VIEW ARTICLE

Influence of Atrazine on the Severity of Fusarium Root Rot in Pea and Corn. James A. Percich, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824; J. L. Lockwood, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 65:154-159. Accepted for publication 25 July 1974. DOI: 10.1094/Phyto-65-154.

Populations of Fusarium in a loam soil amended in the laboratory of field with atrazine at 10, 30, and 100 µg/g were increased up to 4-fold over those in nonamended soil. A steamed greenhouse soil mixture artificially infested with conidia of Fusarium solani f. sp. pisi and amended with 2.5 to 25 µg/g atrazine had increased numbers of the pathogen at all concentrations. In soil artificially infested with either conidia or chlamydospores of F. solani f. sp. pisi or F. roseum f. sp. cerealis ‘Culmorum’, then amended with atrazine at 30 µg/g, incidence of pea root rot was three times, and of corn seedling blight twice, that in nonamended soil. Germination of macroconidia, growth of macroconidial germ tubes, and subsequent chlamydospore formation by both fungi, were enhanced on soil amended with 10 µg atrazine/g soil. Virulence of the pathogens was not enhanced by growing inoculum in media containing atrazine, nor were pea or corn plants predisposed to greater susceptibility by exposure to atrazine.