1. Not All Herbicides Work the Same Way

Herbicides differ greatly in how they control plants, even if they target the same weeds.

• Contact vs. systemic activity
• Soil-active vs. foliar-only uptake
• Selective vs. non-selective control

Understanding the herbicide’s mode of action helps ensure the product reaches the target weed and controls it effectively rather than just burning back top growth.

2. Timing Often Matters More Than Rate

Applying the right herbicide at the wrong time can lead to poor control—even at higher rates.

• Weed growth stage (seedling vs. mature plants)
• Seasonal movement of carbohydrates (especially for woody plants)
• Soil temperature and moisture for residual products

Many failures come from late applications rather than incorrect product choice.

3. Weather Conditions Can Make or Break an Application

Environmental conditions directly affect herbicide performance.

• Wind speed and direction (drift risk)
• Rainfall before or after application
• Temperature extremes
• Drought stress on target weeds

Reading the label’s environmental restrictions is essential to avoid off-target injury and maximize control.

4. Application Method Is Just as Important as Product Selection

Herbicides can be applied in many ways, and each method serves a different purpose.

• Broadcast spraying
• Spot treatments
• Backpack and hand-sprayer applications
• Basal bark and cut-stump treatments
• Wiper and wick applications

Choosing the right method improves accuracy, reduces herbicide use, and protects desirable vegetation. See our Different Herbicide Application Methods post for more information on this subject.

5. Herbicide Labels Are Legal Documents

The label is not just guidance—it’s the law.

Labels define:

• Approved use sites
• Target weeds
• Application rates
• Personal protective equipment (PPE)
• Re-entry and grazing restrictions

Using a product outside of label directions can result in crop injury, environmental damage, or regulatory violations.

6. Residual Control Can Be a Big Advantage—or a Risk

Some herbicides provide soil residual activity that prevents future weed emergence.

Residual control:

• Extends weed suppression
• Reduces follow-up applications
• Helps maintain clean sites

However, residuals can also affect rotational crops, newly seeded areas, or nearby desirable plants if not carefully managed.

7. Resistance Management Starts With You

Overusing the same herbicide mode of action can lead to herbicide-resistant weeds.

Best practices include:

• Rotating modes of action
• Using tank mixes when appropriate
• Integrating mechanical or cultural control methods
• Targeting weeds early

Resistance prevention protects herbicide effectiveness long-term.

8. Adjuvants Matter More Than Most People Realize

Adjuvants can significantly improve herbicide performance when used correctly.

Common adjuvant functions include:

• Improving leaf coverage
• Increasing penetration
• Reducing spray drift
• Enhancing rainfastness

Not all herbicides require the same adjuvants, so label compatibility is critical.

9. More Is Not Always Better

Applying higher rates than needed does not guarantee better control.

Excessive rates can:

• Increase crop or turf injury
• Raise environmental risk
• Waste product
• Increase resistance pressure

Using labeled rates matched to weed size and pressure is the most effective approach.

10. Herbicides Are Tools—Not Standalone Solutions

The best weed control programs combine herbicides with sound management practices.

Successful programs often include:

• Proper fertility and soil management
• Competitive desirable vegetation
• Mowing or grazing strategies
• Mechanical control when needed

Integrated management delivers longer-lasting results than herbicides alone.

Final Thoughts

Herbicides remain one of the most effective weed management tools available—but success depends on knowledge, planning, and proper execution. By understanding how herbicides work and how to apply them correctly, land managers can achieve better control, reduce costs, and protect both crops and the environment.