Tracking the Invasion Edge of Wavyleaf Basketgrass to Facilitate Targeted Early Detection and Rapid Response

First detected in the United States near Baltimore, Maryland in 1996, wavyleaf basketgrass is recognized as a USDA high-risk invasive species. This shade-tolerant, aggressively sprawling perennial grass is well-adapted to the forest understory. It spreads rapidly to form dense monocultures that can crowd out native herbaceous species. It has potential to impact tree seedling regeneration. Wavyleaf basketgrass seeds have sticky awns that easily attach to nearly anything that passes through an infested area. Once established, this invasive species is very difficult to eradicate.

There are known infestations in at least 15 counties in Maryland and over 20 counties in Virginia since initially identified near Shenandoah National Park in 2005. The invasion continues to expand to the north and west. Patches have been detected in West Virginia, Pennsylvania, Delaware, and Washington DC within the last 5 years. Much of this spread appears linked to recreational activities such as hiking. Left unchecked, forest communities will be impacted as carpet-like patches of wavyleaf basketgrass encroach into the understories.

This project’s goal is to strategically target areas that are at a higher risk of establishment of wavy basketgrass. Multiple stakeholders will coordinate to do regional monitoring to mitigate rapid spread into new regions. The intensive monitoring will help to quickly identify new patches and treat them before seed banks form.

Scientists will use mapped routes of spread based on genetic analyses. This will enable them to strategically target areas that are at a higher likelihood of establishment of this invasive grass. Knowledge of the paths this species is taking can also be used to delineate similar pathways beyond its current range. This project will also use leaf samples collected from peripheral populations in conjunction with existing collections to examine patterns of connectedness and reconstruct routes of spread.

Objectives

Facilitate a coordinated monitoring effort to establish a comprehensive record of the current invasion front for wavyleaf basketgrass. Produce a digital range map that integrates existing databases with new observations. Develop “pest alert” educational materials. Collect leaf samples from newly surveyed peripheral populations along the mapped range limits. Identify patterns of connectedness among populations and reconstruct routes of spread across the region. Use polymerase chain reaction (PCR)-based protocol to quantify patterns of genetic population structure in wavyleaf basketgrass. Characterize the routes and mechanisms of spread and test models of early invasion dynamics.

Expected Results

Outputs

• An intensive monitoring network of several partners.
• Routes of invasion as determined by genetic analyses.
• A current occurrence map of wavyleaf basketgrass and a risk map for spread beyond the current range.
• Documentation and eradication of new populations found beyond the edge of the front.
• Prioritization of the mapped source populations for treatment.
• “Pest alert” educational materials to increase awareness and early detection.

Expected Outcomes

• A network of wavyleaf basketgrass regional partners that can also serve to address subsequent new invaders.
• A model network to serve as an example nationally for detecting emerging invasive species.
• Comparison of the wavyleaf basketgrass risk maps with other invasive plant risk maps to identify general patterns of plant invasion.
• A halt in wavyleaf basketgrass spread beyond its current established range.

Metrics of Success

• Validation of the risk map using genetic markers on plants that were not included in developing the risk map and models.
• A successful network of monitoring evidenced by the attendance and activity of quarterly virtual group updates about new populations and data sharing.
• Creation of a shared Google Docs folder in which all data and maps will be stored for all members to see and use.
• Alerts of new populations beyond the wavyleaf basketgrass front are sent to all members.
• Information is shared with the state departments of agriculture for immediate removal if those documenting the population are unable to do so.

Geographies and High-Risk Landscapes to Be Addressed

Regional

Detection surveys will occur along the periphery of the current known distribution of wavyleaf basketgrass. This includes locations in West Virginia, Pennsylvania, Delaware, Washington, DC, and North Carolina. Monitoring will continue within Maryland and Virginia where the current invasion is centered.