Inoculation with Fusarium and Verticillium to Increase Resistance in Fusarium-Resistant Tomato. Pedro E. Jorge, Professor of Plant Pathology, Instituto Superior de Agricultura, Santiago, Dominican Republic. Ralph J. Green, Jr., and William R. Chaney. Professor Emeritus, Department of Botany and Plant Pathology, and Professor of Tree Physiology, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907. Plant Dis. 76:340-343. Accepted for publication 30 October 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0340.

Increased resistance to Verticillium wilt was confirmed in Fusarium-resistant tomato (Lycopersicon esculentum) cultivars when plants were root-dip inoculated simultaneously with Fusarium oxysporum f. sp. lycopersici (inducer) and Verticillium dahliae (challenger). The level of resistance diminished progressively as the time interval between inducer and challenger inoculations was increased and also as the concentration of the inducer inoculum was reduced in relation to the challenger inoculum. Increased resistance also occurred at lower but significant levels in a Verticillium-resistant tomato cultivar when V. dahliae was the inducer and F. o. lycopersici the challenger organism. Increased resistance in both cases appears attributable to either pathogen antagonism at the root surface or a localized, rather than a systemically induced, host response.