Garlic Mustard: Tasty in the Kitchen, Not in Michigan Forests

By:  Natalie Wienold

Many Americans embark on their summer trips to iconic destinations, sometimes choosing between California on the West Coast or Cape Cod and Nantucket on the East Coast.[1] However, they often overlook a stunning  “third coast”: Michigan.[2] Northern Michigan is an underrated area, for its natural beauty with its array of trees and greenery, freshwater lakes, beaches, and picturesque small towns.[3] As Michiganders and visitors enjoy the idyllic landscape; they must remain vigilant for invasive species that threaten the vibrant ecosystems of Michigan forests. One of the most prevalent invaders that Michiganders continue to be advised on is garlic mustard.[4]

Garlic Mustard

Garlic mustard (alliaria petiolata) is an invasive species that is toxic to many native plants and animals throughout the United States.[5] An invasive species is any species that is non-native and causes harm to the environment, economy, or harm to human health.[6]

European settlers introduced garlic mustard to North America in 1868, primarily for medicinal and herbal purposes.[7] The weed was first recorded in the United States on Long Island, New York, and has since spread throughout the Northeast, Midwest, and Northwest.[8]

Garlic mustard has a two-year life cycle, in its first year, it lays low to the ground, forming small, rosette-like leaves.[9] In its second year, the weed grows several feet upward and produces bright white flowers that bloom in the early spring.[10] The plant is self‐pollinating, allowing a single plant to produce thousands of seeds.[11]

Garlic mustard produces an abundance of glucosinolates, a family of sulfur-containing chemicals, which are excreted by the roots.[12] The glucosinolates kill some of the symbiotic mycorrhizal fungi that most native plants and tree species use to draw nutrients from the soil, however, garlic mustard can survive without such fungi.[13] The lack of nutrients significantly affects native plants’ ability to grow, and garlic mustard soon dominates these areas. [14] This is especially true since garlic mustard grows earlier in the spring than other plants and can thrive in deeply shaded areas.[15] This combination of survival factors makes garlic mustard a menace to forests and native plants.[16]

How do Garlic Mustard and other Invasive Species Spread so Easily?

Garlic mustard has tiny seeds, making it quite easy for the invader to spread even when preventative measures are taken.[17] Garlic mustard may be transported by way of human activity, as it can get blown by motor vehicles or stick to clothing.[18] Grazing mammals, such as deer, may also carry the seeds on their fur, then while feeding, inadvertently place them in areas of native plants.[19] Garlic mustard and native plants soon compete for space, but garlic mustard often prevails. The weed persists in forests because it lacks natural predators. Animals do not eat the plant because of its strong taste and chemical properties and therefore it maintains its presence in the forests.[20]

In addition, earthworms, which are also not native to Michigan, might be contributing to the garlic mustard’s overwhelming success.[21] As human activities, like fishing, camping, and general human interference, have introduced earthworms to Michigan forests, there has been an excessive deterioration of the natural leaf litter on the forest floor.[22] Earthworms allow invasive plant species to thrive in forests by increasing nutrient availability and reducing important relationships between fungi and native vascular plants.[23]

Invasive Species Laws and Regulations in Place

Federal laws have been enacted to prevent the introduction and interstate spread of known or potential invaders.[24] Some laws regulate modes of transport, while others regulate the organisms themselves.[25]

One of the most infamous federal laws that protect wildlife from being removed or moved to another habitat in the United States is the Lacey Act. The Lacey Act provides that:

“It is unlawful for any person to import, export, transport, sell, receive, acquire or purchase any fish or wildlife or plant taken, possessed, transported, or sold in violation of any law, treaty, or regulation of the United States or in violation of any Indian tribal law whether in interstate or foreign commerce. All plants or animals taken in violation of the Act are subject to forfeiture as well as all vessels, vehicles, aircraft, and other equipment used in the process.” [26]

The Plant Protection Act also prevents noxious weeds, listed under its Noxious Weed List, from being brought into the United States or moved from state to state.[27] Although it is not officially listed as a prohibited or restricted plant species, garlic mustard is still considered a noxious weed and aggressive invasive plant species in Michigan.[28] Although it is not listed under the federal Plant Protection Act, garlic mustard should still not be transported purposefully to other areas as it is highly invasive and can cause destruction to ecosystems.[29]

Preventative and Management Measures

Prevention of transport and the introduction of invasive species is the primary way to avoid a new invasion in the United States.[30] The Barack Obama Administration enacted Executive Order 13751—Safeguarding the Nation From the Impact of Invasive Species, aiming to prevent the introduction, establishment, and spread of invasive species across the country.[31] The Order directed federal agencies to coordinate efforts to detect, control, and eradicate invasive plants and animals to minimize their negative impacts on the environment, economy, and health.[32] Such preventative measures included promoting public education and action on invasive species; coordinating with state, territorial, and local governments, to expand the membership of the National Invasive Species Council (NISC) and to clarify its operations; and maintaining the Invasive Species Advisory Committee (ISAC).[33]

In 2017, the United States government spent nearly $3.0 billion across several federal agencies and activities to prevent, control, and eradicate invasive species domestically.[34] The majority of such funds went towards its prevention efforts totaling $1.1 billion alone.[35]

For garlic mustard in particular, there is conflicting research on the best methods for preventing its spread. Multiple resources state that to manage the spread, it is best to properly remove them by uprooting them in the early spring before the seed pods develop.[36] Michigan law permits the disposal of invasive species like garlic mustard in landfills or incinerators.[37] Therefore, Michigan residents and visitors should place the uprooted garlic mustard into a garbage bag and dispose of it in a garbage receptacle or incinerator. [38] Several small communities throughout the state of Michigan encourage their citizens and businesses to pull the toxic weeds whenever they can.[39] Northwest Michigan counties have held contests to see who can pick the most garlic mustard, as well as host “garlic mustard workbees” to encourage volunteers of all ages to pull garlic mustard.[40]

However, other research states that it is best to leave them alone in the long term and that the weed’s effects are not all that bad.[41] Dr. Berndt Blossney, a Cornell University conservation biologist who specializes in invasive plant species, states that it is worse to address and uproot large swaths of garlic mustard than to leave it alone.[42] He found that over a long period of time, within 10-12 years, garlic mustard will become scarce as a species, and dwindle in biomass.[43] It’s suggested that with such large areas of garlic mustard, it is not worth spending resources to eradicate the weed once it is established.[44]

Since garlic mustard is edible, it can be used for different delicious cooking dishes and be quite tasty and nutritious.[45] However, the weed should only be used in small doses as there are traces of cyanide in it.[46] With the glucosinolates it excretes, garlic mustard has a pungent smell and sharp taste that can give different sauces, like horseradish and yellow mustard, a bit of a spicy kick![47]

If you choose to not use garlic mustard for personal cooking purposes, such infestations can also be reported to the Midwest Invasive Species Information Network for eradication.[48]

All in All

Michigan’s greenery is what makes the Mitten State so special to locals and visitors. Protecting such a treasure from invasive species, like garlic mustard, whether government-enforced or by personal motivation, will help maintain Michigan’s vast forests for everyone to enjoy for years to come.

 

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[1] Christine Chitnis, Northern Michigan Is Ready for the Summer Spotlight, Vogue (May 11, 2023), https://www.vogue.com/article/northern-michigan-is-ready-for-the-summer-spotlight

[2] Id.

[3] Id.

[4] Rebecca Finneran, Garlic mustard: Michigan’s worst woodland weed, Michigan State University Extension (May 22, 2020), https://www.canr.msu.edu/news/garlic_mustard_may_be_michigans_worst_woodland_weed

[5] The Nature Conservancy, Garlic Mustard: Invasive, Destructive, Edible (Jul. 22, 2020),  https://www.nature.org/en-us/about-us/where-we-work/united-states/indiana/stories-in-indiana/garlic-mustard/

[6] Id.

[7] Id.

[8] U.S. Forest Service, Alliaria petiolate, U.S. Department of Agriculture, Forest Service, Fire Effects Information System (last visited Oct. 12, 2024), https://www.fs.usda.gov/database/feis/plants/forb/allpet/all.html

[9] Douglas Main, Invasive garlic mustard hurts native species–but its harmful powers wane over time, National Geographic (Apr. 26, 2021), https://www.nationalgeographic.com/environment/article/garlic-mustard-toxic-invader-power-waning-edible-cyanide#:~:text=Plant%20explosion,and%20producing%20bright%20white%20flowers.

[10] Id.

[11] Michigan Natural Features Inventory, Garlic Mustard, Michigan Department of Natural Resources (March 2018), https://mnfi.anr.msu.edu/invasive-species/GarlicMustardBCP.pdf.

[12] Main supra note 9.

[13] Main supra note 9

[14] Id.

[15] Id.

[16] Id.

[17]  The Nature Conservancy supra note 5.

[18] Id.

[19] U.S. Forest Service supra note 8.

[20] Id.

[21] Karina Martinez, Attack of the Invasive Species: Garlic Mustard and Exotic Earthworms Affect Plant Diversity, Harvard Forest (July 26, 2017), https://harvardforest.fas.harvard.edu/blog/attack-invasive-species-garlic-mustard-and-exotic-earthworms-affect-plant-diversity.

[22] Id.

[23] Id.

[24] State of Michigan, Don’t buy, sell, keep or move invasive species, Michigan Invasive Species (last visited Oct. 18, 2024),  https://www.michigan.gov/invasives/laws/dont-buy-sell-keep-or-move-invasive-species

[25] Id.

[26] Id.

[27] Id.

[28] Id.

[29] Id.; The Nature Conservancy supra note 5.

[30] Invasive Species: A Brief Overview, Congressional Research Service (October 26, 2018), https://crsreports.congress.gov/product/pdf/IF/IF11011/4

[31] Safeguarding the Nation From the Impacts of Invasive Species, 81 FR 88609 (December 5, 2016).

[32] Id.

[33] Invasive Species supra note 31.

[34] Supra note 30.

[35] Id.

[36] Michigan Natural Features Inventory supra note 11.

[37] Invasive Species, Portage, MI (last visited Oct. 18, 2024), https://www.portagemi.gov/415/Invasive-Species#:~:text=Proper%20removal%20and%20disposal%20are,and%20properly%20remove%20Garlic%20Mustard.

[38] Id.

[39] Invasive Species supra note 31.

[40] Scott Fraley, Contest aims to see who can pick the most garlic mustard in Benzie County (May 4, 2022), https://www.recordpatriot.com/news/article/ISN-Watch-out-for-invasive-garlic-mustard-this-17145540.php; News Advocate Staff, Invasive Species Network to hold garlic mustard workbees, The Benzie County Record Patriot (May 16, 2024), https://www.recordpatriot.com/news/article/invasive-species-network-hold-garlic-mustard-19461601.php

[41] Paul Hetzler, Do nothing about these invasive plants, North County Public Radio (April 9, 2021), https://www.northcountrypublicradio.org/news/story/43550/20210409/do-nothing-about-these-invasive-plants

[42] Id.

[43] Id.

[44] Main supra note 9.

[45] Id.

[46] Main supra note 9.

[47] Id.

[48] Invasive Species: Garlic Mustard, Michigan Invasive Species (last visited Oct. 18, 2024), https://www.michigan.gov/invasives/id-report/plants/herbs/garlic-mustard