Until perfect herbicide comes along, wheat growers should stay with basics

Tom Peeper, professor, Oklahoma State University, recently described a perfect herbicide:

  • It kills all weeds and weed seeds.

  • It will mix with any carrier immediately.

  • It never harms the crop.

  • It is so inexpensive all you are paying for is the package, so profit potential is high.

  • It can be applied any time you get to it.

  • It does not have to be applied uniformly.

  • It will not injure any rotational crops or non-target species.

  • It will not drift, even in a 25 mile per hour crosswind.

  • It is perfectly safe to humans and all animals.

  • EPA thinks that more of it should be used.

Sadly, that perfect herbicide for wheat (or any other crop) remains as elusive as Bigfoot, leprechauns and dollar cotton.

“But we're making progress,” Peeper says.

He said growers and crop consultants are left with the challenge of selecting the right herbicide and applying it at the right time.

Peeper discussed weed management options in wheat, including controlling herbicide resistant ryegrass, during the recent Agriculture Technology Conference at Texas A&M-Commerce.

“We've made progress with herbicides for grass control in wheat,” he said. But he added that growers, dealers and custom applicators must work together to understand the weed complex, herbicide options and best application window to achieve best results.

“Know the target weeds. Know what the label says and apply the material according to label instructions.”

He said crop growth stage, spray tip selection, carrier used, additives and crop conditions all may affect herbicide efficacy.

Peeper said applicators and dealers should follow up with customers to make sure certain products worked. He said lowest label rates are not always effective. “Why do they put high rates on the label?”

Peeper said proper timing, especially on wheat, is often difficult and that labels may be confusing about proper growth stage of the crop or target pest.

“Planting date is a critical concern. Growers wonder if they should wait for all weeds to come up or to spray the early ones. Those first emerged weeds will cost most yield,” he said, and should take top priority. “Late ones may emerge after a rain but they will not hurt yield potential as much as the first ones up.”

Peeper said Hoelon, the old standby for ryegrass and wild oat control in wheat, has been around since the late 1970s. “It provides just enough residual activity to pick up stragglers. Full season grazing restrictions have been reduced to 28 days.”

He said Hoelon is labeled for both pre-emergence and post emergence applications. “We don't use it pre-emergence in Oklahoma. It needs rain within 7 days after applications. If the soil moves, it does too.”

Peeper said Hoelon continues to work well in Oklahoma although North Texas growers have seen some ryegrass resistance. “If ryegrass is resistant, growers can't tell it was sprayed.”

He said most growers don't apply Hoelon as early as the label recommends.

Oklahoma wheat farmers are beginning to see a better selection of Clearfield varieties, tolerant of Beyond and Clearmax herbicides. “These are pretty good on most grasses in wheat but not a sure thing on ryegrass.” He recommends the higher rate. He also said the Clearfield systems works best with a competitive wheat crop.

“I think we'll see some (Clearfield) varieties adapted to Northeast Texas soon,” he said.

Peeper said herbicide application is often delayed too late for most effective control. “For wheat seeded in September, we're already too late for optimum control,” he said in the mid-December meeting. “Most weeds in wheat seeded by October 20 are already past the stage to spray with (most labeled) herbicides.”

But Peeper said with wheat at near record prices, growers should continue to apply herbicides. “They should have sprayed earlier, as indicated on the label, and by waiting they have reduced crop yield. They won't get as good weed control, but they need to treat and then try to spray on time next year.”

Peeper discussed two new weed control options, Axial, a Syngenta product, and Power Flex, from Dow AgroSciences.

Axial (16.4 ounces per acre):

  • Controls ryegrass and wild oats.

  • Post emergence, no residual control.

  • Same chemical family as Hoelon, so if you have Hoelon resistance don't use it.

  • Best of the bunch for ryegrass control in our research plots.

  • Seems to work well even in spring.

  • 50-day grazing restriction.

  • Up to 50 percent UAN carrier.

Power Flex: — Broad spectrum grass and broadleaf.

  • May be hard to get this year, label expected in January. We plan to put spring demos out.

  • Post emergence, good growing conditions.

  • Very good crop safety.

  • Short residual.

  • Wide window of application? (2-leaf to 2-tiller)

  • Cost not yet known.

  • 7-day grazing restriction.

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