During the dormant season, some vegetation management programs are put on the shelf and left to wait until the following spring. However, the ideal vegetation management program has the ability to be effective year-round, and the dormant season is no exception.
The size or diameter of the trees, along with the density of brush, site characteristics and timing of application, determine dormant-season treatment options. There are three main application types that are recommended during the dormant season: basal bark, cut-stump and dormant stem.
This method uses a low rate of herbicide to control trees with ideal effectiveness, occurring when stems are less than 6 inches in diameter. As stem diameters increase, low-volume basal treatments become less effective.
This treatment method is highly efficient for treating long stretches of low-density brush on rights-of-way with fewer fill-ups. Low-volume basal treatments are effective at selectively removing the undesired vegetation and maintaining desirable plants, as opposed to mechanical removal methods, which are nonselective.
Basal bark treatments can be used year-round — except when snow, ice or water prevents spraying to the ground line. Use basal bark treatments for trees that are less than 6 inches in diameter in areas with low to medium stem density (less than 2,000 stems per acre). Spray the lower 12 to 15 inches of bark circumference until wet, but not to the point of runoff, using a solid- or adjustable-cone nozzle. And remember — if the solution turns white when applied to bark, it’s an indicator that the bark is too wet and the treatment may be less effective.
Keep in mind that old or very rough bark requires more spray than smooth, young bark.
Another viable option, depending on brush density, is a dormant-stem treatment. High-density areas that can’t be treated in the summer because they are adjacent to crops or other sensitive areas are a good fit for dormant-stem treatments. Applications can be made in late fall after the leaves have dropped, or during winter.
This method is best for dense stands of woody plants that are difficult to control individually and are less than 3 inches in diameter. Plants with diameters larger than 3 inches may not be controlled, and re-sprouting may occur. Using this method in the dormant season has minimal brownout and prevents brush from leafing out in the spring.
Closely resembling a foliar treatment, dormant-stem treatments are delivered through a powered hydraulic sprayer or handgun. In the Western states, applications should be made anytime after woody plants are dormant. In other areas, spray target brush within 10 weeks of bud break, generally February through April.
Where tree removal is part of maintenance operations, a cut-stump treatment is worth consideration. If the money’s been spent to remove a tree mechanically, cut-stump makes the most sense to keep the vegetation from re-sprouting. Using this treatment method will help defend any investment you have in mechanical cutting and chipping. If treating near highly visible areas, there is no unsightly brownout since only the stumps are treated.
There are two different herbicide types that are effective for cut-stump treatments: oil-based and water-based herbicides. Both can be made anytime of the year, except when snow, ice or water prevents spraying to ground level.
When using oil-based herbicides, applications can be made anytime after cutting. Optimum timing for oil-based herbicides is as soon as possible or within two weeks after cutting. Treat the cambium and outer 2 inches of sap wood (xylem) inside the bark around the entire circumference of the exposed bark as well as any exposed roots around the stump to ground level, but not to the point of runoff.
Water-based treatments should be made immediately after cutting. Treat only the cambium and outer 2 inches of sap wood (xylem) inside the bark around the entire circumference. If the bark has ripped off the stump, then treat around the ripped area as well as the top of the stump. Avoid treating during heavy sap flow (usually in early spring), since this can reduce herbicide effectiveness.
Article provided by Dow AgroSciences. For more information on dormant-season treatment methods to keep your program efficient year-round, visit www.vegetationmgmt.com Always read and follow label directions.
Photos courtesy of Dow AgroSciences.