Don’t Let Weeds Win After Wheat Harvest
By Lonnie Mengarelli- Southwind Extension District
Yes, we are wet here in the Southwind District, and many producers are using this time to get equipment field-ready across the district. Many combines have already headed to the wheat fields in some parts of Kansas, and producers are already looking ahead to the next crop. One management task that deserves immediate attention after harvest is weed control in wheat stubble. This is especially important in 2026, as weather-related challenges throughout the growing season led to thinner wheat stands in many areas, allowing more weeds to establish and compete.
While it may be tempting to delay weed management until later in the summer, allowing weeds to grow unchecked after harvest can be costly. Once the wheat crop is removed, weeds that were suppressed by the crop canopy quickly take advantage of sunlight, moisture, and nutrients. Some weeds damaged during harvest can also rapidly regrow. Left unmanaged, these weeds rob valuable soil moisture, reduce the effectiveness of future weed control efforts, and contribute thousands of seeds that can create problems for years to come.
Successful weed control in wheat stubble starts with timely action. The primary goals are controlling weeds that have already emerged and preventing additional flushes later in the season. For the best results, producers should target weeds before they exceed four to six inches in height. Smaller, actively growing weeds are much easier to control than large, mature plants. In addition to controlling existing weeds, residual herbicides play an important role in preventing future weed emergence and reducing the need for multiple herbicide applications throughout the summer. Herbicide-resistant weeds continue to be a major concern across Kansas. Species such as Palmer amaranth and kochia have developed resistance to several herbicide groups, making control more challenging.
Glyphosate combined with 2,4-D or dicamba remains an important tool in many post-harvest weed control programs. However, these products alone often struggle to provide adequate control of pigweed and kochia, particularly during the hot, dry conditions commonly experienced after wheat harvest. Because of these challenges, producers should consider incorporating additional herbicide modes of action into their weed management programs.
Paraquat products, including Gramoxone and generic formulations, continue to provide effective control of emerged pigweed and kochia when applied correctly. Research conducted in western Kansas has shown strong control of large Palmer amaranth with paraquat-containing treatments. Because paraquat is a contact herbicide, spray coverage is essential. Higher spray volumes and proper adjuvants are necessary to maximize effectiveness. Producers should also remember that federal regulations require paraquat applicators and handlers to complete specialized training every three years.
Although Syngenta has announced it will discontinue production of Gramoxone this year, generic paraquat products are expected to remain available.
When selecting herbicides, producers must think beyond this season and consider crop rotation plans for next year. Products such as atrazine can provide both burndown and residual weed control but may limit crop options the following season. Atrazine use in wheat stubble is restricted to specific crop rotations, including wheat-corn-fallow and wheat-sorghum-fallow systems.
Metribuzin offers another option that can provide residual activity while allowing greater crop rotation flexibility. It may also help manage certain atrazine-resistant weed populations.
Several Group 14 herbicides can be valuable additions to post-harvest weed control programs.
Saflufenacil (Sharpen) and tiafenacil (Reviton) provide effective control of emerged broadleaf weeds, including Palmer amaranth and kochia, while also offering short-term residual activity.
Flumioxazin (Valor) and sulfentrazone (Spartan) provide longer-lasting residual control and can help reduce future weed emergence. However, these products may carry crop rotation restrictions that producers should carefully review before application.
As with all residual herbicides, adequate rainfall is needed for activation and optimum performance.
In many parts of Kansas, preserving soil moisture is one of the most important reasons to control weeds promptly after wheat harvest. Every inch of moisture conserved can benefit the next crop, especially during dry summers. Effective weed management also reduces weed seed production, helping lower future weed pressure and potentially reducing herbicide costs over time.
The weeks immediately following wheat harvest present an excellent opportunity to gain the upper hand on troublesome weeds. Producers should:
- Control weeds as soon as possible after harvest.
- Target small, actively growing weeds.
- Include residual herbicides to manage future weed flushes.
- Consider next year’s crop plans before selecting herbicides.
- Carefully follow all label directions and crop rotation restrictions.
A timely post-harvest weed control program can help conserve moisture, reduce weed seed production, and set the stage for a more successful crop next season.
Lonnie Mengarelli is a Kansas State University Extension Agriculture agent assigned to the Southwind District. He may be reached at mengo57@ksu.edu or 620-223-3720
**The use of trade names is for clarity and educational purposes only and does not imply endorsement by K-State Research and Extension. Always read and follow current pesticide label directions.