One species that tends to get people's attention when it comes to invasive species is Japanese Barberry. This species, commonly used for landscaping around homes and businesses, comes in different colors and shapes, which make it such a popular shrub. It provides a barrier between properties, with the added security of small thorns that run up and down the stems. However, the reasons that it has become so popular in our cultivated landscapes are also reasons that this plant is one of the most widespread invasive shrubs on the East Coast, and a prime vector for Lyme Disease.
Lyme Disease has been well documented as a problem here in the East. The Center for Disease Control calls it one of the fastest growing diseases in the U.S. and a significant reason for this increase is due to the invasive plants clogging up our forest understories. Plants such as Japanese Barberry, Japanese Honeysuckle, and others are not browsed by the deer, which prefer the native plants surrounding them. this leads to increased space for these invasives to flourish. Lyme disease is commonly known as a tick-spread disease so many people may be left wondering, what do plants have to do with it?
Invasive plants make up so much of our forest biomass at this point that animals utilize them to the best of their ability. Though many native species skip over these invasives when looking for food, the low branches of barberry provide perfect habitat for two species, ticks and mice, which are the main vectors of Lyme. Mice are drawn by the cover and thorns that protect them from predators such as raptors, and the ticks are present in the foliage, waiting for a meal. The ticks latch on to the mice, where they acquire the bacteria that causes Lyme disease. The public health problem that we have with Lyme now started in our gardens in the 1800s.
Barberry has been popular due to its ability to tolerate a wide range of environments. It produces many seeds which then get spread by wildlife into our forests and fields. Its so popular in fact that many people became upset when it was finally downgraded to prohibited from its restricted designation. It is a best-seller in many nurseries, specifically because it is hardy and deer don't browse it. I have heard people say things like "well, maybe I'll go to Pennsylvania and bring some back," as if our NY forests did not already have barberry in spades. People in the nursery industry are hard at work trying to find an exception or cultivar to get past the regulations, or simply trying to get the species taken off the prohibited list. To me it seems that they are missing the point. It takes so long to get a species designated as prohibited, most often plants don't make it on that list until they have become a widespread problem. By designating a species as prohibited, the state is saying that they finally have enough evidence to conclusively prove that this species causes more problems then it has benefit, and people trying to get around these regulations in whatever way possible shows that Lyme Disease, ecological impact, invasive potential... those things matter less to them than having a shrub that they don't have to put that much effort into.
The state has said if you already have a barberry plant in your yard, you don't have to get rid of it. But on the other hand, if you value the nature of New York State or have kids that enjoy using that lawn without the worry of ticks and Lyme Disease... maybe it'd be best to grab a shovel or a pickaxe and take that invasive shrub out of the ground.
Don't miss that tap-root.
NBC New York is starting a five part series on Lyme Disease. You can watch the first part here.