Getting Rid of Japanese Barberry: Why and How

Japanese barberry, (Berberis thunbergii). Note the slightly elongated, oval-shaped berries.

Japanese barberry, (Berberis thunbergii). Note the slightly elongated, oval-shaped berries. Photo credit: Wikipedian in Residence in Botanical Garden Jevremovac

Japanese barberry, (Berberis thunbergi), arrives in the woods by birds eating the fruits in winter and pooping/planting them. It can grow in full shade and established woods. Nobody, (especially not deer), eats the leaves or the prickly twigs. It can root where branches touch the ground and where seeds are dropped in place to make eventually an extensive, dense cluster. Its leaves break down quickly and raise the nitrogen level in the soil, encouraging earthworms and discouraging native woods plants. It offers mice shelter from predators, encouraging them to congregate and share germs. Its dense foliage keeps the area underneath it moist so that ticks can be active almost all the time.

Research by Tom Worthley, ( University of Connecticut Dept of Extension in College of Agriculture & Natural Resource), Scott Williams, ( University of Connecticut Dept of Natural Resources & Environment), and Jeffrey Ward (Connecticut Agriculture Experiment Station Dept of Forestry & Horticulture), found:

  • 120 Lyme infected ticks per acre where barberry was “not contained”
  • 40 Lyme infected ticks per acre where barberry was “contained”
  • 10 Lyme infected ticks per acre where barberry was absent

So that’s why I pull barberry at Fraser Preserve every January & February.

A little snow is helpful, but you can't pull barberry if the ground is frozen.

Potowmack chapter removes barberry at Fraser last year. A little snow is helpful, but you can’t pull barberry if the ground is frozen.

I’ve often said that we can work with snow on the ground. Snow actually insulates the ground and keeps it from freezing; it also increases contrast and helps you spot the small barberry sprouts. But we can’t work when the ground is frozen. Last year I had to cancel half the work sessions I’d scheduled because of frozen ground: you just can’t pull plants from frozen ground. The tops just break off and leave the crown of the plant behind, which leaves it alive and harder to pull the next time you try. Other years only one or two scheduled workdays have had to be cancelled: we really don’t get a lot of ground freezing around here, especially not in the woods with a good layer of leaf litter. The barberry at Fraser is not found in bare ground locations where the ground would freeze more readily.

Barberry is what Alan, (Alan Ford, Potowmack Chapter President), calls a “crown plant:” you kill it by removing the junction between the topgrowth and the roots. Often it’s easiest and causes less soil disturbance if you clip the roots and just remove the crown. It does not grow back from bits of root left in the ground. It does grow from seeds dropped under larger plants, so that it is very worthwhile to return to places where there were large plants or patches to pull sprouts until the seed bank is exhausted — I don’t have statistics on this, but most of them are gone after 3 years of sprout-pulling.

Margaret Chatham
Potowmack Chapter Newsletter Editor

Read the Potowmack Chapter Newsletter, which includes information about helping to remove barberry this winter at Fraser: Potowmack News

Comments

  1. John Hopkins says:

    So why is it that Lyme ticks are more often found where this invasive plant is not present?

    • communications says:

      I think you misinterpreted the data. Lyme infected ticks are found in greater numbers where Japanese barberry is “not contained,” meaning, where Japanese barberry is present and not being kept from spreading. From the article:

      120 Lyme infected ticks per acre where barberry was “not contained”
      40 Lyme infected ticks per acre where barberry was “contained”
      10 Lyme infected ticks per acre where barberry was absent

      So where barberry was absent, there were the lowest number of Lyme infected ticks. The research is has been extensive on this point, if you would like further corroboration, check out the several links Margaret provided.

  2. Pam Humphrey says:

    I have had good results eliminating Japanese Barberry here in SW Virginia and on property near Asheville, NC, by cutting back the tops and painting the stumps with concentrated Roundup. I apply it with an old shoe polish bottle with a brush top.
    This fits well in my pocket and is easy to carry while I work.
    I work in the warm months when the sap is running in the bushes to carry the Roundup to the roots.

    • communications says:

      Thanks, Pam, that is also a good way to go. The winter work has the advantage of being able to avoid using the herbicides. Thanks fro your comment and your efforts to keep Japanese barberry out of our ecosystems!

  3. Randy Puerinton says:

    Is there a product that can be sprayed on a barberry bush before it grows leaves in the spring – a product that prevents leaf growth; like a pre-emergent prevents seeds from sprouting. I understand that there are defoliants that kill leaves and deny roots the chlorophyll they need to thrive but is there a way to prevent leaves from growing so I don’t need a defoliant. Is there a way to prevent leaf buds from sprouting?

    • VNPS Communications says:

      Randy, there are several methods of controlling this invasive plant, and what you choose depends partly on the size of the area you want to treat. In general mechanical methods are preferred, and because the root system of barberry is shallow, complete removal of the roots in early spring when the ground is moist is a good way to go. You have to make sure that you monitor the newly created space to ensure replacement by natives. However, sometimes a chemical choice may be desirable. Here is a reputable source describing some options: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_015219.pdf
      Thank you for making the effort!

  4. And the deer ticks are on the wind now.

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