Effects of Leaf Rust and Septoria Leaf Blotch on Yield and Test Weight of Wheat in Arkansas. E. A MILUS, Assistant Professor, Department of Plant Pathology, University of Arkansas, Fayetteville 7270. Plant Dis. 78:55-59. Accepted for publication 12 September 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0055.

Leaf rust, caused by Puccinia recondita, and Septoria leaf blotch, caused by Septoria trilici, are the most serious foliar fungal diseases of wheat in Arkansas. This study was conducted to determine the relationship of leaf rust and leaf blotch severities at the soft dough stage to yield and test weight losses. Field experiments were conducted on three wheat cultivars during two growing seasons at two locations. For each cultivar, foliar fungicides caused differences in leaf rust and leaf blotch severities, yield, and test weight. Regression was used to determine the relationship of leaf rust and leaf blotch severities to yield and test weight losses. Average yield losses for cultivars Florida 302 and Rosen were 0.30 and 0.25% for each 1% increase in rust severity, respectively. The average test weight loss was 0.08% on Florida 302 and 0.03% on Rosen for each 1% increase in rust severity. Average yield losses caused by Septoria leaf blotch were 0.43, 0.47, and 0.32% for each 1% increase in leaf blotch severity on Florida 302, Rosen, and Caldwell, respectively. The average test weight loss for each 1% increase in leaf blotch severity was similar on Florida 302 (0.05%), Rosen (0.05%), and Caldwell (0.06%). Results of this study support the use of foliar fungicides on wheat in Arkansas to control leaf rust and leaf blotch, and to protect yield and test weight potential. Estimates of rates of yield and test weight losses should be useful for making disease management decisions.