INTRA-HOST INTERACTIONS OF SOIL-BORNE PATHOGENS AND AN INSECT HERBIVORE IN FIELD PEA

Increased production of field pea (Pisum sativum L.) in Canada has led to a greater incidence of disease and the range expansion of insect pests. Aphanomyces euteiches Drech. and several Fusarium species are soil-borne pathogens responsible for causing severe root rot disease in pea and related leguminous plants, while the feeding activity of the pea leaf weevil (Sitona lineatus L.) significantly reduces nitrogen fixation. All three organisms are associated with the roots of their mutual host, thus there is a high potential for synergistic interactions to occur that may ultimately reduce yield. Two independent greenhouse trials indicated that simultaneous exposure of pea to Fusarium avenaceum and S. lineatus increased both disease expression and insect survival in comparison to controls. There are currently no effective management strategies available, therefore field trials are currently underway to test the efficacy of nine seed, foliar and soil treatments in slowing insect and pathogen spread. Preliminary results indicate that combined fungicidal and insecticidal treatments may suppress pathogen growth and herbivory in both pea and faba bean (Vicia faba L.), particularly at early growth stages. These results lend important insight into the design of appropriate strategies aimed at mitigating these critical threats to pulse production.