Field experiments were established to investigate the effects of tank-mixing sethoxydim or quizalofop with imazaquin, chlorimuron, or lactofen for barnyardgrass control in soybeans. Sequential applications, where the grass herbicide was applied 24 h before or after the broadleaf weed herbicide, were also evaluated. There was an antagonistic decrease in barnyardgrass control when sethoxydim or quizalofop was tank mixed with any of the broadleaf weed herbicides. Antagonism was also observed when either grass herbicide was applied 24 h after imazaquin or lactofen, but not with chlorimuron. Control was not affected when the grass herbicide was applied 24 h before the broadleaf weed herbicide. In greenhouse experiments, the effects of tank-mixing sethoxydim, quizalofop, fluazifop-P, haloxyfop, fenoxaprop, or clethodim with imazaquin, lactofen, chlorimuron, acifluorfen, fomesafen, bentazon, or 2,4-DB were also evaluated for barnyardgrass control. Although acifluorfen provided 45% barnyardgrass control, tank-mixing it with fluazifop-P, haloxyfop, or fenoxaprop was antagonistic. Antagonism also occurred when chlorimuron was tank mixed with any of the grass herbicides except fenoxaprop. Barnyardgrass control by all of the grass herbicides applied in the field or greenhouse was most severely antagonized by tank mixes containing imazaquin.

Field studies were conducted in 1996, 1998, 1999, and 2000 to determine the effect of glyphosate (isopropyl amine salt) on rice injury and yield when applied postemergence at 0, 70, 140, and 280 g ai/ha to dry-seeded rice in the three- to four-leaf (3- to 4-L), midtiller (MT), panicle initiation (PI), and boot (BT) growth stages. Glyphosate at 140 and 280 g ai/ha applied at the 3- to 4-L, MT, and PI growth stages resulted in the greatest foliar injury, and 280 g ai/ha was more injurious than 140 g ai/ha at the first rating, with the exception of MT and PI 2000, where they were equal. Glyphosate treatments resulted in the least visible foliar injury when applied at the BT stage. Rough rice yield was reduced by glyphosate applied at 280 g/ha to rice in the MT growth stage three out of four years. Applied to rice at PI, glyphosate at 140 g/ha reduced yields two out of four years, and three out of four years when applied at 280 g/ha. BT-stage applications of glyphosate at 70, 140, and 280 g/ha reduced yields two out of four, three out of four, and four out of four years, respectively.

Quizalofop controlled 2- to 3-leaf and 5- to 6-leaf red rice better than fluazifop-P, haloxyfop, or sethoxydim applied alone. Red rice control increased when acifluorfen was tank mixed with haloxyfop, fluazifop-P, or sethoxydim. Antagonism was most severe when imazaquin was tank mixed with any of the grass herbicides. The efficacy of sethoxydim, fluazifop-P, and haloxyfop was reduced when applied with chlorimuron or bentazon. In greenhouse experiments, all of the grass herbicides, except for fenoxaprop, reduced fresh weight of red rice 71% or more. Based on fresh weight reduction, acifluorfen, fomesafen, and lactofen only reduced the activity of fluazifop-P, while imazaquin decreased the activity of all grass herbicides.

Mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide}+bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] at 0.14 + 0.84 kg ai/ha was the most injurious of five herbicide treatments applied once to one- to two-leaf red rice (Oryza sativa L. ♯3 ORYSA). The most injurious treatment to five-to six-leaf red rice was DPX Y6202 {ethyl [2-[4-[6-chloro-2-quinoxalinyl]oxy]phenoxy] propionate} at 0.56 kg ai/ha. Two applications, regardless of red rice growth stage, of all treatments except fluazifop {[±]-butyl-2-[4-[[5-trifluoromethyl]-2-pyridinyl] oxy] phenoxy] propanoate} resulted in 86 to 99% injury.

Responses ofRhizoctonia solaniKuhn to napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], were evaluated by measuring whole-cell respiration, mitochondrial respiration, ATP synthesis, and membrane leakage. Whole-cell respiration, measured with an O2electrode, was stimulated in the presence of napropamide at 1.1, 2.2, and 4.4 × 10−5M. Mitochondrial respiration was stimulated at 1.1 × 10−11M, but higher concentrations were inhibitory. The addition of 10−5M napropamide to isolated mitochondria ofR. solaniresulted in reduced ATP synthesis, measured by the firefly luciferase assay, and in increased membrane permeability as measured by increases in electrical conductivity of filtrates fromR. solanigrown in culture medium containing napropamide. These results indicate that, under laboratory conditions, napropamide reduced ATP synthesis, caused membrane leakage, and stimulated respiration inR. solani.