City Collaborates with Local Conservation Group to Tackle Invasive Species
By: Michael Ramsey
North Country Cooperative Invasive Species Management Area (NCCISMA)
Ornamental plants are an attractive and positive part of city yards: they add appeal to individual yards, offer homeowners a sense of pride, and most can be managed with pruning – even by novice gardeners. However, some ornamentals can rapidly outcompete and overgrow other plants and be so destructive that they are considered invasive: fitting the definition of an invasive plant by impacting the environment and the economy.
Statements about plants describing them as hard to kill, fast growing, and quick spreading, can be red flags that the plant may be invasive in nature. These species are often further spread by human hands, as most gardeners love plants and enjoy sharing them with friends and family. The term invasive species has become synonymous with plants and animals that are in some way harmful, but that leaves understanding and public opinion open to many relative factors. What may seem harmless to a gardener in a landscaping setting could be entirely different from a conservationist’s observation of a species in the wild – as it outcompetes native plants. Therefore, it is important to understand all that goes into managing invasive species, like Knotweed (Fallopia japonica), in urban settings. Well intended control efforts can do more harm than good, as such species require specific approaches for effective management. To that extent, the City of Ludington is working to address concerns about specific invasive species that have the potential to damage infrastructure and negatively impact local economy.
While it may not be possible to home in on an exact date regarding the introduction of Knotweed to the area, its history likely goes back over 100 years, possibly to the early days of the Worldwide ornamental trade boom. In that era, anyone could purchase exotic ornamental clones from local nurseries and seed packets from mail-order catalogues, so it seems likely that it has been here a very long time. One of the most common questions that the Ludington City Council is asked about invasives is “Why would someone plant something if it is invasive?” The short answer is that people could not have understood the threats posed by non-natives until they acted in an invasive way and that extremely few non-native plants become invasive. Invasive species experts explain this probability with what is called “The 10% rule,” which claims that only about 10% of introduced non-native species become established, and only about 10% of those that take a foothold will become invasive. One other major contributing factor to their presence is that state legislative steps are required to designate an invasive species as prohibited or restricted. These designations prevent the sale of invasive species, but often come with pushback from the ornamental industry as many exotic species, like Barberry, are top sellers. To date, there are only 5 land-based plants on the Michigan Prohibited and Restricted Species list – “species that are unlawful to introduce, import, sell, or offer for sale as a living organism” - including Japanese Knotweed.
The City of Ludington recognizes the problems that this plant can cause – not for how it appears when it becomes overgrown, but – in how it penetrates underground and because it is incredibly difficult to eradicate. Knotweed roots can run down as far as 15 feet deep and extend out up to 65 feet in the search of water. These roots are strong enough to break through asphalt, creating considerable concern for city planners as they can invade water systems, clog drainage, and force through concrete cracks to damage sidewalks and foundations. Problems are often compounded when efforts are made to remove the plant, as it is invigorated by cutting. To make matters worse, cut stalks can root and form entirely new patches. Over the summer of 2024, NCCIMSA staff conducted surveys from Ludington city roads and alleys to identify locations of Knotweed, as well as two other invasive plants - invasive bittersweet (Celastrus orbiculatus) and tree of heaven (Ailanthus altissima).
Using this information, NCCISMA is creating a management plan to help guide control efforts for these species within the city limits, addressing them in a strategized and cost-effective manner. Surveys performed in summer not only identified properties impacted by invasive plants, but also found out where these species were creating safety concerns: by blocking alleys, impeding site line views for motorists, and creating potential hazards for utility lines. Survey results will be shared at the next council meeting, December 9th. The City of Ludington hopes to kick off management efforts in 2025 by addressing Knotweed as it is relatively sparse within the city (compared to invasive bittersweet and tree of heaven), but disproportionately impactful to city infrastructure.
Additional information will be published in coming months regarding the direction of invasive species efforts and management plan creation for Ludington. A full list of properties impacted by the three invasive species surveyed will be available in late December. Any invasive species control work conducted by or on behalf of the City of Ludington will be done through collaboration with each land owner - who will in no way be obligated to participate if they wish to opt out – and NCCISMA will be available to help teach landowners proper treatment methods and best practices for those who wish to tackle these invasives themselves. Management of these species typically occurs from July to September, so residents are encouraged to leave them undisturbed throughout spring: as cutting or trimming can stimulate growth, worsening the problem. For resources on Knotweed and other invasive species, visit www.northcountryinvasives.org.
