Effect of Planting Date, Cultivar, and Seed Treatment on Leaf Rust Severity of Wheat Along the Gulf Coast

Abstract

The effects of planting date, cultivar, and seed treatments on wheat leaf rust (Puccinia triticina Ericks) were studied in the 1995 and 1996 at two sites in Louisiana. Three winter wheat (Triticum aestivum L.) cultivars, differing in susceptibility to leaf rust, were planted 21 to 35 days early and at a recommended date. FFR 525 was susceptible, Coker 9835 was moderately susceptible, and Pioneer brand 2566 was moderately resistant to prevalent races of leaf rust. Seed fungicide treatments were: Vitavax® 200 and Baytan® 30 plus Captan® 30-DD, plus a non-treated control. Across cultivars, early planting resulted in higher leaf rust levels in both years compared to planting wheat at the later date. The rust susceptible FFR 525W, when planted at the recommended date, had lower areas under rust progress curves than when planted early. The moderately resistant Pioneer 2566 may be planted early or at the recommended date, while Coker 9835 should be planted at the recommended date. Seed treatment fungicides provided limited control of leaf rust in only one environment. Planting within the recommended planting period with a resistant cultivar provided the most reliable disease control.