Systemic seed-treatment insecticides including Gaucho (imidacloprid) and Cruiser (thiamethoxam) can control aphids during the fall after planting. Unfortunately, by the time contact insecticides are applied, aphids frequently have already transmitted the virus(es) that cause BYD. This can be done by applying contact insecticides to kill aphids, or by treating seed before planting with a systemic insecticide. ![]() Third, control aphids that transmit the viruses that cause BYD. Second, some wheat varieties (e.g., Duster, Endurance, Gallagher, Iba, Doublestop CL+, Bentley, Everest, Winterhawk, Redhawk) tolerate BYD better than other varieties however, be aware that no wheat variety has a high level of resistance to the aphid/BYD complex. ![]() First, a later planting date (after October 1 in northern Oklahoma and after October 15 in southern Oklahoma) helps reduce the opportunity for fall infection. Several steps can be taken to help manage BYD. BYD infections that occur in the fall are the most severe because virus has a longer time to damage plants as compared to infections that occur in the spring. For more information on mite-transmitted virus diseases, see OSU Fact Sheet 7328 (Wheat Streak Mosaic, High Plains Disease and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma)Īphid/barley yellow dwarf (BYD) complex: Viruses that cause BYD are transmitted by many cereal-feeding aphids. In addition to these cultural controls, two winter wheat varieties (RonL from Kansas and Mace from Nebraska) have resistance to WSM however, their adaptation to production is limited to northwestern Oklahoma. Thus, destroying volunteer wheat at least two weeks prior to emergence of seedling wheat will greatly reduce mite numbers in the fall. It is critical that volunteer wheat is completely dead for at least two weeks prior to emergence of seedling wheat because WCMs have a life span of 7-10 days. However, planting later in the fall (after October 1 in northern OK and after October 15 in southern OK) and controlling volunteer wheat are two practices that provide some control. Seed treatments are not effective in controlling these virus diseases. Wheat infected in the fall is either killed by the next spring or will be severely damaged. In the fall, WCMs spread to emerging seedling wheat, feed on that seedling wheat, and transmit virus to the young wheat plants. WCMs and these viruses survive in crops such as wheat and corn, as well as many grassy weeds and volunteer wheat. ![]() All are transmitted by wheat curl mite (WCMs). These include wheat streak mosaic (WSM), wheat mosaic (formerly called high plains disease), and Triticum mosaic (TrM). For more detailed information on planting date and seed treatment considerations on wheat, see CR-7088 (Effect of Planting Date and Seed Treatment on Diseases and Insect Pests of Wheat) Planting wheat early significantly increases the likelihood that diseases such as mite-transmitted viruses, the aphid/barley yellow dwarf complex, and root and foot rots will be more prevalent and more severe. In a grain-only system, wheat is generally planted in October, but in a dual-purpose system wheat is planted in early to mid-September to maximize forage production. In this system wheat is grazed by cattle from late October to early March, and then harvested for grain in early summer. Planting date : Much of the winter wheat in Oklahoma is sown with the intent of being used as a dual-purpose crop.
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