Plant-parasitic nematodes and fungi associated with root rot of peas on prince edward island.

Eight commercial pea fields on Prince Edward Island were sampled in June and July over a 2-year period (1986-87) to determine soil population densities and the incidence of nematodes and fungi associated with root rot of peas. Root lesion nematodes (Pratylenchus spp.) were the dominant endoparasitic nematodes recovered from roots and soil. Low populations of the northern root-knot nematode (Meloidogyne hapla) were also present. Tylenchorhynchus spp. and Paratylenchus spp. were recovered frequently from soil in the root zone, and Helicotylenchus spp. were also frequent, but in low numbers. Fusarium solani was the most common fungal species isolated from the epicotyl and hypocotyl tissues of pea. Fusarium oxysporum was also isolated frequently, and both Fusarium species were found in soil from all fields. Rhizoctonia solani and Verticillium albo-atrum were common in hypocotyl tissue, but V. dahliae was isolated infrequently. Root rot was rated as severe in all fields and was positively and significantly correlated (P </= 0.05) with densities of Tylenchorhynchus spp. in soil and with incidence of F. solani in pea tissue. The incidence of F. solani root infections was positively and significantly correlated with densities in soil of Tylenchorhynchus spp. (P </= 0.01), Helicotylenchus spp. (P </= 0.01), and Paratylenchus spp. (P </= 0.05).