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Issue No. 1, Article 6/March 19, 2009

Herbicide Updates for 2009

We begin the new season of newsletter articles with an overview of changes in herbicide options. The number of new herbicide active ingredients is relatively few, and many of the items listed here describe new premixes of existing active ingredients or changes in labels or formulations. This article is not intended to provide a complete summary of all changes that have occurred, and all who use herbicides are encouraged to consult current product labels for additional information.

Authority Assist 4SC (sulfentrazone + imazethapyr) contains the active ingredients of Authority and Pursuit. Application rates are based on soil texture and organic matter content and range from 6 to 12 fluid ounces per acre. Authority Assist can be applied from 45 days before planting up to 3 days after planting; do not apply if soybean seedlings are emerging. Sulfentrazone has good activity against several small-seeded broadleaf weed species (such as Amaranthus species and common lambsquarters), and the addition of imazethapyr will improve control of certain large-seeded broadleaves (such as velvetleaf) over that of sulfentrazone alone.

Authority MTZ 45DF (sulfentrazone + metribuzin) contains the active ingredients of Authority and Sencor. Application rates range from 8 to 20 ounces per acre and are determined by soil texture and organic matter content. Authority MTZ will provide suppression or control of several small-seeded broadleaf species, as well as certain large-seeded species (such as Pennsylvania smartweed). Duration of weed control will generally be directly related to product application rate and timing.

Enlite and Envive (chlorimuron + flumioxazin + thifensulfuron) are new soybean herbicide premixes from DuPont. Both products contain the same active ingredients, but active ingredient ratios are such that Enlite 47.9WDG is better suited to northern areas and higher pH soils (i.e., less chlorimuron) while Envive will be positioned across a broader geography of Illinois. Envive 41.3DG can be applied from before planting until 3 days after planting but before soybeans emerge. Application rates range from 2.5 to 5.3 ounces per acre but should not exceed 2.5 ounces for soils with a composite pH of greater than 7.0.

Require Q (rimsulfuron + dicamba) and Resolve Q (rimsulfuron + thifensulfuron) are new premix products for postemergence applications in corn. Each product contains a safener to reduce the potential for corn injury and can be tank-mixed with glyphosate for use in glyphosate-resistant corn hybrids. Require Q is applied at 4 ounces per acre, while Resolve Q is applied at 1.25 ounces per acre. Resolve Q can be applied to corn that is up to 20 inches tall, but it should not be applied to corn exhibiting 7 or more leaf collars. Require Q can be applied any time after corn has reached 4 inches in height (V2) and before it exceeds 20 inches tall or exhibits 7 or more leaf collars. Accent Q 54.5WDG and Steadfast Q 37.7WDG are new formulations of Accent and Steadfast, respectively, that contain the same safener found in Require Q and Resolve Q.

Rage D-Tech 4.06EC (carfentrazone + 2,4-D ester) can be used for burndown control of existing vegetation prior to planting corn or soybean. The label lists required intervals that must elapse between preplant application and crop planting. Rage D-Tech at 8 fluid ounces per acre can also be applied postemergence to corn from spiking until corn has 5 leaves or is 8 inches tall.

Flexstar GT 3.31SL (fomesafen + glyphosate) combines the active ingredients of Flexstar and Touchdown for postemergence application in glyphosate-resistant soybean varieties. The commercial formulation includes a proprietary additive system to optimize performance without the absolute need for other spray additives. Application rates will range from 3 to 4.5 pints per acre. Registration is expected sometime in early 2009.

Impact 2.8SC (topramazone) rotational crop intervals will be changed in 2009. In particular, the soybean rotational interval following an application of Impact at up to 0.75 fluid ounce per acre will be 9 months regardless of geography.

Cadet 0.91EC (fluthiacet), a postemergence herbicide for use in corn and soybean, is a PPO inhibitor similar to Aim and Resource that is very active on velvetleaf. A tank-mix partner will improve the spectrum of weed control. Applications can be made to corn between V2 and 48 inches tall and to soybean from first trifoliolate to full flower. Application rates range from 0.4 to 0.9 fluid ounce per acre.

Valor SX (flumioxazin), at up to 2 ounces per acre, may be applied 14 to 30 days prior to planting to minimum or no-till field corn. Do not use on popcorn, sweet corn, or corn grown for seed.

Ignite 280 (glufosinate) will replace Liberty 1.67L for use in glufosinate-resistant corn hybrids and soybean varieties. The Ignite formulation was commonly used in the south for many years and will become the primary formulation sold for use in agronomic crops. The standard application rate of 22 fluid ounces per acre of Ignite is equivalent to 32 fluid ounces per acre of Liberty. For glufosinate-resistant soybean, up to 2 applications per season are allowed from emergence up to but not including the bloom stage. Do not apply more than 44 fluid ounces per acre per season and do not graze the treated crop or cut for hay. In glufosinate-resistant corn, broadcast applications can be made from emergence until corn is 21 inches tall or in the V7 growth stage.

Balance Flexx 2SC (isoxaflutole + safener) contains the same active ingredient of Balance but is formulated with a safener (cyprosulfamide) to reduce the risk of corn injury. Balance Flexx can be applied up to 30 days prior to planting (with a planned postemergence program; otherwise, apply 21 days before planting) through the V2 stage of emerged corn. Atrazine can be tank-mixed with Balance Flexx and applied postemergence, but do not use a crop oil concentrate or MSO with postemergence applications. Application rates, ranging from 3 to 6 fluid ounces per acre, are determined by soil characteristics and application timings. The weed control spectrum of Balance Flexx is very similar to that of Balance, but several important differences exist between these formulations: most notably, the Balance Flexx formulation (2SC) contains half the active ingredient as Balance (4SC) so adjust application rates accordingly; and the ability to apply Balance Flexx after corn emergence due to the safener contained within the commercial formulation. Do not apply Balance 4SC after corn emergence or severe crop injury will result.

Corvus 2.63SC (isoxaflutole + thiencarbazone + safener) contains the two components of Balance Flexx (isoxaflutole and safener), but also contains thiencarbazone, an ALS-inhibiting herbicide, to improve control of annual grasses. As with Balance Flexx, Corvus can be applied from EPP to V2 corn. It will be positioned as a one-pass product for control of broadleaf and grass weed species. Tank-mixing with atrazine will enhance control of certain broadleaf weeds and provide additional soil-residual weed control.

Degree Xtra 4.04CS (acetochlor + atrazine) can be used in grain sorghum. Soil applications can be made only if the sorghum seed was treated with a safener. Postemergence applications can be made to grain sorghum up to 11 inches tall. Lumax, Lexar, and Camix labels will soon be expanded to include use on grain sorghum.

Distinct 70WDG (dicamba + diflufenzopyr) can be applied as a preplant burndown treatment at least 30 days before soybean planting. A minimum of 1 inch precipitation and a 30-day waiting interval are required before planting soybean.

Optimum GAT Hybrids (Glyphosate ALS Tolerance) are expected to receive U.S. approvals during the first quarter of 2009. These hybrids demonstrate resistance to glyphosate and a large number of ALS-inhibiting herbicides (sulfonylurea and imidazolinone) and are being developed and commercialized by Pioneer and DuPont. DuPont will position GAT hybrids and several new herbicide premixes as tools that can complement glyphosate by including providing soil-residual weed control, improving control of species not easily controlled by glyphosate alone (such as annual morningglory), and enhancing control of certain glyphosate-resistant biotypes. These new herbicide premixes are listed hereafter:

Traverse (12.5% rimsulfuron + 12.5% chlorimuron): burndown prior to corn or soybean

Instigate (4.7% rimsulfuron + 4.7% chlorimuron + 31.2% mesotrione): preemergence corn

Trigate (6.7% rimsulfuron + 5% tribenuron + 33.3% mesotrione): postemergence corn

Diligent (6.31% rimsulfuron + 6.31% chlorimuron + 25.25% flumioxazin): preemergence soybean

Freestyle (12.5% chlorimuron + 18.75% thifensulfuron + 18.75% tribenuron): postemergence corn and soybean

Roundup Ready 2 Yield (glyphosate-resistant) soybean varieties are scheduled to be commercially available in 2009. Most available varieties will be in maturity groups 2 and 3. Monsanto anticipates having sufficient seed available for approximately 1 million acres. Expect a full "conversion" to RR2Y varieties by 2013.

Liberty Link soybean (glufosinate-resistant) are scheduled to be commercially available in 2009. Bayer CropScience, working with approximately 80 seed companies to develop commercial varieties (primarily in maturity groups 0.5­4.9), expects to have sufficient seed available for approximately 1 million acres.

Products of the Future

BASF: Kixor (BAS 800) is the trademark of products that will contain the new active ingredient saflufenacil. This new active ingredient is a soil-applied PPO inhibitor that demonstrates very good activity on many large and small-seeded broadleaf species. Several herbicide products will contain saflufenacil, including Integrity EC (saflufenacil + dimethenamid), OpTill DG (saflufenacil + imazethapyr) and Sharpen SC (saflufenacil). Expect availability of these products in 2010.--Aaron Hager

Author:
Aaron Hager

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