Resistant head scab found in northeastern U.S.
Colleagues in New York have just documented an isolate of Fusarium graminearum from N.Y. wheat that is highly resistant to tebuconazole (an active ingredient in Prosaro, Folicur and others) from just a small pilot survey of N.Y. isolates.
This is alarming because the triazole group of chemicals is the main fungicide tool we have in the fight against vomitoxin.
Be selective about your use of these and other fungicides–every application gets us a bit closer to fungicide resistance in our fungus populations. Resistant wheat leaf disease fungi have been found in Europe and the US, and now we know that resistant head scab fungi are out there too. We tend to get the best bang for our buck in PA by a single fungicide application to protect the flag leaf as it emerges.
In situations where powdery mildew is a problem (high humidity, mild temperatures, heavily N fertilized, susceptible cultivars grown), an early application of a fungicide can also provide an economical yield benefit. Be sure the applications you make fit your situation for disease control. In other words, a fungicide in the tank at topdressing or herbicide time might not give you as much benefit as you think when you consider the possible consequences.
The most recent fungicide efficacy chart has been released by the North Central Regional Committee on Management of Small Grain Diseases. This combines data across several states from many different studies to provide information on the most common products and how well they work on our most common wheat diseases.
This helpful resource can be found here: Fusarium Head Blight Prediction Center
While it’s still pretty early to be thinking about wheat head scab, do yourself a favor and bookmark this FHB predictor tool (http://www.wheatscab.psu.edu/). Visit this website as your wheat approaches the flowering stage to find out if weather conditions put it at high risk.
I will add commentary about disease risk in our area to give some human perspective, and you can have this commentary sent to your e-mail or phone by signing up for U.S. Wheat & Barley Scab Initiative’s (USWBSI) FHB Alerts.
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