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Pre-Emergent Herbicide Planning for Next Season

Pest Control · November 2025 · 5 min read

Planning your pre-emergent herbicide program in fall gives you time to evaluate this year's weed escapes, rotate chemistries, and take advantage of early-order discounts from suppliers. Resistant weed populations continue to expand, making soil-applied residual herbicides more important than ever for maintaining effective control. A layered approach with multiple modes of action is the foundation of modern weed management.

Soil-Applied Residual Herbicides

Residual herbicides applied to the soil surface before weeds emerge provide a critical window of control that reduces early-season competition. Products in Groups 5, 14, and 15 are the backbone of most residual programs in corn and soybeans. The key is selecting products that target your specific weed spectrum while avoiding chemistries that have shown resistance in your fields.

Residual activity depends on soil type, organic matter, and rainfall to activate the product. Sandy soils with low organic matter need lower rates to avoid crop injury, while heavy clay soils may need higher rates for adequate weed control.

Overlapping Residuals and Resistance Management

The overlapping residual strategy applies a second residual herbicide at the post-emergence timing to extend soil activity into mid-season. This approach keeps residual protection active during the critical weed-free period and catches any weeds that escape the initial application.

• Use at least two effective modes of action in every application
• Rotate herbicide groups between years and applications within the same season
• Never rely on a single mode of action, especially Group 9 (glyphosate) alone
• Scout fields after each application to identify escapes and adjust future programs

Fall Burndown and Spring Timing

A fall burndown application controls winter annual weeds like marestail, henbit, and chickweed before they become established. Fall-emerged marestail is much easier to control with herbicides than spring rosettes that have developed extensive root systems. Adding a residual product to the fall burndown extends control into early spring.

For spring pre-emergent applications, timing is critical. Apply close to planting for maximum residual activity during the early-season weed flush. Applications made too early may lose activity before the most critical period. Review product labels for plant-back restrictions and rotational crop limitations before finalizing your program.