Proper disposal of invasive plants
You may be noticing that plants have greened up fast and hopefully you know some of those plants are invasive, meaning they are not native to the ecosystem and harm the environment, economy, or human health.
During the spring, some of the first invasive plants you will see growing around your house may include garlic mustard (Alliaria petiolata), Japanese or giant knotweed (Fallopia japanica or F. sachalinensis), and common or glossy buckthorn (Ramnus cathartica or Frangula alnus).
These species represent plants that reproduce or spread very differently from each other, and thus require different disposal techniques to prevent their spread.
The Michigan DNR has an online guide for invasive plant disposal (https://www.michigan.gov/-/media/Project/Websites/invasives/Documents/Action/Guide_Invasive_Plant_Disposal.pdf?rev=0e05e0f0fa8040cd8659810626426acb), which has useful information on laws and disposal techniques for different groups of invasive plants.
Below, we have also provided some examples of common invasive species in Baraga, Houghton, and Keweenaw county and their respective disposal techniques.
Garlic mustard is a herbaceous plant that only lives for 2 years and spreads prolifically by seed alone, but these seeds can continue to develop from flowers even after being cut or pulled.
Due to this trait, this type of plant needs to be burned immediately after removal or bagged and sent to the landfill with your other bags of garbage.
Never compost garlic mustard, other invasive plants with similar reproductive traits, or the fruiting bodies of any invasive plants.
For more information about garlic mustard identification, management, and native alternatives go to KISMA’s garlic mustard webpage (https://www.mtu.edu/kisma/terrestrial-invasive-species/garlic-mustard/).
Woody seed producers
Common and glossy buckthorns are woody shrubs or small trees that also reproduce by seed.
The same goes for Japanese and European barberries (Berberis thunbergii and B. vulgaris), which you should remove from your yard.
However, these species also will regrow when their stems are cut, because they have a perennial root system that stores energy.
It is best to manage woody plants by removing aboveground plant parts and roots or smothering the cut stem and about a foot around the stem.
Seedlings and saplings that you pull out with roots can be hung by their roots from tree branches to dry before letting them come in contact with the soil.
Go to KISMA’s webpage on common buckthorn (https://www.mtu.edu/kisma/terrestrial-invasive-species/common-buckthorn/) or KISMA’s webpage on Japanese barberry (https://www.mtu.edu/kisma/terrestrial-invasive-species/japanese-barberry/) for identification, management, and native alternatives to buckthorn and barberry.
Best practices for buckthorns and barberries include managing before they seed. The woody stems of the plant can be chipped or burned. If you manage woody plants after they have developed seed, you can pile the seeded branches on a tarp and transfer that to a burn area along with seeds that fall off, or you can pull all the seeds off and bag them for the landfill.
Woody material can be chipped or composted, but not the seeds. In this instance, the timing of management plays a role in determining the appropriate disposal technique, as the seeds should not be composted or chipped.
Herbaceous vegetative reproducers
Japanese and giant knotweeds tend to vegetatively reproduce via plant fragmentation.
This means if any part of the plant (stem or root tissue) with a node touches the soil, it can grow a whole new plant.
The same goes for snow-on-the-mountain, also known as Bishop’s goutweed, (Aegopodium podagraria) that you might have in your yard.
Once removed, these plants should never be piled where they can touch the soil while fresh. You can pile the pulled plants on cement or tarps to dry in the sun, and, once completely brown, crisp, and dry, they will not regrow.
If you cannot dry out fresh material, then it needs to be bagged and sent to the landfill.
Never compost fresh plant parts of Japanese knotweed, giant knotweed, Bishop’s goutweed, or other invasive plant species that can reproduce vegetatively through fragmentation.
For more about knotweed identification, management, and native alternatives go to KISMA’s giant knotweed webpage (https://www.mtu.edu/kisma/terrestrial-invasive-species/giant-knotweed/).
When considering burning a plant, native or invasive, it is important to determine whether burning the plant will release any toxins or irritants into the air that may harm humans or wildlife.
One example of a native plant that should never be burned is poison ivy (Toxicodendron radicans). When burned, poison ivy produces a smoke that, if inhaled, can lead to lung irritation (CDC, https://www.cdc.gov/niosh/docs/2010-118/pdfs/2010-118.pdf).
Other poisonous plants can have similar effects when burned.
Additionally, weather conditions and fire warnings need to be consulted before burning.
The state of Michigan provides a burn permit website (https://www.michigan.gov/dnr/managing-resources/forestry/fire/burn-permit?utm_source=govdelivery) to determine if it’s safe to burn in your area.
The season is hot and dry already.
As described in the above examples, the proper disposal technique for an invasive species will differ depending on the species’ reproductive traits, dispersal capabilities, and the time of year.
Thus, when it comes to disposing of invasive plants, it is crucial to be cognizant about your chosen disposal method and consider whether the species’ reproductive strategies and modes of spread have been accounted for.
Sigrid Resh (firstname.lastname@example.org) is the Coordinator for Keweenaw Invasive Species Management Area (KISMA), and Research Assistant Professor at Michigan Technological University; Erin Mauk (email@example.com), Wildlife Ecology and Conservation at Michigan Technological University