. Minnesota plant diseases. Plant diseases. 304 Minnesota Plant Diseases, protective covering to the central spores, which have retained their germinating power. Thus the functional spores obtain an additional protection by means of the surrounding layer of sterile spores. There are usually two or three functional spores in each spore mass. Upon ger- mination the spores produce a tube from which secondary spores are formed in the man- ner usual for smuts. Jensen's hot water method has been recommended when the fun- gus appears in abundance. Formalin would probably prove useful. Powdery mildew
. Minnesota plant diseases. Plant diseases. 304 Minnesota Plant Diseases, protective covering to the central spores, which have retained their germinating power. Thus the functional spores obtain an additional protection by means of the surrounding layer of sterile spores. There are usually two or three functional spores in each spore mass. Upon ger- mination the spores produce a tube from which secondary spores are formed in the man- ner usual for smuts. Jensen's hot water method has been recommended when the fun- gus appears in abundance. Formalin would probably prove useful. Powdery mildew of grasses {Erysiphe graminis DC). The cereal grasses are sometimes seriously damaged by the at- tacks of this disease. A fine whitish mycelium is formed on the leaves in the summer time. The mycelium threads derive their nourishment from the skin cells of the host by short sucker branches sent in- to these cells. These sucker branches are known as haus- toria. Summer spores are produced in large numbers and rapidly carry the disease from leaf to leaf and plant to plant. These spores are spherical or egg-shaped cells microscopically small; they are formed in chains which stand upright, often over the whole upper surface of the leaf. Toward fall the sacs with their spores are formed in sac-capsules. As is usual in powdery mil- dews, the capsules appear as small black spheres about the size of a pin point. In the earlier stages these capsules are whitish. Fig. 152.—Powdery mildew of grasses (Ery- siphe graminis), on wild grass-plant leaves. The white coat of the fungus mycelium is very conspicuous. 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 Freeman, Edward Monroe, 1875-. Saint Paul, Minn.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectplantdi, bookyear1905
