CITO week is fast approaching, and as geocachers, we love to take care of our playground. Events all over the world will celebrate our desires to keep the planet clean. Along with the tons of trash that we hope to pull out of the woods and fields that we enjoy, another “trash” is lurking in plain sight. Invasive species are polluting our wonderful playground as they force out natural species through competition and alteration of the ecosystem. One of the most prominent invasive species in Wisconsin is garlic mustard.

Garlic mustard, an invader of our state parks, forests, and the hiking and biking trails across the state of Wisconsin, is a biennial plant that was introduced from Europe in the 1860s, probably as a culinary herb. During its first year of growth, the plant forms a low-growing cluster of distinctive kidney-shaped leaves. These ground clusters remain green throughout the winter. Mature flowering plants will grow up to 40 inches tall in their second year and can be recognized by their 4-petaled white flowers and stalked, triangular-shaped leaves with toothed edges. Garlic mustard plants produce copious amounts of seeds, with as many as 3,000 seeds per plant.  These seeds can survive for up to 10 years in the soil, creating a lasting problem at invaded sites. Garlic mustard alters the chemistry of the soils where it grows by adding chemicals to the soil that prevent the growth of other plant species. In invaded areas, garlic mustard forms a single-species carpet on the forest floor.

The Wisconsin DNR recommends hand pulling the plants in early spring, before they go to seed. Flowering plants should be placed in plastic bags for trash disposal, or disposed of in a controlled burn when conditions permit. Plants should be cut at the base after the stem has grown, but before the flowers have bloomed if possible. Sites of infestation should be marked, as sometimes repeat treatments may be necessary.

Remember this coming week that not all trash is soda bottles and burger wrappers. Some of the most damaging things to the environment can simply be a plant or animal that doesn’t belong in a particular ecosystem. Being in nature a lot more than your average person gives us, as geocachers, more opportunity to discover these hazards to our state’s natural resources. If we can educate ourselves not only on garlic mustard, but on all kinds of invasive species, we can keep Wisconsin’s parks, trails, lakes, and rivers teeming with the natural wildlife that we enjoy experiencing on our caching adventures.