Common Cocklebur Control Research Articles

Influence of Adjuvants on Efficacy of Imazapic and 2,4-DB

Abstract Adjuvants can have a major influence on efficacy of postemergence herbicides. Imazapic and 2,4-DB are applied postemergence in peanut (Arachis hypogaea L.) to control a variety of weeds. Determining how adjuvants influence efficacy of these herbicides could lead to more efficient weed management. Field experiments were conducted during 1997 and 1998 to determine the influence of nonionic surfactant, crop oil concentrate, organosilicone surfactant, and a blend of organosilicone surfactant and methylated seed oil on efficacy of imazapic and 2,4-DB. No-adjuvant and nontreated controls were also included. Adjuvants did not increase redroot pigweed (Amaranthus retroflexus L.) or common cocklebur (Xanthium strumarium L.) control by imazapic. Only minor differences in control of eclipta (Eclipta prostrata L.), entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray), and pitted morningglory (Ipomoea lacunosa L.) by imazapic were noted among adjuvants. Sicklepod [Senna obtusifolia (L.) Erwin and Barneby] and pitted morningglory control increased when 2,4-DB was applied with adjuvants. Common cocklebur control was improved in one of three experiments when adjuvants were applied with 2,4-DB. Redroot pigweed and entireleaf morningglory control by 2,4-DB was not affected by adjuvants.

Weed Control with Reduced Rates of Chlorimuron Plus Metribuzin and Imazethapyr in No-Till Narrow-Row Soybean (Glycine max)

Field studies were conducted at three locations in 1993 and 1994 to evaluate weed control and crop response to combinations of glyphosate, metolachlor, 0.5 X and 1 X label rates of chlorimuron plus metribuzin applied prior to planting (PP), and 0.5 X and 1 X label rates of imazethapyr applied early postemergence (EPOST) or postemergence (POST) in no-till narrow-row soybean production. Giant foxtail densities were reduced with sequential PP followed by (fb) EPOST or POST treatments. Large crabgrass was reduced equivalently with all herbicide combinations involving chlorimuron plus metribuzin PP fb imazethapyr. Common cocklebur control was variable but was usually greater with treatments that included imazethapyr. Ivyleaf morningglory densities were not reduced with any herbicide combinations. Sequential PP fb EPOST or POST treatments tended to provide slightly better weed suppression than PP-only treatments, but the difference was rarely significant. Soybean yields with treatments utilizing 0.5 X rates were usually equal to 1 X rates.

Weed Control and Economic Returns with Postemergence Herbicides in Narrow-Row Soybeans (Glycine max)

Field studies were conducted at three sites in 1993 and 1994 to evaluate weed control, crop response, and economic returns to 0.5× and 1× postemergence rates of chlorimuron, chlorimuron plus quizalofop, bentazon plus acifluorfen, fluazifop plus fenoxaprop, imazethapyr, and imazethapyr plus clethodim in no-till narrow-row soybean production. Common lambsquarters, ivyleaf morningglory, and common ragweed were controlled equally with 0.5× rates applied early postemergence and 1× rates applied mid-postemergence. Control of giant foxtail, large crabgrass, and common cocklebur was generally greater with 1× rates mid-postemergence than with 0.5× rates early postemergence. Soybean yields were equivalent with 0.5× and 1× rates. Soybean yields and net income were highest with 1× and 0.5× rates of chlorimuron plus quizalofop and imazethapyr plus clethodim, and metolachlor preemergence (PRE) followed by 0.5× bentazon plus acifluorfen.

Application Timing Affects Weed Control with Metolachlor Plus Atrazine in No-Till Corn (Zea mays)

Field trials were conducted in no-till field corn in northern Missouri to compare weed control and crop response of metolachlor plus atrazine applied under five preplant herbicide management practices. The practices consisted of (1) applying the entire dose of metolachlor plus atrazine 15, 30, or 45 d early preplant (EPP), (2) applying a split application of an EPP (67%) followed by (fb) a PRE (33%), (3) applying the entire dose PRE, (4) applying metolachlor PRE fb dicamba early post (EPOST), or (5) applying atrazine alone EPOST. Weed control at 7 wk after planting was more variable with EPP treatments than with EPP fb PRE or PRE treatments. Giant foxtail and fall panicum control was greatest with treatments that included metolachlor PRE. Velvetleaf and common cocklebur control was greatest with atrazine or dicamba EPOST and was generally unacceptable (< 80%) with any soil-applied herbicide treatment. Common lambsquarters control was greater than 90% with all treatments that included metolachlor, atrazine, or dicamba, regardless of timing. Corn yields were slightly higher with EPP fb PRE and PRE fb EPOST dicamba than with EPP alone. The results suggest that herbicide applications made nearer to the date of planting provide less variable weed control and corn yield than treatments made more than 15 d EPP.

Preemergence Broadleaf Weed Control and Crop Tolerance in Imidazolinone-Resistant and -Susceptible Corn (Zea mays)

Field studies were conducted in 1994 and 1995 at Dekalb and Urbana, IL, to evaluate preemergence broadleaf weed control and crop tolerance in imidazolinone resistant (IR) and susceptible (non-IR) corn using atrazine, imazethapyr, AC 263,222, CGA-152005, MON 12000 with and without MON 13900 (a safener), and flumetsulam + clopyralid. When sufficient rainfall occurred within 28 d of application to insure herbicide absorption, the IR corn variety was more tolerant than the susceptible variety to imazethapyr, AC 263,222, CGA-152005 at 40 and 80 g/ha, and MON 12000 with and without MON 13900. Overall crop tolerance of IR corn was equal to that of corn treated with atrazine for all herbicide treatments except CGA-152005, which injured IR corn. Control of velvetleaf, common lambsquarters, Pennsylvania smartweed, tall morningglory, and jimsonweed for all herbicide treatments was equal or superior to that of atrazine at 1.7 kg/ha. However, control of common cocklebur was significantly greater with atrazine compared to imazethapyr and the low rate of CGA-152005.

Response of Sulfonylurea-Tolerant Soybean (Glycine max) and Selected Weed Species to Imazethapyr and Thifensulfuron Combinations

Sulfonylurea-tolerant soybean (STS soybean) tolerance to imazethapyr (70 g/ha) plus thifensulfuron (4.4 g/ha) tank mixture was evaluated in 1993 and 1994 at two locations in Illinois. Thifensulfuron injury was reduced from 27% in non-STS soybean to 1% in STS soybean 14 days after treatment (DAT). STS and non-STS soybean did not differ in response to imazethapyr alone with < 6% injury 14 DAT. Injury from the tank mix was reduced from 40% in non-STS soybean to 24% in STS soybean 14 DAT. However, a synergistic interaction between the herbicides exists in STS soybean. The yield of injured soybean was not reduced in either STS or non-STS soybean. Injury to STS soybean from the tank mix was decreased by reducing the rate of imazethapyr from 70 g/ha to 52.5 or 35 g/ha. Reducing the thifensulfuron rate mixed with imazethapyr at 70 g/ha did not decrease injury in STS soybean. Control of smooth pigweed, common lambsquarters, and common cocklebur was not affected by reducing the rate of either herbicide in the tank mixture.

Evaluation of Band vs. Broadcast Herbicide Applications in Corn and Soybean

Weed control in corn (Zea 'nays) and soybean [Glycine mar (L.) Merr.] with band applications of herbicides plus cultivation was evaluated in these studies. Giant foxtail (Setaria faberi Herrm.) and velvetleaf (Abutilon theophrasti Medik) control in corn with band applications plus cultivation was equal to or better than control with broadcast applications without cultivation of the same herbicides 2 of the 3 yr. Ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] control was less consistent with band applications plus cultivation than with the broadcast applications. There was no difference in yellow nutsedge (Cyperus esculentus L.) control between the band applications plus cultivation and broadcast applications averaged over years. Giant foxtail, velvetleaf, ivyleaf morningglory, common cocklebur (Xanthium strumarium L.), and yellow nutsedge control in soybean with band application plus cultivation was equal to or better than the control with the broadcast application of the same herbicides without cultivation. Corn and soybean yields were related to the level of weed control. Weed control costs in corn and soybean were lower with the band application plus two cultivations than with the broadcast application of the same herbicides. Band application plus cultivation reduced the total amount of herbicide applied per acre by 66%.

Common Cocklebur (Xanthium strumarium) Control in Soybean (Glycine max) with Reduced Bentazon Rates and Cultivation

Common cocklebur is a very competitive and difficult to control weed species in soybean production. Field research was conducted at Rosemount, MN, from 1989 to 1991 to evaluate reduced rates of bentazon applied broadcast or banded over the crop row in combination with interrow cultivation for common cocklebur control in soybean. Bentazon at 0.6 kg ai ha−1applied in a 38-cm-wide band over the soybean row followed by two cultivations controlled almost 90% of the common cocklebur when environmental conditions were favorable, and the majority of the common cocklebur emerged prior to bentazon application. However, when precipitation was below normal prior to bentazon application and a high proportion of the common cocklebur emerged after the initial bentazon application, sequential bentazon treatments controlled more common cocklebur and resulted in greater soybean yields than combinations of bentazon plus cultivation. Differences in soybean yield were attributed to differences in common cocklebur control rather than injury from cultivation or bentazon.

Broadleaf Weed Control in Soybean (Glycine max) with Chlorimuron plus Acifluorfen or Thifensulfuron Mixtures

Chlorimuron applied alone and in combination with acifluorfen or thifensulfuron was evaluated for POST control of common lambsquarters, common ragweed, common cocklebur, and a mixture of pitted, ivyleaf, entireleaf, and tall morningglory in soybean. Common cocklebur control was similar with thifensulfuron at 3 and 4 g ae ha−1and with chlorimuron at 7 and 9 g ae ha−1, Common ragweed and morningglory control was greater with chlorimuron while common lambsquarters control was greater with thifensulfuron. Control of all species was good with combinations of chlorimuron at 7 g ha−1plus thifensulfuron at 2 g ha−1or acifluorfen at 140 g ae ha−1and similar to or greater than the control with chlorimuron at 9 g ha−1. Soybean yields with all POST herbicide treatments were equivalent to that of the weed-free check.

Common Cocklebur (Xanthium strumarium) Control with Reduced Rates of Soil and Foliar-Applied Imazaquin

Field studies were conducted to evaluate common cocklebur control in soybean with imazaquin applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) at rates ranging from 24 to 140 g ai ha-1. With logistic regression analysis, predictions of common cocklebur control with imazaquin at 140 g ha-1ranged from 92 to 95% (PPI), 87 and 92% (PRE), and 88 to 98% (POST) when rainfall was received for activation of PRE treatments and when weeds were not moisture stressed at time of POST application. When imazaquin was reduced to 70 g ha-1under the same conditions, weed control was no higher than 88% PPI and 78% PRE. For all locations and years, common cocklebur control ranged from 79 to 91% for imazaquin POST at 24 g ha-1. Soybean yield was positively correlated with common cocklebur control (r = 0.66, P < 0.05).

Herbicide Programs in No-Tillage and Conventional-Tillage Soybeans (Glycine max) Double Cropped After Wheat (Triticum aestivum)

Postemergence and commonly used preemergence plus postemergence herbicide programs were evaluated for weed control in conventional and no-tillage soybeans double cropped after winter wheat in the northern Mississippi River Delta. Broadleaf weed species present varied with tillage, location, and year. Large crabgrass was present in both tillage systems for all locations and years. Conventional tillage usually resulted in higher densities of large crabgrass, common cocklebur, and smooth pigweed. Soil-applied preemergence herbicides alone did not provide season-long ivyleaf and entireleaf morningglory or common cocklebur control in either tillage system. For weed control and soybean yields comparable to weed-free controls, postemergence broadleaf herbicides were required in both tillage systems following the soil-applied herbicide programs, alachlor plus linuron and alachlor plus metribuzin. Postemergence herbicide programs provided excellent season-long annual grass and broadleaf weed control when sethoxydim was applied separately from the broadleaf herbicides. Antagonism of large crabgrass control resulted when sethoxydim was tank mixed with postemergence broadleaf herbicides, compared to separate applications of the postemergence grass and broadleaf herbicides. In three out of four studies, soybean yields in handweeded controls were similar between tillage systems.

Effect of Application Rate, Weed Species, and Weed Stage of Growth on Imazethapyr Activity

Field experiments were conducted in 1986, 1987, and 1988 to evaluate imazethapyr rate and time of application on postemergence control of 24 weed species. Contour graphs were developed that predicted imazethapyr rates required for various levels of weed control based upon weed leaf number at application. Rates below the labeled rate (70 g ha−1) provided 90% or greater control of common cocklebur, smallflower morningglory, and smooth pigweed if applied to 3 true-leaf or smaller weeds and of barnyardgrass, seedling johnsongrass, and Palmer amaranth if applied while weeds were in the cotyledon or 1 true-leaf stage. A rate of 70 g ha−1provided 90% control of large crabgrass in the 1 true-leaf stage. Entireleaf morningglory, red rice, pitted morningglory, and velvetleaf are not susceptible enough to imazethapyr for 90% or greater control to be obtained with rates lower than 70 g ha−1at the 1 true-leaf growth stage. These data demonstrate how control data can be used for developing effective reduced-rate herbicide recommendations based on weed leaf number.

Interactions of Diphenylether Herbicides with Chlorimuron and Imazaquin

Field experiment were conducted to determine interactions of chlorimuron or imazaquin with fomesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with fomesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when low rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with fomesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai ha–1imazaquin was combined with 210 g ai ha–1fomesafen or 110 or 220 g ai ha–1lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai ha–1chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g ha–1imazaquin was combined with 110 g ha–1lactofen or 210 g ai ha–1acifluorfen; however, at higher rates of chlorimuron or imazaquin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.

Effect of Adjuvants on Weed Control and Soybean (Glycine max) Tolerance with AC 263,222

Field experiments were established to observe the effects of adjuvants and time of application on weed control and ‘Terra-Vig 515’ soybean tolerance with POST applications of AC 263,222. A nonionic surfactant or a crop oil concentrate increased sicklepod control with AC 263,222 applied at either V2 or V6 soybean growth stages. Sicklepod control increased as AC 263,222 was increased from 35 to 70 g ai ha–1only when applied without an adjuvant. Late in the season, there was no difference in sicklepod control between V2 and V6 applications. Adjuvants and application timing within herbicide treatments had no effect on pitted morningglory control, and, though adjuvants increased common cocklebur control, all treatments controlled more than 85% of both species. AC 263,222 with adjuvants at all rates and timings injured and stunted soybean more 2 wk after treatment compared to AC 263,222 alone. AC 263,222 at 35 or 70 g ha–1with crop oil concentrate reduced yields more than AC 263,222, with either a surfactant or no adjuvant when applied to V2 soybeans.

Timing of Chlorimuron and Imazaquin Application for Weed Control in No-Till Soybeans (Glycine max)

Field studies were conducted to evaluate the influence of herbicide application timing on weed control in no-till soybean production. Row spacing generally had no effect on weed control. Herbicide treatments containing chlorimuron plus metribuzin applied as many as 45 days prior to planting in 1988 and 1989 controlled broadleaf weeds throughout the growing season. Imazaquin applied 45 and 30 days prior to planting provided poor control of common cocklebur in 1989. Giant foxtail control was inconsistent with all herbicide treatments. Soybean yields subsequent to early preplant herbicide applications were greater than or equal to those in which applications were made at planting when late-season weed control was adequate. Herbicides applied preemergence did not control high densities of common lambsquarters in 1989.

Incorporation Depths of Imazaquin, Metribuzin, and Chlorimuron for Common Cocklebur (Xanthium strumarium) Control in Soybeans (Glycine max)

Field experiments were conducted in 1986 and 1987 to evaluate the effect of herbicide incorporation to various depths on common cocklebur control with imazaquin, a tank mix of imazaquin and metribuzin, and a preformulated mixture of chlorimuron and metribuzin in soybeans. Herbicide rates included were two-thirds and the full registered rate. All treatments, except chlorimuron plus metribuzin (50 plus 320 g ai/ha, respectively), controlled more common cocklebur when incorporated to depths of 2.5 to 7.6 cm than when left unincorporated. Also, imazaquin at 90 g ai/ha and the tank mix of imazaquin plus metribuzin at 90 plus 280 g ai/ha, when incorporated, controlled more common cocklebur than higher rates of the same combination when not incorporated. Common cocklebur control was similar with 2.5-, 5.0-, and 7.6-cm soil incorporation depths.

Application Timing of Metribuzin, Chlorimuron, and Imazaquin for Common Cocklebur (Xanthium strumarium) Control

Field experiments were conducted in 1986 and 1987 to evaluate the effect of herbicide rate (two-thirds and maximum labeled rate) and timing of application before soybean planting on common cocklebur control. In 1986, chlorimuron plus metribuzin at 50 plus 320 and 80 plus 480 g ai/ha and imazaquin at 90 g ai/ha applied at planting controlled common cocklebur better than when applied 4 weeks before planting (WBP). Imazaquin at 140 g/ha applied at planting controlled common cocklebur better than when applied 6 WBP. All treatments at two-thirds of the labeled rate applied at planting controlled common cocklebur comparable to the full labeled rate applied 2, 4, or 6 WBP. In 1987, all treatments applied 2 WBP controlled common cocklebur better than when applied 4, 6, or 8 WPB.

Effect of Tillage Systems on the Efficacy and Phytotoxicity of Imazaquin and Imazethapyr in Soybean (Glycine max)

Field experiments were conducted to evaluate the interactions of tillage systems with imazaquin and imazethapyr on weed control and soybean injury and yield. Control of jimsonweed, common cocklebur, ivyleaf morningglory, velvetleaf, and giant foxtail from imazaquin and imazethapyr in conventional tillage was generally equal to or greater than control in no-tillage. However, under limited rainfall, weed control in no-tillage was generally equal to or greater than control in conventional tillage. Reductions in soybean heights due to herbicide treatment were evident in both tillage systems in 1985 and 1986 but not in. Soybean yields were reduced in 1985 from imazaquin at 140, 210, and 250 g/ha and imazethapyr at 105 and 140 g/ha. Yields were not reduced in 1986 and. Imazaquin and imazethapyr appear to provide adequate control of jimsonweed, common cocklebur, ivyleaf morningglory, velvetleaf, and giant foxtail in conventional and no-till systems.

Effects of Tillage on the Efficacy and Persistence of Clomazone in Soybean (Glycine max)

Experiments were conducted in 1985 to 1987 to evaluate the effects of conventional and no-tillage systems on the weed control provided by clomazone applied preemergence in soybeans. The persistence of clomazone in soil of the two tillage systems was also determined. Increasing the clomazone rate from 0.8 to 1.4 kg/ha did not increase weed control. Clomazone controlled 80% or more of jimsonweed, velvetleaf, and giant foxtail. Common cocklebur control ranged from about 50 to 70% in no-till and from 80 to 90% in conventional tillage. Generally, soybean pods/plant and yields were lower from clomazone treatments than from handweeded treatments due to inadequate common cocklebur control. Over 40% of the clomazone applied did not reach the soil surface; it was either intercepted by wheat straw, volatilized, or both. Clomazone persisted longer in conventional tillage than in no-tillage in. However, in 1986, clomazone was equally persistent in the two tillage systems. The half-life of clomazone was 34 and 6 days in 1985 in conventional and no-tillage, respectively, and in 1986, 18 and 16 days in conventional and no-tillage, respectively. Significant clomazone concentrations were not found below 10 cm in the soil profile. Corn planted without tillage (no-till) approximately 1 yr after clomazone application was not injured and yields were not reduced due to prior clomazone use.

Efficacy of Bentazon and MSMA as Affected by a Humic Acid-Type Polymeric Polyhydroxy Acid Adjuvant

Foliar applications of14C-bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] with PPA (polymeric polyhydroxy acid) at 1 or 2% (v/v) or nonoxynol (9.5 POE) [α-(p-nonylpheny1)-ω-hydroxypoly(oxyethylene)] at 1% (v/v) or mixtures of PPA and nonoxynol did not increase absorption or translocation of14C-bentazon in soybeans [Glycine max(L.) Merr. ‘Lee 74′] or common cocklebur (Xanthium strumariumL. # XANST). PPA alone at 1 to 2% (v/v) did not significantly affect absorption or translocation of14C-bentazon in smooth pigweed (Amaranthus hybridusL. # AMACH), but PPA with nonoxynol significantly increased translocation out of the treated leaf. Both PPA and nonoxynol decreased absorption and movement of14C-MSMA [monosodium salt of methylarsonic acid] out of the treated leaf of johnsongrass [Sorghum halepense(L.) Pers. # SORHA]. In greenhouse research, PPA at 0.25 and 0.5% (v/v) did not increase the level of control of common cocklebur obtained following postemergence applications of bentazon at 0.24 and 0.48 kg ai/ha. Similarly, PPA at 0.25 and 0.50% (v/v) did not increase the toxicity of MSMA at 0.3 and 0.6 kg ai/ha to either johnsongrass or common cocklebur.