Look before you leap! Invasive plants are formidable, resilient creatures. Knowing the options available for management of invasive plants is critical; using multiple methods increases the likelihood of success. For best results, you must know which method is the best fit for the situation.
Plan First, Then Control
Invasive plant management should be regarded as one part of the stewardship of wildlands and natural communities. Take some time to observe the landscape and the factors affecting it. Know what you are getting into, and plan a long game. Some reasons for invasive plant management are
- site preparation for restoration planting,
- removal of competition in established communities,
- protection of sensitive species or habitats, or
- prevention of the expansion of recently-established invaders.
Strategy
Each invasive plant population should be evaluated as a combination of biological and ecological factors. The biology of the target species strongly influences which treatment options will be successful. The environmental conditions where the plants are growing are equally important to consider.
Life History
Learn the growth pattern of the target invasive species, because it will determine the main options for the timing of control and removal. No matter what the growth cycle of a plant is, the key is preventing the plant from reproducing by seed or by vegetative cloning.
Growth Form
Exploit the weak point in the growth cycle of the target species. If necessary, manipulate the growth of the plant to use up its reserves of energy, while timing control to protect adjacent vegetation.
Control timing
Make calculated decisions. There are optimal times for removing invasive species, and there are optimal times for minimizing harm to the native plant and animal communities at a site. The trick is finding the balance point among timing and treatment methods.
Site-based or Species-based Approach
Sometimes we put all our time and effort into getting one site clean. Other times we crisscross the region hunting for the latest arrival of a troublesome species. Most of the time, it’s a combination of both methods.
Treatment Methods
Knowing the options available for managing invasive plants is critical. More importantly, you must know which method is the best fit for the situation.
To be most effective and environmentally responsible, removal of invasive species should use a variety of methods to control and restore sites. The major treatment methods for invasive plants are mechanical, chemical, and biological. Each method has its own timing and technical advantages or disadvantages, and the best methods to use will depend on the site.
Mechanical Control
This is using any means to physically remove or destroy the invasive plants. Mechanical control methods alone are rarely enough to completely control an invasive plant problem, though they are a good way for homeowners to begin managing property.
Chemical Control
Chemical control methods are reliable for combating invasive plants; some herbicides are designed to kill the entire plant, above and below ground, while others merely kill the above-ground portion of the plant.
Biological Control
Biological control uses natural agents – mostly insects, but sometimes fungi, pathogens, or larger animals – to eat or otherwise damage the invasive plant species. Getting biocontrol to work as planned is very expensive and complicated, but it offers some of the best long-term maintenance of invasive plant populations.
Restoration
There is little reason to zealously remove invasive species unless there are plans in place for the rehabilitation of native plant and animal communities. Keep in mind that the purpose of invasive plant management is to allow natural systems some time and space to recover as much of their native composition and structure as possible, in order to sustain the biological and geochemical cycles that make life possible.
Restoration of a site to some historical reference condition is highly unlikely in the urbanized, developed, and generally disturbed landscapes in our region. That’s okay. Stewardship, whether protection of natural areas, or replanting of abandoned landscapes, is essential in an era of global climate disruption. Restoration is a way to repair the shredded strands of the food web, clean the waters, and clear the air among humans and the rest of the planet.