A red fescue (Festuca rubra L.)- Kentucky bluegrass (Poa pratensis L.) turf was treated annually with amidochlor {N-[(acetylamino)methyl]-2-chloro-N-(2,6-diethylphenyl)acetamide} at 2.2, 2.8, and 3.4 kg ai/ha, mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} at 0.4 kg ai/ha, and ethephon [(2-chloroethyl) phosphonic acid] at 5.6 kg ai/ha for three consecutive years. Recuperative potential of treated turfgrass was determined in the field and in a greenhouse study. Amidochlor and mefluidide treatments injured turfgrass (11 to 64%) four weeks after application. However, turfgrass recovered after eight weeks. Amidochlor at 2.8 to 3.4 kg/ha and mefluidide at 0.4 kg/ha suppressed (75 to 100%) seedhead development. Ethephon at 5.6 kg/ha was ineffective. Turfgrass recovered normally each spring after amidochlor treatments, with no delay in spring green-up. Root length, root weight, and root:shoot weight ratio of the plugs from the greenhouse study were unaffected by three consecutive annual applications of amidochlor, mefluidide, and ethephon. One annual spring application of amidochlor, mefluidide, and ethephon for three consecutive years caused no adverse effects that would limit their use on red fescue-Kentucky bluegrass turf.

The effect of spray carrier volume on the antagonism of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} by bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] was investigated under greenhouse and field conditions. In the laboratory, the spray droplet overlap between components of a sequential spray application increased from 17 to 50% as carrier volume was increased from 94 to 374 L/ha, respectively. Carrier volume had a significant influence on treatments of sethoxydim alone and sethoxydim sequentially applied with bentazon, but not on the tank mixture of the two herbicides. Carrier volumes of 94 and 187 L/ha used to deliver sethoxydim alone and the sethoxydim/bentazon sequential treatment were superior to the use of 374 L/ha for the control of large crabgrass [Digitaria sanquinalis (L.) Scop. # DIGSA], fall panicum (Panicum dichotomiflorum Michx. # PANDI), and goosegrass (Eleusine indica Gaertn. # ELEIN). There was no difference in grass control between sethoxydim alone and the sequential treatment except at carrier volumes of 187 L/ha or more with which the sequential treatment was less effective. Rates of 0.06 and 0.11 kg ai/ha of sethoxydim were influenced more by changes in carrier volume than 0.22 kg/ha in both the alone and sequential treatments.

Field evaluations were made on the effects of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} on Florida beggarweed [Desmodium tortuosum (SW) DC. # DEDTO] and sicklepod (Cassia obtusifolia L. # CASOB) control in peanuts (Arachis hypogaea L.). Crop yield was reduced at 392 and 504 g ae/ha and with preemergence applications. Florida beggarweed control was not achieved with this herbicide. Maximum sicklepod control (approximately 80%) was achieved with 392 and 504 g/ha applied postemergence. In a separate study, several herbicide systems utilizing imazaquin were compared to a standard weed control program. All these systems provided weed control and yields that were comparable to the standard weed control system; thus the inclusion of imazaquin offered no advantage over the standard system.

One and two postemergence (POE) applications of the butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy]phenoxy] propanoic acid} or sethoxydim (2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} following preemergence (PRE) application of fluometuron {N,N-dimethyl-N′-[3-(trifluoromethyl)phenyl] urea} were compared to a preplant-incorporated (PPI) application of trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] or pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] plus fluometuron PRE or pendimethalin plus fluometuron PRE for annual grass control in cotton (Gossypium hirsutum L.) and net economic return to land, overhead, and management. One POE application of either fluazifop or sethoxydim following fluometuron PRE resulted in greater control of a high population of broadleaf signalgrass [Brachiaria platyphylla (Griseb.) Nash. # BRAPP] and greater yield and net return than a PPI application of trifluralin or pendimethalin plus fluometuron PRE. A second application of fluazifop or sethoxydim increased late-season control but did not increase yield or net return. In a high population of large crabgrass (Digitaria sanguinalis L. # DIGSA), fluometuron PRE plus two POE applications of fluazifop or sethoxydim resulted in grass control, lint yield, and net return similar to trifluralin or pendimethalin PPI plus fluometuron PRE. No differences in grass control, crop response, or net return were noted between PPI application of trifluralin or pendimethalin. Control of broadleaf signalgrass and large crabgrass with pendimethalin plus fluometuron PRE was less than with pendimethalin PPI plus fluometuron PRE. In fields with a low population of large crabgrass, fall panicum (Panicum dichotomiflorum Michx. # PANDI), and goosegrass [Eleusine indica (L.) Gaertn. # ELEIN], fluometuron PRE provided excellent season-long control. No benefits were obtained from addition of a grass herbicide. No treatments affected cotton maturity or fiber quality.

Wheat (Triticum aestivum L.) grain yields were reduced an average of 4.2% for every 10 Italian ryegrass [Lolium multiflorum (Lam.) # LOLMU] plants/m2 within the range of 0 to 100 Italian ryegrass plants/m2. Yield reductions caused by Italian ryegrass were attributed primarily to decreased crop tillering. Italian ryegrass densities as high as 80 plants/m2 had little effect on wheat head or kernel weights. In greenhouse experiments, the growth response of Italian ryegrass to increasing concentrations of NO3– and K+ was greater than that of wheat. Net uptake rates for NO3– by both species growing in nutrient solution were 1.5 times greater than net uptake rates for K+. Nitrate and potassium Imax values for Italian ryegrass were approximately twice the corresponding values for wheat. Although Italian ryegrass responded more to changes in nutrients and had greater ion uptake rates compared to wheat, Italian ryegrass accumulated more biomass when grown in monoculture than when grown in association with wheat. This difference was probably due to the initial size of the seedlings. Wheat seedlings were much larger than Italian ryegrass seedlings during the first 20 days following emergence.

In field and greenhouse experiments, sicklepod (Cassia obtusifolia L. # CASOB) control with postemergence application of imazaquin {ammonium salt of 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} was similar with spray volumes of 50, 185, and 360 L/ha. Application of DPX-F6025 {ethyl ester of 2-[[[[(4-chloro-6-methoxypyrimidin-2-yl) amino] carbonyl] amino] sulfonyl] benzoate} in 50 L/ha resulted in greater control than application in 185 or 360 L/ha in the greenhouse, but no effect of spray volume was noted in field studies. In the greenhouse, control was 25 and 63% less with imazaquin applied to three- and five-leaf plants, respectively, compared to one-leaf plants; control was 40 and 62% less with DPX-F6025 applied to three- and five-leaf plants, respectively, compared to one-leaf plants. In the field, initial control was greater with imazaquin and DPX-F6025 applied to one-leaf plants than to three- or five-leaf plants. Following cultivation, control was similar regardless of plant size at time of application. In the field, postemergence applications of imazaquin and DPX-F6025 were equally phytotoxic following preplant-incorporated application of vernolate (S-propyl dipropylcarbamothioate) or preemergence application of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide]. A synergistic interaction was observed in the greenhouse with imazaquin applied postemergence to sicklepod grown in vernolate- or alachlor-treated soil and with DPX-F6025 applied to sicklepod grown in alachlor-treated soil. Antagonism was observed with DPX-F6025 applied postemergence to sicklepod grown in vernolate-treated soil.

Field and growth chamber experiments were conducted from 1983 to 1985 to determine the relationships between loss in plant productivity and plant residue-crop-weed density in no-till wheat (Triticum aestivum L.) and to document chemical management and cultivar options for such a cropping system. Untilled stubble left on the soil at rates of 0.5 and 3 t/ha reduced wheat density and grain yield in continuous winter wheat. Stem densities of cheat (Bromus secalinus L. # BROSE) and downy brome (B. tectorum L. # BROTE) in mulched treatments averaged about 682, 679, and 38 stems/m2 in 1983, 1984, and 1985, respectively. In the nonmulched treatment, weed density and standing dry matter ranged from 5 to 30 stems/m2 and 2 to 6 g/m2, respectively. Removal of residues eliminated key habitat characteristics required for the establishment of Bromus spp. Preemergence and early postemergence applications of BAY SMY 1500 [4-amino-6-(1,1-dimethylethyl)-3-(ethylthio)-1,2,4-triazin-5(4H)-one] at 2 kg/ha controlled both species of Bromus in no-till wheat. The herbicide treatment slightly delayed maturity of 10 wheat cultivars, but control of cheat and downy brome allowed nine cultivars to attain their yield potential, improving grain yield over that of untreated plots. ‘Vona’ wheat did not tolerate the herbicide and was susceptible after emergence. BAY SMY 1500 widens the spectrum of weed management and wheat cultivar options for an annual conservation production system of winter wheat.

Management systems for direct-seeded and transplanted sugarbeets (Beta vulgaris L. ‘Mono Hy D2′) were compared for weed control and sugarbeet selectivity from 1983 through 1985 in western Nebraska. Broadleaf weed density was similar, but yellow foxtail [Setaria glauca (L.) Beauv. # SETLU] density was lower in transplanted compared to direct-seeded sugarbeets. Preplant soil-incorporated applications of cycloate (S-ethyl cyclohexylethylcarbamothioate) plus trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] at 3.3 plus 0.6 kg ai/ha or ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] plus trifluralin at 2.2 plus 0.6 kg/ha was noninjurious to transplanted sugarbeets but caused severe injury to direct-seeded sugarbeets. The combination of cycloate or ethofumesate with trifluralin improved weed control over that obtained when cycloate or ethofumesate was used alone. By combining the improved weed control obtained from cycloate plus trifluralin or ethofumesate plus trifluralin with the transplanting crop establishment technique, a superior sugarbeet weed control program was developed.

Field and greenhouse experiments were conducted during 1984 through 1986 to examine the efficacy of the seed protectants CGA-92194 {α-[(1,3-dioxolan-2-yl-methyl)imino]benzacetonitrile} and flurazole [2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylic acid] for protecting grain sorghum [Sorghum bicolor (L.) Moench.] from alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], and propachlor [2-chloro-N-(1-methylethyl)-N-phenylacetamide] injury. In the field, CGA-92194 and flurazole protected sorghum from injury, stand reduction, and yield loss due to alachlor and metolachlor. In general, sorghum was protected with either antidote, and protected response to alachlor or metolachlor was similar to sorghum subjected to propachlor. Greenhouse experiments were conducted to examine the response of bronze and yellow pericarp color to seed protectants, six sorghum hybrids to these antidotes, and the effects of cool soil temperature on the early seedling vigor of sorghum protected with the antidotes. The response of sorghum with yellow and bronze pericarp color was similar when compared across antidotes. However, there were differences among the sorghum hybrids when compared across protectants. The potential of CGA-92194 and flurazole to protect against alachlor injury was reduced when sorghum was grown in cool soil.

Imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} was evaluated in the field for weed control in flue-cured tobacco (Nicotiana tabacum L.) during 1983 and 1984. The 75 DG formulation of imazaquin was used at 0.28 and 0.42 kg ai/ha. Methods of application were: preplant incorporated, over the top immediately after transplanting, postbed incorporated, and early postemergence. Imazaquin controlled 90%, or better, of common lambsquarters (Chenopodium album L. # CHEAL), common ragweed (Ambrosia artemisiifolia L. # AMBEL), redroot pigweed (Amaranthus retroflexus L. # AMARE), spiny amaranth (Amaranthus spinosus L. # AMASP), ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. # IPOHE], sicklepod (Cassia obtusifolia L. # CASOB), and prickly sida (Sida spinosa L. # SIDSP) with all application methods except early postemergence. It controlled 80 to 89% of large crabgrass (Digitaria sanguinalis L. # DIGSA) by the soil-applied methods. Postemergence applications of imazaquin controlled common ragweed, pigweed spp., ivyleaf morningglory, prickly sida, and sicklepod. Imazaquin was less effective postemergence on lambsquarters and large crabgrass. Tobacco tolerated use of imazaquin by all methods of application except preplant incorporation.

The ethyl ester of fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy] phenoxy] propanoic acid} was applied to rice (Oryza sativa L.) that was heavily infested with barnyardgrass [Echinochloa crus-galli (L.) Beauv. # ECHCG] during a 3-yr study. Applications were made to two- to three-leaf, three- to four-leaf, five- to six-leaf, or tillering barnyardgrass. Barnyardgrass control at 9 weeks after final treatment was greater than 90% for all growth stages except the 0.1 kg ai/ha rate applied to three- to four-leaf barnyardgrass in 1983. In 1984, the sequential application of fenoxaprop made at the three- to four-leaf stage controlled more than 95% when rated at 9 weeks. Rates of 0.17 and 0.2 kg ai/ha and the sequential treatment of 0.1 kg ai/ha followed by 0.1 kg ai/ha 7 to 10 days later controlled greater than 90% at 9 weeks when applied to three- to four- and five- to six-leaf barnyardgrass in 1985. In general, barnyardgrass was controlled by fenoxaprop rates greater than 0.1 kg ai/ha when applied to any growth stage evaluated up through the five- to six-leaf stage. However, acceptable control of tillering barnyardgrass was achieved in only 1 of 3 years. Yields were increased due to barnyardgrass control all years with all treatments except those applied at tillering. However, control was sufficient to increase yields over that of the check for all tillering treatments except the 0.1 kg ai/ha rate in 1984 and 1985 and the 0.17 kg ai/ha treatment in 1985.

A 4-yr study was conducted to evaluate the response of rice (Oryza sativa L. 'Starbonnet′) to sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl-3-hydroxy-2-cyclohexen-1-one}, haloxyfop {2-[4-[13-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and quizalofop {(±)-2-[4-(6-chloro-2-quinoxalynyloxy)phenoxy] propanoic acid}. In general, rice was more sensitive when herbicides were applied at panicle initiation than at the tillering stage of development. Quizalofop severely reduced rice yield when applied wih a surfactant. Applied at tillering, sethoxydim at 210 g ai/ha did not reduce rice height, grain yield, milling yield, or seed quality.

Fluorochloridone {3-chloro-4-(chloromethyl)-1-[3-(trifluoromethyl)phenyl]-2-pyrrolidinone} effectively controlled wild mustard (Sinapis arvensis L. # SINAR) in sunflowers (Helianthus annuus L. ‘Hybrid 894′). Preemergence (pre) treatments were more effective than preplant-incorporated (ppi) treatments at rates of 0.3 to 1.1 kg ai/ha. Applied as a foliar spray, fluorochloridone at rates of 0.12 to 0.25 kg ai/ha controlled 96% or more of wild mustard but some crop injury occurred. When fluorochloridone was mixed with trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] or EPTC (S-ethyl dipropyl carbamothioate) and applied ppi, several annual grasses as well as wild mustard were controlled.

A 3-yr (1982, 1983, and 1984) study was conducted to determine the relationship between tillage and six weed control treatments for soybean [Glycine max (L.) Merr. ‘Williams 79′] production on silt loam (Udollic and Mollic Ochraqualfs). Conventional tillage consisted of spring moldboard plowing and secondary tillage with a combination tool just before planting. No-tillage consisted of a foliar application of glyphosate [N-(phosphonomethyl)glycine] at the time of planting. Weed control treatments included combinations of no weed control with and without soybean plants, preemergence herbicide application only, postemergence herbicide application only, and combined preemergence and postemergence applications with and without additional handweeding. In 1982, a year of above-normal seasonal rainfall, conventional tillage had significantly greater soybean grain yields than no-tillage for all weed control treatments except the preemergence-only treatment. Yields within tillage systems and between weed control treatments in 1982 were not significantly different because adequate rainfall reduced the effect of weed competition for soil moisture. Soybean seed yields in 1983 and 1984 in no-tillage were equal to or significantly greater than those of conventional tillage. No-tillage treatments had greater soil moisture conservation and soil moisture availability resulting in less plant water stress during podfilling in periods of drought in 1983 and 1984. In all 3 yr, conventional tillage had significantly greater early weed growth than no-tillage in the treatments with and without soybean plants where no preemergence or postemergence herbicides were used. Comparing treatments with and without soybean plants indicated an average increase of 36 and 38% weed control for no-tillage and conventional tillage, respectively.

Postemergence applications of atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], tridiphane [2-(3,5-dichlorophenyl)-2-(2,2,2-trichloroethyl) oxirane] and atrazine, and tridiphane and cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl] amino]-2-methylpropanenitrile} resulted in 90% or better control of giant foxtail (Setaria faberi Herrm. # SETFA) less than 2.5 cm in height. Delaying the application of tridiphane plus atrazine or atrazine alone reduced the control of giant foxtail in 1984, control of giant foxtail over 2.5 cm in height was significantly greater with a mixture of tridiphane and atrazine (0.4 and 1.7 kg ai/ha) than with atrazine alone (2.2 kg/ha) or tridiphane plus cyanazine (0.6 and 1.8 kg/ha). Two successive applications of tridiphane and atrazine combinations controlled giant foxtail 8 to 16 cm tall (four to five leaves). Cultivation following applications of tridiphane plus atrazine improved giant foxtail control but was less effective than a second application of atrazine or tridiphane plus atrazine. Giant foxtail control in greenhouse experiments was similar to control obtained in the field. Tridiphane plus atrazine controlled 70% of giant foxtail in the four- to five-leaf stage, while atrazine applied alone resulted in only 23% control, indicating a synergistic effect.

Field and laboratory studies were conducted to evaluate the efficacy of several herbicides applied after small-grain harvest on Russian thistle (Salsola iberica Sennen and Pau # SASKR) control and subsequent seed germination. Best postharvest control of Russian thistle was with chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} treatments, paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), and bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) plus metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one], where control ranged from 73 to 96%. During the summer-fallow year, chlorsulfuron and paraquat decreased Russian thistle population and biomass compared to the untreated control. Germination of large seeds from plants treated with paraquat and both rates of chlorsulfuron was reduced at least 64% compared to seeds of similar size from untreated plants.

Experiments were conducted for 3 yr to evaluate the effects of the ethyl ester of fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy] phenoxy] propanoic acid} on rice (Oryza sativa L. 'Starbonnet′) applied at 112 and 168 g ai/ha or as two applications of 112 g ai/ha applied 10 to 14 days apart. Fenoxaprop did not adversely affect grain yield, panicle weight, seed weight, or seed germination when applied before the booting stage of both sprinkler-irrigated and flooded rice. Rice height was sometimes reduced by treatment at earlier growth stages, but yields were not affected. With the exception of applications at early jointing (internode elongation = 6 mm) in 1983, milling yield was not adversely affected by fenoxaprop applications made prior to booting of both sprinkler-irrigated and flood-culture rice. Applications during heading adversely affected most yield parameters.

Postemergence applications of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} controlled higher levels of purple nutsedge (Cyperus rotundus L. # CYPRO) in common bermudagrass [Cynodon dactylon (L.) Pers.] and hybrid bermudagrass (′Tifgreen’ and ‘Tifdwarf′, C. dactylon × C. transvaalensis Burtt-Davy) than monosodium salt of methylarsonic acid (MSMA). Control was better at 560 or 840 g ai/ha of imazaquin than at lower rates. Postemergence applications of imazaquin plus 2240 g ai/ha of MSMA controlled more purple nutsedge than equivalent rates of imazaquin alone. Preemergence applications of imazaquin were not effective. Bermudagrass discoloration was observed in some experiments on turfs mowed at a height of 1.3 cm or less but usually disappeared within 2 to 3 weeks, especially when MSMA was used in combination with imazaquin. No injury was observed on bermudagrasses, zoysiagrass (Zoysia japonica Steud. ‘Meyer′), St. Augustinegrass [Stenotaphrum secundatum (Walt.) Ktze. ‘Raleigh′], and centipedegrass [Erernochloa ophiuroides (Munro) Hack.] maintained at mowing heights above 1.3 cm.

Foliar absorption of imazaquin {ammonium salt of 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} following postemergence application was not necessary for control of sicklepod (Cassia obtusifolia L. # CASOB). Application of imazaquin to the soil resulted in control similar to application to the soil plus foliage. A 0.6-cm simulated rainfall 0.05 h after postemergence application of 140, 280, or 560 g ae/ha of imazaquin did not reduce sicklepod control. Foliar absorption was necessary for control with postemergence application of DPX-F6025 {ethyl ester of 2-[[[[(4-chloro-6-methoxypyrimidin-2-yl)amino]-carbonyl] amino] sulfonyl] benzoate}. Application of DPX-F6025 to the foliage resulted in control similar to application to the soil plus foliage. Sicklepod control resulting from postemergence application of 18 g ae/ha of DPX-F6025 was reduced when 0.6 cm of simulated rainfall was received 1 h after application but not when received 4 h after application. With application of 9 g/ha of DPX-F6025, simulated rainfall 24 h after application reduced control. Sicklepod control resulting from postemergence application of sublethal rates of imazaquin and DPX-F6025 was greater when plants were exposed to 3 or more days of 24/18 C day/night temperature than when grown at a continuous 32/24 C temperature. Exposure to low temperature for 3 days immediately before imazaquin application resulted in greater enhancement of control than did exposure for 3 days immediately after application. The reverse was found with DPX-F6025. Control obtained with both imazaquin and DPX-F6025 increased as the number of days of exposure to low temperature increased from 3 to 6. Enhancement of control with low temperature diminished as the herbicide application rate increased.

Field experiments were conducted in Princeton, KY, in 1982, 1983, and 1984 to evaluate johnsongrass [Sorghum halepense (L.) Pers. # SORHA] control programs in no-tillage, doublecropped soybeans [Glycine max (L.) Merr. ‘Essex′]. Sequential applications of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} or fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} at 0.2 kg ai/ha provided 36 to 94% johnsongrass control. The lower control values from these treatments were obtained in the droughty 1983 growing season while the higher and acceptable control ratings were obtained in 1982 and 1984 when rainfall was more plentiful. Preplant applications that contained glyphosate [N-(phosphonomethyl)glycine] provided johnsongrass control greater than those containing paraquat (1,1′-dimethyl-4,4′-bypyridinium ion). Soybean yields and soil moisture were greater with preplant applications of glyphosate than with preplant applications of paraquat or foliar applications of sethoxydim, fluazifop, or glyphosate. Greatest yields were obtained with a combination of a preplant application of glyphosate and a postemergence application of sethoxydim.