Invasive plants. They may have innocent enough names, such as porcelainberry and tree-of-heaven and Oriental bittersweet. But make no mistake about it, they are killers and they want to take over your garden -- right here in Greenwich. So, the battle lines must be drawn or soon you may find your property blanketed by garlic mustard or covered in Japanese knotweed.
Yesterday, Greenwich Land Trust fired the first shot in this season's war against these non-native invasive plants, holding an all-day Invasive Plant Workshop with experts offering the how-tos of halting the non-native plant invasion.
So which plants are the major invaders and how can they be controlled or eliminated? Greenwich Citizen asked Steve Conaway, Stewardship & Outreach Manager for the Greenwich Land Trust. Conaway, who has a background in plant pathology and weed ecology, is bringing his expertise to the Land Trust's mission to make invasive weed control a major aim in its stewardship efforts.
Q: What are the invasive weeds that are a concern in Greenwich?
A: Some top weeds that we encounter a lot are: Oriental bittersweet, garlic mustard, and phragmities common reed -- as well as porcelainberry, Japanese barberry, Japanese knotweed, European privet, mile-a-minute, Japanese stiltgrass, multiflora rose, Norway maple, winged euonymus and tree-of-heaven.
Q: How much of a problem is it in town?
A: Aside from mile-a-minute, most of the weeds listed are ubiquitous throughout Greenwich. Invasive plants may impact residents' lives in more ways than they realize. Natural spaces provide us with a plethora of valuable actions that are often referred to as "ecosystem services." Ecosystem services such as cleaning the water and air can be negatively impacted when invasive species push an ecosystem out of balance. Invasive plants can also have major effects on infrastructure such as bringing down power lines, eroding road edges, damaging foundations and clogging pipes.
Q: Are there parts of town where the problem is more prevalent?
A: Greenwich contains a wide variety of different ecosystems. Each is threatened by unique invasive plant species and faces problems unique to each area. Our coastal land can lose vital nesting area for migratory birds and have the movement of water dramatically changed. Forests can lose biodiversity and become more prone to storm damage and erosion. Meadows and open areas can lose their ability to support pollinator species that we depend on for growing food. Wetlands can be dramatically altered and become habitat for pests such as disease-carrying mosquitoes.
Q: What do you do if you are invaded? Five tips?
1. Learning what plants are problematic in Greenwich and how to identify them is the first step in controlling invasive weeds in your own backyard. The Connecticut Invasive Plant Working Group is a good resource to start with: www.cipwg.uconn.edu.
2. There are many look-a-like native plants that you should familiarize yourself with so you don't accidentally kill beneficial species.
3. Each invasive plant species has its own unique biology and, therefore, its own best management. Focusing control efforts on the roots, stems or seeds of a plant depends on the lifecycle of that plant and how it spreads. For example, mowing the seed heads of a plant that spreads primarily from its roots like Japanese knotweed will do very little to control it over time.
4. Keeping invasive plants under control requires vigilance. Neither cutting, mowing, pulling, using synthetic or organic herbicides provide a silver bullet. Repeated controls season after season exhaust the plant's resources and reduce the seed bank they have established in the soil. Mapping where problem weeds are one year will allow you to find them easily and remove them the next year and will eventually control or eradicate them.
5. Once invasive plants are removed from an area, it becomes susceptible to other invasive species spreading in to take advantage of the exposed resource. Use mulch, and encourage native plants in order to prevent new invasive species from becoming established in their place.
Q: If you haven't been invaded, how do you prevent an invasion?
A: Prevention is very important. Invasive plants are often aided by human activities. Many of the invasive plants that Greenwich spends money managing originated as horticultural plantings. Some plants that are recognized as problematic weeds (i.e., Japanese barberry and European privet) are still sold and planted in backyards all across town!
Ask your local nursery or landscaper for native alternatives to exotic landscape plants. There are many attractive native species that can be planted in the home landscape. They are adapted for local conditions but will not spread uncontrollably, and an additional benefit is that they provide food and habitat to local wildlife. Many resources are available online and from your local University Extension service in selecting appropriate native plants for your home.
Encourage your neighbors to plant native plants as well. The invasive plants that compose your neighbor's hedge row will likely become your problem eventually!