Managing incompatible woody brush is crucial for the success of roadside and utility vegetation management programs. Dormant stem broadcast herbicide applications help vegetation managers increase efficiency by extending the spraying season.
Dormant stem applications are broadcast treatments applied in late fall, winter, and early spring. The herbicides are mixed with an oil carrier and sprayed directly onto the stems of standing brush.
APPLICATION BENEFITS
Dormant stem brush applications extend the broadcast spraying window into winter, minimizing the risk to non-target species and enabling trained crews with calibrated equipment to continue working.
One key advantage of these treatments is the absence of brownout, making them an ideal choice for managing dense brush in high-visibility areas such as roadsides and utility rights-of-way. Selective herbicides target problematic woody species while promoting the growth of grasses that enhance biodiversity and support wildlife habitats.
TIMING
In the eastern U.S. and Midwest, the optimal time for dormant stem treatments is late winter, ideally within 10 weeks before bud break. During this period, plants are still dormant but preparing for new growth, making them more susceptible to herbicide absorption. Late fall and early winter applications are generally less effective due to the slower uptake of herbicides by woody plants.
In the western U.S., treatments can be applied anytime after woody plants become dormant, with more flexibility due to the region’s climate.
EQUIPMENT
There are several methods for applying dormant-stem treatments, with the most common being truck-mounted manifold sprayers and handgun applications.
Truck-mounted manifold sprayers are typically attached to the side or back of a truck, spraying to one side. The spray head consists of multiple nozzles (a mix of straight stream, off-center, and flat-fan) mounted in a shielded manifold to ensure a wide, even swath. Various commercial spray heads, such as Radiarc® and Directa-Spray, are available to control droplet size.
Handgun applications use high-pressure pumping systems, often with a hose reel and an adjustable gunjet-type sprayer. These applications can be made while walking or from the back of a truck. Proper adjustment of the spray pattern for the range and size of the brush is essential for good coverage without over-saturating the target.
Dormant-stem treatments also work well for spot or individual plant treatments using backpack sprayers for scattered brush.
APPLICATION
Uniform application is very important to successful dormant stem broadcast applications. Truck mounted sprayers apply a set volume of spray mix at a prescribed speed, delivering a precise rate per acre. Handgun application volume will vary by brush density.
Optimum volume per acre for dormant stem applications is about 100 gallons of total mix per acre. This is needed for good coverage of the entire crown, all stems and branches targeted in the treatment zone. Thoroughly wet all portions of the brush, but not to the point of runoff. The herbicide is carried into the plant by penetrating the thin bark layer on the branches and trunk.
A skid sprayer, backpack, or pressurized hand sprayer outfitted with a narrow cone nozzle operated at 35-40 PSI also provides an adequate spray pattern.
PRODUCTS
Ester, or oil-based herbicides, are the foundation formulations for dormant-stem treatments.
Garlon® 4 Ultra and TerraVue are the most commonly used products for broadcast dormant stem applications. They mix well in basal carriers and provide effective, broad spectrum control of many woody species. These are selective herbicides that will not affect desirable grasses needed to hold slopes and prevent erosion.
KEYS TO SUCCESS
- Do not apply when the ground is frozen or covered in snow.
- Apply only when the bark, stems, and branches are dry. Applications made when bark is wet will cause the spray mix to emulsify (turn milky white) and reduce efficacy.
- Keep soil active products out of the root zone of desirable trees.
- Spray brush up to 10 feet tall or 2 inches in diameter.
- Prevent spray drift onto sites where crops will be grown during the next growing season.
- Ensure complete coverage of the entire stem and trunk of targeted plants
- Use basal oils to improve herbicide penetration, enhance coverage and optimize results.
- Constant spray tank agitation while spraying is required.
- Do not spray stems over desirable vegetation that is not dormant, or non-target plant injury may occur.
- Complete all applications before bud break on deciduous brush species.
HOW TO GET HELP
Contact your local Azelis A&ES rep for recommendations on dormant stem applications in your area.
Azelis A&ES has experienced representatives that can help you make the right decision for your land management objectives. We are ready to provide you with a safe and effective solution. Talk to one of our technical experts to get started today!