. Diseases of plants induced by cryptogamic parasites : introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae . Plant diseases; Parasitic plants; Fungi. 284 USTILAGINEAE. formation of conidia ensues; the conidia multiply in a yeast- like manner, and only grow out as hyphae on exhaustion of nutritive material. Infection takes place on seedling-plants. Kiihn cultivated this species on Sorghum saccharatum and S. vulgare, and suggests that a common disease of Durra in South Africa may be caused by this parasite. Ust. sorghi (Link.) {Ust. Tulasnei Kiihn) ( America):
. Diseases of plants induced by cryptogamic parasites : introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae . Plant diseases; Parasitic plants; Fungi. 284 USTILAGINEAE. formation of conidia ensues; the conidia multiply in a yeast- like manner, and only grow out as hyphae on exhaustion of nutritive material. Infection takes place on seedling-plants. Kiihn cultivated this species on Sorghum saccharatum and S. vulgare, and suggests that a common disease of Durra in South Africa may be caused by this parasite. Ust. sorghi (Link.) {Ust. Tulasnei Kiihn) ( America): This is another widely distributed parasite of Sorghum vulgare and S. saccharatum. Its external appearance is described by Kiihn somewhat as follows: " Diseased plants attain to almost their normal size, and the flower-head is developed as far as the glumes. The ovary, however, is completely metamorphosed into a sac filled with spores, its outer wall forming a delicate Pig. 154.—Ustilago cruenta. Spikelet enlarged from a bead of Sorghum. The ovaries are transformed into long flask- shaped sacs, from slits of which the spores are emerging as a black powder. ^ natural size. (v. Tubeuf del.). Pig. 155.—Ustilago cruenta. Germin- ating and sprouting conidia from a cultivation in plum-gelatine, (v. Tubeuf del.) whitish coat, which is easily torn, and, when the spores liave escaped, a columella will be found to occupy the centre of the smut-mass. The stamens may also become filled with spores, and be externally more or less irrecognizable. As a rule, all the flowers of a head are smutty; if any escape, they remain more or less rudimentary.'' The spores, according to Brefeld, germinate only in nutritive solutions. They produce a four-celled promycelium, on which few conidia are formed. Ust. sacchari Eabh. Dust-brand of cane sugar. This fungus injures the stems and heads of Saccharum officinale, S. cylindricum, and S. Erianthi in Italy, Africa, and Java. Ust. sacchari-ciliaris
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