Wheat Disease Update and Fungicide Options

As wheat is approaching flag leaf stage in Tennessee, start scouting if you haven’t already for disease. Depending on variety susceptibility you may already see powdery mildew and/or wheat blotch (Septoria and/or Stagonospora blotch); but if no disease present start considering Fusarium Head Blight management.

There have been reports in Tennessee of powdery mildew (Image 1) on certain varieties this season, that have needed earlier fungicide applications. There are also levels of blotch (Septoria and/or Stagonospra blotch – Image 2) that can be found mainly in lower canopies. The main cause of concern is when any foliar diseases are on or threatening the flag leaf – as this leaf, the last to come out of the whorl, is the largest contributor to yield and needs to be protected from disease. Short descriptions of fungal wheat diseases which include conditions for disease development, symptoms and specific management options can be found along with images in the Fungal Wheat Disease Identification publication (https://extension.tennessee.edu/publications/Documents/W662.pdf). General disease scouting time line and guidance on timing of fungicide can be found in the UT Extension Wheat Disease Management publication (https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2023/10/W663.pdf).

Image 1 – Powdery mildew – white fluffy growth usual found in lower canopies in dense growth.

Image 2. Septoria-Stagnospora leaf blotch usual in the lower canopy.

Be mindful about picking fungicide products that can protect yield from multiple diseases and be sure to clearly identify what diseases you are seeing in wheat by using the mobile friendly field guide at guide.utcrops.com or previously resources listed. The wheat fungicide efficacy table, that university wheat pathologists across the nation contribute to, is a good source to match fungicide efficacy to specific diseases, the overall publication can be found at the Crop Protection Network (https://cropprotectionnetwork.s3.amazonaws.com/cpn3002_fungicideefficacywheatdisease2023-1684787198.pdf). Each state may have its own version of the table, here is the TN Wheat Fungicide Efficacy publication (https://extension.tennessee.edu/publications/Documents/W341.pdf).