Field studies were conducted to evaluate residual herbicides applied alone and with a contact weed control program in peanut in Georgia and Alabama. Residual herbicide treatments included pendimethalin preemergence (PRE) at 924 g ai/ha, diclosulam PRE at 18 and 26 g ai/ha, flumioxazin PRE at 70 and 104 g ai/ha, sulfentrazone PRE at 168 and 280 g ai/ha, and imazapic postemergence (POST) at 71 g ai/ha. All herbicides were applied alone and in combination with an early postemergence (EPOST) application of paraquat plus bentazon. Peanut injury ranged from 0 to 7% for diclosulam, from 0 to 28% for flumioxazin, from 0 to 59% for sulfentrazone, from 0 to 15% for imazapic, and from 4 to 12% for paraquat plus bentazon. Across locations and years, Florida beggarweed control was 92% or greater with flumioxazin PRE at 104 g/ha, 77% or greater with diclosulam PRE at 26 g/ha, 80% or greater with sulfentrazone PRE at 280 g/ha, ranged from 54 to 86% for imazapic POST, and was 68% or less for paraquat plus bentazon EPOST. For diclosulam, sulfentrazone, and imazapic, including paraquat plus bentazon EPOST improved Florida beggarweed control vs. these treatments alone. However, flumioxazin alone provided consistent and season-long Florida beggarweed control without paraquat plus bentazon EPOST. Sicklepod control with imazapic was consistently greater than 90%, but it was 70% or less with diclosulam, flumioxazin, and sulfentrazone. Paraquat plus bentazon EPOST used with the residual herbicide treatments resulted in variable sicklepod control ranging from 40 to 99%. Yellow nutsedge control was 95% or greater with sulfentrazone, varied from 56 to 93% with diclosulam, and was 87% or greater with imazapic. Tall and smallflower morningglory, wild poinsettia, Palmer amaranth, and bristly starbur control varied by residual herbicide treatment. Yields were similar for diclosulam, flumioxazin, sulfentrazone, and imazapic treated peanut.
Nomenclature: Bentazon; diclosulam; flumioxazin; imazapic; paraquat; pendimethalin; sulfentrazone; bristly starbur, Acanthospermum hispidum DC. #3 ACNHI; Florida beggarweed, Desmodium tortuosum (Sec) L. # DEDTO; sicklepod, Senna obtusifolia (L.) Irwin and Barneby # CASOB; smallflower morningglory, Jacquemontia tamnifolia (L.) Griseb. # IAQTA; tall morningglory, Ipomoea purpurea (L.) Roth # PHBPU; wild poinsettia, Euphorbia heterophylla L. # EPHHL; yellow nutsedge, Cyperus esculentus L. # CYPES; peanut, Arachis hypogaea L.
Additional index words: Peanut injury, peanut yield, susceptibility to herbicides.
Abbreviations: EPOST, early postemergence; POST, postemergence; PPI, preplant incorporated; PRE, preemergence.