As we move closer to wheat planting here in Kansas, fungicide seed treatments can be a wise input. In 2020 and 2021, Kelsey Andersen Onofre, K-State Extension Plant Pathologist reports that Kansas had higher than usual levels of common bunt throughout the region. Common bunt can result in yield, quality loss and often times rejection at the elevator. Many producers received discounts on their wheat after the 2020 and 2021 harvests. Common bunt can result not only in losses for individual producers, but can also dramatically reduce the quality of grain destined for the market. Fungicide seed treatments are an important and highly effective tool for controlling common bunt and a host of other seed borne diseases.
Some facts about common bunt - common bunt is also referred to as “stinking smut” because of the foul, fishy odor produced by the fungus. The tough, black spores “stick” to the surface of otherwise healthy seed and can infect plants after emergence (if seed treatments are not used). This disease then remains “silent” within plants (no symptoms) until grain fill, when the starch within grain is completely replaced with black spores. These spores can be released during harvest, contaminating the entire grain or seed lot.
Other seed-borne diseases to keep in mind for 2021 - there are other reasons why fungicide seed treatments are particularly warranted for the 2022 season. Kelsey reports “we saw higher than usual amounts of Fusarium head blight in parts of the state that typically do not see this disease.” Although Fusarium head blight is a result of fungal inoculum in residue during flowering, seed that was infected with the fungus that causes Fusarium head blight can cause a seedling blight and can reduce stand after planting. Therefore, seed lots that had some levels of “scabby” kernels from a Fusarium head blight infection should be prioritized for seed treatment after cleaning to ensure good stand establishment. In addition, this year, reports Kelsey, we saw higher than usual loose smut which, although it doesn’t cause quality loss, can reduce overall yield.
Flag smut is another fungal disease of wheat that occurs in many wheat-producing regions of the world. Historically, flag smut was known to occur in the northwestern United States, but it had not been detected in the Great Plains since the 1930s. In May of 2015, flag smut was detected in multiple counties within central and western Kansas.
The spores of the fungus that causes flag smut can survive in the soil for at least four years and can be moved to adjacent fields by wind, plant debris, or equipment. The fungus also can be moved on seed contaminated with the fungal spores.
Flag smut can be effectively managed with seed-treatment fungicides. Crop rotation with non-host crops such as soybeans, sorghum, and corn also may reduce the risk of severe disease.
Tips for product
selection
For more information about common seed treatment products and their effectiveness for the control of the diseases mentioned in this article please see Seed Treatment Fungicides for Wheat Disease Management, /bookstore.ksre.ksu.edu/pubs/mf2955.pdf. All products listed in this publication are labeled for the suppression or control of common bunt. This is due to the presence of a mode of action group three fungicide or “triazole” fungicide in each of these products (tebuconazole, difenoconazole, prothioconazole, etc.). It is recommended that seed treatments with a minimum of one product within this mode of action of fungicides are selected. In addition to product selection, it is essential to have good seed coverage for optimal control. Seed treatments failures can sometimes be traced back to inadequate coverage.
Stacy Campbell is an Agriculture and Natural Resources agent for Cottonwood Extension District. Email him at scampbel@ksu.edu or call the Hays office, 785-628-9430.
