Single Application Of Glyphosate Research Articles

Ten-Year Growth Response of Young Douglas-Fir to Variable Density Varnishleaf Ceanothus and Herb Competition

Abstract The effect of different densities of varnishleaf ceanothus (Ceanothus velutinus var. laevigatus) and herbaceous vegetation control on stem diameter, height, and volume of plantation Douglas-fir (Pseudotsuga menziesii vat. menziesii) seedlings was examined during the 10 yr following planting. Initial densities of ceanothus ranged between 0 and 15,000 seedlings/ha and were obtained by interplanting ceanothus germinants or chemical thinning after clearcutting and broadcast-burning. Herbaceous vegetation control was achieved by a single application of glyphosate following planting, with shrub seedlings covered. Ceanothus density in the range of 0 to 6,750 plants/ha did not have an effect on Douglas-fir diameter, height, or volume at age 10; however, Douglas-fir growth was significantly decreased when ceanothus densities reached 15,000 plants/ha. Ten years after planting, Douglas-fir volume in the treatments with 6,750 ceanothus/ha or less was 1.7 times greater than that in the 15,000 ceanothus/ha treatment. On the other hand, removal of herbaceous vegetation after planting significantly increased tree diameter, height, and volume, regardless of ceanothus density. Even 10 yr after the application of the treatment, trees without early herb competition grew faster and had mean dbh, height, and volume that were 1.02 cm, 0.55 m, and 12.98 dm³/tree greater respectively than those with herbs. Thus, a treatment at plantation establishment to control herbaceous vegetation and to reduce ceanothus density to less than 7,000 plants/ha will ensure an increase in growth and stocking for at least 10 yr. West. J. Appl. For. 14(4):208-213.

Preharvest Applications of Glyphosate for Canada Thistle (Cirsium arvense) Control

The effectiveness of single and repeated annual preharvest glyphosate applications (1 to 2 wk before crop harvest) to reduce Canada thistle populations was evaluated in field experiments near Bezanson, AB, Scott, SK, and St. Albert, AB. Single applications of glyphosate at 0.45 to 1.8 kg/ha at Bezanson and St. Albert reduced Canada thistle shoot density by more than 75% but in the three experiments at Scott 1.8 kg/ha was required to consistently obtain a similar reduction. Four consecutive, annual applications of glyphosate at 0.45 kg/ha or more did not eliminate Canada thistle but reduced shoot densities by more than 98% at Bezanson. At Scott, similar reductions occurred in two of three sites following two consecutive, annual preharvest applications of glyphosate at the same rates. In the third Scott site the 1.8 kg/ha rate of glyphosate provided a similar reduction but lower rates did not. At Bezanson, barley yields following the first, second, and third applications of glyphosate at 0.45 kg/ha or more were 14% greater than check plots where MCPA was applied in the spring. Yields of wheat seeded 1 yr after a single application of glyphosate at St. Albert were 26% greater than from unsprayed checks. Barley yields seeded 1 yr after each glyphosate application at Scott were not affected because Canada thistle populations were sparse.

Peanut Control in Rotational Crops

Abstract Volunteer peanut (Arachis hypogaea L.) can reduce the effectiveness of crop rotation as a component in a peanut disease management program. Experiments were conducted in three states to evaluate peanut control with glyphosate [N-(phosphonomethyl)glycine] or with herbicides commonly applied postemergence for broadleaf weed control in corn (Zea mays L.) and cotton (Gossypium hirsutum L.). Two sequential applications were needed for acceptable control with corn and cotton herbicides. Greater than 80% control of peanut was achieved with dicamba (3,6-dichloro-2-methoxybenzoic acid) applied early postemergence (EPOST) followed by dicamba or ametryn [N-ethyl-N′-(l-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] applied late postemergence (LPOST). MSMA (monosodium salt of methylarsonic acid) applied EPOST followed by oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] + MSMA LPOST and fluometuron [N,N-dimethyl-N′-[3-trifluoromethyl) phenyl]urea] + MSMA applied EPOST followed by prometryn [N,N′-bis(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] + MSMA, cyanazine [2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropanenitrile] + MSMA, lactofen {(±)-2-ethoxy-1-methyl-2-oxoethyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]- 2-nitrobenzoate} + MSMA, or oxyfluorfen + MSMA LPOST controlled peanut at least 80%. Single applications of glyphosate at 0.84 to 1.12 kg ae/ha controlled peanut at least 80% and were at least as efficacious as the same total rate of glyphosate applied sequentially.

Measurement of Light Transmission in Young Conifer Plantations: A New Technique for Assessing Herbicide Efficacy

Abstract A rapid and accurate technique, using a simple measure of light intensity, for assessing the efficacy of herbicide treatment is proposed. Herbicide treatment efficacy was independently measured 1, 2, and 3 years after a single application of glyphosate on three adjacent plantations of black spruce reinvaded by red raspberry and fireweed in eastern Quebec. Each plantation represents a given time, 1, 2 or 3 years, after herbicide application. Light intensity, expressed as percent of full sunlight in the PAR spectral region (400-700 nm) reaching the upper one-half of the tree seedlings, significantly discriminates released and unreleased tree seedlings. Spruce seedlings receiving 60 to 100% of full sunlight grew significantly better in height and basal stem diameter and had significantly fewer stems and less height growth of competing vegetation than seedlings receiving less than 60% of full sunlight. This indicates that measuring the intensity of light reaching the tree seedlings is an easy and effective way to assess efficacy of herbicide treatment and also competition between spruce seedlings and surrounding vegetation. It is suggested that light reaching tree seedlings be measured instead of quantifying the competition variables. The proposed technique eliminates all potential bias from subjective standard procedures which in turn makes possible quantitative comparisons between evaluations of herbicide treatment efficacy. North. J. Appl. For. 9(3):112-115.

Screening Cover Crops for Use in Conservation Tillage Systems for Vegetables Following Spring Plowing

Several prospective cover crops were sown into 1-m2 monoculture plots on 9 Mar. 1987 and 10 Mar. 1988 at Bixby, Okla., and on 14 Mar. 1988 at Lane, Okla., after sites were plowed and fitted. Densities and dry weights of cover crops and weeds were determined in late April or early May of both years. Plots also were evaluated for degree of kill by glyphosate in 1988. Fourteen cover crops were screened at Bixby in 1987. Kentucky bluegrass (Poa pratensis L.) and three fescues (Festuca rubra L., Festuca rubra L. var. commutata Gaud.-Beaup., and Festuca elatior L.) were eliminated from further consideration due to inadequate cover density and inability to suppress weeds. Screenings of the 10 remaining covers were conducted at both locations in 1988. Annual ryegrass (Lolium multiflorum L.) and three small grains [rye (Secale cereale L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L.)] were the most promising cover crops with respect to cover density, competitiveness against weeds, and degree of kill by glyphosate. Crimson clover (Trifolium incarnatum L.) and hairy vetch (Vicia villosa Roth) were the most promising legumes, but they generally were less satisfactory than the grassy covers in all tested aspects. A single application of glyphosate was ineffective in killing hairy vetch at both locations. Chemical name used: N-(phosphonomethyl)glycine (glyphosate).

No-till establishment of perennial, warm-season grasses for biomass production

Herbaceous biomass crops have the potential to capture solar radiation and store energy as a renewable fuel resource. Establishment procedures that can be used successfully without damage to the environment are essential. The objective of this research was to develop procedures to establish perennial, warm-season grasses, such as switchgrass ( Panicum virgatum L.) and lovegrass ( Eragrostis curvula L.), without tillage and preparation of a fine seedbed. Two applications of paraquat spaced 3 weeks apart or a single application of glyphosate can be used to suppress sod before no-till plantings. Carbofuran applied in the row at 1.1 kg ha −1 with the seed increased seedling vigor and populations. Application of 1.1 kg ha −1 of atrazine when seedlings began to emerge provided post-planting weed suppression. Weed encroachment occurring in years after establishment was halted by 2 kg ha −1 of simazine applied before first growth in the spring. These data provide guidelines for successful establishment of herbaceous perennial, warm-season grass biomass crops.

Fall-Applied Glyphosate for Canada Thistle (Cirsium arvense) Control in Spring Wheat (Triticum aestivum)

Effects of repeated late-fall applications of the isopropylamine salt of glyphosate at 1.7 kg ae/ha plus 0.5% (v/v) surfactant on adventitious root buds, thickened propagative roots (> 1.3 mm diam), and shoot density of Canada thistle were studied in continuous hard red spring wheat over a 4-yr period. Glyphosate suppressed Canada thistle shoot density more quickly and to a greater extent than thickened root fresh weight or root bud number. A single fall application of glyphosate drastically decreased Canada thistle shoot density for 1 yr after treatment. However, shoot density was the same as the untreated control by 2 yr after a single fall treatment. Two consecutive late-fall applications of glyphosate in 2 yr decreased Canada thistle shoot density 94% in the fall 1 yr after the last treatment. Glyphosate reduced Canada thistle thickened root fresh weight 70% in the first fall 1 yr after a single fall treatment. However, 2 yr after a single fall application of glyphosate, root fresh weight equalled the controls. Two consecutive fall applications of glyphosate reduced thickened root fresh weight 77% 1 yr after the second treatment.

Orobanche crenata (Forsk) control in Vicia faba (L.) with glyphosate as affected by herbicide rates and parasite growth stages

SummaryThe broomrape (Orobanche crenata Forsk) susceptibility to glyphosate applied on faba‐bean (Vicia faba L.) as affected by the parasite growth stages at the time of application was studied under field conditions. Glyphosate treatments delayed O. crenata emergence. Single glyphosate application to faba‐bean infected with O. crenata predominantly at the stage (a) (small nodule) and (b) (nodules with initial vestigial roots) resulted in a moderate to low control. When the stages (c) (shoot bud already visible) or (d) (shoot and vestigial roots well developed) were the predominant stages, an excellent control was achieved with a single glyphosate application at 60 g ha−1. Increased development stages, with the shoot emerged from the shoot bud, decreased its susceptibility to glyphosate. La lutte contre Orobanche crenata en culture de férerole avec le glyphosate; influence des doses d'herbicide et du stade de développement du parasite

Fragrant Waterlily (Nymphaea odorata) Control with Multiple Applications of Glyphosate

A single foliar application of glyphosate [N-(phosphonomethyl)glycine] at 2.2 kg/ha controlled fragrant waterlily(Nymphaea odorataAit.). Seeds that germinated during the year of glyphosate treatment or the following spring reestablished the fragrant waterlilies. A second application of glyphosate, once the seedlings had reached the surface of the water, resulted in long-term control.

Chemical Control of Wild Allium Species1

AbstractWild Allium sp. often occur in pastures, lawns, and small grain fields in the Southeastern U.S. They are on the noxious weeds lists of several states in this area. Commonly two or more applications of 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] per year for up to 3 years are the current recommended practice for their control. Single applications of glyphosate [N‐(phosphonomethyl) glycine] and 2,4‐D were made in February or April on wild garlic (Allium vineale L.) and wild onion (Allium canadense L.) growing in fields in the Piedmont and Limestone Valley regions of Georgia. Scape counts, 6 and 14 weeks after treatment, indicated that excellent control was obtained from treatments of 4.48 and 6.72 kg/ha glyphosate especially when a surfactant was used. The 2.24 kg/ha treatment rate usually equalled or surpassed the 2,4‐D treatments in control.