VIEW ARTICLE

Repeated Germination and Sporulation of Microsclerotia of Verticillium Albo-atrum in Soil. J. D. Farley, Assistant Research Specialist, University of California, Berkeley 94720, Present address of senior author: Assistant Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691; S. Wilhelm(2), and W. C. Snyder(3). (2)(3)Professors of Plant Pathology, University of California, Berkeley 94720. Phytopathology 61:260-264. Accepted for publication 9 September 1970. DOI: 10.1094/Phyto-61-260.

Soil, artificially infested with microsclerotia of Verticillium albo-atrum, was air-dried and remoistened with sucrose or water nine consecutive times. Microsclerotia germinated and sporulated after each remoistening. Germination percentage and number of germ tubes and conidia formed by each microsclerotial germination decreased with succeeding germinations. Pregerminated microsclerotia were capable of vigorous germination. When they were removed from treated soil and germinated in agar or the rhizosphere of cotton, there was little difference in germination percentage and number of germ tubes produced per germination between microsclerotia which had germinated one, four, or eight times. The propagules responsible for population increases in microsclerotial-infested soil moistened with sucrose solution or water were conidia. Conidia formed by germinated microsclerotia in soil were isolated and germinated in agar and in the rhizosphere of cotton.