Basal Bark Treatment: What is it and how is it used?

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Basal Bark Treatment: What is it and how is it used?

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The spring season ushers in new growth, someof it good and others not so good.

  • The good: Trees are lush with leaves, lawns grow, and April showers bring forth May flowers. How beautiful it is when spring arrives!
  • The not so good: Breaking the serene landscape, weedy and invasive plants emerge to fill whatever space is available as they seek to survive and perhaps dominate habitats. Among the weedy invaders area variety of species and lifecycles rangingfrom easy-to-control herbaceous plants to hardier woody plants and annuals to perennial plants.The woody perennials are a beast to manage.

As each plant species fights for space and becomes established, it is the hardier woody plants that will eventually become the dominant species. This scenario plays out each year in areas that don’t receive adequate management like our crops or lawns do. For example, the vegetation along roads, railways, and utility rights of way.

When habitats are invaded by hardier woody plants, a basal bark treatment can be used as a highly effective go-to management technique.

What is a basal bark treatment?

A basal bark treatment is a control method for woody invasive plantswhere herbicide spray mixture carried in oil is sprayed onto the basal stem portion of target plants.However, to be effective, the basal bark treatment should be appliedwhenthebasal stem diameter of the woody invasive plant is no more than six inches.

Why are basal bark treatments important?

Management of vegetation along the nation’s highway, railway, and electric utility rights of way is critical for sustaining our way of life. The total acreage in the United States that must be managed to prevent hard wooded species from becoming established encompasses over 4 million miles of roads, 140,000 miles of railway, and 160,000 miles of electrical powerlines.

The consequences of unmanaged vegetation

Roadside vegetation.Poorly managed and overgrown woody plants inroadside vegetation will affect visibility of drivers and possiblylead to vehicle accidents. In some instances, such as during inclement weather,significant amounts of plant debris and tree branches from roadside vegetation could end up on the road and impede traffic or cause accidents.

Railway right of way vegetation.Poorly managed and overgrown woody plants, plant debris, or fallen trees on railway tracks can impede railway traffic which could lead to derailments.

Electricalright of way vegetation.Poorly managed woody plants can have devastating impacts on the electrical power supply. For example, in August 2003, the largest electricity blackout in the United States and Canada happened when powerlines and trees came into contact with each other in Ohio. The short circuit led to a blackout which affected 50 million people, caused at least 11 deaths, and had an estimated cost of $6 billion.

The potential impact of woody plants to livelihoods everywhere and to the economy is significant and warrants attention. Invasive woody species are difficult to control using over the top herbicide spraying techniques. Basal bark treatments, on the other hand, provide an effective way to target small woody plants species.

How do basal bark treatments work?

Herbicides mixed with oil-based surfactants can penetrate the relatively thin bark of smaller trees, shrubs, and woody vines. The herbicide spray mixture is transported by the vascular tissue to the root system, preventing regrowth. Injury symptoms may not be observed for several weeks, and woody plant may not die for months following treatment.

Highlights of basal bark treatments

  • Basal bark treatments can be applied any time of year. However, control may be reduced in the spring when trees are flush with new growth.
  • Winter is often the most ideal time to make basal bark treatments because of cool temperatures which enforce dormancy among trees and herbaceous plants.
  • Basal bark treatments will not provide rapid control and symptoms of injury will not be observed for several weeks after application. Complete control may require several months.
  • Basal bark treatments are not effective on older trees greater than six inches in diameter or trees with very thick bark.

How to use basal bark treatments

  1. Select a herbicide that is approved for application in rights of way. Be sure to read the herbicide label carefully and completely. For best results, select an oil soluble herbicide with instructions for basal bark treatment application.
  2. Select the proper adjuvant that is designed for basal bark treatments. For example:
    1. Brewer Basal Oil™ – A spray diluent for basal bark treatments of herbicidesthat is composed of all-natural vegetable oil and is a carrier for oil-soluble herbicides.
    2. Brewer Basal Oil Blue LT™- A low temperature spray diluent for basal bark treatments of herbicide. It is composed of a blend of petroleum based basal oils and is a carrier for oil-soluble herbicides.
    3. JLB Oil Plus™- A spray diluent for basal bark treatments forbrush control herbicides. It is composed of a blend of basal oils and eliminates the need fordiesel or kerosene as a surfactant.
    4. Improved JLB Oil Plus™ – A spray diluent for basal bark treatment for brush control herbicides. It is composed of all natural vegetable oils and eliminates the need for diesel or kerosene as a surfactant.
  3. Applybasal bark treatments using a handheld sprayer or backpack sprayer.
  4. Apply herbicide spray mixture to the lower 12 to 18 inches of the bark of woody plants with trunks that are no more than six inches in diameter. Herbicide spray should be applied to wet the surface, and not so much as to generate runoff. To be effective, all sides of the plant must be covered with the herbicide spray.

Benefits of using Basal Applications

  • The herbicide – oil mixture will penetrate the bark and be transported down to the root system where it will cause the most harm to the targeted plant.
  • Nearby off-target desirable trees and shrubs should not be impacted.
  • The technique can be successfully accomplished on sites where foliar herbicide applications are difficult to make due to plant foliage being out of reach or is intermingling with desirable non-target plants.
  • The technique is effective when plants are dormant, even when leaves are absent, as long as temperature and environmental conditions allow.

Read the label

For the best results, read the label and follow all instructions.

Further Reading


Brewer International ( has been a leader in land and water chemistry since the 1980’s and for over 40 years has proudly served it’s national and regional distributors.

Our products are used widely across the United States in agriculture, aquatics, forestry, rights of way, and land management.

Our customers trust our dedication to quality ingredients, tried and true formulas, and positive outcomes.

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