By: Glenn Major
As a child, our mother sent us out to collect Bittersweet vines. Their attractive fruit mixed with gourds from the garden made for a festive holiday decoration of table or mantle. Folks wove them into colorful Christmas wreaths and candle rings. There lies the problem; these attractive vines imported from Asia in the 1860s as an ornamental plant have spread like wildfire and now threaten much of our North American habitat.
Oriental Bittersweet (Celastrus orbiculatus) is an non-native, invasive, aggressive climbing vine. Birds are attracted to the red fruits and rapidly spread the seeds widely. Left unchecked, it can completely overtake a forest by wrapping around trees and choking them, shading out adult trees and understory plants, and pulling trees down by their sheer weight. Also, Oriental Bittersweet crossbreeds with our less aggressive native American Bittersweet (Celastrus scandens) threatening genetic extinction.
Unfortunately, Oriental Bittersweet is here to stay. So what can we do to mitigate the damage to our ecosystems?
- Stop retail sales – Indiana has wisely banned sales of Oriental Bittersweet as nursery stock, but still is sold in places like Etsy and Ebay.
- Control Oriental Bittersweet infestations in natural areas, backyards, and landscaping
- Educating folks concerning the importance of control of this invasive species.
Controlling Oriental Bittersweet Infestations
Some type of bittersweet mitigation can be performed any time of the year.
- Manual pulling: easiest when soil is thawed and not dry, especially in sandy soils(March thru early summer, generally)
- Chemical spraying: requires vegetation (May thru September)
- Cutting Vines: vines too large to pull can be cut anytime.
- Herbicidal treatment with cutting: Best October through February when sap is not running, which decreases the effectiveness of herbicide
To recognize National Invasive Species Week, we will be discussing a few of the most common invasive plant species that Shirley Heinze Land Trust has to manage on our nature preserves. National Invasive Species Week is actually two, non-consecutive weeks – February 22 – 28, 2021 is dedicated to learning about and advocating for management of invasive species. In May, we will recognize the second week of this event, which is for taking action. At Shirley Heinze Land Trust, a major part of managing nature preserves involves managing invasive species to make room for native species, and increase biodiversity in northwestern Indiana. We hope that these Invasive Species Profiles will inspire you to learn more about how a few species can play a major role in the health of our ecosystems.