Wooster, Ohio, USA
November 2010
Mark Loux and Tony Dobbels
Department of Horticulture and Crop Science
The Ohio State University
PDF document
Corn Herbicides (labeled within the past year or so)
Balance Flexx (Bayer) is a new formulation of isoxalutole that contains the safener, cyprosulfamide, which reduces the risk of corn injury. This product can be used in field corn and certain corn inbreds, and replaces Balance Pro. Balance Flexx can be applied preplant, preemergence, or postemergence up to the V2 stage of corn. Postemergence application of Balance Flexx alone will generally not control weeds larger than the 1-leaf stage, but it can be mixed with atrazine to improve control.
Callisto Xtra (Syngenta) is a premix of Callisto and atrazine for postemergence use on field corn, seed corn, sweet corn, and yellow popcorn. Can be applied from emergence until corn is 12 inches tall.
Capreno (Bayer) is a premix of tembotrione (Laudis) and thiencarbazone-methyl, a new ALS-inhibiting herbicide that has foliar and residual activity on annual grass weeds. This product can be used on field corn and certain corn inbreds. Capreno can be applied postemergence from the V1 through the V7 stage of corn growth, although it should be applied with drop nozzles after the V6 stage. Capreno is most effective when broadleaf weeds are less than 6 inches tall, and grasses are less than 3 inches tall and not tillering. The addition of atrazine can improve the speed of control, and effectiveness on certain weeds. The label specifies application with crop oil concentrate and either UAN or AMS.
Corvus (Bayer) is a premix of isoxaflutole and thiencarbazone-methyl, along with cyprosulfamide, the same safener that is in Balance Flexx. Corvus can be applied preplant, preemergence, or postemergence up to the V2 stage of field corn and certain corn inbreds. Preplant applications of Corvus in burndown can control weeds up to 6 inches tall. Corvus provides broad-spectrum residual control of grass and broadleaf weeds when applied preemergence, but the addition of atrazine will improve control of large-seeded broadleaf weeds (giant ragweed, cocklebur, morningglory). The addition of atrazine will also improve control of emerged weeds in burndown or postemergence applications. Adjuvants or herbicides other than atrazine should not be included in postemergence Corvus treatments.
Peak (Syngenta) is now labeled for postemergence use in field corn. Peak contains prosulfuron, the component of Exceed that provided residual control of burcucumber, so a primary use of Peak in Ohio may be to mix with other postemergence herbicides to improve residual control of this weed. Peak can be applied to corn up to 30 inches tall, but should be applied as a directed spray using drop nozzles when corn is past the 6- collar stage or more than 20 inches tall. Crop rotation is restricted to corn where rates above 0.25 oz/A are used or when used north of I-70 and mixed with Spirit. See label for other recrop guidelines.
Prequel (DuPont) is a premix of rimsulfuron and isoxaflutole (Balance Pro) for preplant and preemergence use on field corn hybrids. This product is intended for use in a planned preemergence followed by postemergence program. Prequel provides residual control of grass and broadleaf weeds, which can be improved with the addition of atrazine. Prequel can control small, emerged weeds in no-till, but the addition of atrazine or a burndown herbicide is required for weeds more than 3 inches tall.
Soybean Herbicides (labeled within the past year or so)
Authority XL (FMC) is a premix of chlorimuron and sulfentrazone for fall, preplant, or preemergence use in soybeans. A previously available product, Canopy XL, contained these same ingredients, and was widely used in Ohio. The ratio of sulfentrazone to chlorimuron is higher in Authority XL compared with Canopy XL, which can result in improved residual control of black nightshade and ALS-resistant waterhemp and marestail. Can be applied to soils with pH up to 7.6, but recrop intervals are extended to at least 18 months for all crops except small grains where soil pH is 7.2 or higher.
Flexstar GT (Syngenta) is a premix of glyphosate and fomesafen (Flexstar) for postemergence use in Roundup Ready soybeans. The product is formulated with adjuvants, but it should generally be applied with ammonium sulfate. The label recommends the addition of crop oil concentrate, methylated seed oil, or nonionic surfactant for “difficult to control” weeds, or under adverse conditions. OSU research results have shown that the addition of crop oil concentrate or methylated seed oil is necessary when using this product to control glyphosate-resistant ragweeds or waterhemp. The adjuvants in glyphosate formulations are not adequate to maximize fomesafen effectiveness on these weeds.
Warrant (Monsanto) contains acetochlor, and is labeled for postemergence application to soybeans, to provide residual control of later-emerging weeds, including annual grasses, pigweeds, waterhemp, black nightshade, and lambsquarters. Warrant does not control emerged weeds, so it should be mixed with glyphosate in postemergence applications to Roundup Ready soybeans. Optimum timing of application (mixed with glyphosate) is when weeds are 2 to 4 inches tall and soybeans are at V2 to V3.
Kixor products
BASF introduced three new products in 2010 based on a new active ingredient, saflufenacil, a broad-spectrum broadleaf weed herbicide. Kixor is the overall name for saflufenacil-based herbicide technology. The three new products included: Integrity, a premix of dimethenamid (Outlook) and saflufenacil for field corn and popcorn; Sharpen, which contains just saflufenacil and is labeled for corn, soybeans, and wheat; and and Optill, a premix of saflufenacil and imazethapyr (Pursuit) for soybeans. Saflufenacil is a PPO inhibitor (group 14), which is the same mode of action as Valor, Authority, Cobra, and Flexstar. Changes for 2011 include: a name change – “Integrity” has been renamed “Verdict”; and Verdict is now labeled for use in soybeans at 5 oz/A (which provides the same amount of saflufenacil as 1 oz/A of Sharpen). Labels have been changed to recommend only MSO with saflufenacil in burndown situations, whereas the previous labels allowed COC or MSO.
Saflufenacil products are labeled for preplant or preemergence use only, but the foliar activity can control or help control emerged weeds in no-till fields, especially when combined with atrazine, glyphosate, or Ignite. Verdict, which has residual activity on many annual grass and broadleaf weeds, is intended for use in a planned preemergence followed by postemergence program in corn. The amount of saflufenacil in the Optill, Sharpen, and Verdict soybean rates is lower compared with Verdict corn rates, which reduces burndown activity and residual control of most broadleaf weeds. As a result, although it has considerable activity on marestail, safulfenacil products should be combined with glyphosate or Ignite for burndown in no-till soybeans. It should also be combined with other residual soybean herbicides to obtain adequate residual control of broadleaf weeds. Soybean use directions prohibit combinations of saflufenacil products with other group 14 herbicides (Valor, Authority, Prefix), so the most effective partners with Sharpen to improve residual control may be Canopy DF/EX, metribuzin, and Scepter.
Small Grain Herbicides (newly available within the past year or so or at least new to us)
Axial TBC (Syngenta) is a premix of pinoxaden (Axial) and florasulam for control of ryegrass, foxtails, and barnyardgrass in wheat and barley. Axial TBC also controls some broadleaf weeds, but should generally be mixed with a broadleaf herbicide if these are present. Apply with Adigor Adjuvant when wheat is in the 3-leaf to boot stage. Axial TBC can be applied in a spray solution containing up to 50% nitrogen fertilizer solution (e.g. 28%). Allow 9 months between application and planting soybeans.
Axiom (Bayer), a premix of metribuzin and flufenacet, can be applied early postemergence (in fall) in wheat for control of small winter annual weeds and residual control of winter annual grasses, including bromes and annual ryegrass. Axiom can be applied from spike to 3-leaf stage of wheat. For best results, control emerged weeds at the time of wheat planting with tillage or burndown herbicides, and apply Axiom prior to the 1-leaf stage of weeds. Soybeans can be planted anytime after Axiom application.
Cleansweep D and Cleansweep M (Nufarm) are premixes of bromoxynil (Buctril), fluroxypyr (Starane), and 2,4-D or MCPA, respectively, for control of broadleaf weeds in wheat, oats, and barley. Cleansweep D can be applied from the fully-tillered stage of crop growth until (but not including) the jointing stage. Cleansweep M can be applied from the 2-leaf stage up to and including flag leaf emergence. Labels do not specify whether these products can be applied in the fall, or applied using 28% as the spray carrier. Allow 4 months between application and soybean planting.
Finesse (DuPont) and Report Extra (Cheminova) can be applied to wheat for postemergence control of annual bluegrass and a number of winter annual broadleaf weeds. These products are premixes of chlorsulfuron and metsulfuron methyl, two longresidual sulfonylurea herbicides (ALS inhibitors). Wheat should be in at least the 1-leaf stage at the time of application. Apply in the fall for most effective grass control, and to minimize recrop problems. STS soybeans can be planted 6 months after application, but this extends to 18 months for corn or non-STS soybeans. Apply with NIS. These herbicides can be applied using UAN as the spray carrier, and the rate of NIS varies with the UAN rate.
Huskie (Bayer) controls many winter and summer annual broadleaf weeds in wheat, oats, and other small grains. Huskie is a premix of bromoxynil and pyrasulfotole, which is an
HPPD inhibitor (same site of action as Callisto). Appy in fall or spring after crop reaches the 1-leaf stage, up to flag leaf emergence. Apply with AMS (0.5 to 1 lb/A) or UAN (1 to 2 qts/A) for most effective control. Can be applied using UAN as the spray carrier. The fertilizer solution should not exceed 50% nitrogen, and the nitrogen rate should not exceed 30 lbs/A. Soybeans can be planted 4 months after herbicide application.
Olympus Flex (Bayer) is a premix of propoxycarbazone-sodium (Olympus) and mesosufuron-methyl (Osprey) for control of winter annual grasses in wheat, including annual ryegrass, annual bluegrass, cheat, and downy brome. Apply from when the first fully expanded leaf of wheat is visible, up through jointing. Apply with nonionic surfactant plus either nitrogen fertilizer solution or ammonium sulfate, or with methylated seed oil (nitrogen fertilizer not required). The spray solution can contain up to 15% nitrogen fertilizer solution. Application in fall will generally provide the most effective winter annual grass control. This product controls some broadleaf weeds but should generally be combined with a broadleaf herbicide if these are present. Soybeans can be planted when both these conditions have been met: 5 months has elapsed and 18 inches of precipitation has occurred since application.
Orion (Syngenta) controls winter and summer annual weeds in wheat, oats, and other small grains. Orion is a premix of MCPA and florasulam, which is an ALS inhibitor. Apply when weeds are in the seedling stage, and the crop is in the 3-leaf to joint stage. The use of an adjuvant is not necessary with the product. The product label does not specify whether it can be applied using UAN as the spray carrier. Soybeans can be planted 9 months after herbicide application.
PowerFlex (Dow AgroSciences) is labeled for control of annual grass and broadleaf weeds in wheat. The active ingredient is pyroxsulam, an ALS inhibitor (group 2). PowerFlex can be applied in the fall or spring when wheat is in the 3-leaf to jointing stage. Most effective control results from treatment of grasses at the 2-leaf to 2-tiller stage of growth, and when broadleaf weeds are no more than 2 inches tall or in diameter. Apply with nonionic surfactant or crop oil concentrate. PowerFlex can be applied in spray solutions containing nitrogen fertilizer solution (UAN), but the spray solution should not be composed of more than 50% UAN and should not exceed 30 pounds of actual nitrogen per acre. When PowerFlex is applied in spray solutions containing UAN, use a non-ionic surfactant at a maximum of 0.25% v/v, instead of crop oil concentrate or methylated seed oil. Temporary crop injury may result when liquid nitrogen is used as the spray carrier. Grass control can be reduced if PowerFlex is mixed with dicamba or amine formulations of 2,4-D or MCPA. Allow 5 months between application and soybean planting.
Pulsar (Syngenta) is a premix of fluroxypyr (Starane) and dicamba for control of broadleaf weeds in wheat and barley. Pulsar applied alone has a fairly narrow spectrum of control, and should generally be mixed with MCPA ester or another broadleaf herbicide. Apply before the jointing stage of wheat (label does not specify whether fall application is allowed). Pulsar can be applied with nonionic surfactant to improve control under less than optimum environmental conditions, and can be applied in a spray solution containing up to 50% nitrogen fertilizer solution. Allow 9 months between application and soybean planting.
Liberty Link soybeans
Postemergence applications of Ignite in Liberty Link soybeans are an effective tool for management of common and giant ragweed and marestail populations that have developed resistance to glyphosate and/or ALS inhibitors. Ignite is a broad-spectrum herbicide that can control most of the annual grass and broadleaf weeds that occur in soybean fields. However, it is most effective on weeds that are less than 4 to 6 inches tall, and there is the risk of inadequate control where growers assume that Ignite is capable of controlling large weeds. As a result, the most consistently effective control will occur where Ignite is applied postemergence following the preemergence application of residual herbicides. Essential steps to success with the Liberty Link soybean program include:
- Weed-free start at planting through use of preplant burndown herbicides or tillage.
- Preplant application of broad-spectrum residual herbicides, which should have activity on lambsquarters, pigweeds, waterhemp, giant ragweed and marestail, and grasses where the grass population is moderate to high. Barnyardgrass and yellow foxtail should be controlled by the residual herbicide or through the addition of a grass herbicide (clethodim, Fusion, Assure, etc) to the postemergence Ignite application.
- Apply Ignite postemergence at 22 oz/A when weeds are no more than 4 to 6 inches tall. Use a spray volume of at least 15 gpa, and nozzles that produce medium droplets (avoid nozzles that produce large droplets). Ignite is most effective when applied with AMS. The current Ignite label for soybeans does not specify the use of AMS, but also does not prohibit use.
- Apply Ignite again if necessary to control late-emerging weeds or giant ragweed that survived the first application. This should generally occur about 3 weeks after the first application.
Other resources
More information on weed and herbicide management can be found in numerous publications available at no charge on the OSU Weed Management website,
There is a charge for the Weed Control Guide for Ohio and Indiana (although the online pdf is free), which can be purchased from OSU county extension offices, online at the OSU Extension eStore (http://estore.osu-extension.org/index.cfm), or by calling the OSU publications office at 614-292-1607.
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