Diseases of cultivated plants and Diseases of cultivated plants and trees diseasesofcultiv00massuoft Year: [1910?] 298 DISEASES OF CULTIVATED PLANTS Mint rust, caused by Puccinia fnenihae (Pers.), often com- pletely destroys entire beds of mint. All stages of the fungus are produced on the same host. The cluster-cup condition of the fungus appears first somewhat early in the season, and is most abundant on the stems, which become much twisted, distorted, and swollen, and more or less covered with the I'iG. 87.—Puccinia asparagi. 1, aecidium stage on a young shoot of asparagus ; 2, teleuto
Diseases of cultivated plants and Diseases of cultivated plants and trees diseasesofcultiv00massuoft Year: [1910?] 298 DISEASES OF CULTIVATED PLANTS Mint rust, caused by Puccinia fnenihae (Pers.), often com- pletely destroys entire beds of mint. All stages of the fungus are produced on the same host. The cluster-cup condition of the fungus appears first somewhat early in the season, and is most abundant on the stems, which become much twisted, distorted, and swollen, and more or less covered with the I'iG. 87.—Puccinia asparagi. 1, aecidium stage on a young shoot of asparagus ; 2, teleutospore stage on a summer plant; 3, aecidiospores; 4, uredospores; 5, teleutospores. l*'ig- 2 reduced, remainder variously mag. bright orange spores. The pustules of summer-spores and winter-spores develop at a later stage, and arc mostly con- fined to the leaves, where they appear under the form of minute brown or blackish pustules which soon become powdery. I. Forming large orange patches on stem and leaves. Spores subglobose, minutely warted, pale yellow, 35-45 X 18-25 /i. II. Small brown pustules on leaves mostly, spores sub globose or elliptical, pale brown, minutely warted, 18-28 x 15-20 /t. III. Blackish pustules on the leaves, spores elliptical or almost cylindrical, scarcely constricted, end rounded, thick- ened, minutely warted, brown, with a pale papilla, 25-35 X 18-23 /I, stem larger than spore. The mycelium of the aecidium stage is perennial in the creeping underground portion of the stem, hence when a plant is once infected it produces the disease every season.
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