Update on Biocontrols for Invasive Plants

There are four methods for managing invasive plant species: cultural, biological, mechanical, and chemical. The biological control method uses living organisms such as insects, pathogens, or goats to weaken, kill, or stop the seed production of a targeted invasive plant. The only biocontrol agent that targets a specific invasive plant species in Arlington is a weevil, which affects the Mile-a-Minute Weed.

The Mid-Atlantic Invasive Plant Council (MAIPC) is one of the best sources for up-to-date information on invasive plants in the Arlington region. MAIPC was established in 2000 and includes representation from federal, state and local government agencies, non-governmental organizations, and industries, academia, and individuals from Delaware, Maryland, New Jersey, Pennsylvania, Virginia, West Virginia, and the District of Columbia.

MAIPC strives to provide regional leadership to effectively address the threat of invasive plants to the native flora, fauna, and natural habitats of the Mid-Atlantic. The council coordinates regional efforts to gather and share information on the identification, management, and prevention of invasive species, to provide training and volunteer opportunities, and to identify research needs.

The MAIPC Biological Control Work Group collects information on biological control agents relevant to the mid-Atlantic region that may affect invasive plant species. The information below contains updates on biocontrol research from the MAIPC Working Group’s most recent report.

Japanese StiltgrassJapanese Stiltgrass (Microstegium vimineum)

Japanese stiltgrass is a highly invasive grass found in Arlington. It is an annual species that spreads quickly in disturbed sites.

According to the MAIPC Biocontrol Working Group, two species of the Bipolaris plant disease threaten the Japanese stiltgrass located in the Eastern United States with leaf spots and death.

The host range of the diseases has not been fully tested and research is on-going.

 

Garlic MustardGarlic Mustard (Alliaria petiolata)

Garlic mustard is a very common herbaceous invasive plant found in Arlington. It is a biennial plant that flowers in the spring.

The MAIPC Working Group has reported that four weevil species in the Ceutorhynchus genus are being studied at the University of Minnesota as a biocontrol for Garlic Mustard.

The root-crown mining weevil has been proposed for release in North America but is currently under review.

 

Japanese KnotweedJapanese Knotweed (Fallopia japonica)

Japanese knotweed is a large herbaceous perennial that is commonly found in Arlington, especially in riparian areas.

The MAIPC Working Group reports that “between 2007 and 2012, four natural enemies from knotweed’s native range were tested as potential biological control agents for knotweeds in North America–a leaf beetle, two moths, and a psyllid (Grevstad et al. 2013).”

The psyllid has been proposed for release in the United States; though its approval seems likely, it’s still under-research. According to the MAIPC Working Group, this insect was released in England and Wales in 2010 with no apparent negative effects.

 

Multiflora RoseMultiflora Rose (Rosa multiflora)

Multiflora rose is an invasive perennial shrub that is commonly found in Arlington. MAIPC reports that at least two native or naturalized pests (a mite and a disease) help limit the shrub’s spread to some extent.

The native eriophyid mite Phyllocoptes fructiphilus, can spread Rose Rosette disease, which has reduced the density of multiflora rose populations in the Eastern United States.

 

Tree-of-HeavenTree-of-Heaven (Ailanthus altissima)

Tree-of-heaven is an invasive tree species that is widespread in the Eastern United States. The MAIPC Working Group reports on several opportunities for biocontrol agents for this species.

The native, soil-borne fungus Verticillium nonalfalfae, has killed large amounts of the Tree-of-Heaven species in south-central Pennsylvania and north-western Maryland. Although the fungus appears to be host-specific, natural distribution of the fungus is limited. Researchers are currently working on determining the best way to utilize the fungus as a biocontrol agent. Additionally, the webworm Atteva punctella, may have expanded its host range from southern Florida, where it has caused serious damage to seedlings and small trees.

 

For more information about biocontrol agents for invasive plant species in Arlington County or to read the full MAIPC Biocontrol Working Group Report, please contact Sarah Archer at sarcher@arlingtonva.us.