. Fig. 22.—Helminthosporium leaf spot of oats. Leaf infection by Helmintho- sporium causes dying of narrow, oblong strips of leaf tissue between veins. The dead tissues turn rustv brown. the fungus enters the hull surrounding the kernel and may even penetrate the kernel itself. An attacked kernel turns brown at the basal end. Life History.—The fungus causing Helminthosporium leaf spot overwinters as spores on the outside of the seed and as mycelium within the seed. When infected kernels sprout, the fungus within the seed renews its growth, or the spores on the seed germinate and produce infect
. Fig. 22.—Helminthosporium leaf spot of oats. Leaf infection by Helmintho- sporium causes dying of narrow, oblong strips of leaf tissue between veins. The dead tissues turn rustv brown. the fungus enters the hull surrounding the kernel and may even penetrate the kernel itself. An attacked kernel turns brown at the basal end. Life History.—The fungus causing Helminthosporium leaf spot overwinters as spores on the outside of the seed and as mycelium within the seed. When infected kernels sprout, the fungus within the seed renews its growth, or the spores on the seed germinate and produce infected spots on the seedling leaves. Spores produced in these spots are dispersed by various means to other leaves of the same plant, as well as to other plants, and produce new spots. Successive crops of spores borne on both old and new spots provide an abundance of infective material for new leaves as they form and for the grain as it develops. Importance.—Diseased plants, because of the destruction of leaf tissue, are handicapped in the manufacture of food sub- stances, and the reduction in food results in light or shriveled kernels, as does also direct attack of the disease on the kernels. Helminthosporium leaf spot is present every year in Illinois oats fields, but usually the loss due to it is slight. It fluctuates from year to year both in prevalence and in severity of attack. and in Illinois fields has ranged in prevalence from 15 per cent to as high as 75 per cent, with a corresponding destruction of leaf area ranging from to per cent. Data extending back to
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Keywords: ., bookcentury1900, bookcolle, bookpublisherurbana, booksubjectgrain
