Integrated Pest and Crop Management
News and Resources for Wisconsin Agriculture from the University of Wisconsin-Madison

Control Your Weeds to Reduce Production Costs in 2020 and Beyond

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Waterhemp

Nicholas Arneson, University of Wisconsin-Madison Cropping Systems Weed Science Outreach Specialist, Daniel H. Smith, Southwest Regional Agronomist- Nutrient and Pest Management Program, University of Wisconsin-Madison, Rodrigo Werle, University of Wisconsin-Madison Cropping Systems Weed Scientist and Extension Specialist

Top Five Reasons to Invest in Your Weed Control Program

  1. An Ounce of Prevention is Worth a Pound of Cure: Preventing early season weed competition is essential to optimize yield potential. Preventing the establishment of herbicide-resistant weeds is often less expensive than trying to control them after the fact
  2. Not in Your Fields?: Be aware that herbicide resistance is widespread in Wisconsin (for more information see WiscWeeds blog posts: Wisconsin Waterhemp Herbicide Resistance Project Update and An Overview of Herbicide Resistance in Wisconsin)
  3. Zero Tolerance Approach: No Seed = No Weed: Troublesome weeds such as waterhemp, Palmer amaranth, and giant ragweed can produce a vast amount of seeds. One plant turns into few, while few can turn into an infestation within a few growing seasons.
  4. Don’t Forget About the Little Guys: Each year presents new challenges and potential for new problem weeds; a neglected weed species today could become the problem weed of tomorrow. For example, we have seen marestail (aka horseweed) become an emerging problem weed as more growers switch to no-till.
  5. There is No Silver Bullet: Crop rotation provides additional chemical control options. Diversifying and mixing effective herbicide sites of action can delay herbicide resistance. Growers should always adopt integrated weed management strategies to lower additional selection for weed herbicide resistance.

Top Ten Ways to Control Weed Control Costs

  1. Know the troublesome weeds in each field and target management practices towards controlling these weeds.
  2. Calibrate and perform preventative maintenance to application equipment: calibrated equipment ensures the appropriate application rate is being delivered and preventative maintenance ensures application equipment will perform as expected. Proper applications minimize the potential for poor weed control or resistance selection if lower rates were delivered and alleviates potential carryover concerns if higher rates of herbicides with soil activity were unintentionally applied.
  3. START CLEAN with the use of pre-plant cultivation or effective chemical burndown and STAY CLEAN with the use of an effective soil residual herbicide program (DON’T CUT RATES). Controlling troublesome weeds early in the season is often more cost-effective than managing them POST-emergence later in the season.
  4. Target effective POST-emergence applications when weeds are small (<<< 4 inches) to ensure adequate coverage and the highest level of control.
  5. Do your homework: Shop around and find the best prices. Compare prices of premixes with mixing brand and/or generic products. Always check the labels and run a jar test to evaluate the tank-mix compatibility before mixing.
  6. Promote good agronomics: the faster the crop makes canopy, the better it will compete with weeds.
  7. Utilize effective crop rotations to improve diversity of weed control options, application timings, and additional competition. For example, including winter wheat in a corn-soy rotation can “trick” weeds with providing crop canopy competition at a different time of the season.
  8. The use of cover crops can directly compete with fall-emerging and early spring-emerging weeds while also providing residue to suppress weeds emerging during the growing season.
  9. Prevent weeds from going to seed: no seeds added to the seedbank = fewer weeds to manage in the future.
  10. Clean equipment: prevent field to field spread of weed seeds and/or rhizomes. Be strategic when selecting tillage/harvest sequence. Start with clean fields (or with no suspected resistance) and move to infested (suspected/confirmed resistance) last.

Additional useful resources to help guide weed management decisions:

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