As the growing season winds down some vegetation managers across the country may have wished for an extended summer so they could have managed more acres of brush on their rights-of-ways. The majority of brush managed with herbicides is performed during the growing season but the dormant season offers several opportunities to extend the brush control season well beyond leaf out to leaf drop.
Dormant season applications have been around for more than 20 years and provide proven methods for managing brush. These applications can start as early as the fall when many deciduous species begin leaf senescence and continue into the early spring just beyond bud break. These types of applications require using the right herbicides and application methods.
Managing brush during the dormant season may also provide several unique benefits. These benefits include managing brush around sensitive sites to reduce visibility or potential off-target movement as well as utilizing budget dollars while they are available and keeping good reliable crews working so they aren’t lost. Complaints resulting from foliage brown-out may also be reduced since most species do not have leaves at the time of application.
Two common types of dormant season applications are basal bark and dormant stem treatments. The foundation herbicide used with both treatments is Garlon® 4 Ultra. Depending on the site and management objectives other herbicides such as Milestone®, Tordon® K, or Stalker may be added for enhanced control. These mixtures may be mixed on site or ordered as a custom blend through the Continuum® System.
Basal bark applications are best suited for low density sites (no more than 500 stems per acre) on brush with ½ -6 inch diameter. This application method provides extreme selectivity to desirable species which can be important especially on sensitive or highly visible sites. Standard mixes consist of 20-25% Garlon 4 Ultra plus 75-80% basal oil and are applied by treating the bark on the lower 12-15 inches of each individual stem. This treatment is effective on virtually all woody plants.
Dormant stem treatments can be used on sites with varying brush densities but works best on brush with 2 inch or less in diameter. Application methods ranging from low volume backpack to hydraulic high volume may be used but the appropriate method should be matched to fit the brush height. These applications are similar to foliar treatments in crew productivity and volume applied per acre but differ in that the applicator targets the stems versus foliage. These treatments consist of a diluted solution of Garlon 4 Ultra plus oil which is then mixed with water.
Dormant Season Treatment Recommendations
Garlon® 4 Ultra specialty herbicide is an oil-soluble formulation and is the key to a successful dormant season vegetation management program.
| Herbicide Rates | Specific Recommendations |
| Basal Bark or Cut-Stump: 20-25% Garlon 4 Ultra + 75-80% basal oil | Effective all year. Do not apply to wet or saturated bark. Can be performed immediately or up to weeks later. |
| Dormant Stem Brush Control (High volume) 4-8 quarts of Garlon 4 Ultra + 3 gallons of Crop Oil Concentrate per 100 gallons of water (Low volume) 5-6% Garlon 4 Ultra + 0.25-0.33% Milestone + 0.33-0.75% Stalker |
Do not apply to wet or saturated bark as poor control may result. Use continuous adequate agitation. Apply during mid to late winter and very early spring typically from early January – late March. Best suited on brush with 2 inch or less diameter. |
Contact your local Dow AgroSciences representative for more information on how these treatments may fit within your program or visit www.vegetationmgmt.com.
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. State restrictions on the sale and use of Garlon 4 Ultra apply. Consult the label before purchase or use for full details. Milestone is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Tordon K is a federally Restricted Use Pesticide. Always read and follow label directions.