[Guest post by Debbie Roberts as part of the Most Hated Invasive Plants series]
I have a confession to make. Almost two decades ago, when I was a first time homeowner and newbie gardener, I actually bought and planted Japanese barberry (Berberis thunbergii). Not only did I not know any better, I was encouraged to buy it. I visited my local nursery and told them I was looking for a shade-tolerant, drought-tolerant, low-maintenance shrub that had to be deer resistant. The rest of the particulars really didn’t matter to me.
I was shown a few different cultivars and told any of them would work well in my garden. So I grabbed three purple-leafed shrubs (the exact cultivar long forgotten) and went home and planted them. And basically forgot about them for years because they thrived in my garden. Little did I know that by planting those shrubs, I was negatively impacting the local ecosystem and I was endangering my family.
While many gardeners know about Japanese barberry’s strongly invasive habits, at least 20 states have reported it be invasive, many gardeners may not realize that the presence of Japanese barberry has been linked to an increased risk for Lyme disease.
A multi-year study, taking place in Connecticut, is looking at the relationship between Japanese barberry (Berberis thunbergii), white-tailed deer, white-footed mice and blacklegged ticks. The results were recently released from the first two years of the study and are a bit surprising. In essence, the study found the larger the number of this plant in an area, the higher the incidence of Lyme disease carrying ticks.
Among the study’s early conclusions:
• White-tailed deer do not browse Japanese barberry, helping it to outcompete native shrubs.
• Dense stands of Japanese barberry provide favorable habitat for all life stages of blacklegged ticks. As ticks mature, they require host mammals of increasing size.
• Larval blacklegged ticks feed primarily on small host mammals, white-footed mice are a favorite. Several characteristics of Japanese barberry, including early leaf-out, dense thorns and an a wealth of fruit, all combine to create an ideal habitat for mice that is free from predators and has abundant food.
• Mature Japanese barberry is the perfect height for questing adult ticks to attach themselves to deer as they pass by.
• Eliminating Japanese Barberry will decrease the number of blacklegged ticks which in turn will significantly reduce the risk of Lyme disease.
But the sad fact is that today, even here in Connecticut where Japanese Barberry is on the invasive plant list, a first time homeowner and newbie gardener who walks into a local nursery and asks for a shade-tolerant, drought-tolerant, low-maintenance shrub that has to be deer resistant will probably be pointed towards Japanese Barberry.
With a little education, we can help gardeners and plant sellers realize there are many native alternatives to Japanese barberry, including dwarf fothergilla (Fothergilla gardenia), highbush blueberry (Vaccinium corymbosum), New Jersey tea (Ceanothus americanus) and Virginia sweetspire (Itea virginica).
By simply choosing a native shrub that thrives in the same site conditions as Japanese barberry, we can create more wildlife habitat, reduce invasive species, protect local ecosystems and safeguard the health of ourselves and our families.
What’s your most hated plant? You know, the one that makes you cringe when you see it growing in someone’s garden? Or worse yet, for sale at a local nursery?
Debbie Roberts is a landscape designer and accredited organic land care professional who nurtures a habitat garden in southwestern Connecticut. Visit her blog at Garden of Possibilities and follow @Deb_Roberts on twitter. .
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