. Agricultural botany, theoretical and practical. Botany, Economic; Botany. 7o6 FUNGI by the fungus, Macrosporiu7n Solani Ell. et Mart., only conidial forms of which are known. The conidia and hyphae bearing them are brown. Each of the former when fully developed is somewhat spindle-shaped and formed of several cells as at A, Fig. 236. The mycelium is colourless and penetrates into the tissues of the leaves upon which it usually causes small greyish- brown patches, which are much slower in development and paler in colour than those due to Phytoph- thora infestans. The disease often occurs earl
. Agricultural botany, theoretical and practical. Botany, Economic; Botany. 7o6 FUNGI by the fungus, Macrosporiu7n Solani Ell. et Mart., only conidial forms of which are known. The conidia and hyphae bearing them are brown. Each of the former when fully developed is somewhat spindle-shaped and formed of several cells as at A, Fig. 236. The mycelium is colourless and penetrates into the tissues of the leaves upon which it usually causes small greyish- brown patches, which are much slower in development and paler in colour than those due to Phytoph- thora infestans. The disease often occurs early in the season when the plants are not more than 5 or 6 Fig. ^4, Portion of hyphae inches high, especially in dry weather and conidiophores of a species of - . \ . -r Macrospnium, showing two com- and m dry situatiODS. in Severe pound conidia. B, the same of a 1,11 1 species of ^ter»ar/^ (enlarged =50 cascs, where the leavcs or large areas laraeters). ^^ them are killed at an early stage of growth, the crop of tubers is necessarily small but is always sound. A fungus, designated Alternaria Solani by Sorauer, and very nearly related to the above Macrosporium if not identical with it, has beeiKobserved to cause a leaf-disease of the potato plant in many parts of Germany similar in all respects to the American ' Early Blight.' Both these species belong to an imperfectly known group of fungi which are mainly saprophytes, but which appear to be cap- able of attacking plants when the latter have been previously weakened or injured by excessive heat, dryness of soil and atmo- sphere, and depredations of insects. The application of Bordeaux mixture is found to be very beneficial in such attacks. Ex. 285.—Examine dead patches on the surfaces ot potato leaves with a low power and search for Macrosporium or Alternaria Solani. If found, the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and a
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