May 26, 2004 | By: Laura Skillman

A disease that can cause serious damage to winter wheat has been reported in several areas of the state.

Fusarium head blight, also known as head scab, has been seen in some fields in southern and western Kentucky . It is common to see 30- to 50-percent incidences in some fields in Christian, Todd and Logan counties, said Don Hershman, a plant pathologist with the University of Kentucky Collegeof Agriculture. In McLean County , several fields were reported to be approaching 80 percent.

The first symptoms were noticed about a week ago, he said. Infection occurs during flowering and it takes about a week to 10 days before symptoms are noticeable.

“At this time I really do not know the full extent of Fusarium head blight statewide,” Hershman said. “I do not think conditions were such that we will have a statewide epidemic but I may be mistaken.”

Based on the Fusarium Head Blight Prediction Center’s findings during the past month, it appeared that most areas of the state had only brief periods of weather favorable to the disease, he said. But this model is still under development, so accuracy may be less than desired. Time will tell.

This late in the season, no new infections are likely to occur, but severity can continue to increase up to crop maturity.

Farmers should scout their fields now to determine if they have a problem. Head scab is easier to identify before wheat begins to mature, he said. Checking fields now also will allow farmers to decide how to harvest, bin and market their wheat.

Kentucky was approved by the United States Environmental Protection Agency for a Section 18 Emergency Exemption for 2004 to use Folicur 3.6F to combat Fusarium head blight and deoxynivalenol (DON) accumulation in harvested grain. However, the crop is now too mature for a fungicide to be effective and the exemption expired May 20.

When used with other management tactics, Folicur will reduce the risk of head scab but, the fungicide is not a silver bullet and a great deal of research suggests that about a 30-percent reduction in symptoms is a reasonable expectation for winter wheat.

How much of the fungicide was used this year is not yet known, nor is its success. However, the amount used will eventually be known because suppliers are keeping records and the product was only labeled for wheat in Kentucky , he said.

Fusarium head blight appeared 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 DON, or vomitoxin. DON is a 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.

“If you have head blight you are going to probably have excess DON,” Hershman said.



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