VIEW ARTICLE

Ecology and Epidemiology

Influence of the Antagonist Laetisaria arvalis on Infection of Table Beets by Phoma betae. S. B. Martin, Postdoctoral research associate, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; G. S. Abawi(2), and H. C. Hoch(3). (2)(3)Associate professors, respectively, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456. Phytopathology 74:1092-1096. Accepted for publication 14 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1092.

Interactions of the fungal antagonist, Laetisaria arvalis, with the seedborne pathogen, Phoma betae, were studied in natural (unpasteurized) and pasteurized beet field soils in greenhouse tests. Portions of natural and pasteurized soils were amended (5%, v/v) with preparations of L. arvalis. These soils were planted with seedballs of the table beet cultivar Ruby Queen that were nontreated (~80% infested with P. betae), hot water treated to eliminate P. betae, or treated with metalaxyl to prevent infection by Pythium ultimum in the natural field soils. In pasteurized soils (lacking P. ultimum and Rhizoctonia solani), disease induced by P. betae was greatly reduced by soil amendments with L. arvalis or by coating seedballs infested with P. betae with sclerotia of the antagonist. In beet field soils naturally infested with P. ultimum and R. solani, preemergence and postemergence damping-off and wire-stem symptoms were reduced when such soils were amended with L. arvalis in comparison to unamended soils.