Autumn olive

Asked August 7, 2018, 4:39 AM EDT

Fifty years go I planted these shrubs with the recommendation of the Conservation Dept. Now I want to get rid of them. I understand that they are to be cut back and then a poison applied. I am in the process of cutting them back - some are 5, 6, 7 ft tall, but some are new little twigs. What poison do i use next? How is it applied? I have about an acre of these among our 21 acres. Help!

Grand Traverse County Michigan

1 Response

Control of autumn olive and Russian olive is similar. Below is a description I previously prepared for Russian olive.

Physical and thermal means of controlling Russian olive such as cutting, mowing, or burning have been found to be ineffective and sometimes exacerbate the problem.

Chemical treatment with herbicides or a combination of physical measures with herbicides has proven to be effective in controlling Russian olive. Below is an outline of the application method options for applying herbicides (* most recommended method):

  • Foliar- herbicide is applied directly to the leaves of the plant during active growth. Foliar application is the least effective method of controlling autumn olive, 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.
  • 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.
  • *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.

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 (*most recommended herbicide).

  • *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/Russian olive, especially used as a cut stump or basal bark application
    • Cons
      • Foliar treatment of Russian 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 4 Specialty herbicide (Russian olive is not explicitly listed on the label, however directions for cut stump treatment should yield similar results)
  • 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 at controlling Russian olive
    • 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 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