March 2014

Dormant-stem Treatments Can Extend the Application Season

Unwanted trees and brush can be a real scourge to vegetation managers whose job it is to keep rights-of-ways properly maintained. The presence of trees or brush under transmission or distribution lines may reduce accessibility, which is important during storm outages, or increase the risk of a power outage if they grow into the lines.

Vegetation managers oftentimes rely on herbicide treatments to help control unwanted vegetation, while preserving desirable vegetation. And although this is an ongoing challenge, there is the tendency for crews to slow or shut down during the cooler months when most vegetation goes dormant. One option to stay on top of encroaching brush is to use dormant-stem treatments that can be made later in the fall, throughout the winter months and even into spring when many have put their application equipment up until the next growing season. These treatments can not only extend the application season but also keep good, productive crews working.

Low-volume Backpack Treatment
Used in the winter to early spring time period, this dormant-stem treatment allows the application season for brush control to begin at fall leaf senescence and continue until early bud break. This timing offers the opportunity for a reallocation of work crews from late to early in the season when most crews are shutting down for the season.

Treatments are recommended between fall leaf senescence and up to 25 percent plant leafout. The application technique is similar to foliar applications except there is no foliage to spray (except with evergreen species such as conifers, which are treated the same as dormant deciduous trees).

For low-volume backpack treatments, the recommended tank mixes are listed in the charts below.

These rates are recommended for low to medium brush density (up to 1,500 stems per acre) at heights of 5 to 8 feet tall or less and are applied at total volumes between 6 to 30 gallons per acre of mixed solution. Rates will vary by target vegetation and brush density. Always read and follow all labeled rate restrictions.

Excellent Control With Added Benefits
Utilities using these treatments have seen anywhere from 85 to 90 percent control on hardwoods such as maple and oak, as well as conifers such as hemlock and pine. Another benefit of the selective mix is its selectivity to grasses, lilies, ferns and monocots, as well as providing for early spring greenup of desirable plants. For roadside managers, the treatment also has exhibited control on broadleaf weeds in spring.

In addition, depending on application timing and species, many targeted plants simply don’t leaf out in the spring following application so there is no visible brownout effect (except on evergreen species), reducing public visibility and potential complaints. Many evergreen species brown out slowly instead of rapidly due to reduced plant growth during the dormant period. Also, because of the soil activity of Milestone® specialty herbicide, the treatments will provide seedling control of weeds sensitive to activity with Milestone.