Influence of agronomic traits on the expression of tissuespecific resistance to mycosphaerella blight in field pea

Abstract

Mycosphaerella blight, caused by Mycosphaerella pinodes, is the most destructive disease of field pea (Pisum sativum L.) in western Canada. A 3-yr field study conducted at two field locations examined the effect of differences in lodging, growth stage and maturity on disease development among field pea cultivars that possess different forms of partial resistance. Significant differences in disease development, measured as area under the disease progress curve (AUDPC), and as disease severity on the leaves, stems and pods were observed among the field pea cultivars. These measurements of disease development were only influenced by differences in crop maturity in 2005. Only cultivars that were either intermediate or late maturing had low disease severity ratings or AUDPC values. Differences in the degree of lodging had a small inconsistent effect on the mycosphaerella blight ratings. These results suggest that differences in maturity should be considered in order to avoid inadvertent selection for late maturity while evaluating field pea lines or cultivars for mycosphaerella blight resistance. Key words: Mycosphaerella pinodes, field pea, Pisum sativum, maturity, lodging.