Triclopyr is a selective, systemic herbicide highly effective against broadleaf weeds, vines, and woody plants that resist common weed killers. As a synthetic auxin, it mimics plant growth hormones, causing uncontrolled growth that leads to plant death. Determining the correct concentration—how much Triclopyr per gallon of water—is essential for effective control without wasting product or damaging desirable plants. The required mixing rate is not a single value but depends entirely on the specific product formulation, the type of weed being targeted, and the application method.
Understanding Triclopyr Formulations
Triclopyr is commercially available in different chemical structures, most commonly as an Amine salt or an Ester formulation. This distinction heavily influences its use and mixing requirements. Amine formulations, often labeled with a low acid equivalent such as 3 pounds per gallon, are water-soluble and less volatile than the ester version. This lower volatility makes the Amine formulation suitable for general turf applications, especially in warmer temperatures, because the risk of damaging nearby desirable plants from vapor drift is reduced.
In contrast, Ester formulations typically have a higher acid equivalent, often around 4 pounds per gallon, and are oil-soluble. The Ester form penetrates the waxy cuticle of leaves and bark more effectively, making it the preferred choice for controlling tougher, woody brush and for basal bark treatments. Because the Ester formulation is more volatile, it should be used with caution when temperatures exceed 85 degrees Fahrenheit to prevent the chemical from vaporizing and drifting. Always check the product label for the specific concentration, as this figure dictates the final amount of product needed per gallon of water.
Standard Dilution Rates for Common Weeds
For general control of broadleaf weeds such as dandelions, clover, or plantain in turfgrass, a low-concentration mixture is typically used for foliar spray applications. These rates are designed to be strong enough to kill the weed without harming the turf, which is generally tolerant of Triclopyr. A common starting point for many concentrated products is to mix 0.38 to 0.75 fluid ounces of the product per 1,000 square feet.
When adapting this to a single gallon of water for a spot treatment using a backpack or hand sprayer, a typical rate is between 0.5 to 1.5 fluid ounces of concentrate per gallon of water. The exact amount depends on the weed’s resistance and stage of growth; younger, actively growing weeds often require the lower end of the range. These guidelines must be cross-referenced with the specific instructions on the product label, which contains the legally mandated application rates. Using a non-ionic surfactant with these mixtures is often recommended to help the spray stick to and penetrate the weed’s leaf surface more effectively.
Mixing for Tougher Brush and Woody Plants
Controlling established brush, vines, and small saplings like poison ivy, multiflora rose, or various hardwoods requires significantly higher concentrations of Triclopyr. For high-volume foliar treatment of woody plants, the mixing rate can be as high as 1 to 3 quarts of concentrate per 100 gallons of spray mixture. When converting to a single gallon for spot treatments on brush, the concentration can range from 2 to 4 fluid ounces of product per gallon of water.
For the most difficult woody plants, or for basal bark treatment, the application is often made with an oil-based carrier instead of water to improve penetration through the bark. A mixture of 20 fluid ounces of the Ester formulation in one gallon of an oil-based carrier, such as fuel oil or mineral oil, is highly effective for basal bark applications.
Essential Safety and Application Guidelines
Safe handling of Triclopyr requires the use of appropriate Personal Protective Equipment (PPE). This protection includes chemical-resistant gloves, protective eyewear, long-sleeved clothing, and closed-toe shoes with socks. Always work in a well-ventilated space when mixing the concentrate and ensure that children and pets are kept away from the product and the treatment area.
Environmental precautions are necessary to prevent off-target damage and contamination. Avoid applying Triclopyr when wind speeds are high to minimize spray drift onto desirable plants or water sources. The Amine formulation may be used in or near water if it has an aquatic label, but the Ester formulation is highly toxic to aquatic organisms and should never be applied directly to water. After application, properly clean all equipment with water and a detergent, disposing of the wash water in accordance with local regulations to prevent environmental contamination.