VIEW ARTICLE

Dimorphism in Verticillium albo-atrum as Affected by Initial Spore Concentration and Antisporulant Chemicals. N. T. Keen, Assistant Professor, Department of Plant Pathology, University of California, Riverside 92502; M. C. Wang(2), Margaret Long(3), and D. C. Erwin(4). (2)(3)(4)Research Associate, Staff Research Associate, and Professor, respectively, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 61:1266-1269. Accepted for publication 28 May 1971. DOI: 10.1094/Phyto-61-1266.

Verticillium albo-atrum exhibited increasing tendency to grow as spores in shaken liquid cultures when initial spore concentrations were increased from 10⁴ to 10⁸ spores/ml; at initial concentrations above 10⁸ spores/ml, negligible amounts of mycelium were formed. In order of increasing activity, semicarbazide, phenylhydrazine, deoxyadenosine, gossypol, and 5-fluorodeoxyuridine (FUdR) were effective as antisporulants in shaken cultures initiated with less than 10⁸ spores/ml. Except for gossypol, these compounds had little or no effect on total culture dry weight, but all caused greater accumulation of mycelium than in nonsupplemented cultures. Attempts to control Verticillium wilt of cotton with soil applications of 5-FUdR or deoxyadenosine were unsuccessful.