What is it?
You probably know garlic mustard even if you don’t know you know it. Odds are, it has invaded forest areas near you as it has much of the midwest. Garlic mustard, Jack-In-the-Bush, or Alliaria petiolata is a non-native understory invasive plant in North America. Garlic mustard was brought to the Americas nearly two hundred years ago from Europe as a medicinal and culinary herb. Today, it can be found in nearly every county of Ohio.
Crushed garlic mustard leaves have a distinct garlic-y smell, giving the plant one of its names. Its scent is one way to identify the plant. Otherwise, garlic mustard is a biennial (it has a two-year life cycle) and looks different based on its life stage. First-year garlic mustard grows in rosettes close to the ground. Young leaves are round or have kidney shapes and often have purple stems. In its second year, garlic mustard is easier to identify and grows up to three or four feet. It has triangular, heart-shaped leaves with toothed edges. Garlic mustard’s flower is white and four-petaled. To learn more, check out this online resource from the Ohio Invasive Plants Council.
Why is it a problem?
Non-natives follow the “Tens Rule,” meaning that one in ten non-native species will become established in their new environment, but only one in ten of those established species will become invasive. Those few invasive species pack a big punch. Like all non-native invasives, garlic mustard wreaks havoc by out-competing native plants in foreign locations with no natural controls. For instance, our growing deer population does not eat garlic mustard because deer did not evolve and adapt to eat it. This means native understory plants are eaten by deer when garlic mustard continues to spread. Native food-webs and ecosystems are thrown out of balance by invasives like garlic mustard.
One garlic mustard plant can release thousands of seeds that will remain viable in the environment for up to seven years. This makes it easier for garlic mustard to spread and overwhelm an area, decreasing its biodiversity and health. Most commonly, the plant thrives in forest and edge habitats. Garlic mustard sprouts earlier in the spring than most native species. When native species eventually emerge, garlic mustard blocks sunlight making it more difficult for natives like our beautiful wildflowers to grow. Garlic mustard is particularly damaging because it secretes a compound called sinigrin into the soil that destroys fungal networks that support native species. This makes it even more difficult for resident native plants to thwart the invasive and lessens native plant’s biotic resistance.
Garlic mustard has transformed our natural ecosystems. It can out-compete tree seedlings which halts the recovery of forests. Garlic mustard alters the habitat of mollusks and salamanders, threatening their survival. The West Virginia White Butterfly is particularly endangered by garlic mustard. The butterfly lays its eggs on the plant because it secretes chemicals similar to the butterfly’s host plants. In reality, this is just a disguise as garlic mustard is toxic to the butterfly.
What to do about it?
Removing garlic mustard requires time and vigilance. Because garlic mustard seeds last in the environment, it can take nearly seven years to exhaust the seed bank. Nonetheless, we can all try to fight back against this invasive plant. Garlic mustard can be mechanically removed via pulling and cutting in your yard and local areas. Some chemical solutions exist and even biological controls are being explored. Here, we will focus on mechanical controls. To pull garlic mustard, pull from the base of the stem to remove the entire root system. Try to pull the weed before it seeds. In large infestations, it may be more manageable to cut garlic mustard close to the ground. Either way, be sure to bag and throw out your pulled or cut plants rather than composting them or leaving them at the site, as this will only continue to spread the seeds.
Or, rather than sending the weeds to a landfill, you can eat them as the Europeans intended! Garlic mustard is a tasty and nutritious plant that is an excellent source of vitamin C. Garlic mustard can be added to salads, made into pesto, and much more. You can find a collection of various recipes here. Garlic mustard should be harvested when young because older plants are more bitter and contain cyanide so therefore must be cooked thoroughly. Garlic mustard shoots are similar to garlic scapes and snap peas while the plant’s roots taste like horseradish. To quote the USDA, let’s eat it to beat it!
This spring, an Americorps team joining FLOW will be removing garlic mustard from the Sawmill Wetlands, the Stratford Ecological Preserve, and the Methodist Theological School of Ohio to combat the spread of the invasive non-native species in the Olentangy watershed. To learn about other invasive species in Ohio and what is being done to control them, check out FLOW’s website or the Ohio Invasive Plants Council’s website.
Cover photo: FLOW volunteer pulling garlic mustard at Sawmill Wetlands (pre-COVID).