Farmers in ever-increasing numbers are adding seed treatments to their arsenal of weapons against pests, but growers may be missing a step in the planting process, said Kansas State University agronomy professor Dale Fjell.

"For years, planter manufacturers have recommended that producers add talc or graphite to their planters when they plant,"said Fjell, who is a crop production specialist with K-State Research and Extension. "But a lot of people don't read the directions. I think it's rarely done."

Treating seed with pesticides or fungicides helps keep problems at bay, which can boost yields, but the treatment also adds to the weight of the seed and affects how it flows through the planter, he said.

"If you leave the planter on the same adjustment for treated seed that you used for untreated seed, the seed drop will be less," he said, citing research that has been done in several states.

For example, if a planter is set to drop 30,000 seeds, all 30,000 will likely go through the planter if the seeds are untreated. If, however, the planter is set to drop 30,000 seeds and the grower is using treated seed, it may only drop about 26,000 seeds, Fjell added.

Producers also might need to change (increase) the pressure on vacuum planters when using treated seed. Again, it's a good idea to read the manual or check with the equipment manufacturer, the agronomist said.


K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus in Manhattan.