Article by Jordan Sission
Crop Sales Specialist
AGRIS Co-operative - MUIRKIRK
As we approach the new growing season, most pre-buying decisions for fertilizer, seed, and other inputs are complete. While seed and fertility take top priority in crop planning, herbicide strategies must not be overlooked. With the rise of herbicide-resistant weeds and evolving crop chemistries, a well-thought-out herbicide plan is critical to maximizing yield and maintaining long-term weed control.
Why Herbicide Resistance Happens
Herbicide resistance develops over time due to repeated exposure to the same modes of action. Here’s how it happens:
- Genetic Variation – Some weeds naturally have genetic mutations that make them less susceptible to herbicides.
- Application Pressure – Repeated use of the same herbicide kills susceptible weeds, allowing resistant ones to survive.
- Survival & Reproduction – These resistant weeds pass their genes to the next generation, leading to stronger resistance.
- Increased Resistance – With ongoing herbicide use, resistant weed populations dominate, making control more difficult.
Factors That Accelerate Herbicide Resistance
- Overusing a single herbicide (e.g., glyphosate) increases resistance risk.
- Lack of rotation with different herbicide groups allows resistance to thrive.
- Insufficient herbicide rates leave partially resistant weeds behind, allowing them to adapt.
How to Combat Herbicide Resistance
Farmers can take proactive steps to manage weed pressure effectively:
- Rotate herbicides with different modes of action.
- Use tank mixtures containing multiple herbicide groups.
- Plant cover crops to suppress weed emergence.
- Practice crop rotation to disrupt weed life cycles.
- Use tillage strategically to manage weed seedbanks.
- Apply a pre-plant (PP) or pre-emergence (PRE) residual herbicide to gain early control.
The Benefits of Residual Herbicides
Adding a pre-emergent residual herbicide to your program enhances control and reduces weed competition before the crop emerges. Here’s why it matters:
1. Early Weed Control
- Eliminates weeds before they compete for sunlight, water, and nutrients.
- Provides residual activity, giving crops a head start without competition.
- Reduces the need for multiple post-emergence applications.
- Improves post-emergence herbicide effectiveness by targeting late-emerging weeds.
2. Increased Crop Yield
- Weeds steal essential nutrients, leading to yield loss.
- Starting clean = staying clean, ensuring better crop establishment and yield potential.
3. Resistance Management
- Diversifies herbicide modes of action, reducing selection pressure.
- Lowers reliance on post-emergence herbicides, slowing resistance development.
4. Long-Term Weed Seed Bank Reduction
- Prevents weeds from producing new seeds, reducing weed pressure in future seasons.
- Leads to lower weed populations over time, making long-term control easier.
Plan Ahead for 2025
Integrating pre-emergent residual herbicides into your weed management strategy ensures a cleaner start, stronger crops, and more sustainable weed control.
Contact your local AGRIS Crop Specialist today to discuss your herbicide program for 2025 and take control of weed management before the season begins!