Early in his career, agronomist Tom Irwin learned the critical difference between a dead weed and a mad weed. Now, he asks his grower-customers which they would prefer — a weed that is temporarily knocked down or one that is no longer a threat to their crop?
“Do you want the weed dead, or do you want it mad?” Irwin asks. “There are four steps you can take to improve your weed control. Rotate your crops and your herbicide modes of action; don’t cut your herbicide rates; and use the product that will successfully target your problem weeds.”
In southwestern North Dakota where Irwin and fellow agronomist Tim Bieber scout cereal crops for Mott Equity & Agronomy, kochia, green and yellow foxtail (cheatgrass), Russian thistle, Canada thistle, wild buckwheat and common mallow are all major headaches. Additionally, barnyardgrass is becoming a nuisance weed.
Bieber and Irwin say they generally recommend a fall burndown herbicide treatment followed by an in-crop weed control program.
“I don’t know that the list of crop rotation benefits ends.”
— Tim Bieber
“You’ve got to get creative with some of these weeds, especially Canada thistle,” Bieber says. “It’s a perennial plant and a perennial problem. Without a diligent fall burndown, we can struggle with it in-season.”
The pair generally recommend Stinger® HL herbicide to burn back Canada thistle in-crop.
Rezuvant® herbicide is also a great fit for the area’s barley and wheat crop, offering a wide window of application through many leaf stages up to flag leaf emergence. With Rezuvant, Bieber and Irwin can successfully target grasses, including green and yellow foxtail, wild oats, and Persian darnel. Broadleaf weeds, such as kochia, wild buckwheat, pigweed and marestail, are also controlled with Rezuvant.
The two agronomists strongly recommend aggressive crop rotation.
“Much of our wild oat and pigeon grass pressure is caused by planting wheat after wheat with little to no crop rotation,” Irwin says.
The benefits of diversification and rotation are vast, they say.
“Rotating crops improves pest control, provides yield enhancement, helps you take better care of your soil and spreads out your harvest workload. There are huge financial incentives you gain by not having all eggs in one basket,” Irwin says. “I don’t know that the list of benefits ends with crop rotation. It’s foolish to grow wheat on wheat year after year.”
“We struggle with Group 1 and Group 2 weed resistance issues, and much of that can likely be traced back to using reduced rates of crop protection products,” Bieber says. “Our recommendation is to never cut labeled rates.”
In addition to potential resistance development, cut-rate applications can result in weed escapes.
“If you are going to spend the time and money to make a spray treatment with the goal of getting dead weeds, it’s worth a little bit more money to do it right by applying the full labeled rate of herbicide,” Bieber says. “Doing so means you likely won’t have to come again with a second treatment and will preserve the yield you would have otherwise given up to the weeds that continued to compete with your crop.”
Repeated use of the same herbicide modes of action decreases weed control efficacy. Crop rotation helps force the issue, say Irwin and Bieber.
“Crop rotation is huge. If you rotate crops, you’ll most likely rotate products, resulting in a mode-of-action rotation,” Irwin says. “Crop rotation also results in varied application timing of products such as glyphosate at different times of the year and at different growth stages. That hits differently.”
The broad range of cereal crop protection products offered by Corteva Agriscience increases weed control options.
“The Corteva Agriscience portfolio of herbicides provides flexibility of product choice and application window,” Bieber says. “With Corteva, we’ve got options. Corteva has a broad enough portfolio to enable us to find a product that fits any situation, and in the small grains market, Corteva has more options than anybody else.”Irwin adds, “We also find value in Corteva being an American-based company. We can support a company that supports us.”
Rezuvant™ is not registered for sale or use in all states. Arylex® is a registered active ingredient. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Stinger® is not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. State restrictions on the sale and use of Stinger apply. Consult the label before purchase or use for full details. Always read and follow label directions.
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