Broadleaf weed control in hard red spring wheat (Triticum aestivum) with F8426

Studies were conducted at Rosemount and Crookston, MN, in 1994 and 1995 to determine weed control efficacy and crop injury of F8426 (proposed common name carfentrazone-ethyl) in hard red spring wheat. F8426 alone and with 2,4-D or dicamba generally controlled common lambs-quarters, kochia, and velvetleaf 90% or more at 0.026 and 0.035 kg/ha. F8426 alone and with 2,4-D or dicamba controlled Pennsylvania smartweed, wild buckwheat, and wild mustard 39 to 100% and was less consistent than control of the aforementioned species. Weed control varied little among the F8426 rates. Weed control was inconsistent between location, year, and species when F8426 was combined with crop oil concentrate, urea-ammonium nitrate solution, and nonionic surfactant. Control was more consistent when 0.28 kg/ha 2,4-D or 0.07 kg/ha dicamba was tank mixed with either F8426 rate. The best control with an F8426 treatment was similar to control from MCPA tank mixed with thifensulfuron plus tribehuron, bromoxynil, or dicamba. Weed control 30 and 45 days after treatment (DAT) was less for F8426-containing treatments than standard treatments, which likely was related to reduced crop competition after severe crop injury. Increasing F8426 rate from 0.026 to 0.035 kg/ha did not greatly increase wheat injury, whereas adding 0.28 kg/ha 2,4-D to either F8426 rate greatly increased crop injury. Wheat yield was reduced up to 63% by F8426 and 2,4-D combinations.