NITROGEN CARRIER AND SURFACTANT INCREASE FOLIAR HERBICIDE INJURY IN WINTER-WHEAT (TRITICUM-AESTIVUM)

A three-year field study in west-central Kansas investigated the effec ts of combinations of spray carrier, nonionic surfactant (NIS), triasu lfuron, and/or 2,4-D on winter wheat foliar injury and grain yield. He rbicides applied in water without NIS caused little or no foliar injur y in two of three years. Urea-ammonium nitrate (UAN) at 112 L/ha (40 k g N/ha) alone or as a carrier for herbicides caused moderate to severe foliar injury in all three years, Adding NIS to UAN spray solutions i ncreased foliar injury, especially with the tank mixture of triasulfur on + 2,4-D, Effects of triasulfuron + NIS or 2,4-D applied in UAN were additive, Foliar injury was related inversely to temperature followin g application, Foliar injury was most evident 4 to 7 d after applicati on and disappeared within 2 to 3 wk, Diluting UAN 50% with water lesse ned foliar injury in two of three years, especially in the presence of NIS, regardless of whether herbicides were in the spray solution, Tre atments did not reduce wheat grain yield in any year despite estimates of up to 53% foliar injury one year.