Protocol for removing invasive autumn olive, barberry and asian bittersweet.

Asked November 5, 2018, 12:36 PM EST

Hello, I was wondering if you could please clear up some confusion about how to best remove invasive autumn olive, barberry and asian bittersweet from our otherwise beautiful oak/hickory/maple forested lot of about 12 acres. I have heard that we can do a "stump cut" method right now at this time of year for all of these plants, where we would cut the plant, then paint a glyphosphate solution on the cut trunk, vine or stem. Some people say to use a glyphosphate product at 5%, 20%, or a professional industry person said 41%. (My friend tried 20% glyphospate and said after 2-3 years much of the invasives are back. :( ) Others say glyphosphate won't work well at all and we should use another chemical (whose name I am forgetting, but it starts with "tri...."). Some say we should just wait until spring because it's too late to do anything now. We are digging plants out by the roots wherever we can (as we are basically organic gardeners), but there are some plants too big to dig out. Thank you so much!

Washtenaw County Michigan invasive species herbicides

1 Response

This is kind of a long-winded response to you question, but should answer the things that you asked. Also, I always like to explain a little bit about the weeds before getting into control. Understanding what we're up against is always important.

Autumn olive (Elaeagnus umbellata) is a deciduous invasive shrub (or tree) that can be found throughout Michigan. The tree reproduces both sexually by seed and asexually by new shoots emerging from crowns, root pieces and stem cuttings. Seeds are dispersed by birds that consume the fruit. Seed remains viable for up to 3 years within the soil.

Oriental bittersweet (Celastrus orbiculata) is a deciduous, vigorous growing plant that belongs to a family of woody shrubs with climbing, twining vines. Leaves are simple, alternate in arrangement and oval to round in shape. The dark green leaves are serrated with a pointed tip. This aggressive vine can grow to 20 feet or longer. It is often found growing in fence rows or on trunks and tops of trees. It virtually grows on anything in sight. The fruit is a three-lobed capsule with a yellow to orange inner wall and crimson-colored seeds. The fruit ripens in October and is extensively harvested and used for dried flower arrangements.

Barberries (Berberis spp.) are deciduous shrubs with small leaves and arching branches with thorns. Species include the native American barberry and the introduced species common barberry and Japanese barberry. Barberries reproduce both by seed and underground shoots.

Control.

Physical and thermal means of controlling autumn olive, oriental bittersweet, and barberry, such as cutting, mowing, or burning have been found to be ineffective and can often exacerbate the problem by stimulating new shoots to emerge from the root system. Removing roots can be effective, but will take diligence.

Chemical treatment with herbicides or a combination of physical measures with herbicides has proven to be effective in controlling autumn olive, oriental bittersweet, and barberry. Below is an outline of the application method options for applying herbicides:

*Before purchasing or making any herbicide application it is important to throughly read and follow all labeled instructions*

· Foliar- herbicide is applied directly to the leaves of the plant during active growth. Foliar application is the least effective method of controlling these species, likely requiring multiple applications.

· Basal bark- herbicide is applied directly to the bark at the base of the tree. Oil (basal bark oil) or petroleum (diesel fuel) needs to be added to aid in absorption. This method may only be appropriate for small diameter trees/shrubs.

See basal bark image from Univ. of MO

· Frill cut- notched are cut in the base of the tree into the sapwood, peeling back the bark and wood (still attached), then undiluted herbicide is applied or injected in the notch.

See frill cut image from Univ. of MO

· *Cut stump- the tree is cut down and the stump is treated with concentrated herbicide immediately after (prior to the cut drying), focusing on the cambium layer just beneath the bark.

See cut stump image from Univ. of MO

There are also a few different herbicide active ingredient options available. Selection of a product may depend on the desired method of application and the intended use of the land following application (i.e. carryover duration). Remember with any herbicide application to read and follow all labeled directions.

· *Triclopyr

Triclopyr is a growth regulator/synthetic auxin herbicide (Group 4) that exhibits activity on annual and perennial broadleaf plants, vines, and woody plants and is most often used for control of brush and poison ivy in grass pastures, non-crop areas, right-of-ways, etc. Triclopyr is absorbed primarily by the foliage of plants but can also be absorbed by cut stems and roots.

  • Pros
    • Most effective herbicide of those tested for controlling autumn olive, especially used as a cut stump or basal bark application.
    • Cut stump methods can be used in winter months.
  • Cons
    • Foliar treatment of Russian olive, a similar species to autumn olive, was not effective for control.
    • Care is needed to avoid drift onto desirable broadleaf species if using as a spray. Avoid injury of nearby broadleaf plants from volatilization of the herbicide by applying under temperature/weather conditions stated on the label.
    • May have a planting restriction of 30 days or more following application depending on the desired species to plant and the environmental conditions. Broadleaf species are more prone to injury as compared to grasses (consult label).
  • Products available
    • Pathfinder II- Ready to use product
    • Garlon 3A or Garlon 4 Ultra (these species are not explicitly listed on label, however directions for cut stump treatment should yield similar results)

· Imazapyr (not recommended in this situation!)

Imazapyr is an amino acid synthesis inhibitor (Group 2) that is commonly used to control many species of broadleaf and grasses weeds in non-crop/bareground areas.

  • Pros
    • Effective control
  • Cons
    • This product has the highest risk of off-target plant injury. Care is needed to avoid drift onto desirable broadleaf species if using as a spray. Avoid injury of nearby broadleaf plants from volatilization of the herbicide by applying under weather conditions stated on the label.
    • If the root system of desirable woody plants nearby are grafted/intertwined with the plant(s) being treated, injury or plant death can occur.
    • Imazapyr has intermediate-high runoff/leaching potential and its activity is long lasting (142 day half-life), with high application rates potentially negatively impacting the growth of plants for several seasons.
    • Should not be applied in the spring during heavy sap flow
    • Do not use near potable water sources.
  • Products available
    • Habitat
    • Arsenal

· Glyphosate

Glyphosate is an amino acid synthesis inhibitor (Group 9) that is commonly used for broadspectrum control of both broadleaves and grasses in glyphosate-tolerant crops and non-crop areas. It is also used as a burndown application prior to planting of a variety of other crops/plants.

  • Pros
    • Desirable grass and broadleaf plants can be planted in the area as soon as the herbicide has had time to dry.
  • Cons
    • Provides only moderate control and retreatment will likely be required
    • Will kill or severely injure any plant with which the product contacts green foliage, damaged/green bark, or exposed roots
  • Products available
    • Rodeo
    • Roundup Pro
    • There are many generic herbicides with the active ingredient glyphosate available, check that this is the only active ingredient and that it is a concentration >40% for maximum activity

* Indicates recommended treatment for this situation.

Treated populations should be monitored to assess any regrowth and the need for retreatment. Multiple applications may be necessary to achieve eradication.

There is a non-profit invasive species management groups in your area, the Jackson, Lenawee, and Washtenaw Cooperative Invasive Species Management Area that may have additional information and/or resources. The contact listed for this group is Shikha Singh (517) 395-2089 (http://www.michiganinvasives.org/jlwcisma/).

Michigan Department of Natural Resources: Natural Features Inventory

Autumn olive- https://mnfi.anr.msu.edu/invasive-species/AutumnOliveBCP.pdf

Oriental bittersweet- https://mnfi.anr.msu.edu/invasive-species/OrientalBittersweetBCP.pdf

Japanese barberry- https://mnfi.anr.msu.edu/invasive-species/JapaneseBarberryBCP.pdf