The recent cooler weather and projections for more cool weather have some people wondering whether seed treatments that contain insecticides would be helpful. As most people know, the longer corn seeds lie in cool soil, the more likely that seed-attacking insects such as wireworms and seedcorn maggots, if they are present, will cause problems. The slower corn grows, the longer it will be exposed to subterranean insects.|
For most of the recent past, we have recommended the use of seed treatments that contain diazinon and lindane (for example, Kernel Guard and Agrox D-L Plus) to protect corn seeds in fields where one or both of these insects might be present. Trace Chemicals, Inc., recently began to market Kernel Guard Supreme, a seed treatment that contains the insecticide permethrin and the fungicide carboxin. The permethrin is intended for control of seedcorn beetle, seedcorn maggot, and wireworms. The recommended use rate for field corn, sweet corn, and popcorn is one canister (1.5 oz) per 42 pounds of seed. The recommended use rate for soybeans is one canister (1.5 oz) per 50 pounds of seed. As with other similar seed treatments, Kernel Guard Supreme should be applied to seed in the planter boxes and mixed in thoroughly.
Thorough mixing of seed treatments to coat the seeds is very important. As the Kernel Guard Supreme label states, "Use only at the recommended rate. Lower amounts may not give desired control. Excessive amounts may cause seed injury." Many of you may recall that in 1996, some growers experienced reduced corn populations because they did not mix the seed treatment thoroughly with the seed. As a consequence, some of the seeds were not treated, and some of the seeds were treated with an excessive amount. The cool, wet soils that year hindered corn growth, so the insecticide in the seed treatment injured some of the seedlings. Other growers experienced problems because they treated the seed, and then rainfall interrupted planting, sometimes for days. Again, prolonged exposure of the seed to the insecticide in the seed treatment resulted in some injury. The Kernel Guard Supreme label warns, "Treat only those seed needed for immediate use, minimizing the interval between treatment and planting."
Seed treatments that contain insecticides are reasonably cheap "insurance" for growers who do not plan to apply a soil insecticide at planting. When applied properly, seed treatments offer good protection against attack by wireworms and seedcorn maggots, with little potential for seed injury caused by the insecticide. However, proper application and thorough mixing are required.--Kevin Steffey