January 14, 2004 | By: Laura Skillman
HOPKINSVILLE, Ky.

There is no one item that can guarantee Kentucky farmers won’t sustain damage to their wheat crop from a disease that this past year left much of the crop too high in a toxin and rejected by millers.

But experts say that doesn’t mean producers can’t mitigate the problem by using a risk management plan. Experts from the University of Kentucky College of Agriculture as well as representatives from two private consulting firms outlined some items that farmers should have in their plan during the recent UK Wheat Science Group’s winter wheat workshop.

Fusarium head blight made an appearance in many wheat fields across the commonwealth in 2003 in the highest levels since 1991 and much of Kentucky’s wheat crop had high levels of dioxynivalenol, also called DON or vomitoxin, in the wheat crop.

DON is a fungal toxin produced by the fungus as it is infecting and developing in the wheat heads. Excess DON can seriously impact a farmer’s ability to sell his crop in some markets. Many grain purchasers will not buy grain with a level above 4 parts per million with millers specifications at a maximum of 2 ppm for human consumption.

The inability to sell grain, or the ability to sell it but at a tremendous price reduction, has farmers concerned about what they can do to combat a disease that is not always a problem. It takes susceptible plants in the flowering stage under wet, cool weather conditions for head blight to be a problem.

UK Plant Pathologist Don Hershman said farmers should make preplanting decisions that allow them to escape from head blight problems. Escape occurs, he said, when one or more aspects of the disease triangle do not line up together resulting in much reduced or no disease.

One tool farmers can use in their arsenal against head blight is to plant varieties with multiple maturities and spread their planting dates over an extended period of time. This tactic increases the chances of escaping a problem by encouraging varied flowering dates, he said.

Hershman also suggested using no-till and till systems as another variance.

Chris Bowley with Wheat Tech Inc., agreed with Hershman that producers should use multiple varieties and spread out planting dates.

“Variety management is probably still the best way we have coming down the line to control head scab infection,” he said.

Other preplant decisions that can result in less severe head blight symptoms, lower DON accumulation and better seed quality include tilling corn residue prior to planting and planting moderately resistant varieties. But don’t expect tilled crops to perform much differently than no-till fields if disease is severe, Hershman said.

Fungicides haven’t been available to Kentucky producers in the past for head scab but officials are seeking permission from the federal Environmental Protection Agency to receive approval to use Folicur during the 2004 season. Hershman said he expects the state to receive permission to use this chemical or another type in the coming year.

Getting good control using a fungicide in wheat requires application at the proper stage, large volumes of water and the proper equipment to get good coverage across the entire head.

Philip Needham with Miles Opti-Crop said farmers need to check fields and determine exactly when they are flowering, and uniformity is very important in order to get control from a fungicide. He also noted that farmers need to travel slowly through the fields or they will not get proper coverage on all sides of the wheat head.

Chemicals cannot provide complete control and may not be necessary many times. Using models that combine weather conditions with other factors related to crop growth can aid in determining if using a fungicide would be helpful. Kentucky will be utilizing a forecasting model this year and Hershman said he hopes to have it available on the Internet where farmers can plug in the numbers specific to their operations.

Avoiding any practice that might encourage crop lodging is also important.

Harvest timeliness and turning up the combine fan to blow as much infected, shriveled seed out the back of the combine as possible may result in higher grain quality and less DON in grain, Hershman said. After harvest, segregate wheat so if there is a DON issue with a specific field, it will not impact the remaining crop.

While there’s no panacea out there to eliminate head blight from a farmer’s field, having and using risk management plans can help them reduce their chances of sustaining heavy losses.

“It’s all about risk management and doing the best that you can do,” Hershman said.

Efforts continue at UK and other institutions participating in the U.S. Wheat and Barley Scab Initiative to find resistant varieties. Focus also is being placed on better understanding of the genetics and accumulation of DON and whether it is an infection factor.

Kentucky is not the largest producer of soft winter wheat in the United States but has the highest yields per acre in the country. Yields have increased by an average of eight tenths a bushel per year for the past 30 years, and within the past few years that has jumped to nearly two bushels per acre. In 2003, Kentucky farmers harvested 330,000 acres of wheat.

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Contact: 

Writer: Laura Skillman 270-365-7541 ext. 278
Source: Don Hershman 270-365-7541 ext. 215