2022 Wheat Disease and Fungicide Update
Rome Ethredge and Alfredo Martinez-Espinoza
- Foliar Diseases – Recent weather patterns in the southern US can contribute to the dispersal and establishment of wheat diseases. Critical wheat growth stages are quickly approaching; therefore, scouting of wheat fields should commence or increase if already occurring. Protecting the flag leaf from foliar diseases is critically important for yield preservation. The decision whether or not to apply a fungicide should be made by carefully weighing variety planted, yield potential, and if current environmental conditions are conducive for disease development at each specific site. Just this week, 3-15-22, Stripe rust has been found in a couple of southwest Georgia counties so we need to be looking closely for it. When seen from a distance it often looks like a dry area, that just looks odd. Here’s some images from the UGA Stripe Rust brochure. https://secure.caes.uga.edu/extension/publications/files/pdf/C%20960_4.PDF
Current Extension recommendations are to apply a fungicide anytime stripe or leaf rust is found in a field and when other foliar diseases (powdery mildew, stagonospora leaf/glume blotch, tan spot) are progressing up the plant and reach two leaves below the flag leaf. Bear in mind that Powdery mildew tends to diminish as temperatures consistently reach above 75ºF and RH falls below 85%. Below are the fungicides available for control of foliar diseases.
- Triazoles – metconazole (Caramba), propiconazole (Tilt, Popimax), prothioconazole (Proline), prothioconazole + tebuconazole (Prosaro), and tebuconazole containing products (Folicur, others)
- Strobilurins – azoxystrobin (Quadris, Equation, Satori), fluxastrobin (Evito), picoxystrobin (Aproach), pyraclostrobin (Headline)
- Mixed mode of action – benzoyindiflupyr + propiconazole + azoxystrobin (Trivapro), cyproconazole + picoxystrobin (Aproach Prima), fluoxapyroxad + pyraclostrobin (Priaxor), fluoxapyroxad + pyraclostrobin + propiconazole (Nexicor), flutriafol + fluoxastrobin (Fortix, Preemptor), fluxastrobin + tebuconazole (Evito T), flutriafol + azoxystrobin (Topguard), pydiflumetofen + propiconazole (Miravis Ace), propiconazole + azoxystrobin (Quilt, QuiltXcel), azoxystrobin + cyproconzole (Azure Xtra), propiconazole + trifloxystrobin (Stratego), prothioconazole + trifloxystrobin (Stratego YLD, Delaro 325), pyraclostrobin + metconazole (Twinline, Multiva), tebuconazole + trifloxystrobin (Absolute, Absolute Maxx), and tebuconazole + azoxystrobin (Custodia)
A complete list of products, rates, timings, restrictions, etc. can be found on pages 49-52 of the 2021-2022 Wheat Production Guide https://grains.caes.uga.edu/content/dam/caes-subsite/grains/docs/wheat/Wheat-Production-Guide-2021.pdf and pages 363-365 of the 2022 Georgia Pest Management Guide. The section in the Wheat Production Guide contains a wheat fungicide efficacy table developed by the North Central Extension and Research Committee (NCERA-184).
- Fusarium Head Blight/Head Scab – Fusarium Head Blight requires humid/wet weather coinciding with wheat at flowering growth stages for infection to occur. There are no symptoms or signs to scout for, therefore, we rely on weather conditions and predictions. The FHB risk tool https://www.wheatscab.psu.edu is now live and available. The platform has been re-designed with new features added so it is important to familiarize yourself with the content again. The application window for chemical control is very tight and must occur during anthesis/flowering. The following are fungicides recommended for control of FHB:
- metconazole (Caramba), propiconazole (Tilt), prothioconazole (Proline), tebuconazole (Folicur), prothioconazole + tebuconazole (Prosaro), pydiflumetofen + propiconazole (Miravis Ace)
More information on FHB can be found in the extension publication C1066 https://extension.uga.edu/publications/detail.html?number=C1066 or on page 51 of the 2021-2022 Wheat Production Guide and page 365 of the Georgia Pest Management Handbook 2022.
- Small Grain Disease Physical Samples – All small grain disease samples should be sent to the Plant Disease Clinic in Athens, GA. For the proper address and sample preparation check https://plantpath.caes.uga.edu/extension/clinic.html.