Sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, CGA-82725 {2-propynyl 2-[4-[(3,5-dichloro-2-pyridinyl)oxy]phenoxy]propanoate}, RO 13-8895 {acetone-O-[D-2-[p-(α,α,α-trifluoro-p-tolyl)oxy]phenoxy]propionyl oxime}, and difenopenten {4-[4-[4-(trifluoromethyl)phenoxy]phenoxy]-2-pentenoic acid} were evaluated as single and/or split applications for postemergence control of johnsongrass [Sorghum halepense (L.) Pers. ♯ SORHA] grown from rhizomes in soybeans [Glycine max (L.) Merr.]. Good to excellent control, crop safety, and yield enhancement were achieved with all herbicides evaluated. Antagonism between postemergence grass and broadleaf herbicides was evaluated by applying sethoxydim, CGA-82725, RO 13-8895, and difenopenten alone to soybeans infested with johnsongrass grown from seed, and applying these herbicides as mixtures with acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid}, bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide], or benazolin (4-chloro-2-oxobenzothiazolin-3-ylacetic acid). Acifluorfen was most antagonistic to the activity of postemergence grass herbicides, with difenopenten and sethoxydim the most susceptible to antagonism. Reductons in johnsongrass control were attributed to antagonism by broadleaf herbicides, which caused soybean yield reductions of up to 67%.

A field study was conducted to develop systems using cultural and chemical methods for control of bermudagrass (Cynodon dactylon L.) in cotton (Gossypium hirsutum L.). Several control options were promising. On areas prepared either with a moldboard plow or a disk, the sodium and magnesium salts of dalapon (2,2-dichloropropionic acid) at 4.7 kg/ha directed to 25-cm-high cotton and repeated at the 40-cm height or the ethyl ester of difenopenten {4-[4-[4-(trifluoromethyl)phenoxy] phenoxy]-2-pentenoic acid} directed to 15-cm-high cotton and repeated at the 30-cm height, with either standard or close cultivation as needed, provided good bermudagrass control. On areas prepared with a moldboard plow, the isopropyl amine salt of glyphosate [N-(phosphonomethyl)glycine] at 4.4 kg/ha over-the-top as a fall application with cultivation as needed was promising.

BAS 9052 {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexene-1-one} and difenopenten {4-[4-[4-(trifluoromethyl)phenoxy]phenoxy]-2-pentenoic acid} concentrations less than 1% (w/w) did not normally inhibit apparent photosynthesis (AP) of corn (Zea mays L. ‘Mo 17 × B73′) leaves for at least 24 h. However, leaf growth was completely inhibited by BAS 9052 within 24 h. Leaf AP was initially more inhibited in soybean (Glycine max L. ‘Corsoy’) than in corn by each herbicide, but within 48 h soybean AP was usually recovering and plants grew normally. Because inhibition of corn leaf growth preceded that of AP, leaf photosynthesis could not be a primary mode of action for BAS 9052.