Oat (Avena sativa L. ‘Elgin′) seedlings were treated with combinations of diclofop-methyl {methyl ester of 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} and 2,4-D amine [dimethylamine salt of (2,4-dichlorophenoxy) acetic acid] or diclofop-methyl and chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1, 3, 5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} to determine the effect of the added herbicide on diclofop-methyl activity. Diclofop-methyl applied alone at rates of 0.50, 0.75, and 1.00 kg/ha killed the oat plants 14 days after treatment. When 2,4-D amine at 0.74 and 1.11 kg/ha was combined with diclofop-methyl, the phytotoxicity of diclofop-methyl was reduced. An antagonistic interaction between diclofop-methyl and 2,4-D was detected. Chlorsulfuron, applied alone, at 20, 40, or 60 g/ha did not affect the growth of oats. Chlorsulfuron additions did not affect the activity of diclofop-methyl. Diclofop-methyl reduced oat coleoptile elongation. Equimolar concentrations of diclofop-methyl and 2,4-D at or above 1 μM significantly reduced the 2,4-D response. A ten-fold increase of either 2,4-D or diclofop-methyl, above an equimolar concentration of 1 μM, significantly enhanced the effect of the herbicide being increased.

Oat (Avena sativa L. ‘Elgin′) and soybean (Glycine max L. ‘Evans′) were treated with 14C-diclofop-methyl {methyl ester of 2-[4-(2,4-dichlorophenoxy)phenoxy] propionic acid]} or 14C-diclofop alone or in combination with 2,4-D [(2,4-dichlorophenoxy)acetic acid] or bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] and 14C-2,4-D alone or in combination with diclofop-methyl or diclofop. More radioactivity was recovered in the treatment zone after 14C-diclofop-methyl applications, alone or in combination, than after similar 14C-diclofop treatments in oat and soybean. Basipetal movement of radioactivity was 4 and 1% and acropetal movement was 1 and 4% in oat and soybean, respectively, regardless of the diphenyl ether treatment or time. Addition of 2,4-D or bentazon did not reduce translocation of radioactivity from 14C-diclofop-methyl treatments in either plant species. Basipetal movement of radioactivity from 14C-diclofop-methyl was greater than from 14C-diclofop in both oat and soybean. The addition of diclofop-methyl or diclofop did not affect the pattern or amount of 14C-2,4-D radioactivity translocated. In oats, radioactivity appeared to accumulate within the intercalary meristematic region with 14C-2,4-D and 14C-diphenyl-ether applications. Diclofop-methyl at 1 kg/ha applied either to an entire oat plant at the three-leaf stage or the apical meristemic region resulted in plant mortality. The extent to which transport contributes to diclofop-methyl efficacy is questioned.

Alfalfa (Medicago sativa L.), beans (Phaseolus vulgaris L.), corn (Zea mays L.), potatoes (Solanum tuberosum L.), spring wheat (Triticum aestivum L.), and sugarbeets (Beta vulgaris L.) were severely injured and had reduced foliage dry weights when grown in soil containing 0.10 ppmw or more terbacil (3-tert-butyl-5-chloro-6-methyluracil). Activated carbon at 150 kg/ha prevented a significant loss in weight of beans and corn in soil containing 0.10 ppmw terbacil and fully protected potatoes in soil containing 0.19 ppmw terbacil. Carbon at 300 kg/ha fully protected sugarbeets and prevented a significant weight loss in alfalfa in soil containing 0.19 ppmw terbacil. Carbon at 600 kg/ha did not protect wheat from 0.19 ppmw terbacil.

Analysis of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] in soil solution after application of 0.5 or 1.0 ppmw revealed up to five-fold differences among three Alabama soils (Lucedale fine sandy loam, Decatur silty clay loam, and Sacul loam). Differences in fluometuron in soil solution were attributed to variable organic matter present and clay fractions. Fluometuron concentration in soil solution for each soil correlated well with control of four broadleaf weed species in a field experiment.

Showy crotalaria (Crotalaria spectabilis Roth) was grown in a controlled-environment greenhouse with a day/night temperature of 32/26C at full sunlight and under 40, 60, or 90% shade. Shading significantly reduced height, dry-matter accumulation, leaf production, leaf-area expansion, axillary-branch development, reproductive development, and the partitioning of plant biomass into stems. Shading increased the partitioning of plant biomass into leaves and the leaf area ratio. Constant shading or shading from 0 through 25 days after planting reduced the leaf area duration (LAD) proportionally more than the net assimilation rate (NAR). Shading from 25 to 67 days after planting reduced NAR and LAD equally. In other experiments reducing the day/night temperature below 32/26C significantly reduced plant height, leaf area, and the rate of leaf production. Dry-matter production decreased significantly at temperatures below 29/23C, because of substantial reduction in LAD. Showy crotalaria flowered and produced seed at temperatures ranging from 23/17C to 32/26C. The results indicate that the geographical distribution of showy crotalaria in the United States probably will continue to increase.