Fungous diseases of plants . brids,etc., are susceptible. In somedistricts certain light col-ored varieties are more re-sistant and the Scuppernongis practically free fromattack. In this case, how-ever, as in many othersalready mentioned, there isa great difference in the re-sistance of varieties accord-ing to their environmentalconditions. For all commer-cial purposes grape growingwould be impossible in mostlocalities, on account of thegreat losses entailed, if thedisease were not practically controllable by spraying operations. The fungus. The mycelium of this fungus is found in theouter por
Fungous diseases of plants . brids,etc., are susceptible. In somedistricts certain light col-ored varieties are more re-sistant and the Scuppernongis practically free fromattack. In this case, how-ever, as in many othersalready mentioned, there isa great difference in the re-sistance of varieties accord-ing to their environmentalconditions. For all commer-cial purposes grape growingwould be impossible in mostlocalities, on account of thegreat losses entailed, if thedisease were not practically controllable by spraying operations. The fungus. The mycelium of this fungus is found in theouter portions of affected berries, but mycelium is never abun-dant. Under favorable weather conditions only about one weekmay be required from the time of infection to the development ofthe pycnidia,—ordinarily 8-12 days are necessary. The pycnidiahave long been known under the name PJioma Jivicola B. & the leaves the pycnidial stage has passed under the namePhyllosticta Labrusae. The pycnidium develops from a stromatic. Fig. no. Grapes affected i5Y Black Rot(Photograph by F. C. Stewart) i ASCOMYCETES 257 mass of mycelium which arises hencath the epidermis. It isbroadly elliptical, with a rather thick wall and no indication of abeak (Fig. 112, a). The conidiophores are short and simple, bear-ing spores — ovate or elliptical — measuring ordinarily 8—10 x 7-8/i. In moist weather the spores are pushed out in vermiform
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