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Mixing it up

If you grow corn this year, you'll have at least eight new preemergence premixes to consider in your weed-control plans. For soybeans, you'll have two new preemerge products, plus a new Roundup formulation from Monsanto.

Before you throw up your hands in wonder over what the New Year has wrought, be aware that the lion's share of the new names contain tried-and-true ingredients that already dominate the market. This is especially true for the new corn weed-control lineup. Six of the eight new premixes are combinations of the top-selling preemerge grass herbicides with various ratios of atrazine.

For example, BASF and Dow AgroSciences are introducing new preemerge herbicides with higher and/or lower atrazine ratios, with a goal of providing a better agronomic fit on more acres. And DuPont is jumping into the fray with three new herbicides that contain active ingredients and atrazine ratios that are the same as those in the Dual/Bicep products from Syngenta.

“These new products will enable more growers to buy a product with the atrazine ratio that fits their soils and cropping program the best,” says Chris Boerboom, extension weed scientist at the University of Wisconsin — Madison. This is especially true if they want to rely on a single company's brands, since comparable herbicides with roughly the same ratios have been available in most instances.

Two new preemerge corn herbicides from Syngenta are exceptions to the atrazine ratio trend. Lumax and Camix herbicides contain mesotrione, the active ingredient in Callisto, the postemergence broadleaf herbicide introduced by Syngenta in 2001. Lumax is a three-way mix of mesotrione, plus S-metolachlor (the active in Dual II Magnum), and a low rate of atrazine. Camix is the same mix without atrazine.

Lumax will be targeted primarily on atrazine-sensitive soils in the northern Corn Belt, though it will be available in smaller quantities elsewhere. Camix will be available only in states where soils or environmental regulations effectively prohibit atrazine.

“With Lumax, having Callisto in the mix really helps out with the level of velvetleaf control you might normally expect at lower atrazine rates,” Boerboom says. “It will still have some challenges, such as giant ragweed.”

On the soybean side, Monsanto's introduction of Roundup WeatherMax herbicide is the big news, given the dominance of Roundup Ready soybeans. But FMC and Valent also have new preemerge products geared for both Roundup Ready and conventional acres.

Boerboom conducted weed-control trials with Roundup WeatherMax in 2002 but didn't see the weed-control advantage Monsanto claims WeatherMax will offer under tough environmental conditions. In his research, weed control has been similar for all tested glyphosate products.

“When deciding what glyphosate herbicide to use, compare the entire program, including its cost and any value you place on guarantee programs,” such as Monsanto's new Roundup WeatherMax warranty, he suggests.

As you evaluate corn and soybean weed-control programs for 2003, consider this final advice from Boerboom: “If you look out across the Midwest, the biggest problems aren't really related to the herbicides being used, but the timeliness of the application or other management problems.”

Here's what corn and soybean herbicide manufacturers have to say about new products and formulation changes for 2003.

Corn herbicides

New Syngenta premixes aim to fill holes in one-pass programs. New Lumax herbicide from Syngenta promises northern corn growers that they can finally control both grass and broadleaf weeds with a one-pass preemergence program that doesn't put them at risk for atrazine carryover.

Camix, another new Syngenta preemergence corn herbicide, carries less weed-control punch than Lumax. But it will bolster weed-control programs in parts of the north where atrazine can't be used, either because of environmental or soil pH restrictions, the company claims.

Lumax is a three-way mix of S-metolachlor, mesotrione and atrazine. Camix contains S-metolachlor and mesotrione in the same ratios as those in Lumax, but with no atrazine. Both herbicides also contain the crop safener benoxacor, which is used in other Syngenta herbicides that contain S-metolachlor.

Adding mesotrione to the Lumax mix allowed the atrazine rate to be reduced below the level typically needed to provide full-season broadleaf weed control, says Matt Comer of Syngenta. At the Lumax rate recommended for soils with 3% or greater organic matter, the atrazine rate is .75 lb./acre.

“We went with the technical ratio that offers the greatest benefit, with an eye on growers who are sensitive to using higher atrazine rates,” Comer says.

Syngenta claims that Lumax will control most grass and broadleaf weeds for six to eight weeks. “This is well into effective canopy closure, even in adverse conditions,” Comer says.

The company claims Lumax offers excellent control of most broadleaf weeds, including those resistant to triazine- and ALS-inhibiting herbicides, such as common ragweed and waterhemp, plus broadleaf weeds demonstrating increasing tolerance to glyphosate herbicides. The list of weeds controlled includes most common small-seeded and many large-seeded broadleaf weeds, plus yellow nutsedge. Control of annual grasses should be superior to control with Dual II Magnum and other acetanilide herbicides alone, both because of a robust rate of S-metolachlor and the boost from atrazine, Comer says. The list of partially controlled grass and broadleaf weeds includes wild proso millet, woolly cupgrass, cocklebur, dandelion, giant ragweed, morningglory and prickly sida.

Camix herbicide's grass and broadleaf weed control won't be as strong as with Lumax because of the absence of atrazine. To bolster one-pass preemergence grass and broadleaf weed control with Camix, Comer suggests adding Princep herbicide to the mix. Otherwise, growers should plan on a follow-up postemergence broadleaf herbicide treatment if there is heavy weed pressure, he adds.

Lumax will be available in significant quantities in Iowa, Wisconsin, Minnesota, South Dakota and North Dakota, and in Delmarva and southeastern Pennsylvania where triazine-resistant weeds are a problem. It will be available in more limited quantities in other key corn-producing states. Camix will be registered for use only in Michigan, Minnesota, Wisconsin and Pennsylvania. Depending on demand, Camix supplies could be tight in 2003, Comer says.

Both products will be available primarily in bulk, although Lumax also will be sold in 220-gal. MagPak mini-bulk containers in limited quantities.

Application timing for the two herbicides is similar. Lumax can be applied from two weeks before planting through 5-in. corn, but in all instances targeted prior to weed emergence for the broadest spectrum of control. Consistent grass control can only be achieved if the herbicide is applied before grasses emerge. Lumax should be applied at 3 qts./acre on all soils of 3% or higher organic matter. For soils of less than 3% organic matter, Lumax may be applied at 2.5 qts./acre.

As with Lumax, the optimum application timing for Camix is prior to both corn and weed emergence. But Camix may also be applied early postemergence, soon after the crop is up, but before weed emergence if grasses are to be controlled. Camix should be applied at 2.4 qts./acre on soils of 3% or higher organic matter, and 2 qts./acre on soils of less than 3% organic matter.

Both products are labeled for use in seed and field corn, as well as corn grown for silage, but not for sweet corn or popcorn.

Major Corn Belt crops can be planted the season after using Lumax, including corn, soybeans, sorghum and cereals. Winter wheat may be planted 4½ months following application. All other crops require an interval of 18 months. Corn may be replanted immediately in cases of crop failure.

Fields treated with Camix can be rotated to most major Corn Belt crops the following spring, including corn, soybeans, sorghum, potatoes, barley, oats and rye. Winter wheat may be planted 4½ months following application. All other crops require an interval of 18 months. Corn may be replanted immediately in cases of crop failure.

Interactions with soil insecticides have not been observed when Lumax or Camix is applied prior to corn emergence, according to Syngenta. If either herbicide is applied after corn emergence, unacceptable crop injury can result if an organophosphate or carbamate insecticide also is applied, either in tank mixture or within seven days of a Lumax or Camix application. Lumax or Camix should not be applied to emerged corn following at-plant applications of Counter CR insecticide.

BASF adds G-Max Lite for the northern Corn Belt. BASF is introducing G-Max Lite for northern corn growers who want less atrazine in their soil-applied grass/broadleaf weed-control program.

Like Guardsman Max, which was introduced in 2002, G-Max Lite is a combination of dimethenamid-P (the active ingredient in Outlook herbicide) and atrazine. At a use rate of 3.5 pts./acre, the Lite version supplies 21 oz./acre of dimethenamid-P and 1.2 lbs./acre of atrazine. At the same dimethenamid-P use rate, Guardsman Max provides 1.9 lbs./acre of atrazine.

The G-Max Lite application rate ranges from 2.0 to 3.5 pts./acre (depending on soil type) and provides atrazine at 0.7 lb. to 1.2 lbs./acre. It will be available in both bulk and 2.5-gal. jugs.

It is labeled for use in field corn, popcorn, seed corn, sweet corn and safener-treated grain sorghum. Rotational restrictions are those normally associated with atrazine.

Dow AgroSciences bolsters acetochlor lineup with Keystone and Keystone LA. Dow AgroSciences will have an acetochlor/atrazine recipe to fit most growers' demands with the introduction of Keystone and Keystone LA herbicides for 2003. Keystone already has full registration for the 2003 use season. Registration for Keystone LA is pending, but is expected before planting.

The two Keystone products bookend Dow AgroSciences' FulTime herbicide, which also contains acetochlor plus atrazine. At the same 2 lbs./acre acetochlor use rate, Keystone supplies atrazine at 1.5 lbs./acre, and Keystone LA provides atrazine at .75 lb./acre. FulTime, an encapsulated acetochlor/atrazine formulation, supplies atrazine at 1.3 lbs./acre.

“We now have products that fit farmers' field situations much closer than in the past,” says Ben Kaehler of Dow AgroSciences. “Along with Surpass and TopNotch (acetochlor-only herbicides), we now have a portfolio that fits the entire corn market.”

Both Keystone herbicides are suspo emulsion formulations. They contain a new surfactant/additive package, plus a new atrazine salt. Together, these improve handling and keep the ingredients evenly dispersed. This results in more consistency in the spray tank and more uniform spraying, Kaehler says.

The new surfactant/additive package also makes the herbicides less viscous and easier to handle than some other acetochlor/atrazine formulations. “I think Keystone and Keystone LA will lead the pack in terms of handling and spraying ease,” Kaehler says.

DuPont joins preemergence herbicide bandwagon with Cinch products. DuPont is adding a trio of preemergence corn herbicides for 2003, broadening the focus of what had been primarily a postemergence corn herbicide lineup.

The three new herbicides are Cinch, Cinch ATZ and Cinch ATZ Lite. All three contain the active ingredient S-metolachlor and the crop safener benoxacor. The ATZ products also contain atrazine.

The active ingredients and ingredient ratios in the three products are virtually identical to those contained in Dual II Magnum, Bicep II Magnum and Bicep Lite II Magnum herbicides. Cinch ATZ contains atrazine at 3.1 lbs./gal. Cinch ATZ Lite contains atrazine at 2.67 lbs./gal.

DuPont recommends using the herbicides in one-pass programs or as part of two-pass programs using Cinch products preemergence, followed by a range of DuPont postemergence herbicides, including Steadfast, Basis Gold or Accent, depending on weeds that are present. For the best results and most consistent corn weed control, DuPont recommends applying one of the Cinch brands at a reduced rate at or before planting, followed by one of its postemergence herbicides.

“Using these recommended products and herbicide programs under the DuPont Performance Plus program gives farmers added cost-management benefits in the event that additional weed-control measures are needed,” adds Kevin Diehl of DuPont. Purchase of DuPont herbicides can be financed through the TruChoice Opportunity Program, which also can be used to finance Pioneer brand seed.

Soybean herbicides

Roundup WeatherMax offers tough-conditions performance warranty. Roundup WeatherMax from Monsanto is a new, more concentrated glyphosate formulation with an enhanced surfactant/additive package that Monsanto says will provide more consistent control of weeds under adverse weather conditions.

To back up that promise, Monsanto is offering a new warranty that guarantees performance of the herbicide as long as it is used according to label directions and the grower participates in the Roundup Rewards program.

The warranty covers applications made during hot weather, dry weather and cool weather, plus early-morning or late-afternoon applications. Applications made up to 30 min. before rain also will be warranted. This compares to the 1-hr. rainfast interval with Roundup UltraMax, which the new formulation replaces in the Midwest and South. If weed control isn't satisfactory following qualifying applications, Monsanto will replace up to the initial Roundup WeatherMax use rate for re-treatment.

“Roundup WeatherMax penetrates the weed leaf in just minutes and begins to translocate through the plant,” says David Hollinrake, Roundup marketing manager. “This allows us to offer these breakthrough warranties. Growers are concerned about spraying in less-than-ideal conditions, and they are interested in tools that allow them to extend their spray day.

“We are so confident that WeatherMax is going to work even under these challenging conditions, provided the grower follows the label, we are willing to stand behind it,” Hollinrake continues. “We have never warranted weed control in the past. We are putting our money where our mouth is with our warranty.”

The new proprietary surfactant/additive package — called TranSorb II — is largely responsible for Monsanto's claim of improved tough-weather performance, says Joe Sandbrink, Roundup technical manager.

“The key differentiator with glyphosate products is the delivery system,” Sandbrink says. “That truly is what makes the difference in providing the rapid uptake, improved translocation and crop safety with Roundup WeatherMax.”

The higher concentration of the Roundup WeatherMax formulation is due to the use of potassium salt of glyphosate instead of the isopropylamine (IPA) formulation used in other glyphosate products manufactured by Monsanto and its competitors. As a result, Roundup WeatherMax is 20% more concentrated than Roundup UltraMax and 50% more concentrated than most competitive products, Sandbrink says. A 120-gal. shuttle of Roundup WeatherMax will treat about 700 acres at the recommended 22-oz. in-crop use rate. This compares to 480 acres for most competitive glyphosate products at recommended use rates.

In addition to allowing Roundup WeatherMax to be more concentrated, the potassium salt formulation isn't as thick as the Roundup UltraMax formulation, so it is easier to pump. “Growers will be able to pump WeatherMax about twice as fast as UltraMax under cold conditions,” Sandbrink says.

Except for changes in the application rate structure because of the increased concentration, use recommendations for Roundup WeatherMax are the same as those for Roundup UltraMax.

FMC's Spartan herbicide is new to soybean market. Spartan preemergence herbicide from FMC contains sulfentrazone, the same active ingredient that is in Authority herbicide, from DuPont.

Though the Spartan brand is new to the soybean market, FMC has marketed it for control of weeds in tobacco and other crops.

Spartan is applied either preplant or preemergence in soybeans to control small-seeded broadleaf weeds, including waterhemp, redroot pigweed, Palmer amaranth, kochia, lambsquarters, morningglory and nightshades, as well as yellow nutsedge. It offers partial control of several large-seeded broadleaf weeds and certain grasses, including foxtails.

Jamie Leifker of FMC sees a special fit for Spartan in fields with waterhemp and pigweed because it is especially effective on those species. The herbicide has a different mode of action — cell membrane disruption — than that of other soybean herbicides, so it is effective for control of weed biotypes that are resistant to ALS-inhibitor and triazine herbicides. Leifker claims that its residual activity makes it a good option on Roundup Ready soybeans where growers want to extend the application window for glyphosate herbicides by delaying emergence of waterhemp, pigweed and other weeds.

Valent's Gangster eyes tough broadleaves. Gangster, from Valent USA, is a multi-pack of the active ingredients in Valent's Valor herbicide and FirstRate herbicide from Dow AgroSciences.

The preemergence herbicide is geared primarily for control of tough broadleaf weeds and suppression of grasses on conventional soybean acres, says Jamie Nielson of Valent USA. Valent is “extremely focused” on weed control for conventional soybeans, he says. “We know this is an important market that is under-served.”

The company claims Gangster provides superior control of waterhemp, lambsquarters, nightshades, velvetleaf, morningglory and ragweed, plus important large-seeded broadleaf weeds, such as cocklebur and wild sunflower.

Valent will be recommending Gangster as the first half of a two-shot program that includes a postemergence application of a tankmix of Select (grass) and Phoenix (broadleaf) herbicides. A grower rebate is planned to encourage use of the program.

“Waterhemp, including ALS-resistant waterhemp, is the driver behind this program,” Nielson says. “We are offering growers an incentive to use the two-shot approach to really get a handle on this weed before it gets out of hand.”

For conventional soybeans, Gangster, which can be applied from before planting until three days after planting, will have a recommended use rate of 3 oz./acre. Ahead of Roundup Ready soybeans, the recommended use rate is 1.8 oz./acre.

Gangster's component herbicides are both water-dispersible granules. They will be packaged in 32-acre units containing a 5-lb. (gallon-sized) jug of Valor's active and a 1-lb. water-soluble packet of the active in FirstRate.

Plant-back and other restrictions are the same as those for the component herbicides. The rotation interval for wheat is three months, and it is nine months for field corn.

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