VIEW ARTICLE

Interaction of Verticillium albo-atrum and the Root Lesion Nematode, Pratylenchus penetrans, in Tomato Roots at Controlled Inoculum Densities. J. J. Conroy, Graduate Research Assistant, Department of Botany & Plant Pathology, Purdue University, Lafayette, Indiana 47906; R. J. Green, Jr.(2), and J. M. Ferris(3). (2)Professor, Department of Botany & Plant Pathology, Purdue University, Lafayette, Indiana 47906; (3)Associate Professor, Department of Entomology, Purdue University, Lafayette, Indiana 47906. Phytopathology 62:362-366. Accepted for publication 25 October 1971. DOI: 10.1094/Phyto-62-362.

The influence of the root lesion nematode, Pratylenchus penetrans, on infection levels by Verticillium albo-atrum at controlled inoculum densities of both organisms and under controlled environmental conditions was considered. Infection of tomato seedlings, cultivar Bonny Best, by V. albo-atrum was 100% at the inoculum density of 200 microsclerotia/g soil, and infection levels were progressively lower at 100, 75, 50, and 25 microsclerotia/g soil. Consistent increases in infection occurred at all inoculum densities when the nematode was also present. Infection incidence by V. albo-atrum also increased with increases in the nematode population. There was no evidence of a synergistic effect on nematode reproduction, since the number of nematodes extracted from roots of tomato also infected by V. albo-atrum was significantly lower than from roots with the nematode alone. The role of the nematode in increasing susceptibility of the host plant to V. albo-atrum was considered, using a split-root technique. There was no increase in susceptibility of tomato to the fungus pathogen when the nematode was on the same root system but in isolation from the fungus.