Keep on treating this fall using basal bark applications

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Man conducting basal bark treatments

There’s no reason to put herbicides on the shelf when fall hits. Basal bark treatments are very effective managing brush in the “off-season” — especially when a more targeted approach is needed.

As foliar season ends, it’s good to have options that allow for the continued treatment of unwanted brush. Low-volume basal bark treatments can be applied anytime, and they also provide a targeted control solution when working in and around sensitive sites. And best of all, they are highly effective when done properly, and using the right herbicide mix.

With these treatments, herbicide is applied to the base of individual woody plants or stems, where it penetrates the bark to reach the cambium. It then translocates to the roots and stems, providing complete control and eliminating resprouting or regrowth.

In general, low-volume basal bark treatments work best in areas with medium to low stem density (fewer than 2,000 stems per acre), and with stems up to 6 inches in diameter and any height. Low-volume basal bark treatments are most effective in the following situations:

“The objective of our research is to protect these landscapes from one of the most problematic weed invaders in the West through proper management,” Dr. Tekiela says. “We’re looking to record the results of multiple different herbicide treatments on leafy spurge in combination with grazing and without grazing.”

  • As a selective treatment where other species are to be left untreated
  • As a follow-up to mechanical clearings or reclamation projects
  • For treating areas of high public visibility or areas that are inaccessible to heavy equipment
  • On sites that require routine — but not intensive — maintenance
  • Where a low profile is required to maintain desirable vegetation
  • On sites not able to be treated during the foliar season

Using a backpack sprayer, apply spray solution with the appropriate nozzle (flat fan or solid cone) to the lower 12 to 15 inches of bark to the ground level. Spray until the bark is wet but not to the point of runoff. Old or rough bark will require more spray than young, smooth bark. When applying to trees with exposed roots, continue treatment down the root collar to the soil line for maximum effectiveness. Treatments can be done anytime, unless snow or water prevents spraying to the groundline or when stem surfaces are saturated with water.


The industry standard for low-volume basal bark treatments is Garlon® 4 Ultra herbicide, which controls more than 80 woody plants and vines. It features a patented, nonpetroleum-based, plant-derived seed oil solvent that helps reduce environmental impact. To control susceptible woody plants with stems less than 6 inches in basal diameter, mix 20 to 30 gallons of Garlon 4 Ultra in enough oil to make 100 gallons of spray mixture.

Adding Milestone® herbicide provides an even broader spectrum of control. This combination is especially effective on root-sprouting species, such as cherry, locust and tree-of-heaven. Mix Milestone at 0.5 percent to 5 percent v/v with Garlon 4 Ultra in a commercially available basal diluent. The basal oil should be compatible with a water-soluble herbicide, such as Milestone. Herbicide concentration will vary with tree diameter, bark thickness, volume used per acre and the susceptibility of the species being treated.


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™®Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Garlon 4 Ultra and Milestone apply. Consult the label before purchase or use for full details. Always read and follow label directions.


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