Early Detection: On the Lookout for Invasive Plants

As the weather starts to get warmer and the days get longer, there are some tasks many of us have in common. We put away our sweaters and coats from the colder months. We do a thorough spring cleaning inside and outside the home. We prep the garden beds and get our seeds started. For me and many others interested in natural resources, there's another item on the spring to-do list - keep an eye out for invasive plants.

Invasive plants -especially shrubs like multiflora rose and autumn olive - are some of the first plants to green up in the spring, often well before our native species. This gives them a head start on the growing season and can also allow them to shade out the native plants that leaf out later. With an early-spring landscape that is mostly twigs and branches, it is extremely easy to spot the pops of electric green that might indicate the presence of an individual or group of invasive plants. These springtime surveys are a useful approach for one of the most effective strategies for dealing with invasive plants - early detection and rapid response.


Invasives are some of the first plants to leaf out in the spring,
making it a good time for early detection efforts.

Most natural resources professionals agree that the best strategy for dealing with invasive plants is prevention. Keeping invasive plants from spreading to new areas and becoming established eliminates the need for further management techniques, making it the least expensive and least labor-intensive strategy when it comes to dealing with invasives. We can prevent the spread of invasive plants by avoiding disturbance to soils and existing plant communities and using on-site materials, for example.

But after prevention, early detection and rapid response is the most effective strategy to prevent or slow new invasive plants from becoming established in an area. Ths is because it is much easier to remove a few plants to stop a species from becoming established than to tackle a species that is abundant and pervasive. Early detection and rapid response (EDRR) can take different forms, but are basically practices that enable land managers to identify new and spreading invasive plants and take management action quickly, before the population grows to the point where it cannot be locally eradicated.

Early detection can take place on multiple scales. For example, perennial pepperweed is an early detection species for the entire state of New Hampshire. It is currently only found in a few areas of the Seacoast and one site in Franconia Notch. At the regional level, autumn olive is prevalent in the central and southern parts of the state, but not elsewhere. So, if you live and work in northern New Hampshire, autumn olive would be considered an early detection species. For an individual property or site, an early detection species might be a plant that hasn’t been found on that particular parcel yet – for example, a few stems of garlic mustard that weren't there the previous season. It's important to learn about and be able to identify the invasive plants that might be considered early detection species in your area or on your property.


Perennial pepperweed, autumn olive, and garlic mustard.

Early detection and rapid response is an important strategy because the cost for invasive plant management and control efforts can be huge - in terms of time, money, and other resources - and many are not successful. Luckily, there are many resources to help you be successful in your efforts to detect invasives early and take action quickly.

  • NH Fish & Game Department has developed a guide called Picking Our Battles: Planning Successful Invasive Plant Management Projects. It contains really useful strategies for dealing with invasives and customized information for each New Hampshire community, including maps of 'hotspots' for invasive plant management and lists of early detection species.
  • Nature Groupie, a project of UNH Extension, has a guide for mapping invasive plants using EDDMaps (Early Detection & Distribution Mapping System). EDDMaps is an app/website that makes it easy to keep track of invasives in your backyard or community. The data is also shared with invasive plant managers at the state-level, so they are aware of any reports that might be considered early detection.
  • The Garlic Mustard Challenge is a collaborative effort, led by Nature Groupie and UNH Extension, to prevent the further spread of the invasive plant garlic mustard, which is considered an early detection species in New Hampshire. There are great resources available for learning how to identify garlic mustard, pull the plants (it's really easy!), and share about your efforts to see our collective impact each year.
  • As part of the NH Invasives Academy led by UNH Extension, we developed and created a series of videos focused on early detection species in New Hampshire to help you learn more about their ecology, identifying characteristics, and potential control options. Check out the videos on garlic mustard, black swallow-wort, perennial pepperweed, and tree of heaven.

By Haley Andreozzi, Wildlife Outreach Program Manager, UNH Cooperative Extension
Spring 2021 Taking Action for Wildlife Newsletter