Conditions for infection of winter oilseed rape leaves by conidia and ascospores of Pyrenopeziza brassicae, causing light leaf spot

Abstract

The optimum temperature for infection of oilseed rape leaves by P. brassicae conidia was c.16°C; an increase of temperature above the optimum and a decrease of temperature below the optimum decreased infection by conidia. Conidia did not infect oilseed rape leaves at 24°C. At the optimum temperature, conidia infected oilseed rape leaves after 6h of leaf wetness. At temperatures below the optimum, longer leaf wetness duration was required for infection by conidia. At 6°C, more than 16h of leaf wetness were required for conidia to infect oilseed rape leaves. The latent period of P. brassicae (time from inoculation to first sporulation) was shortest at c.16°C and increased as temperature increased above the optimum and below the optimum. Ascospores of P. brassicae were more infective than conidia on leaves of winter oilseed rape