Weed Control Strategies - 3

OMAHA (DTN) -- A laundry list of new corn herbicides arrive in the marketplace each year. What isn't always obvious is there are no new modes of action and very few new active ingredients in those offerings.

We see new crop protection products with the same active ingredient available from multiple companies. In today's marketplace, more than one company is often able to license access to a new active ingredient -- even for use in the same crop.

Mark Loux, extension weed scientist at The Ohio State University, agrees that the number of products available has expanded. "Companies now have access to more generic, off-patent products than ever before," Loux told DTN. "Herbicide-resistant waterhemp, Palmer amaranth and giant ragweed continue to present new challenges and new herbicides are needed to target these problem weeds."

NEW CHEMISTRY

According to Loux, pyroxasulfone is the one new active ingredient available for 2013. "Mode of action of pyroxasulfone is similar to the acetochlor and controls most annual grasses, pigweed, waterhemp, lambsquarters, and black nightshade, and also has fair activity on common ragweed and velvetleaf at higher rates. The premix products that contain pyroxasulfone are geared for use in a planned preemergence followed by postemergence program. The lower pyroxasulfone rate in these products is not intended to provide full season weed control, and also results in reduced control of some broadleaf weeds," he said.

BASF will market straight pyroxasulfone, while other companies will offer the new active in a premix. BASF received registration for corn in 2012 and registration on soybeans is anticipated in 2013.

CORN HERBICIDES

BASF

Zidua contains the active ingredient pyrazolone. Zidua is labeled for preplant or preemergence use in corn, sweet corn and popcorn and should be mixed with another herbicide to expand early season broadleaf control. Zidua can also be applied early postemergence, but should be mixed with other herbicides for control of emerged weeds.

Dow AgroSciences

Growers have been anxiously awaiting Dow AgroSciences' Enlist program, featuring an in-the-seed 2,4-D tolerance. The technology for corn was scheduled to debut in 2013. However, that program has been delayed and is expected to be available for commercialization during the 2014 planting season, pending regulatory approvals. Growers will have ample opportunity to see the new trait in plots across the country this coming season. In addition, Dow anticipates registration of four new residual premix herbicides containing acetochlor and atrazine: FulTime NXT, Keystone NXT, Keystone LA NXT and Surpass NXT.

Syngenta

From Syngenta comes Lexar EZ and Lumax EZ to be used as either a pre or postemergence product in corn with a window from 14 days preplant to 12-inch-tall corn. Loux pointed out that Lexar EZ and Lumax EZ have been reformulated and now combine three modes of action including metolachlor (Dual), atrazine and mesotrione (Callisto) to broaden weed control. "They will have longer residual life and control more broadleaf weeds as barnyardgrass, foxtails, Palmer amaranth and waterhemp." Camix, the premix of mesotrione and s-metolachlor, has been renamed Zemax and received registration in 2012.

FMC

FMC is marketing Anthem and Anthem ATZ herbicides as a preplant, preemergence and early postemergence herbicide for control of grasses and broadleaf weeds such as waterhemp in corn. The active ingredients in Anthem are pyroxasulfone and fluthiacet-methyl (active ingredient in Cadet). "Fluthiacet does not provide residual weed control, so this control is due to the added pyroxasulfone," Loux said. Anthem ATZ is a three-way mix of pyroxasulfone, atrazine and fluthiacet. Registration is expected in 2013.

DuPont

DuPont is marketing Instigate herbicide to corn growers in the northern and Eastern Corn Belt. Instigate, containing mesotrione (Callisto) and rimsulfuron (Resolve), provides burndown plus residual weed control of hard-to-control broadleaf and grass weeds. It can be tank mixed with glyphosate, gramoxone (paraquat), atrazine and other atrazine-containing products such as Cinch ATZ (S-metolachlor) or Breakfree ATZ (acetochlor) to provide season-long one-pass weed control. For southern and Delta regions, DuPont is offering LeadOff, containing (dimethenamide plus atrazine). It can be applied preplant or preemergence in corn and has contact and residual properties.

Loux said that application of Instigate alone will generally not be adequate in either a single preemergence or preemergence followed by postemergence program. "A mixture of Instigate plus an atrazine premix should have burndown activity that is similar to Lexar and Lumax, as well as similar residual weed control levels," he said.

Valent

Valent is offering Fierce, a premix of pyroxasulfone and flumioxazin (Valor) for preplant use in field corn. Fierce has to be applied at least seven days before planting corn and can only be used in no-till or reduced-till conditions where crop residue hasn't been incorporated into the soil and where corn will be planted directly into a undisturbed seedbed, previous crop residue or after a cover crop. Fierce controls annual grasses, pigweed, waterhemp, lambsquarters, velvetleaf, smartweeds, and black nightshade, and controls or suppresses common ragweed. When applied as part of a burndown program, Fierce must be tank-mixed with other herbicides to control emerged weeds.

Dan Davidson can be reached at daniel.davidson@telventdtn.com

(PS/ES/AG)

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