Resistance Isn’t Futile: The Fight Against Buckthorn Allelopathy

Halie Gehling, “Resistance Isn’t Futile: The Fight Against Buckthorn Allelopathy”
Mentor: Teresa Schueller, College of General Studies – Mathematics & Natural Sciences

Common buckthorn (Rhamnus cathartica) is a highly invasive plant that is quickly overtaking Wisconsin and much of the Northern Midwest. Buckthorn is an aggressive pioneer species that takes advantage of disturbed ecosystems and edge habitats. One reason why buckthorn is particularly difficult for land managers to control is because of its allelopathy (the ability to create and spread toxins to other plants to negatively influence germination). The top priority for land managers dealing with invasive plants is to keep uninvaded areas clean. To accomplish this, land managers could plant a native, easily controlled crop to occupy the space until the spread of invasives has been diminished. In order to compete with the buckthorn to slow or stop resprouting, we tested three native species’ resistance to the R. cathartica’s drupe allelopathy: mustard (Guillenia flavescens), big bluestem (Andropogon gerardi), and Canada wild rye (Elymus canadensis). Unripe drupes were collected in mid-August and ripe drupes were collected in mid-September, 2019. Drupes were placed in the center of petri dishes that were 15 cm in diameter. Each dish contained six rings of six seeds from one native species. The plants were left to germinate for 19 days under continuous light and daily watering. For both tests, E. canadensis germinated more than the others, and consistently closer to the drupe. Although this suggests E. canadensis may have some resistance to R. carthatica’s allelopathy, is it still uncertain if the native species would be able to out-compete common buckthorn outside of a lab setting, as many variables, like soil composition, microbiomes, and surface substrates, were not tested for. The results of this preliminary experiment show that there is variation in allelopathic resistance between native species of plants, making some more suited to use in remediation or as a cover crop when managing a buckthorn invasion.

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