Efficacy of Corn (Zea mays) Herbicides Applied at Reduced Rates Impregnated in Dry Fertilizer

Abstract

Field studies were conducted in 1992 and 1993 to evaluate the efficacy of EPTC plus R-29148 (EPTC+) plus cyanazine and alachlor plus cyanazine. Materials were applied PPI and PRE to corn at 25, 50, 75, and 100% of labeled rates in an aqueous solution (sprays) and as herbicide-impregnated fertilizer. EPTC+plus cyanazine at all rates applied as sprays or as herbicide-impregnated fertilizer controlled 89% or more of giant foxtail. Velvetleaf and common lambsquarters control was less when alachlor plus cyanazine was applied as herbicide-impregnated fertilizer than when applied as sprays. When sprayed, alachlor plus cyanazine applied PPI controlled 95% giant foxtail only at the 100% rate without cultivation, but at all rates with cultivation. Alachlor plus cyanazine applied as impregnated fertilizer at 50, 75, and 100% labeled rates controlled 88% or more of giant foxtail when these treatments received a interrow cultivation. PRE treatments of alachlor plus cyanazine applied as herbicide-impregnated fertilizer were less effective in 1992 than in 1993 because of lack of timely precipitation following application.