Source: Crop Watch News Service - University of Nebraska Lincoln

In 2003 the incidence of common bunt (stinking smut) was much higher than normally encountered by wheat producers in the central Great Plains. This stimulated many producers to treat their seed last fall prior to planting.

Common bunt problems are again surfacing in Oklahoma, Kansas and Nebraska as the wheat harvest is completed. I’m not sure we fully understand why this is occurring, but it points to a need to pay closer attention to seed quality by having it cleaned and treated before fall planting.

Unless you are growing certified seed, it is best not to use your own seed for planting this fall. Also, if a producer obtains seed from another source such as a neighbor, it should definitely be treated with a seed treatment fungicide before planting. The best defense against common bunt is to plant treated certified seed. The economic risk of having bunt in the harvested grain is enormous. In most instances the elevator will reject the wheat which leaves the grower with few alternatives. The bunted wheat could be used in ethanol production if the plant will accept it. Feeding it to livestock usually is not feasible particularly if the level of bunt is high. The strong odor makes the grain unpalatable to swine and cattle.

The preferred methods of treating seed are to either use a commercial seed treater that fits onto the auger and applies the chemical as the wheat moves through it, buy treated seed or have a seed conditioner treat it after purchase. These methods ensure more uniform coverage of the seed which is important in eliminating the smut spores on the outside of the seed coat. When treating seed in the drill box, it is critical that the seeds be uniformly covered. Definitely avoid having some seeds heavily covered and others lightly or poorly covered. With some products, applying too much fungicide can restrict germination.

Fusarium head blight (scab) was widespread in wheat in eastern Nebraska this year. This is another head disease that will cause producers to evaluate seed quality after harvest. I saw fields this June with at least a 30% incidence of scab. Severity on individual heads ranged from light to heavy. The concern with scab is two-fold. First it could mean a toxin situation in the harvested grain. Scab-infected grain can contain the mycotoxins, vomitoxin and zearalenone. Vomitoxin causes vomiting in nonruminant animals and is the cause of the “feed refusal factor” if fed to swine. Zearalenone is an estrogenic mycotoxin and may cause infertility in domestic animals. The presence of scab in harvested grain does not ensure that mycotoxins have been produced, but any suspect grain should be tested if it is to be fed to livestock.

Contaminated grain can be blended with uncontaminated grain to bring the toxin level below the threshold. Scabby grain contains tombstone kernels, which if used for seed can lead to seedling blight and reduced stands. Seed harvested from fields that had scab should not be used for planting. If for some reason it is to be used as seed, it definitely should be cleaned to remove the infected kernels and then treated with a fungicide before planting.

The table is a partial list of wheat seed treatments that can be used to prevent common bunt, stinking smut and seedling blights.

This would be a good year to buy and plant certified seed that has been treated. In the long run, the additional expense may pay.

John Watkins
Extension Plant Pathologist