Answers to Frequently Asked Questions About Woody Plant Control in Prairies Using Vastlan™ (Garlon® 3A)* and Garlon® 4 Ultra

  • What is the difference between Vastlan specialty herbicide and Garlon 4 Ultra?
  • How do I decide whether to use Vastlan or Garlon 4 Ultra?
  • When do I mix Vastlan and Garlon 4 Ultra with water and when do I mix with basal oil
  • What is the difference between basal cut stump and cut stump applications?
  • When can I use a low volume basal bark treatment?
  • What air temperature can I apply Garlon 4 Ultra as a basal bark treatment?
  • Woody plants in prairies often grow in riparian areas and near waterways – what are the guidelines for using Vastlan and Garlon 4 Ultra near water?
  • When do I add Milestone® specialty herbicide to either Vastlan or Garlon 4 Ultra to control woody plants?

 

WHAT IS THE DIFFERENCE BETWEEN VASTLAN™ AND GARLON® 4 ULTRA?

Both Vastlan and Garlon 4 Ultra are formulations of the same active ingredient, triclopyr. Garlon 4 Ultra is a 4 pound acid equivalent per gallon (lb ae/gal) low volatile ester in a plant based oil carrier, whereas Vastlan is a 4 lb ae/gal water soluble amine in water.

HOW DO I DECIDE WHETHER TO USE VASTLAN™ OR GARLON ®4 ULTRA?

Garlon 4 Ultra will provide better woody plant control in general than Vastlan when applied as a foliar, basal cut stump, and basal bark treatment. Vastlan will provide good control as a cut surface application (always mix with water) and will provide fair to good control when applied as a foliar treatment (must have an adjuvant also). Vastlan should be used when applying in aquatic sites. The addition of Milestone to either product improves control of many species when applied as a foliar treatment, for example blackberries and Scotch broom.


WHEN DO I MIX VASTLAN™ AND GARLON® 4 ULTRA WITH WATER AND WHEN DO I MIX WITH BASAL OIL?

Mixing with Water

Always mix Vastlan or Garlon 4 Ultra with water for foliar applications with the addition of a nonionic surfactant or seed oil surfactant (e.g. methylated or ethylated seed oil). 
Always mix Vastlan with water for cut stump treatments; there is no need for the addition of a surfactant for this type of application. Note: applications with Vastlan must be made as soon as possible or at least within 30 minutes after cutting the stems.

Mixing with Basal Oil

Always use basal oil with Garlon 4 Ultra for basal bark, cut stump, and basal cut stump applications. Applications of Garlon 4 Ultra in basal oil for cut stump or basal cut stump can be made up to a week after cutting. The oil mixture normally penetrates the suberized (scar) layer that forms on the cut stump; however, if the scar layer is too thick, the stem may need to be re-cut to allow for application to the cambium. It is recommended that applications are made as soon as possible but no longer than two weeks following cutting to provide the greatest level of control. 

Note: Mixing Garlon 4 Ultra with oil requires vigorous agitation to form an oil solution. Once a solution is formed it will stay stable; however, agitation after four hours is recommended. 

WHAT IS THE DIFFERENCE BETWEEN BASAL CUT STUMP AND CUT STUMP? 

Basal cut stump applications involve cutting approximately six inches above the ground level and treating both the bark and exposed cambium (pictured below). Use only Garlon 4 Ultra for basal cut stump applications.

Cut stump applications involve cutting the tree close to the ground and treating only the exposed cambium in a continuous ring around the tree stump (including around any bark torn away from the stem) with the herbicide solution (photo, next page). A higher application rate is necessary (up to an undiluted rate) for cut stump treatments compared to modified cut stump treatment because less surface area is being treated. Both Garlon 4 Ultra and Vastlan can be used for cut stump applications.

Application Rates

  • Basal cut stump = Garlon® 4 Ultra at 25 to 30% volume to volume (v/v) in oil. [For example, mixing 1 quart of Garlon 4 Ultra with 3 quarts of basal oil would yield one gallon of a 25% solution].
  • Cut stump = Vastlan™ at 50% v/v in water or undiluted, or Garlon 4 Ultra at 20-30% v/v in oil or undiluted for hard to control species.
Comparison of a modified cut stump application (left) and cut stump application (right).

Comparison of a modified cut stump application (left) and cut stump application (right).

 

WHEN CAN I USE A LOW VOLUME BASAL BARK TREATMENT?

In general, woody plants that have stems less than 6 inches in basal diameter can be treated with Garlon® 4 Ultra in oil with a low volume basal bark application. Spray the basal parts of the tree trunks to a height of 12 to 15 inches from the ground, thoroughly wetting the stems but not to the point where herbicide runs off and puddles. Old or rough bark requires treating up to 18 inches from the ground. 

WOODY PLANTS OFTEN GROW IN RIPARIAN AREAS AND NEAR WATERWAYS – WHAT ARE THE GUIDELINES FOR USING VASTLAN™ AND GARLON® 4 ULTRA NEAR WATER?

Both herbicides can be used in seasonably dry wetlands and transitional sites, non-irrigation ditch banks, and other similar sites as described on the labels. Garlon 4 Ultra applications are more restricted around water (see herbicide label for more complete information). Vastlan can be used in and around standing water sites, such as marshes, wetlands, and the banks of ponds and lakes.  

WHEN DO I ADD MILESTONE® SPECIALTY HERBICIDE TO EITHER VASTLAN™ OR GARLON® 4 ULTRA TO CONTROL WOODY SPECIES?

Milestone does not need to be added for basal bark, cut stump or modified cut stump applications. The addition of Milestone to either Vastlan or Garlon 4 Ultra as a foliar treatment will improve control of many woody species including aspen, black locust, boxelder, cottonwood, and elm (Learn More: Woody Plant Control In Northern Prairies). Milestone will also control undesirable broadleaf weeds such as Canada thistle that may be growing in association with the trees.

*Vastlan specialty herbicide is formulated as a soluble liquid and contains 4 pounds acid equivalent per gallon of triclopyr choline. The choline formulation of triclopyr reduced the signal from “Danger” on Garlon 3A to “Warning”. Garlon 3A has a 3 lb acid equivalent per gallon.

APPLICATION RATE CONVERSION FOR GARLON® 3A TO VASTLAN™ SPECIALTY HERBICIDE


Published October, 2014; Updated August, 2017


®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. 

Milestone and Vastlan are 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.

Milestone: When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use for full details. 

State restrictions on the sale and use of Garlon 4 Ultra apply. Consult the label before purchase or use for full details.

Always read and follow label directions.