Table of Contents

Can You Mix Glyphosate and Triclopyr? Understanding Herbicide Tank Mixing

The short answer is yes, you can generally mix glyphosate and triclopyr, but careful consideration of compatibility and application goals is crucial for optimal weed control and to avoid unintended consequences. While the combination can broaden the spectrum of weeds controlled and potentially offer synergistic effects, factors such as water quality, adjuvant selection, and specific weed targets must be carefully evaluated.

The Power of Herbicide Combinations: Why Mix Glyphosate and Triclopyr?

Combining herbicides like glyphosate and triclopyr, a practice known as tank mixing, can be a powerful tool in weed management. However, it’s not a decision to be taken lightly. It requires a solid understanding of herbicide modes of action, weed biology, and potential interactions between the chemicals.

Glyphosate is a non-selective, systemic herbicide that inhibits the EPSPS enzyme, disrupting amino acid synthesis and ultimately killing the plant. It’s highly effective on a wide range of annual and perennial weeds, particularly grasses. Triclopyr, on the other hand, is a selective, systemic herbicide belonging to the pyridine carboxylic acid family. It mimics the plant hormone auxin, causing uncontrolled growth that leads to plant death. It’s particularly effective on broadleaf weeds, especially woody species and brush.

The key advantage of mixing these herbicides lies in their complementary action. Glyphosate excels at controlling grasses, while triclopyr targets broadleaf weeds that glyphosate might not effectively control, particularly woody species and certain persistent broadleaves. This can lead to:

Broader Spectrum Control: A single application can control a wider range of weed species, reducing the need for multiple herbicide applications.
Enhanced Efficacy: In some cases, the combination can exhibit synergism, where the effect of the mixture is greater than the sum of the individual herbicides.
Reduced Weed Resistance: By using multiple modes of action, the risk of weeds developing resistance to either herbicide is potentially reduced.
Increased Efficiency: Single-pass application saves time, labor, and fuel costs.

However, improper mixing or application can lead to:

Reduced Efficacy: Antagonism between the herbicides can decrease their effectiveness.
Phytotoxicity: Damage to desirable plants due to off-target movement or improper application rates.
Tank Mix Incompatibility: Physical or chemical incompatibility can lead to clumping, settling, or nozzle clogging.

Compatibility Considerations: Avoiding Tank Mix Fails

While glyphosate and triclopyr are generally considered compatible, careful attention to detail is crucial. The first step is to consult the product labels of both herbicides. These labels provide critical information on compatibility, mixing instructions, and recommended adjuvants.

Water Quality

Water quality is a critical factor. High levels of minerals, particularly calcium and magnesium (hard water), can bind to glyphosate, reducing its effectiveness. Similarly, a high pH can affect the solubility and stability of both herbicides. A water conditioner or buffering agent may be necessary to adjust the water pH and reduce mineral interference. Always test your water quality before mixing herbicides.

Adjuvant Selection

Adjuvants are substances added to herbicide mixtures to improve their performance. They can enhance spray droplet retention, increase herbicide penetration into the plant, and reduce spray drift. Non-ionic surfactants (NIS) are commonly used with glyphosate to improve its uptake. Triclopyr may also benefit from a surfactant, but always check the product label for specific recommendations. Be cautious when adding multiple adjuvants; they can sometimes interact negatively.

Mixing Order

The order in which you add the herbicides and adjuvants to the tank is crucial. A common recommendation is the “WALES” sequence:

Wettable powders and dry flowables
Agitation (start and maintain throughout the mixing process)
Liquid flowables
Emulsifiable concentrates
Surfactants

Always add the herbicides and adjuvants slowly and with continuous agitation. Conduct a jar test before mixing a large volume in the spray tank. This involves mixing small amounts of the herbicides and adjuvants in a clear jar to observe any physical incompatibility, such as clumping or settling.

Understanding Application Rates and Timing

Applying the correct rates of glyphosate and triclopyr is essential for effective weed control and to minimize the risk of phytotoxicity. The recommended rates will vary depending on the weed species, their size, and the application method. Always follow the label instructions carefully.

Timing is also critical. Applying the herbicides when weeds are actively growing and susceptible is crucial for optimal results. For perennial weeds, applying the herbicide during translocation periods (when the plant is moving nutrients to its roots) can improve long-term control.

FAQs: Mixing Glyphosate and Triclopyr for Effective Weed Control

Here are some frequently asked questions to further clarify the nuances of mixing glyphosate and triclopyr:

1. Can I mix glyphosate and triclopyr with other herbicides?

While possible, adding more herbicides increases the complexity and the risk of incompatibility. Thoroughly research the compatibility of all herbicides being mixed and consider the potential for antagonism or phytotoxicity. Consult the product labels and, if possible, seek advice from an agricultural consultant or extension specialist.

2. What are the signs of incompatibility in a tank mix?

Visible signs of incompatibility include: clumping, settling, foaming, gelling, and changes in color or viscosity. If any of these occur, do not use the mixture.

3. Can I use glyphosate and triclopyr near water bodies?

Always check and adhere to local, state, and federal regulations regarding herbicide application near water. Both glyphosate and triclopyr have the potential to impact aquatic environments. Use appropriate buffer zones and application techniques to minimize the risk of drift. Specific formulations designed for aquatic use may be required in certain situations.

4. What safety precautions should I take when mixing and applying these herbicides?

Always wear appropriate personal protective equipment (PPE), including gloves, eye protection, and a long-sleeved shirt. Follow the label instructions for handling, storage, and disposal of the herbicides. Avoid contact with skin and eyes, and do not inhale the spray mist. Wash thoroughly after handling.

5. Will this mixture kill grass?

Glyphosate is non-selective and will kill most grasses. Triclopyr is generally less effective on grasses. If you want to selectively control broadleaf weeds in a grassy area, consider using triclopyr alone or another broadleaf-specific herbicide.

6. How long after application before I can see results?

The time it takes to see results will vary depending on the weed species, their size, the environmental conditions, and the application rate. Generally, you should start to see symptoms within 7-14 days, but complete control may take several weeks.

7. What if it rains shortly after application?

Rainfall shortly after application can wash the herbicide off the foliage, reducing its effectiveness. The label will specify the rainfast period for each herbicide. As a general rule, allow at least 2-4 hours of dry weather after application.

8. Can I mix glyphosate and triclopyr with liquid fertilizer?

Mixing herbicides with liquid fertilizer can be done, but it increases the risk of incompatibility. Always conduct a jar test first to ensure the mixture is stable. Be aware that the fertilizer may affect the herbicide’s efficacy.

9. What’s the best time of year to apply this mixture?

The best time to apply is when weeds are actively growing and susceptible to herbicide application. This typically occurs during the spring and summer months. Avoid applying during periods of drought or extreme temperatures, as this can reduce the herbicide’s effectiveness.

10. How do I clean my spray equipment after using this mixture?

Thoroughly clean the spray equipment immediately after use to prevent contamination of future applications. Use a commercially available tank cleaner designed for herbicides. Rinse the tank, hoses, and nozzles multiple times with clean water.

11. Can I use this mixture on my lawn?

Generally no. Triclopyr will damage most desirable turfgrass species. Glyphosate will kill everything it contacts. Spot treating weeds very carefully with triclopyr in a lawn situation is possible, but requires precision. Avoid using glyphosate in lawns unless you are prepared to re-seed or re-sod the treated area.

12. Where can I find more information about herbicide compatibility?

Consult the product labels of the herbicides. Contact your local agricultural extension service or an agricultural consultant for specific recommendations for your situation. Many universities also offer online resources and guides on herbicide compatibility.