Effects of Plot Size and Border Width on Assessment of Powdery Mildew of Winter Wheat

A study was conducted to determine the effect of plot size (2.9 and 26 m 2 ), distance between plots (1.7 and 5.1 m), and pairing of cultivar plots (slow-mildewing cultivar paired with a susceptible cultivar or susceptible cultivar paired with a susceptible cultivar) on the development of powdery mildew of wheat in 1989 and 1990. Both plot size and cultivar pairing had a significant (P<0.05) effect on area under the disease progress curve (AUDPC). AUDPC values calculated for the susceptible cultivar in the smaller plots compared with the larger plots were 10 and 17% lower over the 2 yr, respectively (...)