Undesirable or invasive woody vegetation threatens the biology and ecology of grasslands and native woodlands. Understanding various techniques for applying selective herbicides improves success of woody plant control.
HIGH VOLUME FOLIAR APPLICATIONS
High volume foliar herbicide applications are the most cost-effective method for controlling invasive woody plants. It is important to thoroughly cover all stems and fully emerged leaves, including the tops of the woody plants, with a dilute herbicide/water mixture. Control will be greatest with complete coverage of the target plant with the herbicide mixture. The combination of Milestone® and Garlon® 4 Ultra specialty herbicides is recommended to improve control of some woody plants. Herbicide options and tank mixes are shown in Table 1.
Table 1. HIGH VOLUME FOLIAR Treatments for Woody Plant Control
1. Do not apply more than 3.3 oz per acre per growing season in a broadcast application or 6.6 oz per acre on 50% of the site.
2. For small trees only, 3 feet (in height) or less.
Mix herbicide with 100 gallons water. The addition of surfactant is recommended. Spray to thoroughly wet all leaves and stems. Treatments can be made until leaves begin to change color in autumn. Review label guidelines for mixing and application. Follow label instructions. (Shaded bar indicates an effective herbicide treatment for that species).
Herbicide applications to woody plants growing in or adjacent to standing water must follow state and federal permit requirements for aquatic environments. On these sites, the control recommendation for all woody species listed in Table 1 is 2 quarts Garlon® 3A or Vastlan® specialty herbicide + 2 quart DMA4 + 1 quart of aquatic approved surfactant (0.25% v/v) with 100 gallons of water for high volume foliar application to leaves. Surfactants labeled for aquatic use are available from your herbicide supplier. This treatment may not provide the best control for all species, but it is the right option to use in areas where the spray solution will contact standing water.
BASAL APPLICATION TECHNIQUES
Basal treatments on undesirable brush and vines are suited to sites such as fencerows and embankments, urban settings, near desirable vegetation, sensitive areas, and sites with low-density brush and/or vines. Fall, winter, and early spring applications provide the best access for basal applications due to the lack of existing foliage.
BENEFITS OF BASAL APPLICATIONS INCLUDE:
Effective application/control method for trees too tall for foliar application.
Reduces the impact on surrounding desirable plants.
Application is less labor intensive than mechanical removal or tree injection methods.
Controls trees and brush that are too large for foliar applications.
LOW VOLUME BASAL (LVB) treatments are well suited for controlling individual woody plants near desirable vegetation or sensitive areas, in low density brush situations, and for trees less than six inches in diameter that are too tall for foliar application.
Garlon® 4 Ultra specialty herbicide plus basal oil is recommended for low volume basal treatments. Basal bark oils are available from your herbicide supplier. Prepare the herbicide/oil mixture by mixing 25 percent Garlon 4 Ultra with 75 percent oil-based carrier (Table 2). Apply the herbicide solution entirely around the circumference of the stem in a band 12 to 15 inches wide, until the stem is thoroughly wet, but not to the point of runoff or puddling (Figure 1).
Table 2. LOW-VOLUME BASAL and BASAL CUT STUMP tank-mix guide for Garlon® 4 Ultra specialty herbicide alone and in combination with Milestone® specialty herbicide, plus oil-based carrier.
A mixture of Garlon 4 Ultra plus Milestone with oil-based carrier may improve control of some woody plants. These mixtures can be applied any time during the year except when bark is wet from heavy dew or rain. Pathfinder®II specialty herbicide is a ready-to-use formulation so mixing is not required; however, it becomes too thick to spray out at temperatures below 30⁰F.
BASAL CUT STUMP treatments involve cutting six inches above the ground level followed by an herbicide application (Figure 2). Apply the herbicide solution (Table 2) to sides of the stump, including the root collar area, and outer portion of the cut surface (cambium) until thoroughly wet but not to the point of runoff. Avoid cutting followed by herbicide application during heavy sap flow since this can interfere with penetration of oil-based basal mixes and decrease control. Heavy sap flow can also carry the herbicide mixture off the stump resulting in poor control. While it is customary to treat soon after cutting, applications may be made any time after cutting with Garlon 4 Ultra (for example, cut in winter and treat the following spring).
TIPS FOR LOW VOLUME BASAL AND BASAL CUT STUMP TREATMENTS
Do not treat plant stems that are saturated with water/precipitation.
Use a sprayer that has a shut off at the spray tip (Figure 3) to avoid wasting material.
Sprayer seals, hoses and pumps should be resistant to oil-based carriers (Figure 3 & 4).
Use an adjustable cone spray tip, such as Spraying Systems ConeJet 5500-X3 or Y3 up to X8 is ideal.
Apply herbicide spray to plant stems similar to applying spray paint.
Treat all the way around the plant stem in a band from the soil surface (root collar area) to 12 to 15 inches in height.
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Milestone and Opensight specialty herbicides 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. 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. Consult the label before purchase or use for full details.
State restrictions on the sale and use of Garlon 4 Ultra specialty herbicide apply. Consult the label before purchase or use for full details.
Always read and follow label directions.©2019 Corteva
Puablished April, 2018; Revised June, 2019
Figure 1. Low-volume basal application.
Figure 2. Basal cut stump application
Figure 3. Spray wand for LVB applications showing mechanical shut-off at the tip (below).
Figure 4. Model 942 basal brush sprayer for LVB or cut stump applications. Attributes include chemical resistant seals, adjustable brass nozzle, and durability (below).