Effect of Soil Shading by Surface Residues During Summer Fallow on Take-all of Winter Wheat

Artificial inoculum of Gaeumannomyces graminis var. tritici was incorporated 10 cm deep in field plots about 1 mo after harvest of winter wheat and 2 mo before planting of wheat, and plots were either shaded with wheat straw or left bare. Plants grown in shaded plots had more severe take-all and lower grain yields than plants grown in plots left bare. During the oversummering period between wheat crops, soil temperatures at a depth of 5.1 cm were routinely 10 C cooler in shaded plots than in bare plots, and maximum soil temperatures reached 32.5-37.4 and 37.5-42.5 C on more days in bare plots than in shaded plots