Field trials were established in Fayetteville, AR, to determine the effects of glyphosate on biomass and seed production of spurred anoda, entireleaf morningglory, hemp sesbania, and Florida pusley. Inconsistent control of these species by glyphosate allows them to enrich the soil seedbank. Glyphosate rates of 0.42, 0.84, and 1.68 kg ae/ha were applied at 3, 6, and 9 wk after emergence (WAE) and were compared with a nonsprayed control. Spurred anoda seed production was reduced 99.9% by glyphosate at 1.68 kg/ha averaged over application timings and 99.7% by glyphosate applied at 6 WAE averaged over rates. Entireleaf morningglory seed production was reduced 100% by glyphosate at 1.68 kg/ha at 3 WAE and > 93% by the same rate applied at 6 or 9 WAE. Hemp sesbania seed production was reduced 100% by glyphosate at 1.68 kg/ha at 3 WAE and > 96% by glyphosate at 0.42, 0.84, and 1.68 kg/ha applied at 6 or 9 WAE. Florida pusley seed production was reduced 99.9% by glyphosate at 1.68 kg/ha averaged over application timings and 99.4% by application at 3 or 6 WAE averaged over rates. Biomass accumulation for all species was reduced most by early applications, particularly at 1.68 kg/ha.
Nomenclature: Glyphosate, entireleaf morningglory, Ipomoea hederacea var. integriuscula (L.) Jacq. A. Gray IPOHG, Florida pusley, Richardia scabra L. RCHSC, hemp sesbania, Sesbania exaltata (Raf.) Cory SEBEX, spurred anoda, Anoda cristata(L.) Schlecht ANVCR