Why Are Barberry Bushes Illegal in Some States?

Landscaping with shrubs and bushes is a popular way to enhance the beauty and curb appeal of residential and commercial properties. One type of bush that has gained widespread use over the years is the barberry, prized for its vibrant foliage, attractive berries, and deer resistance. However, despite its ornamental qualities, barberry bushes, particularly a variety known as Japanese barberry, have become a major environmental concern in many areas.

This invasive plant has caused such extensive damage to natural habitats that several U.S. states have deemed it illegal and banned its sale and cultivation. But why exactly are barberry bushes illegal, and what makes this unassuming landscaping plant so problematic?

In short, Japanese barberry is considered an invasive species that rapidly spreads into woodlands, fields, and other natural areas, crowding out native vegetation and disrupting ecosystems. Its prolific growth and ability to harbor disease-carrying ticks have made it a major threat in regions where it has been introduced.

This in-depth article will explore the specific reasons behind barberry bans, the extensive environmental impact of this invasive plant, its connection to Lyme disease, identification tips, and alternative options for eco-friendly landscaping. Let’s dive in!

What Makes Japanese Barberry an Invasive Species?

The primary concern surrounding Japanese barberry (Berberis thunbergii) is its highly invasive nature. This non-native shrub, introduced to the United States from Asia in the 1800s as an ornamental plant, has characteristics that allow it to spread rapidly and overtake natural habitats.

One key issue is its dense, prickly growth habit. Japanese barberry forms thick, impenetrable thickets that crowd out and shade native vegetation, preventing other plant species from thriving. Its vigorous root systems also allow it to easily outcompete other plants for vital nutrients and water.

Additionally, Japanese barberry produces masses of red berries that are readily consumed and spread by birds and other wildlife. This effective seed dispersal method enables the plant to continuously expand its range into new areas, including sensitive ecosystems like forests and grasslands.

Once established in an area, Japanese barberry can form extensive monoculture stands, diminishing biodiversity and disrupting the delicate balance of local ecosystems. Its ability to thrive in a variety of soil types and light conditions further compounds the invasive threat posed by this problematic plant.

States That Have Banned Japanese Barberry

Due to the multitude of issues stemming from Japanese barberry’s invasiveness, several U.S. states have taken legal action by banning its sale and cultivation. These include:

• Maine
• Minnesota
• New Hampshire
• New York

Most recently, Pennsylvania added Japanese barberry to its noxious weed list in October 2021, citing the plant’s tendency to spread into sensitive natural areas and disrupt native ecosystems.

Other states are closely monitoring Japanese barberry and may follow suit with similar bans or restrictions if the invasive threat continues unchecked within their borders.

Pennsylvania’s Ban Timeline

Pennsylvania is implementing a phased ban on Japanese barberry to allow nurseries and landscaping businesses time to adjust and deplete existing inventory:

• November 2021: Businesses were notified to reduce propagation and ordering of the plant immediately.
• Fall 2022: Warning letters will be issued to any sellers still offering Japanese barberry.
• Fall 2023: Any remaining inventory is subject to stop sale and destruction orders from the state.

This gradual approach aims to prevent economic harm to businesses while ultimately eliminating an environmentally-damaging invasive species from the nursery trade and landscaping practices within Pennsylvania.

The Link Between Japanese Barberry and Lyme Disease

In addition to its invasiveness and disruption of native plant communities, Japanese barberry has been directly linked to an increased prevalence of Lyme disease in areas where it is present. This connection makes the shrub a public health concern as well as an ecological threat.

Study Findings on Barberry-Tick Connection

A multi-year study conducted in Connecticut examined the relationship between Japanese barberry, white-tailed deer, white-footed mice, and blacklegged ticks (the type of tick that carries the Lyme disease bacteria).

The findings were alarming:

• Dense barberry stands provide an ideal sheltered habitat for mice, a preferred host for immature blacklegged ticks.
• As ticks mature, they require larger mammal hosts like deer, which are able to move through barberry thickets due to the plant’s height.
• Areas infested with Japanese barberry had up to 5 times higher populations of blacklegged ticks compared to barberry-free areas.
• This increased tick abundance correspondingly raises the risk of Lyme disease transmission to humans in those environments.

The study concluded that eliminating Japanese barberry could be a key strategy for reducing blacklegged tick populations and associated Lyme disease cases in affected regions.

Environmental Impact of Japanese Barberry

Perhaps the most significant issue driving bans on Japanese barberry is the grave threat it poses to native ecosystems and biodiversity. As an aggressive invasive species, this shrub outcompetes and replaces native vegetation when left unchecked.

In areas where Japanese barberry becomes well-established, it often forms an understory monoculture that chokes out other plants, including those that provide vital food sources for local wildlife. This can throw the entire food web out of balance and negatively impact insect, bird, and mammal populations in the area.

The loss of native plant diversity also diminishes critical ecosystem services like erosion control, nutrient cycling, and water filtration. Natural habitats are left in a degraded, less resilient state due to the domination of a single non-native plant species.

Japanese barberry infestations directly threaten sensitive areas like forests, grasslands, and conservation lands meant to preserve regional biodiversity and ecological integrity. Bans on this noxious plant aim to protect these vulnerable natural spaces from further harm.

Are All Barberry Varieties Invasive?

While the Japanese barberry poses a significant invasive risk in many regions, there is another common barberry species with a more complicated legal status – the common barberry (Berberis vulgaris).

Rather than being an environmental threat through invasiveness, the common barberry is considered a agricultural pest. This variety acts as an alternate host for a destructive fungal disease called black stem rust that affects wheat crops.

As a result, the sale and cultivation of common barberry has long been banned in many areas like Canada to protect wheat production from this disease. However, the Japanese barberry was not found to be a host for the wheat rust fungus.

This distinction led some areas to lift bans on Japanese barberry over time. More recently though, the plant’s highly invasive behavior in natural areas has prompted new legislation against this variety in multiple states.

To address the invasive issue while still allowing use of barberries for ornamental purposes, plant developers have created sterile cultivars that are seedless and unable to spread into the wild. The “WorryFree” series, which includes varieties like Crimson Cutie and Lemon Glow, offer a safe alternative.

However, due to existing long-standing barberry regulations, these sterile Japanese barberry cultivars are unlikely to be approved for sale in Canada anytime soon despite resolving invasive concerns.

Barberry Identification and Removal

If you suspect Japanese barberry is growing on your property, proper identification is key. This deciduous shrub has thin, green leaves with distinct spines along the stems. In fall, the foliage turns vibrant shades of red. Small pale yellow flowers bloom in spring, later producing oblong red berries.

For small areas of growth, Japanese barberry can be manually removed by digging up and disposing of the entire root system. This laborious task may require multiple attempts due to the plant’s resilient nature.

For larger, well-established infestations, professional removal by trained contractors is recommended to fully eradicate the invasive shrub. Methods may include herbicide treatment, cutting, or a combined approach for maximum effectiveness.

Non-Invasive Alternatives to Barberry

If you’re looking to replace existing Japanese barberry in your landscape or want attractive, deer-resistant alternatives, there are many excellent native shrub options that pose no invasive threat:

• Dwarf Fothergilla (Fothergilla gardenii)
• Highbush Blueberry (Vaccinium corymbosum)
• New Jersey Tea (Ceanothus americanus)
• Virginia Sweetspire (Itea virginica)
• Winterberry Holly (Ilex verticillata)
• American Beautyberry (Callicarpa americana)

Using native plants helps preserve biodiversity, provide food/shelter for local wildlife, and keeps invasive problems from recurring down the road.

Frequently Asked Questions

Is Japanese Barberry Toxic?

While not extremely toxic, Japanese barberry does contain some compounds that can cause mild stomach upset, diarrhea or vomiting if the leaves, flowers or berries are ingested. It’s generally advisable to avoid consuming any part of this plant.

Do All Barberries Attract Ticks?

The Japanese barberry variety has been specifically linked to increased populations of blacklegged ticks that transmit Lyme disease. Its dense, sheltered growth provides an ideal habitat through all stages of the tick’s lifecycle.

Other types of barberries have not been as extensively studied when it comes to harboring ticks. However, any shrub that allows for built-up vegetation litter and shelter for host animals could potentially attract higher tick levels compared to well-maintained plantings.

Are There Non-Invasive Barberry Cultivars?

Yes, in recent years plant breeders have successfully developed sterile cultivars of Japanese barberry that do not produce viable seeds. Since they cannot spread into the wild, these varieties solve the core invasive issue while still providing ornamental appeal.

The “WorryFree” series from the University of Connecticut is a leading example, containing varieties like Crimson Cutie and Lemon Glow. While approved for sale in some states, these sterile barberries may not be available in areas like Canada due to existing barberry regulations.

For gardeners looking to avoid any risk and cultivation issues, exploring native shrub alternatives is recommended over planting even the sterile barberry cultivars.

Conclusion

In conclusion, the primary reasons Japanese barberry has been banned and deemed illegal in several U.S. states are its aggressive invasive behavior, ability to outcompete native vegetation, disruption of natural ecosystems and biodiversity, and link to increasing Lyme disease prevalence through harboring disease-carrying ticks.

While historic as an ornamental landscaping plant, the overwhelming environmental damage caused by Japanese barberry infestations has forced many areas to take legal action against its sale and cultivation. A phased approach has been adopted in some states to allow nurseries time to transition away from this problematic invasive species.

For homeowners, property managers and landscaping professionals, it is crucial to identify and remove existing Japanese barberry plants whenever possible, and to explore the wealth of attractive native shrub options as non-invasive alternatives. Taking these steps can help protect our natural habitats, public lands, and human health from the serious threats posed by invasive plants like the Japanese barberry.