Post-emergence herbicides for corn and soybean

At this time of the year, integrated weed management programs focus on scouting and diversifying management practices including non-chemical methods and herbicide sites-of-action. For more information, please visit the United Soybean Board’s TakeAction website for field management guidelines and to learn more about herbicide sites of action. Michigan State University’s Weed Science website has detailed web pages on common weeds in annual crops with biological information and management recommendations. After each field season, the Herbicide Evaluation Program here at the university publishes efficacy data in a research report. Summary ratings for many weed species are located in “Pest Management in Wisconsin Field Crops” available as a free pdf or in print at Cooperative Extension’s Learning Store.

Triple threat herbicide resistant goosegrass

Researchers from the Australian Herbicide Resistance Initiative report on the first confirmed case of a weed, Indian goosegrass (Eleusine indica), resistant to three non-selective herbicides, glufosinate, glyphosate, and paraquat along with several ACCase inhibitor herbicides (Jalaludin et al., 2014). The goosegrass population was initially reported in Malaysia by a vegetable farmer and a planter from an oil palm nursery (Jalaludin et al. 2010).

In the United States, E. indica occurs in forty five of the fifty states. In Wisconsin, populations have been identified in the following counties: Columbia, Dane, Grant, Lafayette, Rock, Kenosha, and Milwaukee. The first documented case of herbicide resistant E. indica was from North Carolina in 1973 and the latest confirmation was in 2011 (Heap, 2015).

The amount of glufosinate to kill half of the tested resistant plants was equivalent to applying 40 fl oz per acre (e.g. Liberty 280 SL). The maximum rate for the season in corn is 36 fl oz per acre. The next generation of plants from the resistant population required 657 fl oz per acre of glyphosate (i.e. Roundup Powermax) to kill half of the tested population. These plants also were twice as resistant to paraquat compared to the susceptible plants. Half of the resistant population survived applications of the ACCase inhibitors- haloxyfop-P-methyl (e.g. Verdict) and fluazifop-P-butyl (e.g. Fusilade).

  1. Heap, I. 2015 The International Survey of Herbicide Resistant Weeds. Online. Available at www.weedscience.org
  2. Jalaludin, A.; Ngim, J.; Baki, BB.; Zazali, A. 2010 “Preliminary findings of potentially resistant goosegrass (Eleusine indica) to glufosinate-ammonium in Malaysia.” Weed Biology and Management 10: 256-260.
  3. Jalaludin, A.; Yu, Q.; Powles, S.B. 2014 “Multiple resistance across glufosinate, glyphosate, paraquat, and ACCase-inhibiting herbicides in an Eleusine indica population” Weed Research 55: 82-89.

For more information about herbicide resistance management, please visit our documents page, video page and/or the TakeAction on Weeds website.

Certified Crop Advisor Training Series

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Here is another resource brought to you by University of Wisconsin Extension! Free, online certified crop advisor training videos are available now. In addition to CCA training, they are great for adding to your general knowledge about integrated pest management, soil science, and field and forage crops.

Vince Davis has created a series of weed science videos that can be accessed directly from the videos page.

Start the New Year with Herbicide Resistance Management

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Here is another WCWS video discussing strategies to manage herbicide resistance. Get great weed control and save a bag of soybean seed by using a residual herbicide. Check out more WCWS videos at http://wcws.cals.wisc.edu/videos.

On the Bookshelf: 2015 Pest Management in Wisconsin Field Crops

Don’t miss this year’s “Pest Management in Wisconsin Field Crops” from University of Wisconsin Extension. This is a comprehensive guide to insect, weed, and plant disease management in corn, soybean, forage, and stored grain crops.

To obtain a print copy of the guide, go here. For a free electronic copy in pdf format, go here for the download. For mobile access, go to University of Wisconsin Extension’s Pest Management Mobile.

Resource for New and Experienced Pesticide Applicators

The Weed Science Society of America produced a series of articles covering different pesticide handling and application topics. To access the Pesticide Stewardship Series, go here.

Pesticide Stewardship Series titles:

  1. Safety Begins at the Point of Sale
  2. The Buyer Has Important Responsibilities
  3. Hiring a Pest Management Professional
  4. The Importance of Reading the Pesticide Label
  5. Restricted Use Pesticides Require an Extra Level of Care
  6. Certification Programs Fulfill an Essential Need for Competent Pesticide Applicators
  7. Always Be Diligent Concerning Personal Protective Equipment
  8. Employers Play a Central Role in Protecting Agricultural Workers and Pesticide Handlers
  9. Preparation and Oversight are Vital When Storing a Pesticide

The Pesticide Applicator Training program, at the University of Wisconsin-Extension, provides training opportunities, manuals, training aids, and fact sheets. For more information about the program, visit their website. Got questions? Call the program at (608) 262-7588 or send an email to PATprogram@mailplus.wisc.edu