Sarah Lancaster, Weed Management Specialist
Kansas State University
Harvest is always a great time to start planning weed management strategies for the next spring because you can note weed escapes from the combine. Things to take note of include what weed species are present, where weed escapes are present, and any changes in the size or location of weed escapes. Some of your observations might be the result of soil or environmental conditions, while others might suggest problems with herbicide selection or application equipment. However, some of these escapes might indicate the presence of herbicide-resistant weeds in your field – especially if you have used the same herbicide program for a number of years. All of these factors can be addressed for the next growing season – and now is a good time to get started!
Helpful tips when dealing with herbicide shortages
Acting now to address needs for next spring is especially important this fall, due to the anticipated shortages of key herbicides. We have been discussing this topic since the spring and anticipate issues lingering as far as 2023. For example, prices for some glyphosate products are currently as much as 2.5 times higher than last fall. Herbicide concerns are also compounded by shortages of other inputs. Here are some things to consider as you make plans for 2022.
- Take delivery of herbicides as soon as practical. However, be sure you have adequate storage to maintain the quality of the products. One consideration that could simplify storage concerns would be to opt for dry formulations rather that liquids when possible.
- Use the available products in ways to maximize efficacy. This includes generally maintenance of pumps, hoses, etc. This also includes making sure nozzles are right for the job and are functioning properly. It is also a good idea to reconsider application parameters like spray volume and driving speed. Greater spray volumes generally increase the effectiveness of post-emergence products, especially contact herbicides like glufosinate (Liberty, others). Slower driving speed can also increase herbicide deposition on target weeds, increasing the effectiveness of your applications.
- Re-evaluate residual herbicides. Residual herbicides are the foundation for excellent weed control; but this year, you may want to consider updating your pre-emerge program to make sure you have multiple, effective herbicides that will provide extended weed control. Adding layered or over-lapping residuals to your post-emerge program to reduce the need for additional passes will also be more important this year.
- Pay attention to agronomics. Good crop production practices that result in a healthy, competitive crop can go a long way toward managing weeds. Consider how you can optimize crop rotations, planting patterns, and other agronomic practices to promote weed suppression.
- Consider cover crops. Cover crops aren’t for everyone, but this might be a year when added weed suppression could be a factor in favor of planting cover crops. I don’t want to minimize the concern of termination, which is often accomplished with glyphosate. Winter cereals generally provide the best weed suppression, and they can be terminated with Group 1 herbicides like clethodim (Select, others) or quizalofop (Assure II, others). In addition, some farmers may want to consider ‘planting green’, so they can use the same application for cover crop termination and applying residual herbicides.
- Be flexible. Know what you will do if your preferred product is not available. Is there an alternative with the same or similar active ingredient? What other active ingredients are effective on your key weed species? When looking for alternatives, don’t forget premixes that contain glyphosate and glufosinate. The Chemical Weed Control Guide (https://bookstore.ksre.ksu.edu/pubs/SRP1162.pdf) can be a valuable reference to identify alternative products.