Written by: Summer Graham
Management of invasive species is a topic that often comes up when discussing natural environments and native plants. Maybe you are looking to restore an area, but Garlic Mustard (Alliaria petiolata) currently dominates the site. Or, maybe you want to convert your garden into a native plant sanctuary, but already established non-native species like Periwinkle (Vinca minor) and Goutweed (Aegopodium podagraria) are giving you a hard time.
Luckily, there are a variety of techniques that can be used to tackle these invaders, clearing the way for native species to once again thrive. Please note that effective strategies, timing, and appropriate disposal varies for different invasive species, so be sure to check the best management practices for the species you are trying to manage. In this blog, we cover some of the most common methods for tackling invasive species. Take a look to get some ideas, and then refer to the resources below for some species-specific best management practices!
Management Techniques -
Prevention and early detection is the most effective and economic way of controlling invasive species. This method involves managing an area to prevent the introduction and establishment of invasive species. Prevention might include asking hikers to clean off their boots at a trail head, to prevent any non-native seed from being introduced to a natural area. Early detection and rapid response (EDRR) is the next best option, with some organizations using citizen science like EDDMaps to help with early detection of invasive species.
Pros: stops infestations before they begin; often the most economical option
Cons: requires ongoing monitoring and planning to prevent introduction/establishment of invasives
This method uses mowing or cutting of an invasive plant to limit seed production and spread. This method needs to be repeated a couple times a year, and timing varies by plant. Overall, this can be less labour-intensive than other methods while still achieving desired results.
Pros: reduces seed production; relatively easy if accessible by mower
Cons: restricted by timing windows; won’t always kill plants but will reduce spread through seed
Includes re-vegetating and promoting establishment of a healthy ground or crop cover to help hold off invasive species. Helps to establish native plant communities, which is ideal for projects that aim to not only remove invasive species, but also restore native habitat.
Pros: long term management; good for environmentally sensitive areas; introduces native plants to the site
Cons: site and soil can be unfavourable; can be labour-intensive and costly
Works well with single plants and small infestations, and populations can often be removed completely (rather than just managed/reduced in the long term). This method involves manually pulling plants out (when soil is loose and moist) repeatedly and removal from the site. Works well for species such as Garlic Mustard if repeated annually before plants flower and seed. You can also dig out the plant (including roots) to remove them from the site.
Pros: can be used in sensitive areas; can manage small patches or single plants; persistent pulling can manage perennials
Cons: can be labour and time intensive; limited to small populations; many invasives reproduce through rhizomes which are hard to remove; specific timing window for removal due to seeds; must be done repeatedly
Biological control involves the introduction of a predator (often an insect) to control the invasive species by attacking or feeding on it. Invasive species are often considered invasive due to the fact that they were introduced to an area without their natural predators to keep them in check, this method aims to restore the natural balance between species.
Pros: uses natural predators for control; good for environmentally sensitive areas
Cons: slow progress; takes many years to develop and test biological control species; doesn’t “eradicate” the species; aren’t available or approved for most prevalent invasives; introduced control species can also become problematic in an ecosystem
Note: only certified and licensed individuals should undertake spraying of pesticides to control invasive species. All provincial and federal laws, pesticide regulations, and pesticide best management practices and safety protocols should be followed.
Chemical treatment involves spraying of pesticides and herbicides to control invasive species populations. This can often be effective in combination with other methods such as cutting and mowing, to reduce the amount of chemical needed.
Pros: often effective; can be targeted to certain plants/types of plants (e.g. herbaceous vs. woody); less labour than mechanical/manual methods
Cons: precautions need to be taken to limit the effects on surrounding non-target plants; limited use in sensitive environments; concern from public/community groups
September 21, 2021