Experiments were conducted in 2008, 2009, and 2010 to determine the influence of water source as carrier and other agrochemicals on glyphosate efficacy and physicochemical compatibility. Glyphosate efficacy was not affected by most water sources, when compared with deionized water, although response was not consistent across all weed species, including cereal rye, common lambsquarters, common ragweed, goosegrass, Italian ryegrass, large crabgrass, Palmer amaranth, tall morningglory, and wheat. Control by glyphosate was not negatively affected when coapplied with cloransulam-methyl, dicamba, flumioxazin, pyrithiobac-sodium, thifensulfuron-methyl plus tribenuron-methyl, trifloxysulfuron-sodium, and 2,4-D but was affected by acifluorfen and glufosinate. Calcium, manganese, and zinc solutions consistently reduced weed control by glyphosate, whereas boron seldom affected efficacy. Compared with deionized water, Italian ryegrass control was affected by water sources when applied at seedling and jointing stages more so than at tillering and heading growth stages. Calcium, manganese, and zinc reduced control regardless of growth stage. Precipitates were not produced when glyphosate was applied with the water sources or fertilizer solutions. However, transient precipitates developed when glyphosate was coapplied with cloransulam-methyl, flumioxazin, thifensulfuron-methyl plus tribenuron-methyl, and trifloxysulfuron-sodium but not when coapplied with acifluorfen, dicamba, glufosinate, pyrithiobac-sodium, and 2,4-D. Solution pH ranged from 4.11 to 5.60 after glyphosate was added, regardless of solution pH before glyphosate addition.

Nomenclature: 2,4-D; acifluorfen; boron; calcium; cloransulam-methyl; dicamba; flumioxazin; glufosinate; glyphosate; manganese; pyrithiobac-sodium; thifensulfuron-methyl plus tribenuron-methyl; trifloxysulfuron-sodium; zinc; cereal rye, Secale cereale L.; common lambsquarters, Chenopodium album L.; common ragweed, Ambrosia artemisiifolia L.; goosegrass, Eleusine indica (L.) Gaertn.; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot.; large crabgrass, Digitaria sanguinalis (L.) Scop.; Palmer amaranth, Amaranthus palmeri (L.) S. Wats.; tall morningglory, Ipomoea purpurea (L.) Roth; wheat, Triticum aestivum L.

Trials were established in 2007, 2008, and 2009 in Ontario, Canada, to determine the effect of soil residues of saflufenacil on growth, yield, and quality of eight rotational crops planted 1 yr after application. In the year of establishment, saflufenacil was applied PRE to field corn at rates of 75, 100, and 200 g ai ha⁻¹. Cabbage, carrot, cucumber, onion, pea, pepper, potato, and sugar beet were planted 1 yr later, maintained weed-free, and plant dry weight, yield, and quality measures of interest to processors for each crop were determined. Reductions in dry weight and yield of all grades of cucumber were determined at both the 100 and 200 g ha⁻¹ rates of saflufenacil. Plant dry weight, bulb number, and size and yield of onion were also reduced by saflufenacil at 100 and 200 g ha⁻¹. Sugar beet plant dry weight and yield, but not sucrose content, were decreased by saflufenacil at 100 and 200 g ha⁻¹. Cabbage plant dry weight, head size, and yield; carrot root weight and yield; and pepper dry weight, fruit number and size, and yield were only reduced in those treatments in which twice the field corn rate had been applied to simulate the effect of spray overlap in the previous year. Pea and potato were not negatively impacted by applications of saflufenacil in the year prior to planting. It is recommended that cabbage, carrot, cucumber, onion, pepper, and sugar beet not be planted the year after saflufenacil application at rates up to 200 g ha⁻¹. Pea and potato can be safely planted the year following application of saflufenacil up to rates of 200 g ha⁻¹.

Nomenclature: saflufenacil; cabbage, Brassica oleracea var. italica Plenck.; carrot, Daucus carota L.; corn, Zea mays L.; cucumber, Cucumis sativus L.; onion, Allium cepa L.; pea, Pisum sativum L., pepper, Capsicum sativa L.; potato, Solanum tuberosum L.; sugar beet, Beta vulgaris L.

Rice cultivar, growth stage at application, or both may influence rice tolerance to quinclorac. Field studies were conducted to compare the response of five rice cultivars ‘Bowman’, ‘Cheniere’, ‘CL161’, ‘Cocodrie’, and ‘XL723’ to postflood quinclorac applications. Quinclorac at 0.56 kg ai ha⁻¹ was applied 2 and 4 wk after flood (WAF). Pooled across quinclorac application timings, no differences in maturity were detected among the cultivars in 2008, but maturity of Cheniere and XL723 were delayed compared with CL161 and Cocodrie in 2007. Maturity of Cheniere and XL723 was delayed in 2007 compared with 2008. Pooled over cultivar, maturity was similar for 2 and 4 WAF applications in 2007 but was delayed for 2 WAF treatments in 2008. Regardless of year, postflood quinclorac applications reduced rough rice yield of all cultivars except Bowman. Cheniere and XL723 had lower rough rice yields compared with other cultivars in 2007; however, in 2008, rough rice yields of Cheniere, CL161, Cocodrie, and XL723 were similar, but still lower, than that of Bowman. Pooled over cultivar, postflood quinclorac reduced rough rice yields more when applied 4 WAF than at 2 WAF during both years. Our results demonstrate that Cheniere and XL723 are less tolerant than Bowman is to postflood quinclorac applications and that all evaluated cultivars are more susceptible to quinclorac applied at later developmental stages. Consequently, if circumstances necessitate a postflood quinclorac application, the herbicide should be applied no later than panicle initiation and should not be applied to Cheniere or XL723.

Nomenclature: Quinclorac; rice, Oryza sativa L.

There are significant concerns over the long- and short-term implications of continuous glyphosate use and potential problems associated with weed species shifts and the development of glyphosate-resistant weed species. Field research was conducted to determine the effect of herbicide treatment and application timing on weed control in glyphosate-resistant soybean. Ten herbicide treatments were evaluated that represented a range of PPI, PRE, and POST-only application timings. All herbicide treatments included a reduced rate of glyphosate applied POST. PRE herbicides with residual properties followed by (fb) glyphosate POST provides more effective control of broadleaf weed species than POST-only treatments. There was no difference in soybean yield between PRE fb POST and POST-only treatments in 2008. Conversely, PRE fb POST herbicide treatments resulted in greater yield than POST-only treatments in 2009. Using PRE fb POST herbicide tactics improves weed control and reduces the risk for crop yield loss when dealing with both early- and late-emerging annual broadleaf weed species across variable cropping environments.

Nomenclature: Glyphosate; common lambsquarters, Chenopodium album L. CHEAL; common waterhemp, Amaranthus rudis Sauer AMATA; giant ragweed, Ambrosia trifida L., AMBTR.

Development and utilization of dicamba-, glufosinate-, and 2,4-D-resistant crop cultivars will potentially have a significant influence on weed management in the southern United States. However, off-site movement to adjacent nontolerant crops and other plants is a concern in many areas of eastern North Carolina and other portions of the southeastern United States, especially where sensitive crops are grown. Cotton, peanut, and soybean are not resistant to these herbicides, will most likely be grown in proximity, and applicators will need to consider potential adverse effects on nonresistant crops when these herbicides are used. Research was conducted with rates of glufosinate, dicamba, and 2,4-D designed to simulate drift on cotton, peanut, and soybean to determine effects on yield and quality and to test correlations of visual estimates of percent injury with crop yield and a range of growth and quality parameters. Experiments were conducted in North Carolina near Lewiston-Woodville and Rocky Mount during 2009 and 2010. Cotton and peanut (Lewiston-Woodville and Rocky Mount) and soybean (two separate fields [Rocky Mount] during each year were treated with dicamba and the amine formulation of 2,4-D at 1/2, 1/8, 1/32, 1/128, and 1/512 the manufacturer's suggested use rate of 280 g ai ha⁻¹ and 540 g ai ha⁻¹, respectively. Glufosinate was applied at rates equivalent to 1/2, 1/4, 1/8, 1/16, and 1/32 the manufacturer's suggested use rate of 604 g ai ha⁻¹. A wide range of visible injury was noted at both 1 and 2 wk after treatment (WAT) for all crops. Crop yield was reduced for most crops when herbicides were applied at the highest rate. Although correlations of injury 1 and 2 WAT with yield were significant (P ≤ 0.05), coefficients ranged from −0.25 to −0.50, −0.36 to −0.62, and −0.40 to −0.67 for injury 1 WAT vs. yield for cotton, peanut, and soybean, respectively. These respective crops had ranges of correlations of −0.17 to −0.43, −0.34 to −0.64, and −0.41 to −0.60 for injury 2 WAT. Results from these experiments will be used to emphasize the need for diligence in application of these herbicides in proximity to crops that are susceptible as well as the need to clean sprayers completely before spraying sensitive crops.

Nomenclature:Dicamba; glufosinate; 2,4-D; cotton, Gossypium hirsutum L.; peanut, Arachis hypogaea L.; soybean, Glycine max (L.) Merr.

In the southeastern United States many farmers double-crop winter wheat with soybean or cotton. However, there is little information about residual injury of herbicides used in wheat to these rotational crops. Experiments were conducted from 2007 to 2008 and 2008 to 2009 in soft red winter wheat to evaluate response of rotational crops of soybean and cotton after application of various acetolactate synthase herbicides in wheat. Pyroxsulam, mesosulfuron, sulfosulfuron, propoxycarbazone, or chlorsulfuron plus metsulfuron at multiple rates were applied to wheat approximately 110 to 120 d before planting rotational crops. Soils were Tift loamy sand at Ty Ty, GA and Faceville sandy loam at Plains, GA. After wheat harvest, soybean (‘Pioneer 97M50’) and cotton (‘DP 0949 B2RF’) were strip-tillage planted and evaluated for injury, stand density, height over time, and yields. For both locations, wheat was tolerant to all herbicide treatments with little to no visible injury 7 to 90 d after application. Pyroxsulam injury was less than sulfosulfuron or mesosulfuron. At recommended use rates, wheat injury was transient with no effect on yield. Double-crop soybean for both locations had no differences in stand establishment for any herbicide treatments. There was significant carryover injury to soybean and cotton for sulfosulfuron applied to wheat for the Faceville sandy loam. There was no effect of herbicide treatment on cotton stand. There was little to no difference in residual activity on rotational crops between pyroxsulam and other wheat herbicides when labeled rates were applied. This is significant as pyroxsulam is used to control Italian ryegrass and wild radish in this region.

Nomenclature: Mesosulfuron; pyroxsulam; propoxycarbazone; sulfosulfuron; cotton, Gossypium hirsutum L.; soybean, Glycine max Merr. (L.), wheat, Triticum aestivum L.

Yellow nutsedge is an important weed problem in furrow-irrigated fields in the Treasure Valley of eastern Oregon and southwestern Idaho. Field studies were conducted in 2008 and 2009 to evaluate the effect of PPI S-metolachlor or EPTC followed by POST halosulfuron and dicamba plus glyphosate or glyphosate alone on foliar yellow nutsedge control and tuber production in corn. Corn plant height at 8 and 24 d after treatment (DAT) was reduced 20 and 17%, respectively, in POST herbicides alone compared with PPI plus POST herbicide treatments. Yellow nutsedge control at 8 DAT averaged 78% for treatments that included PPI application of EPTC or S-metolachlor 1,600 g ai ha⁻¹ followed by halosulfuron plus dicamba (35 plus 155 g ha⁻¹ or 70 plus 310 g ha⁻¹) plus glyphosate 785 g ha⁻¹ compared with POST treatments alone (49%). The control at 24 DAT was 84% for treatments that contained halosulfuron plus dicamba compared with 73% for POST glyphosate alone. Yellow nutsedge tubers were reduced 56 to 68% among treatments at the end of 2008. Tuber reduction in 2009 was greater with treatments that included PPI herbicides followed by sequential halosulfuron plus dicamba (35 plus 155 g ha⁻¹) plus glyphosate compared with glyphosate alone. Corn yield reflected the level of yellow nutsedge control and early-season weed interference. Treatments that included PPI herbicides had an average yield of 8.2 T ha⁻¹ compared with 6.6 T ha⁻¹ with sequential glyphosate alone. There was a correlation between percent foliar control and the number of yellow nutsedge tubers produced at the end of each year. Application of PPI herbicides followed by POST halosulfuron plus dicamba (35 plus 155 g ha⁻¹ or 70 plus 155 g ha⁻¹) plus glyphosate improved yellow nutsedge control, reduced early corn–weed competition, and produced the highest corn yield under furrow-irrigated conditions.

Nomenclature: EPTC; dicamba; glyphosate; halosulfuron; S-metolachlor; yellow nutsedge, Cyperus esculentus L.; corn, Zea mays L., ‘DK C52-59-RR’.

Field studies were conducted in central Missouri and central Kansas to evaluate the crop tolerance and efficacy of various combinations of atrazine, flufenacet isoxaflutole, flumetsulam clopyralid, isoxaflutole, and S-metolachlor applied PPI or PRE in conventional-till corn. Application technique did not influence crop injury in Kansas. In Missouri, greater crop injury was observed with treatments containing isoxaflutole when applied PPI vs. PRE. Application technique influenced giant foxtail, ivyleaf morningglory, large crabgrass, Palmer amaranth, and common waterhemp control. In dry years, control of these weeds was usually either same or greater with PPI than it was with PRE treatments. In years with average to above average precipitation, isoxaflutole provided greater control as a PRE application than as a PPI application. Palmer amaranth and common waterhemp control was usually greater with atrazine, isoxaflutole, and S-metolachlor applied PRE than it was applied PPI. Differences in control of all weeds between PPI and PRE applications were less obvious with two or three herbicides compared with treatments with a single herbicide. In general, the corn yield was greater with most of the treatments having two, three, or four herbicides than it was with treatments having a single herbicide, which was due to better weed control with the tank-mixtreatments.

Nomenclature: Atrazine; clopyralid; flufenacet; flumetsulam; isoxaflutole; S-metolachlor; common waterhemp, Amaranthus rudis Sauer AMATA; giant foxtail, Setaria faberi Herrm. SETFA; ivyleaf morningglory, Ipomoea hederacea Jacq. IPOHE; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA; corn, Zea mays L.

Management of Italian ryegrass in cereal-based cropping systems continues to be a major production constraint in areas of the United States, including the soft white winter wheat producing regions of the Pacific Northwest. Pyroxasulfone is a soil-applied herbicide with the potential to control broadleaf and grass weed species, including grass weed biotypes resistant to group 1, 2, and 7 herbicides, in several crops for which registration has been completed or is pending, including wheat, corn, sunflower, dry bean, and soybean. Field experiments were conducted from 2006 through 2009 near Corvallis, OR, to evaluate the potential for Italian ryegrass control in winter wheat with applications of pyroxasulfone. Application rates of PRE treatments ranged from 0.05 to 0.15 kg ai ha⁻¹. All treatments were compared to standard Italian ryegrass soil-applied herbicides used in winter wheat, including diuron, flufenacet, and flufenacet metribuzin. Visual evaluations of Italian ryegrass and ivyleaf speedwell control and winter wheat injury were made at regular intervals following applications. Winter wheat yields were quantified at grain maturity. Ivyleaf speedwell control was variable, and Italian ryegrass control following pyroxasulfone applications ranged from 65 to 100% and was equal to control achieved with flufenacet and flufenacet metribuzin treatments and greater than that achieved with diuron applications. Winter wheat injury from pyroxasulfone ranged from 0 to 8% and was most associated with the 0.15–kg ha⁻¹ application rate. However, this early-season injury did not negatively impact winter wheat yield. Pyroxasulfone applied at the application rates and timings in these studies resulted in high levels of activity on Italian ryegrass and excellent winter wheat safety. Based on the results, pyroxasulfone has the potential to be used as a soil-applied herbicide in winter wheat for Italian ryegrass management and its utility for management of other important grass and broadleaf weeds of cereal-based cropping systems should be evaluated.

Nomenclature: Diuron; flufenacet; pyroxasulfone; metribuzin; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot; ivyleaf speedwell, Veronica hederifolia L.; wheat, Triticum spp.

Field studies were conducted near Crowley, LA, in 2005 through 2007 to evaluate the effects of simulated herbicide drift on ‘Cocodrie’ rice. Each application was made with the spray volume varying proportionally to herbicide dosage based on a constant spray volume of 234 L ha⁻¹ and an imazethapyr rate of 70 g ai ha⁻¹. The 6.3%, 4.4 g ha⁻¹, herbicide rate was applied at a spray volume of 15 L ha⁻¹ and the 12.5%, 8.7 g ha⁻¹, herbicide rate was applied at a spray volume of 29 L ha⁻¹. An application of imazethapyr at one-tiller, panicle differentiation (PD), and boot resulted in increased crop injury compared with the nontreated rice. The most injury observed occurred on rice treated at the one-tiller timing. Imazethapyr at one-tiller, PD, and boot reduced plant height at harvest and primary and total (primary plus ratoon) crop yield, with the greatest reduction in primary crop yield resulting from imazethapyr applied at boot. Imazethapyr did not affect rice treated at primary crop maturity.

Nomenclature: Imazethapyr; rice, Oryza sativa L. ‘Cocodrie’.

Greenhouse and field studies were conducted to determine the effect of halosulfuron, imazosulfuron, and trifloxysulfuron applied through drip irrigation on yellow nutsedge. In greenhouse studies, yellow nutsedge control by halosulfuron, imazosulfuron, and trifloxysulfuron was greater (69 to 91%) than the nontreated control (0%). Yellow nutsedge treated with halosulfuron POST had a lower photosynthetic rate (0.6 to 22.6 µmol m⁻² s⁻¹) at 4, 7, and 14 d after treatment than the nontreated control (3.3 to 26.2 µmol m⁻² s⁻¹). Yellow nutsedge treated with trifloxysulfuron had lower photosynthetic rate and stomatal conductance than the nontreated plants. In field studies at Clinton, NC, yellow nutsedge density increased from treatment (day 0) to 56 d after treatment in all treatments. Increase in yellow nutsedge density was 72 and 95% in drip-applied halosulfuron and imazosulfuron treatments compared with yellow nutsedge density increases of 876% for the same period in the nontreated plots. Yellow nutsedge density increased 69 and 57% at Clinton and Kinston, NC, respectively, in the drip-applied 15 g ha⁻¹ trifloxysulfuron treatment compared with 876% in the nontreated control. In field studies at Clinton and Kinston, NC, suppression of yellow nutsedge emergence in POST and drip-applied herbicide treatments was similar. Emergence of yellow nutsedge was similar in the imazosulfuron POST and the nontreated yellow nutsedge. Based on these studies, drip-applied herbicides may be beneficial as a part of a yellow nutsedge control program, but additional measures, such as a POST herbicide, would be needed for effective control. Drip-applied herbicides may give growers an option for herbicide application after drip irrigation tape and polyethylene mulch have been installed in the current vegetable crops. This application method would also allow herbicide treatment under plastic mulch used for multicropping systems.

Nomenclature: Halosulfuron; imazosulfuron; trifloxysulfuron; yellow nutsedge, Cyperus esculentus L.

We tested the effects of seeding date and weed control during switchgrass establishment in a field experiment that was conducted in central Pennsylvania in 2007 and repeated in 2008. Switchgrass was no-till seeded in early May, late May, and mid-June, and three postemergence weed management treatments were evaluated, including Mow (only a single mowing), Broadleaf (2,4-D dicamba), and Broad Spectrum (2,4-D dicamba atrazine quinclorac). Switchgrass density increased at later seeding dates, except in 2008, when the middle seeding date had the lowest density. In both years, weed biomass in late summer was lowest in the last seeding date of the Broad Spectrum treatment. In contrast, switchgrass biomass in late summer was greatest in the first seeding date of the Broad Spectrum treatment in both years. In the year after establishment (production year), plots were split to test the effects of supplemental weed control, composed of metsulfuron 2,4-D applied in May, on total aboveground yield. Supplemental control in the production year increased total aboveground yield in the Mow treatment only, indicating that effective weed control during the establishment year might reduce the need for weed control in the following year. Although maximum aboveground yield was achieved when switchgrass was seeded in May and herbicides were used, results from our experiment suggest that seeding switchgrass at a relatively high seeding rate in June in our study region and mowing annual weeds to reduce competition and prevent seed production could be an effective strategy if minimizing herbicide use is a priority.

Nomenclature: 2,4-D; atrazine; dicamba; quinclorac; switchgrass, Panicum virgatum L.

Field studies were conducted to determine the response of sublethal glyphosate and dicamba doses to processing tomato flowering loss and marketable yield. Dose–response studies for both herbicides were conducted on four commercial processing tomato lines (two different lines within each study) and plants were sprayed at either the vegetative stage or the early bloom stage. Both glyphosate and dicamba caused higher yield losses when sprayed at the early bloom stage. A 25% yield loss was observed with 8.5 and 7.5 g ae ha⁻¹ for glyphosate and dicamba, respectively, at the early bloom stage and 43.9 and 11.9 g ae ha⁻¹ for glyphosate and dicamba, respectively, at the early vegetative stage. Overall, these tomato cultivars were more sensitive to dicamba than to glyphosate. We conclude that glyphosate and dicamba drift could have serious implications on tomato yields especially if the drift occurs during flowering.

Nomenclature: Glyphosate; dicamba; tomato, Lycopersicon esculentum Mill.

Saflufenacil is a new protoporphyrinogen oxidase–inhibiting herbicide registered for use before establishment of field corn and soybean. Generally, peanut plants are tolerant to other herbicides in this class, and no reports document the utility of saflufenacil for in-season weed control. Experiments were conducted to determine whether saflufenacil applied at 12, 25, and 50 g ha⁻¹ could effectively control Benghal dayflower and Palmer amaranth. It was observed that saflufenacil, applied either PRE or POST, was ineffective for Benghal dayflower. The maximum control at 28 d after treatment (DAT) was 79% when 50 g ha⁻¹ was applied to 5- to 10-cm plants. Control of Palmer amaranth from PRE applications was less effective than flumioxazin at 28 DAT. However, POST applications provided > 87% control at 28 DAT when applied to plants 5 to 10 cm in height. For plants 10 to 15 cm in height, > 90% Palmer amaranth control was only achieved by the 50 g ha⁻¹ application rate. For plants 15 to 20 cm in height, no POST application provided > 70% control. Peanut response, in a weed-free environment, to saflufenacil rate and application timing were also evaluated. Peanut stunting ranged from 0 to 36%, relative to application timing. Applications made at 0 d after emergence (DAE) were least injurious, whereas those made at 15 DAE were most injurious. Application of 50 g ha⁻¹ provided the greatest amount of stunting and foliar injury. However, stunting and saflufenacil application rate did not correspond to yield reduction. Saflufenacil application timing did influence peanut yield. Applications made between 0 and 30 DAE did not result in yield loss, whereas applications made at 45 and 60 DAE resulted in a 5 and 19% reduction, respectively. Though saflufenacil has many positive characteristics, higher application rates are required for optimum weed control. However, these higher use rates also resulted in unacceptable levels of injury.

Nomenclature: Flumioxazin; saflufenacil; Benghal dayflower, Commelina benghalensis L.; Palmer amaranth, Amaranthus palmeri S. Watson; peanut, Arachis hypogaea L.

Summer annual grasses such as goosegrass and smooth crabgrass can hinder seeded zoysiagrass establishment. The herbicide fluazifop controls various grassy weed species but can injure mature and seedling zoysiagrass. Research has indicated that fluazifop applications can be safened on mature zoysiagrass cultivars with the addition of triclopyr. Based on these observations, research was conducted to evaluate weed control and tolerance of seeded ‘Zenith’ zoysiagrass to fluazifop (0.11 or 0.21 kg ai ha⁻¹), triclopyr (1.12 kg ae ha⁻¹), or fluazifop plus triclopyr (0.11 or 0.21 kg ha⁻¹ plus 1.12 kg ha⁻¹) applied at seeding, 14, or 28 d after emergence (DAE). All herbicide treatments applied at seeding did not hinder zoysiagrass germination but did not reduce goosegrass populations. Fluazifop alone (0.11 and 0.21 kg ha⁻¹) applied at 14 and 28 DAE injured zoysiagrass seedlings but was reduced with the addition of triclopyr. At the end of the growing season, the greatest zoysiagrass cover was achieved by applications of fluazifop alone (0.11 kg ha⁻¹) applied at 14 DAE or fluazifop (0.11 or 0.21 kg ha⁻¹) plus triclopyr applied at 14 or 28 DAE. Fluazifop (0.11 or 0.21 kg ha⁻¹) applied alone or tank-mixed with triclopyr controlled goosegrass > 70% when applied 14 and 28 DAE. Based on these data, applications of fluazifop tank-mixed with triclopyr can successfully control goosegrass without injuring Zenith zoysiagrass seedlings.

Nomenclature: Fluazifop-P, (R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid; siduron, N-(2-methylcyclohexyl)-N9-phenylurea; triclopyr, [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid; goosegrass, Eleusine indica (L.) Gaertn., smooth crabgrass, Digitaria ischaemum (Schreb.) Schreb. ex Muhl.; zoysiagrass, Zoysia japonica Steud. ‘Zenith’.

Bodies of water that are treated with herbicides for aquatic weed control are often used as a source of irrigation water by landowners near the water body, but there is little information regarding the effects of experimental aquatic herbicides on common garden plants. Therefore, the goal of these experiments was to identify phytotoxicity of four herbicides on vegetables frequently cultivated by home gardeners. Sweet pepper, zucchini, tomato, and bush bean were irrigated with water containing bispyribac-sodium, quinclorac, topramezone, and trifloxysulfuron-sodium to identify the herbicide concentrations that damage these garden vegetables. Experiments were conducted during 2009 and repeated in 2010. Plants were irrigated four times during an 11-d period with the equivalent of 1.27 cm of treated water during each irrigation, then irrigated with well water until they were harvested 41 d after the first herbicide treatment. Values of the concentration of herbicide expected to reduce treated plants by 10% compared with control plants (EC₁₀) were calculated from components of nonlinear regression. Analysis of visual quality and dry weight data revealed that bush bean was the most sensitive of the vegetable plants to bispyribac-sodium, trifloxysulfuron-sodium, and topramezone, whereas the species most sensitive to quinclorac was zucchini. Exposure of bush bean to 7.1, 0.9, and 1.2 parts per billion (ppb) of bispyribac-sodium, trifloxysulfuron-sodium, and topramezone, respectively, would be expected to cause 10% reductions compared with control plants, whereas exposure of zucchini to as little as 11.0 ppb of quinclorac would be expected to cause a 10% reduction in dry weight.

Nomenclature: Bispyribac-sodium; quinclorac; topramezone; trifloxysulfuron-sodium; bush bean, Phaseolus vulgaris L.; sweet pepper, Capsicum annuum L.; tomato, Solanum lycopersicum L.; zucchini, Cucurbita pepo L.

Dimethenamid-p was labeled for preemergence use in potatoes in 2005. The herbicide provides hairy nightshade control; however, a tank-mix partner targeting common lambsquarters must be used in order to provide satisfactory control of that weed. S-metolachlor and metolachlor, also labeled for use in potato, are in the same chemical family as dimethenamid-p and questions have arisen as to whether or not these herbicides provide the same or different levels of hairy nightshade control. The objectives of this study, therefore, were (1) to compare preemergence control of common lambsquarters and other weeds in potato with dimethenamid-p applied at 0.72, 0.94, or 1.12 kg ai ha⁻¹ alone or in two-way tank mixtures to determine appropriate tank-mix partners, and (2) to compare hairy nightshade control by dimethenamid-p with control by S-metolachlor or metolachlor. Two-way tank mixtures of dimethenamid-p with ethalfluralin, EPTC, flumioxazin, metribuzin, pendimethalin, or sulfentrazone generally improved season-long common lambsquarters control compared with dimethenamid-p applied alone at 0.72, 0.94, or 1.12 kg ha⁻¹. When compared with control by dimethenamid-p alone at 0.72 or 0.94 kg ha⁻¹, control by dimethenamid-p at either rate tank-mixed with ethalfluralin or EPTC was not improved as much as control by combinations of dimethenamid-p at those rates with the other tank-mix partners. Hairy nightshade control by three-way tank mixtures of S-metolachlor or metolachlor with various combinations of metribuzin, ethalfluralin, EPTC, or pendimethalin ranged from 60 to 86% and was not as great as the 93 to 98% control by dimethenamid-p at 0.72 kg ha⁻¹ combined with the same tank-mix partners. U.S. No. 1 and total tuber yields of comparative two- and three-way tank mixtures were generally increased when weed control was improved.

Nomenclature: Dimethenamid-p; EPTC; ethalfluralin; metolachlor; metribuzin; pendimethalin; sulfentrazone; S-metolachlor; common lambsquarters, Chenopodium album L. CHEAL; green foxtail, Setaria viridis L. SETVI; hairy nightshade, Solanum sarrachoides Sendter SOLSA; redroot pigweed, Amaranthus retroflexus L. AMARE.

Two field experiments were undertaken at Roseworthy, South Australia from 2006 to 2007 to evaluate the performance of herbicide application strategies for the control of herbicide-resistant rigid ryegrass in faba bean grown in wide rows (WR). The standard farmer practice of applying postsowing PRE (PSPE) simazine followed by POST clethodim to faba bean grown in WR provided consistent and high levels of rigid ryegrass control (≥ 96%) and caused a large reduction (P < 0.05) in spike production (≤ 20 spikes m⁻²) as compared with nontreated control (560 to 722 spikes m⁻²). Furthermore, this herbicide combination resulted in greatest yield benefits for WR faba bean (723 to 1,046 kg ha⁻¹). Although PSPE propyzamide used in combination with shielded interrow applications of glyphosate or paraquat provided high levels of rigid ryegrass control (≥ 93%), these treatments were unable to reduce ryegrass spike density within the crop row (20 to 54 spikes m⁻²) to levels acceptable for continued cropping. Furthermore, a yield reduction (13 to 29%) was observed for faba bean in treatments with shielded application of nonselective herbicides and could be related to spray drift onto lower leaves. These findings highlight that shielded interrow spraying in WR faba bean could play an important role in the management of rigid ryegrass in southern Australia. However, timing of shielded interrow applications on weed control, crop safety, and issues concerning integration with more effective early-season control strategies require attention.

Nomenclature: Clethodim; glyphosate; paraquat; propyzamide; simazine; rigid ryegrass, Lolium rigidum Gaud LORI; faba bean, Vicia faba (L.).

Annual bluegrass is a troublesome weed in turf management and there are currently limited POST herbicides labeled for use in seashore paspalum. Field and greenhouse experiments were conducted to evaluate seashore paspalum tolerance to pronamide and other herbicides for annual bluegrass control. In field experiments, turf injury never exceeded 7% from pronamide applied at dormancy, 50% green-up, or complete green-up of seashore paspalum in spring. Annual bluegrass control from pronamide was initially similar across timings and averaged 67, 90, and 98% control from 0.84, 1.68, and 3.36 kg ai ha⁻¹, respectively, after 6 wk. In greenhouse experiments, the aforementioned pronamide rates caused less than 10% injury on seashore paspalum. Seashore paspalum injury in the greenhouse was excessive (> 20%) from atrazine, bispyribac-sodium, and trifloxysulfuron and moderate (7 to 20%) from foramsulfuron, rimsulfuron, and ethofumesate. Seashore paspalum seedhead count reductions by 4 wk after treatment (WAT) were good to excellent (87 to 98%) from atrazine, bispyribac-sodium, rimsulfuron, and trifloxysulfuron and poor (≤ 0%) from ethofumesate, foramsulfuron, and pronamide. By 4 WAT, seashore paspalum clippings were reduced 0 to 39% from pronamide, whereas atrazine, bispyribac-sodium, and trifloxysulfuron reduced clippings by 54 to 69% from the untreated and ethofumesate, foramsulfuron, and rimsulfuron reduced clippings by 27 to 39%.

Nomenclature: Annual bluegrass, Poa annua L.; seashore paspalum, Paspalum vaginatum Sw.

Greenhouse experiments were conducted to evaluate the effect of selective herbicide placement on sedge shoot number, shoot weight, and root weight. Sulfentrazone, sulfosulfuron, and trifloxysulfuron were applied to soil only, foliage only, or soil plus foliage. Sulfentrazone provided greater yellow nutsedge and false green kyllinga growth reduction compared to purple nutsedge. Sulfosulfuron provided greater purple nutsedge and false green kyllinga growth reduction compared to yellow nutsedge; these species responded similarly to trifloxysulfuron. Soil and soil plus foliar applications provided the highest level of growth suppression, indicating herbicide–soil contact is required for optimum sedge control with these three herbicides. Future research should evaluate techniques that optimize herbicide–soil contact to improve herbicide efficacy.

Nomenclature: Sulfentrazone; sulfosulfuron; trifloxysulfuron; false green kyllinga, Kyllinga gracillima Miq.; purple nutsedge, Cyperus rotundus L.; yellow nutsedge, Cyperus esculentus L.

The presence of weeds during bermudagrass putting green establishment can reduce growth and turf quality. Three field experiments were conducted in Georgia to investigate efficacy of dimethenamid, S-metolachlor, and oxadiazon on the establishment of ‘TifEagle’ bermudagrass from sprigs. Dimethenamid at 0.85 and 1.7 kg ai ha⁻¹, S-metolachlor at 1.1 and 2.2 kg ai ha⁻¹, and oxadiazon at 1.1, 2.2, and 4.4 kg ai ha⁻¹ did not reduce bermudagrass cover from the untreated after 8 wk. S-metolachlor at 4.4 kg ha⁻¹ was the only treatment that reduced sprig cover from the untreated after 12 wk. All S-metolachlor and oxadiazon treatments provided excellent (≥ 90%) green kyllinga control by 8 wk after treatment (WAT) while dimethenamid at 0.85, 1.7, and 3.4 kg ha⁻¹ provided 78, 85, and 92% control, respectively. Dimethenamid treatments provided poor control (< 70%) of spotted spurge but fair control (70 to 79%) was achieved from S-metolachlor at 4.4 kg ha⁻¹ and oxadiazon at 2.2 and 4.4 kg ha⁻¹ by 8 WAT. Overall, low to middle rates of the herbicides tested appear to temporarily inhibit TifEagle bermudagrass sprig establishment but high rates of dimethenamid and S-metolachlor may reduce cover from the untreated.

Nomenclature: Hybrid bermudagrass, Cynodon dactylon × C. transvaalensis Burtt-Davy; green kyllinga, Kyllinga brevifolia Rottb.; spotted spurge, Euphorbia maculata L.

Purple nutsedge response to various rates and timings of imazosulfuron was evaluated in 2007 and 2008 in Abilene, TX. Bermudagrass phytotoxicity never exceeded 4% throughout the duration of the trial and all bermudagrass recovered within 7 d of herbicide application. Imazosulfuron (0.56 kg ai ha⁻¹) followed by (fb) imazosulfuron 1 wk after initial treatment (WAIT), imazosulfuron at 1.12 kg ai ha⁻¹, and trifloxysulfuron at 0.03 kg ai ha⁻¹ exhibited 94 to 96% control 4 WAIT. Imazosulfuron (0.56 kg ai ha⁻¹) fb imazosulfuron 2, 3, and 4 WAIT exhibited 99% control 4 WAIT. Eight weeks later (12 WAIT), imazosulfuron (0.56 kg ai ha⁻¹) fb imazosulfuron 3 WAIT controlled purple nutsedge 91%, whereas similar control (82 to 84%) was observed with a single application of trifloxysulfuron and imazosulfuron (0.56 kg ai ha⁻¹) fb imazosulfuron 2 and 4 WAIT. A single application of imazosulfuron at 1.12 kg ai ha⁻¹ and sequential treatment with imazosulfuron (0.56 kg ai ha⁻¹) on a 1-wk interval only controlled purple nutsedge 51 to 69% 12 WAIT. Timing of sequential imazosulfuron application was identified as an important component of the purple nutsedge control program. Waiting 2, 3, or 4 WAIT for sequential imazosulfuron applications, rather than 1 WAIT, increased purple nutsedge control 31 to 40% 12 WAIT. The highest level of purple nutsedge control (91%) was observed with applications of imazosulfuron (0.56 kg ai ha⁻¹) fb imazosulfuron 3 WAIT applied during midsummer. However, control with this treatment was statistically similar to control with a single application of trifloxysulfuron (82%).

Nomenclature: Imazosulfuron (2-chloro-N-[[4,6-dimethoxy-2-pyrimidinyl-amino]carbonyl]imidazo[1,2-a]pyridine-3-sulfonamide); trifloxysulfuron; common bermudagrass, Cynodon dactylon (L.) Pers. CYNDA; purple nutsedge, Cyperus rotundus L. CYPRO.

Farmers grow crops in the dryland region of the Pacific Northwest (PNW) using tillage practices ranging from moldboard plowing to no-tillage. The objective of this study was to determine the effect of tillage on persistence of imazamox herbicide in intermediate and high precipitation zones of the inland PNW. Along with a nontreated control, imazamox was applied to imidazolinone-tolerant winter wheat in the fall and spring at one, two, and three times the maximum labeled rate at locations near Genesee, ID, Davenport, WA, and Pendleton, OR. Moldboard plow, chisel plow, and no-till tillage treatments were implemented soon after wheat harvest and yellow mustard was planted the following season to determine crop response. Experiments were conducted at each location in 2005 to 2007 and 2006 to 2008. There were significant location by year and year and location interactions. There was no significant tillage by imazamox rate interaction, except at Pendleton in year 2, for all measured yellow mustard responses (crop injury, biomass, and yield). Genesee was colder than Pendleton and had more precipitation than Davenport, resulting in more injury to yellow mustard at Genesee than at Pendleton but less than at Davenport. Davenport had greater injury than the other two locations, likely due to lower soil pH, higher organic matter (OM), and cooler, drier climate, which allowed imazamox to persist longer in the soil. Overall, Pendleton had the least yellow mustard injury, which likely was related to its warmer, wetter climate and the concomitant rapid soil dissipation of imazamox. Tillage did not reduce the persistence of imazamox. Yellow mustard had the lowest injury and had greater mature biomass and seed yield in no-till seeded plots when averaged across imazamox rates compared to moldboard and chisel-plowed plots.

Nomenclature: Imazamox; yellow mustard, Sinapis alba L. ‘IdaGold’, winter wheat, Triticum aestivum L.

Cultivation is a critical component of organic weed management and has relevance in conventional farming. Limitations with current cultivation tools include high costs, limited efficacy, and marginal applicability across a range of crops, soil types, soil moisture conditions, and weed growth stages. The objectives of this research were to compare the weed control potential of two novel tools, a block cultivator and a stirrup cultivator, with that of a conventional S-tine cultivator, and to evaluate crop response when each tool was used in pepper and broccoli. Block and stirrup cultivators were mounted on a toolbar with an S-tine sweep. In 2008, the tripart cultivator was tested in 20 independently replicated noncrop field events. Weed survival and reemergence data were collected from the cultivated area of each of the three tools. Environmental data were also collected. A multivariable model was created to assess the importance of cultivator design and environmental and operational variables on postcultivation weed survival. Additional trials in 2009 evaluated the yield response of pepper and broccoli to interrow cultivations with each tool. Cultivator design significantly influenced postcultivation weed survival (P < 0.0001). When weed survival was viewed collectively across all 20 cultivations, both novel cultivators significantly increased control. Relative to the S-tine sweep, the stirrup cultivator reduced weed survival by about one-third and the block cultivator reduced weed survival by greater than two-thirds. Of the 11 individually assessed environmental and operational parameters, 7 had significant implications for weed control with the sweep; 5 impacted control with the stirrup cultivator, and only 1 (surface weed cover at the time of cultivation) influenced control with the block cultivator. Crop response to each cultivator was identical. The block cultivator, because of its increased effectiveness and operational flexibility, has the potential to improve interrow mechanical weed management.

Nomenclature: Broccoli, Brassica oeracea L.; pepper, Capsicum annuum L.

The nonnative biotype of common reed has invaded wetlands in many states including Nebraska, especially along the Platte River from Wyoming to the eastern edge of Nebraska. Therefore, three studies (disking followed by herbicide, mowing followed by herbicide, and herbicide followed by mechanical treatment) were conducted for 3 yr (2008 to 2010) at three locations in Nebraska. The objective was to evaluate common reed control along the Platte River using an integrated management approach based on herbicides (glyphosate or imazapyr), mowing, and disking, either applied alone or in combination. The level of weed control was determined by visual rating, percent flowering, and stem density. On the basis of visual rating, disking and mowing used alone provided common reed control for only a few months. However, the control was significantly prolonged (e.g., at least three seasons) when disking and mowing were combined with herbicide applications. Disking followed by herbicide and mowing followed by herbicide significantly reduced flowering and plant densities (P  =  0.0001) compared to the untreated check. These results suggest that a combination of weed control methods has potential to control common reed.

Nomenclature: Imazapyr; glyphosate; common reed, Phragmites australis (Cav.) Trin. ex Steud. subsp. australis PHRCO.

Weed control in organic peanut production is difficult and costly. Sweep cultivation in the row middles is effective, but weeds remain in the crop row, causing yield loss. Research trials were conducted in Ty Ty, GA to evaluate implements and frequencies of cultivation to improve in-row weed control in organic peanut. Implements were a tine weeder and power takeoff-powered brush hoe that targeted weeds present in the row. Frequencies of cultivation were at vegetative emergence of peanut (VE), 1 wk after VE (1wk), 2 wk after VE (2wk), sequential combinations of VE/1wk, VE/2wk, and VE/1wk/2wk. All plots were cultivated with a sweep cultivator to control weeds in row middles. The tine weeder tended to be easier to operate and performed more consistently than the brush hoe. Both implements performed best when initial cultivation was at VE. Delaying the initial cultivation reduced overall effectiveness. Plots with the best in-row weed control were hand-weeded once to control escapes and harvested for peanut yield. The best overall combination of weed control, minimal use of salvage hand-weeding, and maximum peanut yield resulted from sequential cultivation at VE/1wk using either the tine weeder or brush hoe, row middle sweep cultivation, and preharvest mowing.

Nomenclature: Smallflower morningglory, Jacquemontia tamnifolia (L.) Griseb.; southern crabgrass, Digitaria ciliaris (Retz.) Koel.; Texas millet, Urochloa texana (Buckl.) R. Webster; peanut, Arachis hypogaea L.

The synergistic interaction between mesotrione, a hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide, and atrazine, a photosystem II (PS II)-inhibiting herbicide, has been identified in the control of several weed species. A series of dose–response studies examined the synergistic effect of these herbicides on a susceptible (S) wild radish population. The potential for this interaction to overcome target-site psbA gene-based atrazine resistance in a resistant (R) wild radish population was also investigated. Control of S wild radish with atrazine was enhanced by up to 40% when low rates (1.0 to 1.5 g ha⁻¹) of mesotrione were applied in combination. This synergistic response was demonstrated across a range of atrazine–mesotrione rate combinations on this S wild radish population. Further, the efficacy of 1.5 g ha⁻¹ mesotrione increased control of the R population by a further 60% when applied in combination with 400 g ha⁻¹ of atrazine. This result clearly demonstrated the synergistic interaction of these herbicides in overcoming the target-site resistance mechanism. The mechanism responsible for the observed synergistic interaction between mesotrione and atrazine remains unknown. However, it is speculated that an alternate atrazine binding site may be responsible. Regardless of the biochemical nature of this interaction, evidence from whole-plant bioassays clearly demonstrated that synergistic herbicide combinations improve herbicide efficiency, with lower application rates required to control weed populations. This, combined with the potential to overcome psbA gene-based triazine resistance, and, thereby, regain the use of these herbicides, will result in more sustainable herbicide use.

Nomenclature: Atrazine; mesotrione; wild radish, Raphanus raphanistrum L. RAPRA.

Glyphosate-resistant (GR) sugarbeet is commonly grown in rotation with GR corn, but there is limited information relating to volunteer GR corn interference or control in GR sugarbeet. Field studies were conducted near Lingle, WY and Scottsbluff, NE in 2009 and 2010 to quantify sugarbeet yield loss in response to volunteer corn density and duration of interference, and determine appropriate control practices for use in GR sugarbeet. Hybrid corn resulted in a similar competitive effect on sugarbeet sucrose yield as clumps of F₂ volunteer corn. Clumps of volunteer corn were controlled 81% compared with 73% for individual plants. Linear regression indicated sucrose yield loss of 19% for each corn plant m⁻² up to 1.7 plants m⁻² at three of four experimental sites. Pearson correlation coefficients between percentage sucrose yield loss and proportion of sunlight reaching the top of the sugarbeet canopy ranged from −0.42 to −0.92. The duration of corn interference required to cause a 5% sucrose yield loss (Y_L5) ranged from 3.5 to 5.9 wk after sugarbeet emergence (WAE) for hand-weeding or herbicide removal, respectively, due to the length of time herbicide-treated volunteer corn continued to shade sugarbeet plants. Differences between herbicide and hand-removal methods were attributed to the time lag between when the treatments were applied and when the corn ceased to block light from the sugarbeet canopy. Sethoxydim generally provided less volunteer corn control compared with either quizalofop or clethodim, and control increased with the addition of an oil adjuvant. If a grower were to implement a volunteer corn control practice 3.5 WAE, economic sugarbeet yield loss would be avoided. In eastern Wyoming and western Nebraska, the sugarbeet crop will typically have between four to eight true leaves at 3.5 WAE, and therefore this would be an optimal time to control volunteer corn. If volunteer corn is being hand weeded, the Y_L5 estimate will also increase, and thus the window of time to control volunteer corn would be wider.

Nomenclature: Clethodim; glyphosate; quizalofop; sethoxydim; volunteer corn, Zea mays L. ZEAMX; sugarbeet, Beta vulgaris L.

Field research was conducted near Saint Joseph, LA, in 2008 and 2009 to evaluate Texasweed interference in drill-seeded rice. Season-long Texasweed interference at 1 plant m⁻² was estimated to cause 5% yield loss. Yield loss from 10 and 50 plants m⁻² was 31 and 61%, respectively. Yield loss was primarily due to a reduction in effective tillers per square meter. Thousand-grain weight of rice was not affected by season-long Texasweed interference. Path analysis indicated yield component compensation, i.e., a reduction in effective tillers per square meter probably caused an increase in grains per panicle. However, that effect was not strong enough to reverse the detrimental effect of reduced effective tillers per square meter on rice yield. The critical period of Texasweed interference to cause more than 5% yield loss was estimated to be between 0 and 6 wk after rice emergence.

Nomenclature: Texasweed, Caperonia palustris (L.) St. Hil. CNPPA; rice, Oryza sativa L. ORYSA.

Yellow nutsedge is a problematic weed in polyethylene-mulched tomato production. Soil fumigation with methyl bromide is the most effective method of controlling nutsedges, but because of ozone depletion, the phase-out of methyl bromide has complicated nutsedge control in polyethylene-mulched tomato and other vegetable crops. Plants belonging to the Brassicaceae family produce glucosinolates, which upon tissue decomposition generate biocidal isothiocyanates and therefore can be used as a biological alternative for yellow nutsedge control. Field experiments were conducted in 2007 and 2009 to study the influence of soil amendment with ‘Seventop’ turnip cover crop on the interference of yellow nutsedge planted at 0, 50, and 100 tubers m⁻² in raised-bed polyethylene-mulched tomato production. There was no advantage of soil amendment with Seventop on reducing yellow nutsedge interference in polyethylene-mulched tomato. Regardless of soil amendment, increasing initial tuber density from 50 to 100 tubers m⁻² increased yellow nutsedge shoot density, shoot dry weight, and tuber production at least 1.7, 1.6, and 1.6 times, respectively. As a result, tomato canopy width, shoot dry weight, and marketable yield decreased with increasing initial tuber densities. However, increased tuber density had minimal impact on tomato height. Relative to weed-free plots, interference of yellow nutsedge at 50 and 100 tubers m⁻² reduced marketable yield of tomato up to 32 and 49%, respectively. Shading of the middle and lower portion of tomato plants by yellow nutsedge shoots could be the major factor for reducing tomato growth and yield in weedy plots. It is concluded that soil amendment with Seventop turnip is not a viable option for reducing yellow nutsedge interference at 50 and 100 tuber m⁻² in polyethylene-mulched tomato.

Nomenclature: Yellow nutsedge, Cyperus esculentus L. CYPES; tomato, Lycopersicon esculentum Mill. ‘Amelia’, turnip, Brassica rapa L. ‘Seventop’.

Dewberry is a weed found on cranberry bogs that spreads quickly, causes high yield loss, and has no effective management strategy. Finding options to manage damaging perennial weeds in a perennial crop system, such as cranberry, is key to long-term industry sustainability. This study presents preliminary data on the use of flame cultivation (FC) in cranberry weed management. Utilizing weeds transplanted from commercial cranberry farms to a prepared area at the UMass Cranberry Station, we evaluated three handheld propane-fueled FC instruments: infrared torch, open flame torch, and an infrared torch with a spike. A single, midsummer exposure (zero, low, medium, or high duration) with each FC was tested. The industry standard of using a single wipe application of an herbicide solution (111 g L⁻¹ ae glyphosate, isopropylamine salt) was also included in the evaluation. Dewberry shoot, root, and total biomass decreased linearly as exposure increased; the effect of FC tool type was not significant. Data indicated that, regardless of the specific torch utilized, spot treatment with FC reduced dewberry biomass. The results of this exploratory study suggest that FC may offer an alternative technique for managing woody weeds and that further research is warranted.

Nomenclature: Glyphosate; dewberry, Rubus spp.; cranberry, Vaccinium macrocarpon Ait.

Late summer goosegrass control is difficult in turfgrass as POST herbicide efficacy is reduced on mature plants. Field experiments were conducted to evaluate single and sequential nicosulfuron applications tank-mixed with foramsulfuron or sulfentrazone for late summer goosegrass control and safety to bermudagrass and seashore paspalum. All single-treatment applications controlled goosegrass < 62%, whereas sequential sulfentrazone, nicosulfuron, and nicosulfuron sulfentrazone applications controlled goosegrass 52, 73, and 84%, respectively. Sequential foramsulfuron applications controlled goosegrass < 55% but nicosulfuron tank-mixtures did not improve control. Bermudagrass was injured < 20% by 1 and 3 wk after all single and sequential treatments. Sequential treatments of nicosulfuron alone or tank-mixed with sulfentrazone caused unacceptable seashore paspalum injury (> 20%) 1 and 3 wk after the second application, whereas foramsulfuron or sulfentrazone alone applied sequentially caused < 17% injury. Seashore paspalum seedhead control at 9 wk after intial treatment was poor (< 70%) from all single-application treatments and sequential sulfentrazone applications, but control was good (80 to 89%) to excellent (> 90%) from all other treatments. Overall, sequential treatments of nicosulfuron alone or tank-mixed with sulfentrazone appear to have potential for POST control of mature goosegrass in bermudagrass, but seashore paspalum injury was unacceptable.

Nomenclature: Bermudagrass, Cynodon dactylon L.; goosegrass, Eleusine indica L.; seashore paspalum, Paspalum vaginatum Sw.

Cultivation tools have a long history of use. The integration of cultivation within current organic and conventional weed management programs is conditional on the availability of functional, practical cultivation tools. However, there are performance and operational limitations with current cultivation tools. Serviceable improvement in weed control is the impetus behind creation of new tool designs. The primary objective of this research was to design and construct two cultivators that might address the limitations of current cultivation tools. A secondary objective was to identify historical influences on the technology, availability, and capability of cultivation tools. Two new tractor-mounted cultivators were designed and constructed as loose extractions of antique handheld tools. The first tool, a block cultivator, has a flat surface in the front of the tool that rests against the soil and limits the entrance of a rear-mounted blade. The second tool resembles a stirrup hoe, where a horizontal steel blade with a beveled front edge slices through the upper layer of the soil. Block and stirrup cultivator units were mounted on a toolbar with a traditional S-tine sweep, so that the novel cultivators could be compared directly with a common standard. Relative to the S-tine sweep, the stirrup cultivator reduced weed survival by about one-third and the block cultivator reduced weed survival by greater than two-thirds. Of the three tools, block cultivator performance was least influenced by environmental and operational variances.

Nomenclature: Block cultivator, cultivation, stirrup cultivator, S-tine sweep