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The Garlic Mustard Wars… and other adventures


By Samantha Hircock

Disturbing the picturesque scenery of Midwestern forests is an army of garlic mustard (Alliaria petiolata). An invasive herb, it has been in North America since 1868. Being quite tasty, it was likely brought as food. It does make a good pesto. Since its arrival, however, it has become one the most invasive plant species of the eastern U.S. and Canada. It is pervasive because it is allelopathic, releasing chemicals that inhibit the growth of surrounding plants, allowing it to spread quickly and blanket a forest understory with seeds that can remain dormant for over a year. Its seeds germinate in early spring and each plant can produce thousands of seeds. Yikes!

How do you battle this enemy? Well, a couple of Ames crews, including my own, became soldiers in the effort at Effigy Mounds in Harpers Ferry, Iowa and got to experience applying chemicals to the herb. Wielding back-pack sprayers, we attacked with glyphosate (Round-Up). We swathed the forest, marking our trail with slappers that leave a chalk circle on whatever you hit. Sometimes the work was tedious, slowly walking in search of micro-adults (unusually small but seeding versions of the plant) and sometimes it was interesting as we moved along uneven terrain, through valleys and ditches and near rock edges. One has to go where the garlic mustard has gone.

There were equipment casualties over the course of the battles and people were stained a little blue from the dye used in the chemical mix (no harmful exposure), but it felt worth it to reduce the population of this invasive. We also learned that another effective way to remove a garlic mustard plant is to hand-pick it, shake off all of the dirt, remove the seed-head and hang it up off the ground for the other garlic mustard to see and be frightened by, or so that the roots don’t retake. This is what they do on the mounds at Effigy as it is not permitted to use chemicals or machines on the site.

The experience we had at Effigy Mounds wasn’t just about the Garlic Mustard Wars, though. We learned a lot from our project hosts about other species of plants and animals in the area and even some about the cultural history of the park. Our team birder was right in it with the park folks, pointing out the variety of great species of birds in the area and discerning their calls. We were allowed to check books out of the office’s small library, and those who worked with us were a wealth of information pointing out this and that as we walked our swaths.

On a rainy day, when we couldn’t spray, we put our time to educational use watching a video about a disease called white-nose that is effecting bat populations in caves across the country, and another video about the builders of the mounds. We even got to play with atlatls: the precursor to the bow and arrow, it’s a long narrow spear that is launched with a hooked stick. So much fun!!

I might close my eyes and see garlic mustard for a week or two but the experience was worth it; it felt good to put a dent in an invasive attacker and to learn as much as we did.