TIMING OF PARAQUAT APPLICATIONS FOR WEED-CONTROL IN VIRGINIA-TYPE PEANUTS (ARACHIS-HYPOGAEA)

Common ragweed was the most difficult to control of the species present and its control appeared to have the greatest effect on peanut yield. Preplant-incorporated (PPI) treatments provided no control of common ragweed but ethalfluralin plus vernolate PPI provided better than 90% control of yellow nutsedge and nearly 50% control of morningglory species. Single applications of paraquat at 0.14 kg ai ha-1 following PPI applications of ethalfluralin or ethalfluralin plus vernolate provided less than 75% common ragweed control. Sequential applications of paraquat applied 1 and 3 weeks after peanut emergence (1 + 3 WAE) provided at least 81% common ragweed control. Peanut yield with ethalfluralin plus vernolate PPI followed by paraquat 1 WAE (4400 kg ha-1) was equivalent to the handweeded yield (4470 kg ha-1). Yields were not significantly less with the same PPI application followed by paraquat 1 + 3 WAE (3730 kg ha-1) or by acifluorfen plus bentazon 3 WAE (3730 kg ha-1), and ethalfluralin PPI followed by paraquat 1 + 3 WAE (3740 kg ha-1). Ethalfluralin plus vernolate PPI and paraquat 1 WAE provided the highest net returns of $1370 ha-1.