. The cotton plant : its history, botany, chemistry, culture, enemies, and uses. Cotton; Cotton. DISEASES OF COTTON. 309 1 .^ curled in various ways, and during favorable weather, as during rains in the hot summer time, a great profusion of hyphse and conidia are developed. The brown hyphae give a blackish appearance to the leaf, while the colorless conidia form a whitish covering to portions of it. The conidia and hyplme, under these circumstances, are very long. On such leaves the perfect, or Splmerella, stage of the fungus is quite likely to be developed. These have been found in several pa
. The cotton plant : its history, botany, chemistry, culture, enemies, and uses. Cotton; Cotton. DISEASES OF COTTON. 309 1 .^ curled in various ways, and during favorable weather, as during rains in the hot summer time, a great profusion of hyphse and conidia are developed. The brown hyphae give a blackish appearance to the leaf, while the colorless conidia form a whitish covering to portions of it. The conidia and hyplme, under these circumstances, are very long. On such leaves the perfect, or Splmerella, stage of the fungus is quite likely to be developed. These have been found in several parts of Alabama, and they undoubt- edly occur in all the A cotton-producing j,?^ States. This stage /;;' of the fungus (Sphce- rella gossypina) was first described iu a bulletin of the Tor- rey Botanical The perithecia are ovate and nearly black, and partly immersed in the tis- sue of the leaf, the ostiolum and the apical portion pro- jecting through the epidermis. They measure GO to 70 /u. The asci vary from clavate to lanceolate or subcylindrical, measuring 40 to 50 by S to 10 fi. They are eight-spored, the spores being ellipti- cal or nearly fusoid, and slightly constricted at the single septum, which divides the spore into two unequal cells. Literature.—Cooke, Grevillea 12 (1883), p. 31. " Cotton-leaf blight," F. Lainson- Scribner, U. S. Dept. Agr. Rpt. 1887, p. 355. "Sphserella gossypina," etc., G. F. Atkinson, Torr. Bot. Club, Bui. 18 (1891), No. 10. Alabama College Sta. Buls. 27, 36, and 41. Bot. Gaz., 16 (1891), p. 62. AREOLATE MILDEW OF Fig. 7.—Arfiolate mildew. (Ramularia areola Atkinson.) This mildew is confined to definite areolate portions of the leaf, the areas being limited by the veiulets. The clusters of short hyphse which project through the epidermis to the outside of the leaf and the num- bers of conidia borne upon them give a mildewed or frosted appearance 'No. 10, Please note that these images are extracted fro
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