Quackgrass Control Research Articles

Timing of atrazine application for control of quackgrass (Agropyron repens)

The use of foliar or soil applied atrazine to control quackgrass (Agropyron repens) in corn (Zea mays) was investigated. Atrazine treatments to control quackgrass significantly increased corn yield. Spring tillage without atrazine had little or no long term effect on quackgrass stand. A single application of 4.5 kg a.i. atrazine ha-1 applied in the fall or spring provided no better control of quackgrass than a split application of 2.25 kg a.i. atrazine ha-1 in either the foliage or bare soil experiments. Quackgrass recovery and soybean (Glycine max) yield were measured for 2 yr afterthe last atrazine application. Quackgrass did not recover to any significant extent within 2 yr after the cessation of the treatments on any of the atrazine treated plots. Atrazine residues from the previous fall applications significantly reduced soybean yield. Two years after the last atrazine treatment, soybean yields were similar, regardiess of former spring or fall atrazine application.

MON-37500 for Weed Control and Alfalfa Seed Production

Alfalfa seed producers have a limited number of herbicide options to manage weed problems. MON-37500 (proposed name sulfosulfuron) is a sulfonylurea herbicide that controls dandelion and quackgrass, two common weeds in alfalfa fields. A study was conducted in two alfalfa fields at Valparaiso and Carrot River, Saskatchewan, Canada, from 1999 to 2001 to evaluate perennial weed control and alfalfa production responses with 0.5×, 1×, and 1.5× label-recommended rates of MON-37500 and also 2,4-DB and hexazinone. MON-37500 applied at the 1× and 1.5× rates at both locations reduced mid-May alfalfa vigor from 100% to between 80 and 90% and increased early-season control of dandelion and quackgrass by about 10 to 40 percentage units, when compared with other herbicide treatments. Improved weed control with 1× and 1.5× MON-37500 rates was sustained into mid-June only at Carrot River and was completely eliminated (100% vigor and 0% weed control), or almost so, by mid-July. MON-37500 did not control Canada thistle. Improved early-season weed control with the 1× MON-37500 rate apparently compensated for the loss of alfalfa vigor at Valparaiso, thus resulting in 27% (57 kg/ha) greater seed yield than with the other herbicide treatments. At Carrot River, hexazinone generally provided levels of weed control similar to MON-37500 but did not injure alfalfa. Consequently, alfalfa yields were highest and the proportion of dead (decaying) seed was least with this treatment. The 0.5× MON-37500 rate often resulted in inferior weed control relative to the 1× and 1.5× rates and never was among the herbicide treatments providing the greatest seed yield. Managing the residual activity of MON-37500 and its negative effect on alfalfa growth, especially at locations with soils having coarse texture and low organic matter content, represents the greatest challenge in making MON-37500 a reliable weed management tool for alfalfa seed producers.

Quackgrass (Elytrigia repens) control in potatoes (Solanum tuberosum) with clethodim

Potato growers require effective control of quackgrass (Elytrigia repens) so as to obtain maximum yield. We examined the effect of different quackgrass growth parameters on effectiveness of clethodim and compared clethodim to selected herbicides. Reduction of the initial top growth of quackgrass with clethodim applied at the five-leaf stage was less than at the three-leaf stage at all rates of application. Shoot regrowth and rhizome production occurred at rates of application from 0.075 to 0.150 kg a.i. ha-1 but only to a very minor level at the highest rate of 0.240 kg a.i. ha-1 at either stage of application. Control was not affected by rhizome length with equal reduction in initial growth, regrowth, and rhizome weight obtained on plants grown from two-node and ten-node rhizome pieces at rates of 0.120 kg a.i. ha-1 or higher. Removal of quackgrass shoots 6 hours after treatment resulted in increased regrowth and rhizome weight at all application rates but the response was progressively overcome by increasing the rate of application.The removal of quackgrass shoots 24 or 96 hours after treatment had no adverse effect on reduction in quackgrass growth indicating rapid clethodim translocation in the greenhouse. In the field, clethodim provided greater than 80% control of quackgrass at the three to four-leaf stage with 0.150 kg a.i. ha-1 when used in combination with ammonium sulphate.

Banded herbicides and cultivation for weed control in potatoes (Solanum tuberosum L.)

Increasing costs of production have resulted in intensified efforts to reduce the amount of herbicides applied in potato production. This research evaluated the potential of applying herbicides in 30-cm-wide bands over the potato row in combination with cultivation between the potato rows to achieve weed control. At a moderate to high infestation of quackgrass and annual broadleaf weeds, control of quackgrass, corn spurry and wild radish was as effective with the banded herbicide + cultivation treatments as with the broadcast herbicide treatment. Potato marketable yields from the banded herbicide + cultivation treatments were comparable to the broadcast herbicide application treatment. A single cultivation at 21 d after planting (DAP) (at ground crack), 28 DAP (potatoes 5 to 10 cm tall) or 35 DAP (potatoes 10 to 15 cm tall) did not give adequate weed control, and potato yields were reduced by 30% or more at all times of cultivation compared to herbicide treatments. This study shows that acceptable weed control without effects on marketable yield is possible by using a 30-cm-wide herbicide band over the row followed by cultivation to remove weeds between the row. The amount of herbicide used per hectare with this technique is reduced by 66% compared to a broadcast herbicide application. Key words: Herbicide, potato, quackgrass, Elytrigia repens L. (Nevski), corn spurry (Spergula arvensis L.), wild radish (Raphanis raphanistrum L.), cultivation

Control of Quackgrass (Elytrigia repens) and Broadleaf Weeds and Response of Potato (Solanum tuberosum) Cultivars to Rimsulfuron1

Studies were conducted from 1992 to 1995 to determine the effect of rimsulfuron on corn spurry, wild radish, narrowleaf goldenrod, and quackgrass and potato cultivars. Rimsulfuron alone gave 100% control of wild radish, 68 to 70% control of corn spurry, and 75 to 90% control of narrowleaf goldenrod. Rimsulfuron plus metribuzin gave 99 to 100% control of wild radish and 85 to 100% control of corn spurry. Quackgrass control varied from 51 to 90% between experiments, indicating that environmental and plant factors affected the activity of the herbicide. Tank mixes with metribuzin slightly reduced the control of quackgrass but resulted in greater foliar injury than that of rimsulfuron to potato. Slight injury to potato plants disappeared within 2 to 3 wk, and tuber yields were not reduced. Russet Burbank, Shepody, and Kennebec potato cultivars had slight (2 to 8%) injury from rimsulfuron. Injury to Shepody (14 to 20%) and Russet Burbank (11%) increased when rimsulfuron was applied with metribuzin. Rimsulfuron had no effect on the number or the fresh weight of sprouts on daughter tubers tested the next spring after application.Nomenclature: Metribuzin; rimsulfuron; corn spurry, Spergula arvensis L. #3 SPRAR; narrowleaf goldenrod, Solidago canadensis L. # SOLCA; quackgrass, Elytrigia repens Nevski # AGRRE; wild radish, Raphanus raphanistrum L. # RAPRA; potato, Solanum tuberosum L. # SOLTU ‘Russet Burbank’, ‘Shepody’, ‘Kennebec’.Additional index words: Daughter tuber sprouting, DPX E-9636.Abbreviations: GC, ground crack; lf, leaf; PEI, Prince Edward Island; POST, postemergence; PRE, preemergence; RH, relative humidity.

Effect of Growth Stages on Quackgrass (Elytrigia repens) Control in Corn (Zea mays) with Rimsulfuron

Experiments were conducted in 1996 and 1997 to determine the effects of postemergence (POST) application of rimsulfuron on quackgrass control. Rimsulfuron applied at 27 g ai/ ha to two-to four-leaf quackgrass controlled 100% of quackgrass 5 wk after treatment (WAT). Rimsulfuron applied to one- to two-leaf quackgrass was not as effective as the same rate applied to two- to four-or four- to six-leaf quackgrass. Stunting and leaf wrinkling of corn were observed 4 WAT when rimsulfuron was applied at 36 g/ha to four- to six-leaf quackgrass. The plants recovered from the stunting as the season progressed and by 12 WAT there was no appreciable stunting. Rimsulfuron (27 g/ha) applied to two- to four-leaf quackgrass increased grain and silage yield of corn by 36% and 45%, respectively, compared to the untreated check. The 27 g/ha rate of rimsulfuron applied to two- to four-leaf quackgrass resulted in 10% more grain yield than the same treatment applied to one- to two- leaf quackgrass. Rimsulfuron at 18 g/ha led to a 17% reduction of sitage yield when applied to the four- to six-leaf quackgrass. At all growth stages of quackgrass, rimsulfuron gave higher grain and silage yields than corn treated with the same rate and timing of nicosulfuron. Rimsulfuron reduced sprouting of quackgrass rhizome nodes, especially at higher rates.

Glyphosate or sethoxydim for quackgrass (Elytrigia repens) control in two tillage regimes

Field experiments were conducted at Lacombe and Ellerslie, Alberta, Canada, to study the interaction of tillage with glyphosate and sethoxydim on quackgrass shoot and rhizome biomass, rhizome bud viability, and crop yield. Glyphosate was most effective in the conventional tillage regime, whereas sethoxydim was effective only in conventional tillage. Tillage reduced viable rhizome buds more than shoot or rhizome biomass. The large tillage effect on quackgrass control with either herbicide would likely be diminished in zero tillage systems that employ preseeding burn-off or preharvest application of glyphosate. Under zero and conventional tillage, glyphosate at 220 g ha−1often was as effective as glyphosate at 880 g ha−1.A split application of glyphosate at 220 g ha−1in the fall and spring was as effective as a single 880 g ha−1treatment in conventional tillage, and sometimes more effective than 880 g ha−1in zero tillage. Glyphosate followed by sethoxydim was usually no better than glyphosate alone. Short-term split applications of sethoxydim offered no consistent advantage over single applications.

Quackgrass (Elytrigia repens) Control in Corn (Zea mays) with Nicosulfuron and Primisulfuron

Quackgrass is a serious weed problem in the northern United States and southern Canada. Field experiments were conducted in 1990 and 1991 to examine the effect of herbicide rate, application timing, quackgrass growth stage, and cultivation on quackgrass control with nicosulfuron and primisulfuron in corn. Nicosulfuron (35 g ai/ha) and primisulfuron (40 g ai/ha) each provided 84% or greater control of two-leaf plants and 93% or greater control of four-leaf quackgrass plants. Sequential applications of both nicosulfuron and primisulfuron provided greater season-long control than single applications of the same rate on two-leaf but not four-leaf quackgrass. Cultivation 10 d after nicosulfuron or primisulfuron application often increased early-season control, but by corn harvest few differences were observed. Postemergence (POST) applications of nicosulfuron and primisulfuron provided at least 88% control, compared with 66 to 86% from an early preplant application of glyphosate. Corn yields were similar regardless of the quackgrass control program.

Effet de la dose de semis et de l'écartement entre les rangs de l'orge sur la répression du chiendent

A 4-yr study (1989–1992) was conducted to evaluate the effect of two row spacings (10 and 20 cm) and five seeding rates (100, 200, 300, 400 and 500 viable seeds m−2) of barley (Hordeum vulgare L. 'Cadette') on the control of quackgrass (Elytrigia repens (L.) Nevski). A control treatment consisted of quackgrass grown in the absence of the cereal. The productivity of quackgrass was measured at cereal harvest during the first year and in the following year. Compared with the control, increasing seeding rates from 100 to 500 seeds m−2, reduced dry weight of quackgrass aerial shoots by 43 to 76%, respectively. The presence of barley also reduced the number of quackgras shoots. The year following the cereal harvest of 1989, 1990 and 1992, the presence of barely during the seeding year caused a reduction in quackgrass aerial shoot dry weight of 32, 37 and 13% respectively. This reduction was only 5% in 1991. On average, the total number of quackgrass shoots was reduced by 23% in the year following the harvest of barley. Row spacing did not influence the number or dry weight of quackgrass aerial shoots during the seeding year or the following year. However, high seeding rates reduced the productivity of quackgrass during both the seeding year and the following year. Nevertheless, quackgrass numbers and aboveground biomass remain relatively high the year following cereal seeding.

Short-Term Split Application Effects of Grass-Specific Herbicides on Quackgrass (Elytrigia repens) Under Field Conditions

Field experiments were conducted at the Lacombe Research Station from 1989 to 1991 to determine if short-term, split applications of grass-specific herbicides would improve quackgrass control relative to single applications. Quackgrass infested plots were planted to canola the first year and barley the following year. Glyphosate applied at 880 g/ha controlled quackgrass to a greater extent and for a longer time period than any of the grass-specific herbicides. In contrast to glyphosate, none of the grass-specific herbicides controlled quackgrass 1 yr after treatment. Quackgrass control with sethoxydim or fluazifop-P was usually similar when applied as single or short-term, split applications. In contrast, quizalofop often provided better quackgrass control and higher crop yields when short-term, split applications were compared to a single application with the same total amount of quizalofop. However, the extent of increased quackgrass control is difficult to justify due to increased application costs and inconvenience.

Quackgrass control with glyphosate and SC-0224 in corn and soybean

Studies on quackgrass control were conducted using a factorial combination of glyphosate or SC-0224, each at 0.28, 0.56 and 0.84 kg ha−1, and ammonium sulphate at 0 and 2.5 kg ha−1 in corn and soybean plots on a severe infestation in southwestern Ontario during 5 yr. The two herbicides at a given rate provided similar degrees of quackgrass control. With the addition of ammonium sulphate, the effective rate of both herbicides was reduced from the recommended rate of 0.9 kg ha−1 to 0.56 kg ha−1, which results in a higher economic return. Although a lower rate, 0.28 kg ha−1, also provided satisfactory initial control of quackgrass, there was a tendency to increasing quackgrass coverage with time despite the repeated application of herbicides over years. After 5 yr of treatment at a consistently low rate (0.28 kg ha−1), quackgrass coverage approached the original level in the soybean field. The increase in quackgrass coverage caused a corresponding reduction in soybean yield. The results suggest that glyphosate or SC-0224 at about 0.56 kg ha−1 is effective when applied in conjunction with ammonium sulphate. Lower rates may be acceptable if used with a high rate at properly chosen intervals. Key words: Quackgrass control, glyphosate, SC-0224, ammonium sulphate, soybean, corn

Critical Period of Quackgrass (Elytrigia repens) Removal in Potatoes (Solanum tuberosum)

Field trials were carried out in 1989 and 1990 at St-Augustin, near Québec City, Canada, to determine the critical periods of quackgrass control in potato submitted to three levels of infestation. Potato yield losses due to quackgrass interference increased with quackgrass infestation and length of duration of interference. Quackgrass interference influenced marketable tuber yields more than total tuber yields. Duration of the critical period varied depending on the level of quackgrass infestation and year. Based on an arbitrary 5% level of marketable yield loss, the critical period started at ca. 15 days after emergence (DAE) of potato at low level of infestation, and at ca. 3 DAE at medium level of infestation. At high level of infestation, the critical period began prior to the emergence of potato. The end of the critical period of quackgrass removal was extremely variable across quackgrass infestation level and year and ranged from 23 to 68 DAE of potato at a 5 % yield loss level. It appears that onset of interference varied less than the end of it, indicating that early quackgrass control is necessary to prevent yield loss.

Effect of Tillage and Glyphosate on Control of Quackgrass (Elytrigia repens)

Field studies were conducted during two soybean-corn rotations to evaluate the effect of tillage systems on quackgrass growth and control with and without glyphosate. In the final year of the study, tillage alone (compared to no-till) resulted in 88%, 78%, 64%, and 31% control of quackgrass with fall moldboard plow, spring moldboard plow, fall soil-saver, and spring soil-saver tillage, respectively. When glyphosate was used to control quackgrass, crop yields increased as tillage was reduced and excellent control of quackgrass in no-till was achieved. Increased shoot growth (in moldboard plowed and fall soil-saver tillage plots), exposure of rhizomes in winter (in fall tilled plots), and increased depth of rhizome burial (in spring tilled plots) increased quackgrass control. In general, the total biomass of quackgrass was reduced in drier years. Nonetheless, drought increased crop yield losses caused by quackgrass interference.

Simulated Environments Influence Primisulfuron Efficacy

The influence of hot-dry and cool-moist environments on primisulfuron efficacy on giant foxtail and quackgrass was compared at the University of Wisconsin Biotron. Primisulfuron was applied POST at 20 and 40 g ai ha-1with nonionic surfactant (NIS) or crop oil concentrate (COC) and with or without 28% nitrogen fertilizer (28% N). Giant foxtail control 3 wk after treatment was not affected by primisulfuron rates or adjuvants. Adding 28% N tended to improve quackgrass control with primisulfuron plus NIS or COC. Primisulfuron was more injurious to both giant foxtail and quackgrass in the cool-moist than the hot-dry environment. Absorption of14C-primisulfuron into giant foxtail tissue 3 days after treatment (DAT) was greater in the cool-moist than the hot-dry environment Translocation of14C out of treated leaf of quackgrass 3 DAT was greater in the cool-moist than the hot-dry environment. More14C was absorbed and translocated in giant foxtail than quackgrass. Absorbed14C was translocated equally to underground and above treated leaf sections of quackgrass, whereas more14C was translocated above the treated leaf of giant foxtail.

Influence of temperature after spraying on glyphosate control of quackgrass (Elytrigia repens(L) Nevski) previously exposed to light frost

Research was conducted in controlled environment chambers to determine the influence of temperature after herbicide application on glyphosate control of quackgrass previously exposed to light frost (−2 °C). Quackgrass topgrowth control and rhizome bud viability reduction was greatest at 900 g ha−1 glyphosate and was enhanced by ammonium sulphate. Quackgrass topgrowth control was greatest at 15 °C/10 °C day/night temperature. In contrast, reduction in rhizome bud viability was different only between 15 °C/10 °C and 10 °C/5 °C. Topgrowth control of quackgrass by glyphosate may be much more affected by temperature than reduction in rhizome bud viability. Key words: Quackgrass, frost, temperature, glyphosate, ammonium sulphate

Quackgrass control in established alfalfa with sethoxydim

Field studies were conducted during 1990 and 1991 in northeast South Dakota to determine the effect of sethoxydim application timing on quackgrass [Elytrigia repens (L.) Nevski] control in established alfalfa (Medicago sativa L.). Sethoxydim was applied as single applications in the fall, spring, after the second cut of alfalfa or as various repeated applications in the fall, spring, and after the first and second cuts of alfalfa. The alfalfa-quackgrass mixture was harvested three times per year, and dry matter yields of alfalfa, quackgrass, and total herbage were determined. Total herbage samples were analyzed for crude protein (CP) concentration. Usually, single application of sethoxydim in either the fall or spring did not control quackgrass as well as multiple applications. However, three and four applications of sethoxydim per year did not consistently control quackgrass any better than two applications per year. Sethoxydim reduced quackgrass yields in most instances, but yields and CP concentrations of total herbage were seldom affected. Use of sethoxydim for quackgrass control in established alfalfa may be warranted only in situations where relatively weed-free forage is desired. Key words: Application timing, forage yield, competition, stand density

Effectiveness of Herbicides and Tillage on Quackgrass (Elytrigia repens) Control in Corn (Zea mays)

Postemergence applications of nicosulfuron and primisulfuron were compared to preplant glyphosate and atrazine plus simazine for quackgrass control in reduced tillage and no-till corn. The level of quackgrass control was reduced by no-till practices. At 6 wk after planting, glyphosate and atrazine plus simazine were most effective in controlling quackgrass. Quackgrass biomass 12 wk after planting indicated that the performance of the herbicides were generally similar, although primisulfuron was less effective in no-till. One year after corn planting, levels of quackgrass control in the tilled plots were the same as or better than in the no-till treatments. Atrazine plus simazine was the most effective herbicide treatment over tillage systems, while primisulfuron was the least effective.

Percentage-Driven Government Mandates for Pesticide Reduction: The Swedish Model

In 1985, the Swedish government mandated a 50% reduction in agricultural pesticide use by 1990. The reference point was based on the average of total pesticide sales (kg ai) between 1981 and 1985. The goal was to halve the risks to users and to the environment. A two-pronged approach dealing with risk and with the actual reduction in agricultural pesticide use was developed. By 1991, 215 ‘unsafe’ or less effective pesticide products were withdrawn by producers or cancelled by the National Chemical Inspectorate, leaving only 322 registered. Additionally, the government was able to report a 47% reduction in agricultural pesticide use where 64, 54, and 2% reductions occurred in insecticides, herbicides, and fungicides, respectively. However, the treated area did not decrease. Pesticide reduction was achieved largely in cereal grain production by switching from high-dose to low-dose herbicides, reducing rates of herbicides, removal of inactive isomers from racemic mixtures, cancellation of TCA for quackgrass control, increased set-aside, and improved sprayer precision. During the same 5-yr period, Scotland achieved an equivalent reduction without government intervention, indicating that the reductions were largely due to changing herbicide technology. Determining the need for similar programs must take into account: 1. initial use rates (in 1987, average total pesticide use rates in the U.S. and in Sweden were 1.8 and 1.5 kg ai/ha, respectively, and following the mandate period, Swedish use has decreased to 0.8 kg ai/ha); 2. measurement criteria; and 3. the long-term effect of reducing herbicide rates on replenishing the soil weed seed bank reserves.

Postemergence control of quackgrass [Elytrigia repens (L) Nevski] with DPX-79406 in corn (Zea mays L)

Laboratory and field experiments were established to determine the optimum dose and timing of postemergence applications of DPX-79406 for quackgrass control. Four node quackgrass rhizome fragments from each biotype were grown under controlled conditions. At the three-to-four-leaf stage, quackgrass plants were sprayed with DPX-79406 and evaluated for control. A significant response of quackgrass biotypes to DPX-79406 was evident only at lower doses. In the field, quackgrass was effectively controlled by all doses of DPX-79406. Significant growth-stage effects were observed for quackgrass shoot and rhizome dry weights in the year of application and in the year following application. There was a significant interaction between year and growth stage. In 1990, quackgrass biomass was greater when DPX-79406 was applied at the two-to-three-leaf stage of quackgrass than at the four-to-five-leaf stage. In 1991, however, the opposite occurred. Within a growth stage, the 6.25 g ha−1 dose was as effective for controlling quackgrass as 18.5 g ha−1, in both years of the study. In 1991, significant decreases in corn yield were observed for DPX-79406 doses of > 12.5 g ha−1 applied at the four-to-five-leaf stage of quackgrass. For all the variables studied, DPX-79406 doses of 6.25–12.5 g ha−1 resulted in consistent control of quackgrass. Key words: DPX-79406, nicosulfuron, rimsulfuron, quackgrass, Elytrigia repens, corn, Zea mays

Primary Linear Alcohol Ethoxylates as Adjuvants for Primisulfuron

Greenhouse experiments were conducted to evaluate the effect of carbon chain length and percent ethoxylation of primary linear ethoxylated alcohols on postemergence control of johnsongrass and quackgrass with primisulfuron. Control of johnsongrass and quackgrass was greatest with primisulfuron plus the experimental ethoxylated alcohols 1412-60 and 1412-70 which had chain lengths of 14 and 12 carbon atoms (60:40 ratio) and 60 or 70% ethoxylation. Control of these two weed species decreased when primisulfuron was applied with ethoxylated linear alcohols of similar chain lengths but decreased percent ethoxylation or with alcohols of similar percent ethoxylation but decreased carbon chain length. Quackgrass and johnsongrass control with primisulfuron plus 1412-60 or 1412-70 was equal to or greater than the control obtained with primisulfuron plus the commercial adjuvants of the nonionic, organosilicone, sunflower methyl ester, or crop oil concentrate types. The experimental adjuvant 1412-70 provided equal or greater uptake and translocation of14C-primisulfuron in johnsongrass and quackgrass compared to four commercial adjuvants.