Fungous diseases of plants . stromatic forma-tions arise a mass of erect tuberculate hyphaebearing numerous spores. Setae are present,originating in the midst of the sporogenoushyphae, each seta produced from the tip of asingle hypha. These vary from 100 to 400 \xin length, and may be from 5 to 8 /u. indiameter near the base. The conidiophores arise much higher up,and they are relatively short, simple, fertile hyphae, each abscisingmany oblong-fusoid to falcate-fusoidal spores (Fig. 149). This fungus grows readily in culture upon ordinary nutrientmedia, and the color of the mycelium varies gre
Fungous diseases of plants . stromatic forma-tions arise a mass of erect tuberculate hyphaebearing numerous spores. Setae are present,originating in the midst of the sporogenoushyphae, each seta produced from the tip of asingle hypha. These vary from 100 to 400 \xin length, and may be from 5 to 8 /u. indiameter near the base. The conidiophores arise much higher up,and they are relatively short, simple, fertile hyphae, each abscisingmany oblong-fusoid to falcate-fusoidal spores (Fig. 149). This fungus grows readily in culture upon ordinary nutrientmedia, and the color of the mycelium varies greatly, being almosthyaline on some and practically black on other media. Upon thehost the sporodochia occur in concentric circles, and these arecommonly subcuticular at first, becoming emmpent. The conidiaare continuous, hyaline to olivaceous, and about the length of thenormal conidiophores. The fungus has only been found on theapple, to which it is probably confined. The disease is easily dis-tinguished from the fruit Fig. 149. VolutellaFRUCTL (After Stevens) FUNGI IMPERFECTI 317 Volutella Dianthi Atk.^ is not uncommon on carnations inmoist situations. It attacks particularly those parts more or lessin contact with a damp soil. In favorable conditions the fungusmay spread with great rapidity and so weaken the plant as tomaterially inhibit the production of flowers. It may, however,be more severe on the cutting bench, especially when sufficientventilation or drainage is not provided. XXII. DRY ROT OF POTATOES Fiisarium oxysponim Schl. Smith, Erw. F., and Swingle, D. 1). The Dry Rot of Potatoes due to Fu-sarium Oxysporum. Bureau Plant Ind., U. S. Dept. Agl. Built. 55 : 1-8. 1904. Much confusion has prevailed concerning the organisms caus-ing some of the diseases of potatoes both in this country and inEurope. Various types of potato rot have been ascribed to a largenumber of different organisms, oftentimes upon insufficient proof,or sometimes merely from a single
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