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Wheat scab warning may be too late

Pennsylvania Ag Department's wheat scab warning may be too late if wheat heads are already flowering or finished. See following recommendations.

John Vogel, Editor, American Agriculturist

May 27, 2016

2 Min Read

On Wednesday, Pennsylvania Department of Agriculture released a warning to farmers to minimize risks of Fusarium head blight, also known as wheat scab. While the concern is valid, the timing may be a little late for many farms to achieve cost-effective control of the organism and resulting mycotoxins.


Conditions have been ideal. “Our unseasonably wet spring has increased the likelihood of growth of Fusarium, and the mycotoxins it may bring, in wheat or other small grains,” says Ag Secretary Russell Redding. “As wheat is beginning to flower across Pennsylvania, the time to prevent Fusarium Head Blight is now. Producers – particularly in the western half and southernmost parts of the state – should take precautions now to safeguard their crops.”

Earlier warning
Two weeks ago, American Agriculturist posted Keep your eye peeled for wheat scab. With warm, wet weather, most wheat moves quickly to the Feekes 10 stage and flowering, noted Nathan Kleczewski, University of Delaware Extension specialist.

Wheat head flowers don't all appear at once. Flowering starts in the middle of the head, then moves to the lower and upper segments. There’s a tight window for effective spraying, so prepare to spray when first flowers appear. Wait for emerging anthers (thin green spikes on the flowerets) to be visible.

University of Illinois research shows that approved scab fungicides worked best at beginning of flowering. The data showed that spraying five days after the ideal timing was better than spraying when no anthers were present. Early detection is crucial for protection.

Anyone planning to use a recommended fungicide for scab suppression (Prosaro, Caramba or Proline) needs to understand that these fungicides won't result in control of scab similar to the controls of rusts and powdery mildew, cautioned Kleczewski. Due to variability with developmental stage of tillers and other factors, one can expect – at best – around 42 to 45% reduction in vomitoxin or DON, a De-Oxy-Nivalenol toxin produced by Fusarium and Aspergillus strains

If flowering is over
According to this week’s Fusarium Head Blight Prediction Center, if you have had fields flower over the last two weeks, you should scout 18 to 21 days after flowering to assess scab. Fields or field areas with high levels of scab should be stored separately from low scab fields or areas if possible.

Harvest should occur as early as possible and grains dried to at least 15%. In severely affected fields, growers should increase combine fan speed to remove tombstones during harvest.

About the Author(s)

John Vogel

Editor, American Agriculturist

For more than 38 years, John Vogel has been a Farm Progress editor writing for farmers from the Dakota prairies to the Eastern shores. Since 1985, he's been the editor of American Agriculturist – successor of three other Northeast magazines.

Raised on a grain and beef farm, he double-majored in Animal Science and Ag Journalism at Iowa State. His passion for helping farmers and farm management skills led to his family farm's first 209-bushel corn yield average in 1989.

John's personal and professional missions are an integral part of American Agriculturist's mission: To anticipate and explore tomorrow's farming needs and encourage positive change to keep family, profit and pride in farming.

John co-founded Pennsylvania Farm Link, a non-profit dedicated to helping young farmers start farming. It was responsible for creating three innovative state-supported low-interest loan programs and two "Farms for the Future" conferences.

His publications have received countless awards, including the 2000 Folio "Gold Award" for editorial excellence, the 2001 and 2008 National Association of Ag Journalists' Mackiewicz Award, several American Agricultural Editors' "Oscars" plus many ag media awards from the New York State Agricultural Society.

Vogel is a three-time winner of the Northeast Farm Communicators' Farm Communicator of the Year award. He's a National 4-H Foundation Distinguished Alumni and an honorary member of Alpha Zeta, and board member of Christian Farmers Outreach.

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