. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. FUNGI IMPERFECT! 359 The Kieffer is practically exempt. In any case, however, the fungus may be readily controlled with Bordeaux. The spots on the leaves are few or numerous, angular, and the size varies greatly with the variety. Three fairly well differentiated zones of color are shown in an affected spot: at the center it is ashen gray, and within this area appear on either surface the minute pycnidia; the next outer zone, or area, is brown, or black in very young leaves; and sur
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. FUNGI IMPERFECT! 359 The Kieffer is practically exempt. In any case, however, the fungus may be readily controlled with Bordeaux. The spots on the leaves are few or numerous, angular, and the size varies greatly with the variety. Three fairly well differentiated zones of color are shown in an affected spot: at the center it is ashen gray, and within this area appear on either surface the minute pycnidia; the next outer zone, or area, is brown, or black in very young leaves; and surrounding this second there may be an area. Fig. 177. Dilution Culture of Septoria Pyricola which is purplish in color (Fig. 176). These color details are lost in very old leaves, but the black papillae indicating the pycnidia then show up clearly. At maturity the spores may ooze out in dark uniform cirras. In cross section the pycnidium is clearly ovate in form. The wall is made up of several layers of dark cells, and the hyaline conidiophores arise from an inconspicuous inner layer (Fig. 178). The spores are flexuous and quite constantly two- septate, measuring about 60 x 3-4 /x. The mycelium is intercel- lular, brownish, and may be detected within the tissues at some little distance from the perithecium. The spores germinate readily in. 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 Duggar, Benjamin M. (Benjamin Minge), 1872-1956. Boston ; New York : Ginn
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