Wheat seed quality and planting issues remain a concern for many growers in Kansas this year, according to two Kansas State University scientists.
Test weight, germination scores, seedbed conditions, and seed-borne diseases are factors that need to be considered this fall, says Jim Shroyer, who is the agronomy state leader for K-State Research and Extension.
Some of these potential problems can be addressed with fungicide seed treatments, according to Erick De Wolf, K-State Research and Extension plant pathologist. The relative usefulness of fungicide seed treatments will depend on the situation.
"We continue to hear concerns about using low-test-weight seed," De Wolf says. "If seed has a test weight of 55 pounds per bushel or less, but no evident disease problem (scab, black point, loose smut, or common bunt), will a fungicide seed treatment be of any benefit? This is a hard question to answer, but it is possible that a fungicide seed treatment can improve or protect seedling vigor under stressful conditions. With the relatively good price of wheat, a fungicide seed treatment is probably a good investment on low-test-weight seed."
Some areas of the state are reporting higher-than-normal levels of seed affected by head scab and black point, De Wolf says. These diseases can reduce germination rates. In many years, fungicide seed treatments result in small differences in germination and stand establishment. However, these products can have a greater impact in years when head scab and black point are affecting the seed quality.
If seed has a low test weight or is infected with scab, the first step should be to have it cleaned hard to remove the lightest and poorest quality seeds, Shroyer says. Once the seed lot has been cleaned, the seed should be tested for germination.
"If the germination is still lower than desired, you will probably want to adjust the seeding rate to make sure you hit your target plant population and may also consider fungicide seed treatment to help improve germination," the agronomist says.
The typical response to a fungicide seed treatment on seed that is badly damaged by scab would be about an 8 to 10 percent improvement in germination, De Wolf says. This level of response makes seed lots with a germination rate of around 80 to 90 percent a strong candidate for a seed treatment. The case is even stronger if the seed lot still contains kernels with signs of scab.
There are a number of good seed treatments available to growers, including Raxil MD, Dividend Extreme, and Charter, De Wolf adds.
"Some results suggest that combing a broad-spectrum fungicide product like Dividend Extreme with a second fungicide, Maxim 4FS, can further improve the efficacy of the seed treatment in scabby seed lots," he said. "The cost of these products should range from about $1.30 to $1.75 per bushel, depending on the combination of active ingredients and rate. It is best to use the full rate of these products when attempting to control the Fusarium fungus that is present in the scabby seed."
More information on wheat seed treatments is available at county or district K-State Research and Extension offices or on the K-State Department of Plant Pathology Fact Sheet "Wheat Seed Treatments"at: www.plantpath.ksu.edu/DesktopDefault.aspx?tabid=536.