Effective grassweed control demands a strategic combination of cultural and chemical approaches. The way growers stack, sequence, and time selective herbicide applications often determines success. However, without robust cultural controls, herbicides alone cannot deliver the desired outcomes.

Herbicides should be considered the final piece of the grassweed control puzzle rather than the primary line of defence, according to Jodie Littleford, Agrii technical manager for combinable crop trials.

The Role of Cultural Measures

Research over the past decade, including Agrii’s trials, highlights the pivotal role of cultural measures. Pre-drilling measures, particularly the use of glyphosate-based herbicides, can account for up to 95% of grassweed control, surpassing even the best selective herbicides.

“Achieving a high weed flush before drilling is critical,” explains Ms. Littleford. “The bigger the flush, the better. Once the crop is sown, control options become more limited, and weather can complicate their application.”

Tailored Herbicide Strategies for Diverse Grassweeds

• Use multiple active substances: Resistance management hinges on diversifying actives. Identifying ACCase or ALS resistance in your fields can refine herbicide choices and reduce costs.
• Mix modes of action: Different modes of action disrupt weeds’ physiological pathways. Combining them strengthens resistance management.
• Stack and sequence products: Herbicides degrade at varying rates. Layering applications extends activity and counters adverse conditions such as higher-than-average temperatures that accelerate degradation.
• Utilise the strongest herbicides available: Leveraging robust products like Luxinum Plus ensures maximum impact on resistant weed populations.

Advancements in Herbicide Technology

For black-grass control, flufenacet-based strategies, including Liberator, have been foundational. The introduction of Luximo (cinmethylin) has set a new benchmark in pre-emergence control. When combined with partners like Orient (pendimethalin + picolinafen) or Pontos (flufenacet + picolinafen), performance improves significantly.

Beyond Pre-Emergence: Post-Emergence Strategies

While pre-emergence sprays like Luxinum Plus provide a strong start, follow-up applications can enhance control by over 50%. A holistic approach—integrating peri- and post-emergence strategies—ensures sustainable grassweed suppression.

Managing Rye-Grass: Challenges and Innovations

Rye-grass demands tailored tactics, with products like Avadex (tri-allate) delivering high levels of control under optimal conditions. However, its efficacy diminishes with modern, robust herbicide programs. Combining Avadex with newer modes of action, such as aclonifen and cinmethylin, has transformed rye-grass control.

Economic Considerations and Rotation Planning

For all grassweed species, escalating costs of chemical control necessitate considering spring cropping as an alternative. “High-level control is achievable, but cost-effectiveness and crop safety must guide decisions,” says Ms. Littleford.

Supporting Strategies: Nozzle Selection and Adjuvants

Trials reveal that nozzle choice significantly influences application efficacy. Drift reduction technology (DRT) nozzles improve compliance with regulations but can compromise performance. Optimising water rates and incorporating adjuvants like Backrow can mitigate this.

Integrating Cultural and Chemical Controls

Glyphosate provides an essential pre-drilling reset, aligning with the broader strategy of managing resistant weeds. Its effectiveness not only improves cultural control outcomes but also reduces dependency on post-emergence applications. By complementing glyphosate with diverse chemical options, growers can strengthen their grassweed management programs.

Conclusion

Achieving grassweed control is a multifaceted challenge requiring cultural, chemical, and technological solutions. By integrating these strategies effectively, growers can tackle resistant weeds, reduce costs, and safeguard crop yields.