Oregon-Grape in Oakland County

[Erin Lavender]

We just discovered a population of Oregon-Grape (Berberis aquifolium) growing in one of our high quality forested natural areas. The plants are in and around a power-line right-of-way that looks like it was cleared a few years back (maybe arriving in the area on clearing equipment or birds using the cleared area).

Does anyone have experience working with this plant in MI? Specifically:

• how invasive does this plant tend to be in natural areas?
• best control techniques?
• most common dispersal technique (birds eating seeds, rhizomes, etc.)?

Thanks for any insight!

[Katie Grzesiak]

I've no experience with this plant (apart from seeing it in Wyoming last week!), but here's what some Googling got me:

• There's very little information on Mahonia aquifolium (aka Berberis aquifolium) being invasive here, as it's native to western North America.  It does appear to be invasive in Germany, so you may look to Europe for more control methods if it does seem to be invading in Michigan.
• A scientific article. It would appear its fruits are a major component of its spread, but they most commonly fall directly below the parent.
• A brief from the NPS on its cousin, leatherleaf mahonia, which is from Japan.  It appears that cut-stump treatments are best for Mahonia bealei.

Good luck!