LEAF SHOWING DEVELOPMENT OP MILDEW. project the hyph^e, or fruiting threads of the fungus,which give off branches on which are borne small ovalbodies. The latter are the spores, or conidia, of thefungus. They are the bodies by means of which thefungus reproduces itself, and are developed on theinfested leaves in enormous numbers. These conidia are easily dispersed by slight air cur-rents, and are carried far and wide en the wings of the 8 PLXGI AND PLXGICIDES
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpathoge, bookyear1896
