. Botany for agricultural students . Botany. POWDERY MILDEWS (PERISPORIALES) 373 tree is killed. The deeply buried mycelium is not reached by sprays, and the total destruction of the infected trees is the only available method of checking the disease. Powdery Mildews (Perisporiales). — This group includes many Fungi, but they arc all very similar in their habits. The mycelium commonly occurs on the surface of leaves, but some- times on the stems and fruits of the higher plants. The myce-. FiG. 324. — Powdery Mildew of the Hop. Below, diagrammatic draw- ing of a section of a Hop leaf, showing t
. Botany for agricultural students . Botany. POWDERY MILDEWS (PERISPORIALES) 373 tree is killed. The deeply buried mycelium is not reached by sprays, and the total destruction of the infected trees is the only available method of checking the disease. Powdery Mildews (Perisporiales). — This group includes many Fungi, but they arc all very similar in their habits. The mycelium commonly occurs on the surface of leaves, but some- times on the stems and fruits of the higher plants. The myce-. FiG. 324. — Powdery Mildew of the Hop. Below, diagrammatic draw- ing of a section of a Hop leaf, showing the superficial mycelium wtiich has grown haustoria into the epidermal cells, and produced erect conidiophores bearing chains of conidia (X about 50). Above, epidermal cell, hypha, and invading haustorium more highly magnified. From Bulletin 328, Cornell University Agr. Exp. Sta. lium forms quite noticeable powdery patches. The asci are produced in closed ascocarps called cleistothecia. In Figure 323 is shown the mildew of the Apple. The Lilac Mildew (Microsphaera) is the one most commonly observed of the Mildews. Often in late summer and autumn, the leaves of the Lilac are so generally covered with the whitish dusty-looking patches, that the entire bush appears covered with street dust. But there are also Mildews that occur on fruit trees, Roses, Gooseberries, Peas, and other cultivated plants, which do considerable damage. From the superficial hyphae. 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 Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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