VIEW ARTICLE

Ecology and Epidemiology

Demonstration of Verticillium albo-atrum Within Alfalfa Seed. A. A. Christen, Research associate, Department of Plant Pathology, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350; Phytopathology 72:412-414. Accepted for publication 28 June 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-412.

Plant to seed transfer of Verticillium albo-atrum was demonstrated in both naturally and artificially infected alfalfa plants. Verticillium was isolated from seed of greenhouse-inoculated alfalfa cultivars: susceptible Apalachee, WQS1 (a Washington line), and resistant Vertus. Colony development from surface-sterilized seed indicated that V. albo-atrum was present within the seed. Scanning electron microscopy revealed that mycelia were located within and between osteosclerid cells of the outer integument of the seed coat. Internal seedborne infection was as high as 25% in the small seed fraction (0.91–1.6 mg) of seed produced on plants inoculated within 2 wk following pollination. Infection occurred less frequently in larger seeds.