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Interactions of Pythium myriotylum with Several Fungi in Peanut Pod Rot. R. Garcia, Research Assistant, Department of Plant Pathology, University of Florida, Gainesville 32611, Present address of senior author: Colegio Superior de Agricultura Tropical, Tobasco, Mexico; D. J. Mitchell, Assistant Professor, Department of Plant Pathology, University of Florida, Gainesville 32611. Phytopathology 65:1375-1381. Accepted for publication 24 June 1975. DOI: 10.1094/Phyto-65-1375.

Interactions of Pythium myriotylum with several fungi in pod rot of peanut were evaluated by exposing pods to fungal pathogens alone or in various combinations in vitro or at defined inoculum densities in soil. The exposure of attached or detached pods to Rhizoctonia solani prevented or reduced the development of rot in pods later exposed to P. myriotylum in soil or in vitro. High populations of Macrophomina phaseolina nullified the antagonistic effect of R. solani on P. myriotylum if the pods were grown in soil, but not if the pods were grown in vermiculite. The isolation frequency of P. myriotylum from pods was reduced after exposure to soil containing R. solani. This effect was most striking with attached or detached pods which were exposed successively to R. solani in soil or in vitro prior to exposure to P. myriotylum in soil. Rhizoctonia solani, on the other hand, was isolated much less frequently or could not be isolated at all from attached or detached pods exposed to P. myriotylum prior to exposure to R. solani. If pods were exposed to Fusarium solani or Trichoderma viride in vitro prior to R. solani and then P. myriotylum in soil, pod rot occurred but no P. myriotylum and little or no R. solani were isolated from the pods. However, when pods were exposed to R. solani in vitro prior to F. solani or T. viride and then P. myriotylum in soil, pod rot was not greater than in the control and R. solani but not P. myriotylum was isolated from the pods.