After receiving a newsletter last summer from the Thousand Islands Land Trust, I realized that the entire back hill on our property (and all along our neighbors driveway and the seasonal road) is covered with the dreaded pale swallowwort.
Besides being near impossible to eradicate, this invasive weed can be deadly to Monarch butterflies. Swallowwort is related to milkweed, which Monarchs traditionally lay their eggs on. Unfortunately, Monarchs can get confused and lay their eggs on the swallowwort instead, and when the caterpillars hatch, they die.
“Some theories suggest that the caterpillars need the compounds found in the appropriate host plants in order to live, or they are poisoned by similar ones in the swallowworts, or they just find the leaves distasteful, won’t eat them, and starve.”
Either way, not a good scene, especially when the swallowwort seems to choke out any milkweed in sight! I plan on getting a butterfly garden going as soon as possible, but I’m not sure if they Monarchs would end up laying their eggs on the swallowwort regardless.
Now how do I plan on getting rid of this weedy nuisance? Therein lies the dilemma, as traditional methods such as burning or mowing down the area with a brush hog only result in, well nothing or spreading the seeds even farther. The entire root system needs to be taken out completely, and with a vining plant like swallowwort, finding the root source/sources is like looking for a needle in a haystack. If I went around diligently plucking seed pods before they burst in late summer, I would only be delaying the inevitable, as the pods from plants on my neighbor’s (ALL my neighbors) propert(ies) would then burst and blow around the neighborhood.
I’d heard about alternative weed removal methods, involving renting goats and cows to munch down the afflicted area, which would have been great since there’s already a flock of cows and goats across the street! But as this article from Boston.com notes, goats seem to like the taste of everything but swallowwort. Other sources implied that the swallowwort might even be poisonous to the goats!
It seems like the only successful method for complete eradication has been repeated application of herbicides (and even that hasn’t been reported as 100% effective). Since we’re running an organic operation over here, I’m hesitant to add anything to the landscape that might be harmful. So until someone invents an all-natural “herbicide” that will work on swallowwort, I’m just going to have to diligently pluck those seed heads to limit the spread on our own property.
UPDATE: For those of you who’ve stumbled upon this post in your search for swallow-wort solutions, I’ve since revisited this topic with some newer information – check it out, here!
Photo and pull quote from Upstate Gardener’s Journal
- Tales from the Field: Monarch Butterfly Update (earthrangers.com)
- Coastal Communities in the Carolinas Turn the Tide against “Beach Kudzu” (prweb.com)
- Letter: Pest plant removal ruining scenery (knoxnews.com)
- Kodiak refuge preps for fighting invasive weeds (mysanantonio.com)