Influences of Temperature and Plant Age on Differentiation of Races of Fusarium oxysporum f. sp. tracheiphilum on Cowpea. T. A. Swanson (deceased),, Former Graduate Student, Department of Nematology, University of California, Riverside 92521. S. D. Van Gundy, Professor, Department of Nematology, University of California, Riverside 92521. Plant Dis. 69:779-781. Accepted for publication 30 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-779.

In race-differential cultivars of cowpea (Vigna unguiculata) inoculated with isolates of races 1, 2, and 3 of Fusarium oxysporum f. sp. tracheiphilum, the extent of vascular discoloration in cross sections through the primary node was more reliable than foliar symptoms as a measure of plant reaction. Age of plants at inoculation (12 or 20 days) did not influence vascular discoloration. Plant death differentiated all three races when plants were grown at high temperatures (27 C), but at lower temperatures, vascular discoloration was the more reliable indicator of compatibility.