Recovery of Pitted Morningglory (Ipomoea lacunosa) and Ivyleaf Morningglory (Ipomoea hederacea) Following Applications of Acifluorfen, Fomesafen, and Lactofen

Abstract

Field experiments were conducted during 1985 and 1986 to determine the response of soybean [Glycine max(L.) Merr. ‘Coker 156’], pitted morningglory (Ipomoea lacunosaL. # IPOLA), and ivyleaf morningglory [Ipomoea hederacea(L.) Jacq. # IPOHE] to acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid}, fomesafen {5-[2-chloro-4-(trifluoromethyl) phenoxy]-N-(methylsulfonyl)-2-nitrobenzamide}, and lactofen {(±)-2-ethoxy-1-methyl-2-oxoethyl-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-dinitrobenzoate}. Acifluorfen and lactofen were more phytotoxic to soybean 15 days after treatment (DAT) than fomesafen. All herbicides at low rates controlled 80% or more pitted morningglory. However, only the high rates (0.6 kg ai/ha) of acifluorfen and fomesafen controlled 80% or more ivyleaf morningglory 90 DAT. Full-season competition from untreated pitted morningglory reduced soybean seed yields 44 and 22% in 1985 and 1986, respectively, compared to 58 and 49% with untreated ivyleaf morningglory. Soybean seed yields were higher in plots receiving acifluorfen or fomesafen applications than lactofen applications.