Effect of mancozeb on the control of mycosphaerella blight of field pea

Mycosphaerella blight (MB) [Mycosphaerella pinodes (Berk. & Blox.)Vestergr. ] causes substantial yield loss to field pea in western Canada in most seas ons and is a disease for which genetic resistance is lacking. The objective of this research was to evaluate the effectiveness of foliar application o f mancozeb for the control of MB of field pea. Field trials of split-plot d esign were conducted at two sites per year from 1996 to 1998 in southern Ma nitoba, with cultivars as main-plots and fungicide treatments as sub-plots. In most site-years, a single application of mancozeb at the early flowerin g stage was effective in reducing MB severity and in increasing yield. Manc ozeb had similar efficacy to chlorothalonil, the only currently registered fungicide for control of MB in field pea. The beneficial effect of both fun gicides was greater for the highly MB susceptible cultivars AC Tamer and Ca rrera than the moderately MB susceptible cultivar Radley.