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Leaf rust severity on the flag leaf in two dryland fields near Waverly and near Lincoln averaged 12% and 15%, respectively, on June 10. At these severity levels, economic yield loss due to leaf rust is unlikely. By mid June, disease levels in western Nebraska were very low even in irrigated fields. Black chaff (Figures 1 and 2), a bacterial disease, was found in irrigated fields in southwestern Nebraska and in the Panhandle. It also was found in an irrigated breeding nursery near Mead.
Starting in May, loose smut (Figure 3) was found at low levels in fields across the state. White heads (Figures 3 and 4) were seen in wheat fields throughout the state. In some cases this condition was found to be caused by the stem maggot. Frost also may have caused white heads in some fields. In many cases, however, the cause of white heads was unclear. Disease did not seem to be the cause, but it is possible that dry weather and above normal temperatures played a role.
Smuts and some other fungal diseases of wheat as well as black chaff are transmitted through seed. The best management strategy for seed-transmitted diseases is to use certified, pathogen- free seed. Treating seed with fungicide can help reduce transmission of smuts and other seed-transmitted fungal diseases. It also protects the seed and seedling from soilborne damping off and crown and root rot fungi. Treating seed with fungicide will not protect against black chaff. Use of certified, pathogen-free seed is the best strategy in preventing occurrence of this bacterial disease.
Stephen Wegulo
Extension Plant Pathologist, Lincoln
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| Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture. | ||
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