Glasshouse and growth chamber experiments were conducted to determine chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} phytotoxicity to kochia [Kochia scoparia (L.) Schrad. ♯ KCHSC] and green foxtail [Setaria viridis (L.) Beauv. ♯ SETVI] as influenced by temperature and humidity for 1 week after treatment, and by soil moisture and nitrogen. Chlorsulfuron was more phytotoxic to both kochia and green foxtail at 95 to 100% than at 45 to 50% relative humidity for 1 week after treatment whether at 10, 20, or 30 C. Chlorsulfuron phytotoxicity was similar with all posttreatment temperatures at each humidity, except that phytotoxicity was lower at 30 C than at 10 or 20 C at 90 to 100% humidity. Surfactant added to chlorsulfuron exhanced control of kochia more than that of green foxtail and overcame temperature and humidity effects on chlorsulfuron phytotoxicity. A simulated rainfall of 2 mm after chlorsulfuron application reduced toxicity of chlorsulfuron to green foxtail more than to kochia. Chlorsulfuron was more phytotoxic to green foxtail growing with a high than a low soil nitrogen level. High soil moisture following chlorsulfuron application enhanced phytotoxicity to kochia and green foxtail compared to high soil moisture before treatment.

In field studies, a preemergence application of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] followed by an early postemergence application of dicamba (3,6-dichloro-o-anisic acid) gave good season-long control of smooth pigweed (Amaranthus hybridus L. ♯ AMACH) in conventional and no-till corn (Zea mays L. ‘Pioneer 3184’ and ‘Pioneer 3382’). In soybeans [Glycine max (L.) Merr. ‘Williams' and ‘Essex’], best control of smooth pigweed was achieved with an early postemergence application of sethoxydim {2-[1-(ethyoxy-imino)butyl]-5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-one} plus acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid}. Tillage played a role in the degree of smooth pigweed control. Best control of smooth pigweed in corn was obtained when the ground was moldboard plowed and disced, and least control was obtained when corn was no-till planted in the previous year's corn stalks or in a rye (Secale cereale L.) cover crop.

Fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} controlled annual grasses in cucumbers (Cucumis sativus L. ‘Calypso’ and ‘Poinsett’), cantaloupe (Cucumis melo L. ‘Edisto 47’), zucchini squash (Cucurbita pepo L. ‘Elite’), and sweet potato (Ipomoea batatas L. ‘Jewel’) when applied as single or repeated applications of 0.3 or 0.6 kg ai/ha during 1982 and 1983 in North Carolina. All crops were generally tolerant to fluazifop and yields were equal to cultivated controls in all but one experiment. Residues detected in the various crops by high-performance liquid chromatography (HPLC) decreased as time elapsed between application and harvest increased. Approximately 1 ppm (w/w) of fluazifop was detected in cucumbers at 8 days after application, but residues were below the least detectable limit (0.05 ppm) when cucumbers, squash, and cantaloupe were harvested at 18 to 29 days after application. Fluazifop concentrations were 0.06 ppm or less in sweet potatoes at 55 days after application, and no fluazifop was detected at 84 days after application. Small cucumbers (<12 cm long) had greater fluazifop residues than larger fruit (>12 cm long) 20 days following application.

Applications of 1.6 kg ai/ha of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] to established alfalfa (Medicago sativa L. ‘Rambler’) at the start of each growing season for 4 yr increased seed yield by 68% and controlled established dandelion (Taraxacum officinale Weber. in Wiggers ♯ TAROF) and smooth brome (Bromus inermis Leyss. ♯ BROIN). A lesser amount of metribuzin was not sufficient for smooth brome control, and a greater amount damaged the alfalfa. Hexazinone [3-cyclohexyl-6-(dimethylamino)-methyl-1,3,5-triazine-2,4(1H,3H)-dione] applied at 1.0 kg ai/ha also controlled dandelion and smooth brome and produced increases in alfalfa seed yield. Mixtures of terbacil (3-tert-butyl-5-chloro-6-methyluracil) with reduced rates of metribuzin or hexazinone controlled dandelion well, but gave only fair control of smooth brome. Alfalfa seed yield was negatively correlated with the smooth brome population.

Yaupon (Ilex vomitoria Ait. ♯ ILEVO) in the Post Oak Savannah of Texas was treated with liquid and dry formulations of herbicides. Sprays of Bay Met 1486 {N-[5-(ethylsulfonyl)-1,3,4-thiadiazol-2-yl]-N, N′-dimethylurea} and picloram (4-amino-3,5,6-trichloropicolinic acid), sprays and pellets of tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea}, and boluses of hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1N,3H)-dione] at 4.5 kg ae or ai/ha were the most effective treatments, reducing the canopy 87 to 99% and killing 68 to 93% of the yaupon after 2 yr. The percentage of dead yaupon after 1 yr was similar to that found 2 or 3 yr after treatment. Most herbicides, except clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), reduced the yaupon canopy sufficiently to allow an increase in understory grass and broadleaf vegetation, particularly 1 yr after treatment.

Bioassay techniques were evaluated for the determination of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} residues in soil and water. A linear response of corn (Zea mays L.) primary root length to chlorsulfuron concentrations (InX+1) of 0.0 to 16.0 μg/L was observed in the water bioassay. Several soil extraction bioassay methods were attempted and found to be highly variable. A Ca(OH)2 soil extraction bioassay technique produced a linear response of primary corn root length to chlorsulfuron concentrations ranging from 0.0 to 64.0 μg/kg. The efficiency of the Ca(OH)2 extraction bioassay was determined by the use of 14C-chlorsulfuron. Recovery efficiency at 1.0 μg/kg was 74% and averaged 62% at all higher chlorsulfuron concentrations.