While shopping at a local garden center or nursery searching for a shade, drought tolerant, low-maintenance shrub that’s also deer resistant, you might find Japanese barberry (Berberis thunbergii) at the top of the list of options.
For the novice gardener who didn’t spend enough time doing their homework before heading to the garden center, this once common ornamental shrub used as a bordering hedge around homes and flower beds is now considered an invasive species throughout much of the United States.
According to PennState University Extension, “It was introduced in the United States as an ornamental plant. However, like many invasive species, it escaped from managed care and is now naturalized. This plant can dominate deep in the woods and along woodland edges. This crowds out native plants and disrupts these ecosystems.”
Japanese barberry is often found throughout the northeastern United States from Maine to North Carolina, and west to Wisconsin and Missouri. It is now considered to be an invasive species in some 20 states with a much larger and more concerning problem emerging.
From PennState University Extension, “Research has shown that the presence of the black-legged tick, which transmits Lyme disease, increases in areas with dense barberry.”
Japanese barberry is especially problematic in Connecticut, where it’s beginning to overtake forests and communities where it’s still a part of household landscapes.
According to the Connecticut Botanical Society, “Japanese barberry is an invasive plant, and probably one of the most destructive invasive plants in Connecticut. It can form thick stands that exclude nearly all native plants. The seeds are spread over long distances by birds.”
The State of Connecticut conducted a multi-year study of the situation and found that in areas with large numbers of plants, the incidence of Lyme disease carrying ticks was overwhelming higher. Some other conclusions include:
- With white-tailed deer shying away from eating Japanese barberry, this allows it to overpower native shrubs.
- The dense habitat provides optimal conditions for all life stages of blacklegged ticks.
- Larval blacklegged ticks feed on small host mammals such as white-footed mice. Japanese barberry with early leaf-out, dense thorns and a wealth of fruit create the perfect habitat for the small mammals.
- Mature Japanese barberry grow to be about three to six feet high becoming the perfect height for adult ticks to attach themselves to deer as they pass by.
Eliminating Japanese barberry from forests and landscapes will most certainly reduce the risk of Lyme disease, though it can be challenging. Early detection of small, newly expanding populations is ideal, but not often possible in dense planting areas. Removal of the plant does not guarantee a resurgence based on root systems and seed spread.
Chemical treatments can be effective, but could pose other ecological issues based on the size of the Japanese barberry coverage area and location.
Management and control are an ongoing process, but there are options to help treat the most dangerous characteristic of the plant – the spread of Lyme disease caused by ticks.
SavATree’s proven Tick Control Treatment and Prevention Programs are ideal for landscapes with a large population of Japanese barberry shrubs which can’t be easily or quickly removed.
If you’re concerned about the presence of ticks in your yard, our arborists can apply a treatment to the ecotone areas (zone between lawn areas and wooded areas – this is the preferred habitat of the deer tick) and, if necessary, to the lawn area as well, which will provide an immediate reduction in the number of ticks on your landscape.