Fungal Diseases in Winter Wheat

Improving profitability by managing fungal pathogens

By Mark Lubbers, WestBred® Wheat Technical Product Manager, Central Plains Region

 

Planning for and responding to fungal diseases in winter wheat is essential for achieving a farmer’s yield goal. Every year is different, and not all environments throughout the central Plains have the same disease spectrum. Preparedness has been particularly challenging this year, considering the drier than normal conditions. However, as spring approaches, so does the increased risk for yield-robbing diseases.

Early-season diseases such as tan spot, leaf blotch complex (Septoria tritici and Staganospora nodorum) and powdery mildew are commonly found in the higher rainfall areas of the central Plains. Under the right circumstances, tan spot can lead to significant yield loss. These diseases primarily overwinter in wheat stubble, so planting tolerant varieties or rotating out of wheat are two effective cultural practices. Fungicides can be very effective at controlling early-season fungal diseases and can be tank-mixed with a spring-applied herbicide if disease is present at the time of application.

Pre-flowering diseases such as stripe rust and leaf rust can lead to significant yield loss if not treated in a timely manner. According to Kansas State University, approximately 16 million bushels were lost to these two diseases in 2020. The flag leaf and the penultimate leaf (leaf below the flag leaf) can contribute up to 70% of a wheat plant’s yield, so protecting these two leaves is critical. It is recommended to apply a high-quality fungicide when the flag leaf is at least 50% emerged.

Fusarium head blight, also known as head scab, is not as common as stripe rust or leaf rust but can be challenging to control. The pathogen that causes head scab is also responsible for Gibberella ear and stalk rot in corn. Infections are most common when long periods of high humidity exist and when wheat is planted into corn residue. Infections occur during flowering since wheat pollen serves as a food source for the fungus. While genetic tolerance is the best option for managing head scab, fungicides can help to improve protection against this disease. Fungicide applications should be made at flowering, even though symptoms won’t be visible until grain fill. Keep in mind that only specific fungicides are labeled for head scab control, and application timings are specific to the flowering.

For additional wheat management tips, contact Mark Lubbers at mark.lubbers@bayer.com.

Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields. WestBred and Design® and WestBred® are registered trademarks of Bayer Group. ©2022 Bayer Group. All Rights Reserved.

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