September 8, 2004 | By: Laura Skillman

Growing conditions for Kentucky’s 2003-04 winter wheat resulted in much of the crop sustaining damage by Fusarium head blight that can result in substandard germination rates for planting this fall. Farmers should have their wheat seed checked for germination rates if they are not buying certified seed to ensure that seed quality is sufficient to produce good stands.

Many substandard germination rates can be improved by use of cleaning and seed treatments. These fungicide treatments are most frequently applied by a certified seed conditioner, but some on-farm formulations are available, said Don Hershman, University of Kentucky Cooperative Extension Service plant pathologist.

Based on samples sent to the UK College of Agriculture’s Division of Regulatory Services’ seed-testing laboratory, a number of seed lots are showing substandard germination. Low germination in most seed lots appears to be caused by Fusarium infection. Ninety percent of the seed lots sent to UK for testing have had Fusarium infection, said Cindy Finneseth, seed testing specialist.

Samples tested at the lab come from individual farmers as well as seed dealers, she said. The bulk of the samples are from industry. Kentucky seed law requires that wheat seed have a minimum of 60 percent germination in order to be sold in the state.

Fungicide seed treatments can have a substantial effect on limiting the impact of Fusarium on seed germination. This year, UK ’s seed testing lab has been treating lots and reporting both untreated and treated test results to producers, according to Finneseth. In some lots, seed treatment increased germination by 10 to 20 percent. In other lots, however, a marginal effect of 1 to 5 percent or no effect was seen. On average, germination after seed treatment has been 84 percent.

Growers may be tempted to use infected seed and adjust planting rates. This is risky unless the grower is certain that untreated seed germination is near the 84 percent germination standard, she said. Increasing seeding rates of low germination seed is unlikely to result in acceptable stands.

In addition to seed from this year’s crop, the seed lab has also tested lots carried over from the 2002-03 wheat production year. These lots are showing less quality problems due to head scab but may have other issues such as storage conditions that affect the overall quality and germination of the seed, Finneseth noted.

There is concern by some producers that planting infected seed this fall may increase the risk that head blight will be higher this spring, said Don Hershman, UK Extension plant pathologist.

There is no relationship between Fusarium levels in seed and the amount of head blight that will occur the following spring, he said.  Seed infection is exclusively a germination/stand consideration. This is because spores that infect wheat heads in the spring and cause head blight, originate from infested crop residue, primarily corn, and not seed or seedlings of the current wheat crop.

If weather conditions are highly conducive to spore production and infection next spring, serious infection is likely to occur even in fields planted with Fusarium-free seed the previous fall. Conversely, if the weather does not favor either situation, low levels are likely even if seed planted had high levels of infection.

The bottom line, Hershman said, is that there is no reason to fear planting seed with high levels of Fusarium as long as germination rates, either before or after treating seed, are acceptable.

Anyone with questions about wheat seed testing, should contact their local county Extension office.



Writer: Laura Skillman 270-365-7541 ext. 278
Sources: Cindy Finneseth, 859-257-2785; Don Hershman, 270-365-7541 ext. 215