Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . ense of the leaf cells, the latter becoming disor-ganized and turning brown. After the mycelium hasdeveloped in this way for some time it produces sporesin certain parts of the spot, rupturing the skin, or cuti-cle, of the leaf, to enable the spores to escaj^e, as shownin a. These spores are blown or washed upon otherleaves where, under favorable conditions, they may ger-minate and start new spots. There is another fungus,quite different in microscopic char
Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . ense of the leaf cells, the latter becoming disor-ganized and turning brown. After the mycelium hasdeveloped in this way for some time it produces sporesin certain parts of the spot, rupturing the skin, or cuti-cle, of the leaf, to enable the spores to escaj^e, as shownin a. These spores are blown or washed upon otherleaves where, under favorable conditions, they may ger-minate and start new spots. There is another fungus,quite different in microscopic characters from the oneillustrated, usually found on the spots, but it is believedto be a secondary form growing on the disorganized 111 112 FUisGi a:nd fungicides tissues, which the fungus under consideration firstproduces. Treatment.—The burning of fallen catalpa leavesin autumn is an advisable preventive measure. Proba-bly early sprayings with Bordeaux mixture, or some sim-ilar fungicide, would prove an effectual remedy. The only important article on this subject that hascome to the writers notice may be found in the report ^5::::^. FIG. 51. CATALI-A LEAF-SPOT,a, Section showing spore production; b, spores; c, spores germinating. Magnified. of the TJnited States Department of Agriculture for188? (pp. 364-306). The Cottonwood Leaf=rust Melampsora populina The leaves of poplars and cottonwoods are quitecommonly covered on the underside with an orange col-ored powder, which consists of the spores of a rust fun-gus. Such leaves usually fall prematurely, so that thetrees may be defoliated long before the proper in the season the orange powder is replaced on theleaf by reddish brown, waxy pustules. This is the win-ter stage of the fungus. Eaking and burning fallenleaves is advised, as a remedial measure. This fungusis discussed in the 1888 Keport of the Department ofAgriculture (pp, 390-392). Eecent experiments have THE MAPLE LEAF-SPOT DISEASE 113 sliown that this malady
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpathoge, bookyear1896
