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James Klett*, Dave Staats, and Matt Rogoyski

During the 2003 season, preemergence herbicide was applied to twelve container grown herbaceous perennials and woody plants and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicide and rates were: Flumioxazin (Broadstar) 113.5 g (label rate), 227 g and 454 g a.i./A. Herbicides were applied to Buxus microphylla `Winter Gem', Cytisus purgans `Spanish Gold', Festuca ovina glauca `Elijah Blue', Hakonechloa macra `Aureola', Lonicera tatarica `Arnold Red', Pachysandra terminalis `Green Sheen', Hydrangea arborescens `Annabelle', Mahonia aquifolium, Phalaris arundinacea `Picta', Carex buchananii, Cerastium tomentosum, and Achillea millefolium `Red Beauty'. Weed control was excellent at all rates and controlled at least 99% of all weeds. No phytotoxicity symptoms were apparent on Mahonia, Buxus, Cytisus, Festuca, Hakonechloa, Pachysandra or Phlaris. Phytotoxicity resulted on some of the other plants. Carex had smaller plants (dry weights) at all rates. Cerastium had severe phytotoxicty at the 227 g and 454 g rates and moderate stunting at the recommended label rate, 113.5 g. Hydrangea became chlorotic and stunted at the 113.5 g rate and some fatal toxicity ocurred at the 227 g and 454 g rates. Phytotoxicity resulted on Lonicera at all rates and ranged from mild chlorosis in leaf veins (113.5 g rate) to plant death (454 g rate). Achillea at the 113.5 g rate only resulted in stunted plant growth while the 227 g and 454 g rates resulted in severe phytotoxcity and plant death.

Open access

Philip L. Carpenter

Abstract

Broad-spectrum herbicides severly injured container-grown (Cotoneaster divaricata, Rehd. & Wils. and Euonymus fortunei, (Turcz.) Hand-Mazz. cv. Coloratus, because of rapid leaching into the root zone as a result of the porous peat-perlite medium. Injury was eliminated when activated carbon at 0.75 kg/m3 was mixed into the medium. Weed control was achieved by applying a 2.5 cm layer of the medium containing herbicide (but not activated carbon). The most effective herbicides were dichlobenil (0.44 g/m2), dichlobenil (0.44 g/m2) plus trifluralin (0.22 g/m2), or simazine (0.44 g/m2).

Open access

Frank N. Hewetson, George M. Greene II, and Richard Craig

Abstract

In order to reduce the cost of fumigation and weed control in seedling nurseries of peach (Prunus persica (L.) Batsch.), a number of herbicides, used with and without Nemagon as a nematicide, were evaluated. While necessary for soil fumigation, the presence or absence of Nemagon did not effect weed control or seedling performance. The best and most economical herbicides were the spring application of simazine at 4.5 kg ai/ha or the fall application of diuron at 3.4 kg ai/ha.

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Linglong Wei, Jarrod J. Morrice, Rodney V. Tocco, and Bernard H. Zandstra

several weed species and an increase in numbers of weeds that are naturally tolerant of these herbicides ( Gower et al., 2004 ; Peachey et al., 2011 ; Richardson and Zandstra, 2006 ). Regardless of resistance problems, chemical weed control is essential

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James W. Shrefler, Charles L. Webber III, and Otis L. Faulkenberry III

Producers of organic vegetables often report that weeds are a troublesome production problem. It has been documented that corn gluten meal (CGM), a by-product of the wet-milling process of corn, is phytotoxic. As a preemergence or preplant-incorporated herbicide, CGM inhibits root development, decreases shoot length, and reduces plant survival of weed or crop seedlings. The development of a mechanized application method for CGM and the ability to apply the material in a banded pattern would increase its potential use in organic vegetable production, especially in direct-seeded vegetables. Therefore, the objective of this research was to develop a mechanized method to uniformly apply CGM to the soil surface in either a broadcast or banded pattern. An applicator was assembled using various machinery components (fertilizer box, rotating agitator blades, 12-volt motor, and fan shaped gravity-fed row banding applicators). The equipment was evaluated for the application of two CGM formulations (powdered and granulated), three application rates (250, 500, and 750 g·m–2), and two application configurations (solid and banded). Field evaluations were conducted during Summer 2004 on 81-cm-wide raised beds at Lane, Okla. Differences between CGM formulations affected the flow rate within and between application configurations. The granulated formulation flowed at a faster rate, without clumping, compared to the powdered formulation. While the CGM in the banded configuration flowed faster than the solid application. It was determined that the CGM powder used with the solid application configuration was inconsistent, unreliable, and thus not feasible for use with this equipment without further modifications. These evaluations demonstrated the feasibility of using equipment, rather than manual applications, to apply CGM to raised beds for organic weed control purposes. Several design alterations may increase the efficiency and potential usefulness of this equipment. If research determines equivalent weed control efficacy between the two CGM formulations, the granulated formulation would be the preferred formulation for use in this equipment. This equipment would be useful for evaluating the benefits of banded applications of CGM for weed control efficacy and crop safety for direct seeded vegetables.

Free access

James E. Klett, Laurel Potts, and David Staats

During the 1998 season, preemergent herbicides were applied to container-grown herbaceous perennials and evaluated on the basis of weed control, phytotoxicity, and effect on plant growth. The herbicides and rates were: Napropamide (Devrinol 10G), 0.72 and 1.44 kg a.i./ha; Oryzalin (Surflan 40AS), 0.36 and 0.72 kg a.i./ha; Oxadiazon (Ronstar 2G), 0.72 and 1.44 kg a.i./ha; Oxyfluorfen + Oryzalin (Rout 3G), 0.54 and 2.16 kg a.i./ha; Oxyfluorfen + Pendimethalin (Scott's OH II), 0.54 and 1.09 kg a.i./ha; and Trifluralin (Treflan 5G), 0.72 and 1.44 kg a.i./ha. Herbicides were applied to Phalaris arundinacea `Picta', Scabiosa caucasica, Sedum × `Autumn Joy', Pennisetum setaceum `Rubrum', Salvia argentea, Penstemon × mexicali `Red Rocks', Osteospermum barberiae v. compactum `Purple Mountain', and Gazania linearis `Colorado Gold'. Phytotoxicity symptoms (visual defects) were apparent with Napropamide on Phalaris (at both rates) but recovered by the end of season. All herbicides provided good weed control.

Free access

J.R. Smart, D.J. Makus, and R.J. Coleman

Field studies were conducted to determine the efficiency and crop safety of trifluralin [2,6-dinitro-N, N-dipropyl-4(trifluoromethyl) benzenamine] in coriander (Coriandrum sativum L.), dill (Anethum graveolens L.), and dandelion greens (Taraxacum officinale Weber) when applied preplant-incorporated at 0.56 and 0.84 kg a.i./ha. Visual injury evaluations, crop fresh and dry weight at maturity, and leaf area were used to determine adverse effects of trifluralin on each crop when compared to an untreated control. Dandelion greens had a 47% and 49% reduction in leaf area when treated with trifluralin at 0.56 and 0.84 kg a.i./ha when compared to the untreated weed-free dandelion treatment. Coriander and dill showed no visual crop phytotoxicity and no adverse effects on crop growth, fresh and dry weight yield, or leaf area when treated with trifluralin. Trifluralin, when used in combination with early season mechanical cultivation, can provide selective weed control of many of the most common winter annual weeds in south Texas while exhibiting a high level of crop tolerance for coriander and dill.

Open access

C. Edward Beste and J. Ray Frank

Abstract

Sequential applications of granular oxyfluorfen (2 G) at 3.3 kg a.i.·ha−1, oxadiazon (2 G) at 3.3 kg a.i.·ha−1, napropamide (10 G) at 4.5 kg a.i.·ha−1, and chlorpropham (20 G) at 1.1 kg a.i.·ha−1 were evaluated for weed control in newly planted Rhododendron obtusum (Lindl.) Planch cv. Hinocrimson azaleas in the field. Granular oxyfluorfen, oxadiazon, or napropamide applied twice per season controlled 99%, 77%, or 73% of the weeds, respectively, for 2 years. A combination of napropamide, oxyfluorfen, and oxadiazon applied twice per season controlled >99% of the weeds at the season's end. Single seasonal applications of oxyfluorfen or oxadiazon controlled 63% and 77% of the weeds, respectively. Phytotoxicity to azaleas was not observed with any treatment. Chemical names used: 2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyel)benzene (oxyfluorfen); 3-[2,4-dichloro-5-(l-methylethoxy)phenyl]-5-(l,l-dimethylethyl)-l,3,4-oxadiazol-2(3 H)-one (oxadiazon); 2-(α-napththoxy)-N,N-diethylpropionamide (napropamide); and 1-methylethyl 3-chlorophenyl carbamate (chlorpropham).

Open access

Calvin E. Arnold and James H. Aldrich

Abstract

Methazole [2-(3,4-dichlorophenyl)-4-methy1-1,2,4-oxadiazolidine-3,5-dione] napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], oryzalin [3,5-dinitro-N4 ,N4 -dipropyl-sulfanilamide], oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-∆2-l,3,4-oxadiazolin-5-one], and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] each at 4.5 kg/ha were applied preemergence on June 17, 1976 in a nursery of 6-month-old seedlings of peach [Prunus persica (l.) Batsch cv. Nemaguard]. Though simazine and oryzalin provided better weed control, oxadiazon increased seedling height and trunk diameter from 25 to 89 days after application. All treatments impeded bark adhesion (slippage) 25 days after application but not after either 56 or 89 days. No phytotoxicity was observed from any treatment.

Free access

Kassim Al-Khatib, Carl Libbey, and Sorkel Kadir

1 Weed Scientist. To whom reprint requests should be addressed. 2 Research Technologist. 3 Research Associate. A/CSS paper 9406-10, project 13K-3419-4940, Washington State College of Agriculture and Home Economics Research Center. This