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Rethinking weed control

By Staff | Jan 2, 2013

It’s vital to take a new approach to weed management, said MikeOwen, an Iowa State University Extension weed specialist, who urges growers to:

  • Use more diverse weed management solutions. Look for ways to rotate effective herbicides with various sites of action to “upset the ecological apple cart,” he said. “The more diversity you can bring to your weed control program, the better off you’ll be.”
  • Target weed control solutions. Just as growers tailor specific hybrids and fertility programs to their acres, it pays to use field-by-field weed management strategies, since certain fields may require extra care.
  • Pay attention to detail. While effective rates and application timing are critical, spraying additives are also important in some cases, said Bob Hartzler, an ISU Extension weed specialist and professor of agronomy. When tank-mixing glyphosate with Cobra or Laudis, for example, crop oil concentrate is required for the mixture to be most effective.
  • Rethink tillage. Tillage has important implications for herbicide resistance, Owen said. As tillage systems have changed in the last 20 to 30 years to include more conservation and no-till systems, marestail and common waterhemp have become more challenging.

While tillage is not a good solution on highly erodible land, it may be useful in other settings, said Owen, who noted that some growers are using a rotary hoe designed for high-residue areas.

  • Realize that little things can make a big difference. One weed control strategy by itself may not provide 100 percent, 80 percent or even 50 percent weed control, but lots of “little hammers” used together can pay off in the long run, Owen said. Also, put more emphasis on return on investment rather than cost when evaluating a complete system of pre-emerge and post-emerge crop protection products, he added.

“In most cases,” Owen said, “we’re seeing a higher ROI with the more costly programs, which makes the higher investment worthwhile.”

Herbicide resistance is one of the biggest issues facing farmers in 2013, Owen said, who encourages growers to consider all the weed control strategies available.

“The evolution of herbicide resistance is not a herbicide problem – it’s a management issue.

“If you can learn to manage weeds in general more effectively, you’ll also manage herbicide-resistant weeds better.”

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