Application of manganese fertilizer with postemergence soybean herbicides

Soybean [Glycine mar (L.) Merr.] grown on Mn deficient soils typically exhibits symptoms of Mn deficiency as inter-veinal chlorosis during early vegetative growth. Manganese sulfate is commonly applied as a foliar spray to correct the deficiency. The need for foliar applied Mn often coincides with the timing of postemergence herbicide application. The feasibility of tank mixing manganese sulfate with postemergence herbicides was evaluated on Mn-deficient Holmdel sandy loams (fine-loamy, mixed, mesic Aquic hapludult) near Adelphia, NJ, and Mn-sufficient Sassafras sandy loams (fine loamy, siliceous, mesic Typic Hapuldult) near Bridgeton, NJ, to study crop nutrition and weed control interactions. Manganese sulfate was foliar applied at growth stage V3 at 0, 0.5, and 2.0 lb Mn/acre alone or tank mixed with the herbicides acifluofen, chlorimuron ethyl, imazethapyr, and bentazon. Maturity group IV cultivars Midstates 395 and Agripro 4100 were grown at Adelphia and Bridgeton, respectively. Application of manganese sulfate alone or tank-mixed with herbicides did not influence the effectiveness of manganese sulfate to correct Mn deficiency. The 2.0 Ib Mn/acre rate generally increased plant tissue Mn more effectively and alleviated Mn deficiency more completely than the 0.5 Ih Mn rate. The addition of manganese sulfate to postemergence herbicides did not influence crop injury or weed control.