Latent period and infection frequency as components of partial resistance to powdery mildew in some winter wheat varieties

Abstract

Partial resistance to powdery mildew (Blumeria graminis f.sp. tritici) of 20 winter wheat varieties and a susceptible control variety Barbee was tested under controlled conditions. To asses the varieties for partial resistance, latent period (LP 50) and infection frequency (number of colonies per unit leaf area) were used. The variety Dragana showed the highest degree of partial resistance that involved a long latent period and low infection frequency. The varieties Angelina, Barbara and NS 27 /03 had a somewhat shorter LP 50, but a similar infection frequency; therefore, it seems likely that they also possess a high degree of partial resistance. Significantly high negative correlations were found between LP 50 and infection frequency (r= - 0.755).