Interactions of Microsphaera diffusa with Soybeans and Other Legumes

Abstract

Conidia of M. diffusa produce as many as 5 germ tubes on germination. Only the 1st germ tube forms an appressorium. The conidium is the center of the mildew colony, and a conidiophore can arise directly from it. Development of the fungus from germination of conidia to production of conidia was followed at 3 and 12 h intervals. Of the 35 Leguminosae tested, 21 were hosts of the fungus. Different degrees of infection on susceptible plants were evident not only between species, but also between cultivars of the same species. These hosts showed 1 or more of the following symptoms: curling of leaves, wilting, defoliation, chlorosis, necrosis, water-soaked lesions, earlier senescence, shriveled seeds and incomplete pod filling. The production of conidiophores and conidia were inhibited in ''Flambeau'', but not in ''Acme'' soybeans [Glycine max].