Soilborne pathogens in a vegetable double-crop with conservation tillage following winter cover crops

Abstract

A cucumber-cucumber double-crop followed by a cucumber-snap bean double-crop was grown in a system using conservation tillage in relay-cropping following winter cover crops. Twenty different winter covers were legumes, grasses, legume-grass mixtures, crucifers, or fallow (no cover, resident vegetation). Population densities of Pythium spp. (primarily P. irregulare) and Rhizoctonia solani anastomosis group (AG-4) were greater following legumes than following grasses or fallow; legume-grass mixtures and crucifers were intermediate. Cucumber fruit rot (induced primarily by R. solani AG-4) was more severe following legumes and crucifers than following grasses; legume-grass mixtures were intermediate. In the snap bean crop following cucumber, root and hypocotyl diseases were more severe following winter covers of legumes or fallow than following grass or legume-grass mixtures; crucifers were intermediate. Root-knot nematodes ( Meloidogyne incognita) caused injury to the second vegetable crop each year in all winter cover rotations.