Control Unwanted Brush with Basal Bark Treatments All Year Long


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Basal bark applications with Garlon 4 Ultra are an excellent way to control unwanted brush species anytime of year. This treatment method is effective on virtually all woody stems and vines and is less labor intensive than mechanical or tree injection methods. Extend your brush control season to include the dormant season with the use of basal bark treatments.

These treatments are perfect for trees and brush that are too large for backpack foliar applications, or where a selective treatment is needed to reduce the impact on surrounding desirable plant species.  

Use basal bark treatments on sensitive sites such as high visibility areas during the fall and winter to control unwanted brush and avoid foliage brown-out.  Fall, winter, and spring applications provide the best access for treatment due to the lack of existing foliage.  Garlon 4 Ultra herbicide mixed with commercial basal oil or other oil-based carriers is a very dependable year-round treatment for controlling unwanted trees and brush.  

Suggested areas to utilize basal treatments

  • Fencerows
  • Bridge ends and embankments 
  • Urban environments 
  • Near desirable vegetation 
  • Back lots on a utility distribution system 
  • Near sensitive sites 
  • Low density brush sites

When using Garlon 4 Ultra as a basal treatment, it is important to remember:

  • Basal applications work best on woody species with trunks less than six (6) inches in basal diameter.  
  • Evenly spray the lower 15 to 18 inches of the stem on all sides, including the root collar, but not to the point of run-off; make sure all sides of the stem are treated. 
  • Do not apply to bark that’s wet from heavy dew and rain. If the herbicide/penetrating oil mix turns white when applied to bark, it’s an indicator that the bark is too wet and the application won’t work.  
  • Typical basal mixtures are 20-25% Garlon® 4 Ultra in 75%-80% basal oil.  Another option for low volume users is Pathfinder® II herbicide

Pathfinder II is a ready to use spray formulation of Garlon 4 Ultra and basal oil.  

  • Since it is ready-to-use, Pathfinder II eliminates the need for mixing and ensures proper rates.  
  • Pathfinder II contains a nonpetroleum diluent, derived from naturally occurring vegetable oils that provides superior penetrating capabilities, even during winter months.  

Recommended Equipment for Basal Applications

  • Apply with a backpack sprayer using low pressure (~20 psi).   
  • Examples of recommended backpack sprayers are  - 10 K Birchmeier or 15K Birchmeier; Solo Model 475 Diaphragm Pump Sprayer; SP Systems SP1 Backpack Sprayer 
  • An adjustable-cone nozzle such as Spraying Systems ConeJet 5500-X3 or Y3 up to X8 is ideal for basal applications and allows applications to be made close up and as far away as about 10 feet through adjustment of the nozzle.   
  • Flat fan or hollow cone nozzles also work but do not allow as much flexibility as the adjustable-cone nozzles

For more information on Garlon 4 Ultra or Pathfinder II, please contact Travis Rogers with Dow AgroSciences. 

Travis Rogers 
Forestry & Vegetation Management Specialist