File:Some diseases of Puerto Rican forage crops (1953) (20352649838).jpg

Title: Some diseases of Puerto Rican forage crops
Identifier: CAT10398040 (find matches)
Year: 1953 (1950s)
Authors: Theis, Thomas
Subjects: Forage plants Diseases and pests Puerto Rico
Publisher: Federal Experiment Station of the United States Dept. of Agriculture
Contributing Library: U.S. Department of Agriculture, National Agricultural Library
Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library

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other fungi grow upon it sapro- phytically (19, p, 613). In Puerto Rico, these saprophytic fungi fre- quently are: Cerebella andropogonis Ces. (fig. 7, D, E); Cladosporium sp. (fig. 7, F, G); Fusarium sp. (fig. 7, H) ; and yeasts. Red leaf Spot The cause of red leaf spot of Melinis minutiflora Beau v. (molasses grass) has not been determined. Though leaf spots were abundant, especially during the vegetative period just prior to flowering, the disease did not appear to be of economic importance. The lesions (fig. 8) are found on the leaf. They are 1-3 mm. in diameter and are irregular in shape. The dark red central portion is sur- rounded by a red-purple border, with indefinite margin. On several occasions attempts were made to isolate the causal organism. Portions of young, dis- eased tissue were isolated aseptically and cultured at room temperature (74°-80° F.) on agar media. (Su- crose, 5 gm.; Difco veast extract, 3 gm.; K2HPO4, 0.2 gm.; XaCl, 0.2 gm.; MgS04, 0.2 gm.; CaCls, 0.1 gm.; agar, 15 gm.; water, 1,000 cc: pH 7.0.) Most of the pieces cul- tured had no growth of any kind. The fungi that gTew were of mauy types and were considered as sec- ondary organisms. In addition, in- fected plants were kept in a moist chamber for several days. Various fungi were observed in older lesions, but the younger, smaller spots were free of fungi or bacterial exudate. Guinea Grass Ergot Ergot oi Panicum maximum Jacq. Var. Common Gumea - (gumea grass, 3^erba de Gumea) is caused by Clariceps maximensis Theis. The sphacelial stage has been fomid 2 Determination of varieties of Panicum maximwn is based on a kej' devised bv Warmke p. I43), throughout the year wherever guinea grass is grown io Puerto
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Figure 8.—Leaf spot on Melinis minuti- flora (molasses grass), the cause of which has not been determined. X 3.8. Rico. The extent of infection va- ried from fields ^^'ith few infected heads to epiphytotics that appeared 9

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