Interactions of root rot pathogens and pea leaf weevil in field pea

Abstract

Additive or synergistic interactions between Aphanomyces euteiches, Fusarium spp., and the pea leaf weevil Sitona lineatus have the potential to increase yield loss in commercial pea crops. Greenhouse studies indicated that A. euteiches and S. lineatus are significant risk factors for increased severity of fusarium root rot. Sensitive, species-specific primers and probes for A. euteiches and field pea were developed, and multiplex qPCR indicated significant changes in colonization dynamics when multiple pathogens were present. qPCR assays also demonstrated that A. euteiches and Fusarium spp. co-infect pea roots under field conditions. The fungicides ethaboxam and fludioxonil did not reduce disease severity in pea or faba bean during a two-year field study. Thiamethoxam reduced nodule and foliar herbivory, whereas lambda-cyhalothrin and nitrogen fertilizer had no impact. No single or combined treatment improved yield or seed size, therefore an effective method of managing these constraints to pea production is still required.