As peak fall foliage is setting in, we admire the tupelos and maples, the bright crimson and orange hues that signal the seasons are shifting. But it’s not only trees that change color in autumn; a handful of shrubs are rather notorious for their especially red pigmented leaves. Some of these plants have also notoriously become widespread invasive species in the northeast.
Since the mid-1800s, burning bush (Euonymus alatus) and barberry (Berberis thunbergii) have been widely planted throughout the US. Japanese barberry was actually a replacement for common European barberry (Berberis vulgaris), as it was ubiquitously used by European settlers as hedgerows, with berries harvested for jams and dyes. When it was discovered that common European barberry was a host for black stem rust (Puccinia graminis), a disease of wheat, Japanese barberry became the replacement of choice. Burning bush was later popularized by botanical gardens, inspiring wealthy Americans to acquire them as statement plants for their yards. Nearly a century later, these plants were beginning to grab the attention of naturalists and land managers as they escaped into forest understories. Right around the turn of the 21st century, each of these plants had made their way to a handful of states’ invasive species lists due to their tendency to escape cultivation; however, many of these lists were more suggestive than prescriptive, and these shrubs were still commonly found in nurseries sold as low maintenance shrubs with fiery fall foliage throughout the early 2000s.
With burning bush and barberry’s strategies in establishment and spread, it’s no wonder they have been so widely favored for foundation plantings or plants for the beginner gardener. They can thrive in shade and full sun, as well as various soil conditions. Both have bright red berries which may be attractive to birds and other wildlife, though these fruits are not particularly nutritious to them. Barberry takes their spread mechanisms one step further with its ability to propagate through swooping stems, with tips that can take root and may continue to survive as a clone if detached from the parent plant. While these plants may not appear to be spreading rampantly through a backyard hedgerow, they can reach woodlands as animals move them around. Left alone, they can then form dense thickets in forest understories as these plants aggressively compete with native plant populations and subsequently reduce quality habitat and food resources for wildlife.
To make matters worse, a 2017 study from the University of Connecticut has found that barberry provides a perfect humid microclimate for ticks to take refuge in, and can help to increase their abundance. These microclimates help to increase the questing time of ticks, and reduce the time they need to spend rehydrating. While the barberry is not palatable to deer, the plant is at a perfect height for a tick to attach to one passing by. Mice, which also vector lyme disease, enjoy these humid, thorny and protected shrubs of barberry as well. This shared home creates a larger opportunity for them to come in contact with ticks. The study went on to show that in places where barberry was removed, the abundance of ticks decreased.
In-spite of these hardy bushes’ known invasiveness, it wasn’t until 2014 that Japanese barberry became designated as prohibited, and burning bush a regulated species in New York. According to the New York State Department of Environmental Conservation who maintains the list of prohibited and regulated species:
“Prohibited invasive species cannot be knowingly possessed with the intent to sell, import, purchase, transport or introduce. In addition, no person shall sell, import, purchase, transport, introduce or propagate prohibited invasive species.”
On the other hand, a regulated species is defined as:
“Species which cannot be knowingly introduced into a free-living state, or introduced by a means that one should have known would lead to such an introduction, although such species shall be legal to possess, sell, buy, propagate and transport.”
This means that prohibited species are not allowed to be sold or purchased, whereas regulated species may still be sold, but must be labeled as an invasive species with guidelines on how to prevent its introduction to the wild.
Though New York State has set these laws in place, beyond our borders these plants may be sold freely and without invasive species labeling. With the rise of online commerce and social media groups for plant trading, it can be especially difficult to regulate what people can and can’t sell or buy. While there are laws surrounding their sale and purchase, having a barberry or burning bush is not illegal, and they are still widely seen in most neighborhoods, shopping centers, and roadsides on Long Island. With the legacy of these plants in our yards and gardens, it can be hard for folks to imagine a replacement for them.
Luckily for us, New York is home to several other shrubs which produce striking red foliage in the fall:
High bush blueberry (Vaccinium corymbosum)
- 5-8’ at maturity
- They love Long Island’s acidic soils, as they are found all throughout the understories of the Pine Barrens.
- Prefer full sun but can tolerate late day partial shade
- Like well drained soils, and are relatively drought resistant
- Edible fruits like the ones from the supermarket! If you are concerned about the birds getting to them first, planting more and planning to share is your best bet.
Red chokeberry (Aronia arbutifolia)
- 5-10’ at maturity
- Beautiful red berries that are held on through late winter, providing a pop of color during the colder days
- Full sun to part shade tolerant
- Deer resistant, which is great in many places across the island
- They have a suckering growth habit which can help create a nice border
Red Osier dogwood (Cornus sericea)
- 7-9’ with a spread of 10’ at maturity, making it another great hedge option
- Another great winter interest plant, with red stems that are visible throughout the winter
- Full sun to part shade
- Extremely adaptable to different soils, can even tolerate growing in wet places, but not excessively dry ones
If you have barberry or burning bush and are interested in removing and replacing these plants in your yard, consider these management strategies:
Burning bush:
Unlike other invasive shrubs (such as barberry), burning bush can be relatively easy to control. Dig or use a tool such as a weed wrench to remove the majority of the roots, which the plant will not be able to recover from. Consider engaging in removal early in the spring (before the end of May) to prevent fruits from dropping to the ground as you pull up the plant. Continue monitoring yearly for seedlings, which you can pull out by hand. If you prefer to use an herbicide to treat many large, established plants that might be difficult to dig up, you can do so using an herbicide such as Garlon 4 Ultra with a cut stump or basal bark method. This can be done at any time during the year, weather permitting. Be sure to always read herbicide label instructions, it’s the law.
Japanese Barberry:
This shrub can easily grow back from any root fragments left behind in the soil, making manual control slightly more difficult. However the root system is relatively shallow, and can be pulled up or dug up early in the season. Pulling early in the season avoids dispersing their prolific berries, as a late season removal might do. If engaging in hand removal, please use good gardening gloves as the thorns that line barberry stems are extremely fine and difficult to remove from skin, as well as take a long time to decompose, which can lead to infection. Chemical control can be done with a mixture of glyphosate and triclopyr at a 2:1 ratio. This also may be done through basal bark sprays or a cut stump method.
The best thing you can do to prevent the spread of barberry or burning bush is to remove them from your landscape, and avoid planting them in the first place. These plants are considered widespread invasive species in the LIISMA region (Tier 4), and you may commonly come across them in your local park or forested area. Because of their extent, regional eradication is highly unlikely. However, catching new infestations of these plants in natural areas can prevent a larger problem – mapping these observations in iMapInvasives is a great way to let us know about them. You can also keep an ear out for volunteer removal events at your local park, or help organize such efforts with your neighbors.
Read More:
About Burning bush and Japanese barberry management:
https://extension.psu.edu/burning-bush
https://extension.psu.edu/japanese-barberry
https://www.fs.fed.us/database/feis/plants/shrub/euoala/all.html
https://www.fs.fed.us/database/feis/plants/shrub/berthu/all.html
About Japanese barberry and ticks:
https://entomologytoday.org/2017/10/04/the-5-year-plan-manage-japanese-barberry-to-keep-tick-levels-low-reduce-lyme-risk/
https://www.dec.ny.gov/animals/99141.html
