Field experiments were conducted to compare large crabgrass control by clethodim or sethoxydim applied alone and with selected fungicides registered for use in peanut. Fluazinam, propiconazole plus trifloxystrobin, or tebuconazole did not affect efficacy of clethodim or sethoxydim. Azoxystrobin, boscalid, chlorothalonil, and pyraclostrobin reduced efficacy of clethodim and sethoxydim in some experiments. Increasing the herbicide rate increased large crabgrass control regardless of the addition of chlorothalonil. In laboratory experiments, ¹⁴C absorption was less when ¹⁴C-clethodim or ¹⁴C-sethoxydim was applied with chlorothalonil. Pyraclostrobin and tebuconazole did not affect absorption of ¹⁴C-clethodim or ¹⁴C-sethoxydim.

Nomenclature: Azoxystrobin, methyl (E)-2-[2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate; boscalid, 3-pyridinecarboxamide,2-chloro-N-[4′-chloro(1,1′-biphenyl)-2-yl]; chlorothalonil, tetrachloroisophthalonitrile; clethodim; fluazinam, 3-chloro-N-[3-chloro-2,6-dinitro-4-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2-pyridinamine; propiconazole, 1-[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl-methyl]-1H-1,2,4triazole; pyraclostrobin, carbamic acid,[2-[[[1-(4-chlorophenyl)-1H-pyrazol-3yl]oxy]methyl]phenyl]methoxy-,methyl ester; sethoxydim; tebuconazole, α-[2-(4-chlorophenyl)ethyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol; trifloxystrobin, benzeneacetic acid, α-(methoxyimino)-2-[[[(E)-[1-[3-(trifluoromethyl)phenyl]ethylidene]amino]oxy]methyl]-,methylester (E,E); large crabgrass, Digitaria sanguinalis (L.) Scop. #³ DIGSA; peanut, Arachis hypogaea L.

Additional index words: Herbicide absorption, pesticide interaction.

Abbreviation: LSS, liquid scintillation spectrometry.