BROADLEAF WEED-CONTROL IN HARD RED SPRING WHEAT (TRITICUM-AESTIVUM) WITH F8426

Studies were conducted at Rosemount and Crookston, MN, in 1994 and 199 5 to determine weed control efficacy and crop injury of F8426 (propose d common name carfentrazone-ethyl) in hard red spring wheat. F8426 alo ne and with 2,4-D or dicamba generally controlled common lambsquarters , kochia, and velvetleaf 90% or more at 0.026 and 0.035 kg/ha. F8426 a lone and with 2,4-D or dicamba controlled Pennsylvania smartweed, wild buckwheat, and wild mustard 39 to 100% and was less consistent than c ontrol 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 c onsistent when 0.28 kg/ha 2,4-D or 0.07 kg/ha dicamba was tank mixed w ith either F8426 rate. The best control with an F8426 treatment was si milar to control from MCPA tank mixed with thifensulfuron plus tribenu ron, bromoxynil, or dicamba. Weed control 30 and 45 days after treatme nt (DAT) was less for F8426-containing treatments than standard treatm ents, which likely was related to reduced crop competition after sever e 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 eit her F8426 rate greatly increased crop injury. Wheat yield was reduced up to 63% by F8426 and 2,4-D combinations.