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March 2015

Extend The Season With Basal Bark Treatments

Low-volume basal bark treatments are an effective tool in vegetation managers’ toolboxes for controlling woody plants, especially when working in and around sensitive sites. These treatments also can be applied anytime, including during winter months, except when snow or water prevents spraying to the groundline or when stem surfaces are saturated with water. This flexibility extends the application season and allows for a potential reallocation of work crews early in the season when they are not as busy and have more time available.

With these treatments, herbicide is applied to the base of individual woody plants or stems, where it penetrates the bark to reach the cambium, then translocates to the roots and stems for complete control. Translocation is what makes the treatment highly effective and eliminates 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:

  • As selective treatments 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 desired vegetation

Milestone® provides flexibility and broader control.
Milestone® specialty herbicide is labeled for use as a lowvolume basal bark treatment, as well as for basal cut-stump and cut-surface treatments alone, for sensitive woody species in the Fabaceae family (legumes), or in combination with Garlon® 4 Ultra specialty herbicide on other woody species. The addition of Milestone to a basal mix provides a broader spectrum of control than with Garlon alone, but an additive may be necessary to mix Milestone into a Garlon 4 Ultra basal mix. Mix Milestone at 0.5 percent to 5 percent v/v alone or 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. These combination treatments are especially effective on rootsprouting species, such as cherry, locust or tree-of-heaven.

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. Again, these treatments can be done anytime, unless snow or water prevents spraying to the groundline or when stem surfaces are saturated with water.