A proliferation of marestail, a weed that is resistant to multiple classes of chemistries.
Even if resistant weeds are not yet prevalent on your farm, it’s important to take an integrated approach to weed control and develop the mindset of managing weeds all year.
Overreliance on a single weed-control method causes resistant weeds to develop, jeopardizing a herbicide-tolerant system, as well as the ability to grow a crop in a specific field. Farmers then face the additional expenses needed for control, such as unplanned herbicide applications, more cultivation and manual removal. In some extreme cases, total crop loss is the ultimate cost.
Integrated weed management techniques – adopting a combination of multiple, effective herbicide modes of action, as well as cultural practices such as crop rotation and mechanical weed control – are effective in reducing problems with herbicide-resistant weed biotypes. It is best to use multiple practices to manage or delay resistance, as no single strategy will be completely effective on its own.
Weed Resistance Best Management Practices
Resistant weed biotypes exist in every field. The only way to avoid selecting for them and increasing the spread of resistant populations is through a program of best management practices (BMPs), which set a standard of zero tolerance to keep weeds from going to seed.
According to Dr. Bryan Young, associate professor of weed science at Purdue University, producers should ask themselves the following questions:
- What is my weed spectrum, and what is the potential for weed resistance? Many aggressive and yield-robbing weeds such as Palmer amaranth, waterhemp, marestail, lambquarters and common and giant ragweed are resistant to multiple classes of chemistries.
- Does my herbicide program control targeted weeds? Does it create a diverse program with multiple, effective modes of action? Do the herbicides I’ve selected provide residual activity for season-long control?
While weed resistance is on the rise, no new herbicide modes of action have been introduced. It is imperative to use BMPs that will sustain existing chemistries to help protect crop yields.
The following are recommended BMPs to help avoid weed resistance headaches and ensure long-term success in protecting crop yields:
- Rotate crops
- Rotate herbicide-tolerant traits
- Use multiple, effective herbicide modes of action
- Know your weeds, know your fields
- Start with clean fields
- Stay clean – use residual herbicides whenever possible
- Apply herbicides correctly
- Control weed escapes
- Zero tolerance of weeds in the soil bank
- Clean equipment
Bayer has a broad portfolio to combat tough-to-control and resistant weeds. A well-thought-out herbicide program, using multiple modes of action, should be implemented to sustainably manage weeds. Before applying any herbicide, please read the entire label for the best possible results and to confirm that the product is effective on the weeds you wish to control. Not every product is suitable for every situation, and use of the correct application technique will ensure the best results.
Please visit our corn and soybean pages for information on a portfolio of products from Bayer to help you better manage weeds.