Unfortunately, I’ve just noticed our invasion of Dog Strangler Vine (DSV – or Swallow-wort) is forming seed pods right now. Because these seed pods have a novel way of spreading, much more of our local countryside will be invaded next year.
Once ripened, the seed pods explode open to expose a fluffy cotton like material which catches the wind to spread the seeds over considerable distances. This tactic makes DSV a master invader, which has been left unchecked for over one hundred years, choking the life out of almost everything in it’s path.
The USDA has taken an interest in this awful plant locally, and have even posted signs in Powder Mills Park, right in a large patch of DSV, where they are studying the plants. It’s so good to know something is happening just a few miles away.
When I contacted the USDA, they mentioned a way to eliminate this weed over large areas was to spray the plants with an approved herbicide. and that it may take several applications and much monitoring to eliminate it completely. However, permits and property owner permissions would be required and this process could be only undertaken by a licensed applicator on Canal Authority property.
I have tried a novel ‘friendly’ home made weedkiller made of 5lbs rock salt, 1 gal hot water, 1/2 cup of dish washing detergent and a quart of white vinegar. Here is the result 24 hours after application on DSV at my home.
Note the USDA discuss how detrimental this DSV is to natural forests. National Heritage site Hart’s Woods is probably at risk. I note that DSV is all around the perimeter of these woods.
An interesting ‘natural’ remedy they are considering is to use what they call bio-control’, introducing fungi and caterpillars to eat the stuff!
The USDA have narrowed down the list of potential bio-controls to two fungi and two moths that, as caterpillars, feed on related species of swallow-worts. One of the moths, Abrostola clarissa, was found in Russia with the aid of collaborators at the Zoological Institute in St. Petersburg. The other moth, A. asclepiadis, was collected in France with help from collaborators at the ARS European Biological Control Laboratory in Montpellier.
The Ontario Government has already started a program using a natural enemy of DSV, the caterpillar of the Hypena Opulenta moth. It feeds exclusively on DSV vegetation, and was introduced into the wild around the Ottawa area in 2014. Defoliation of DSV at release points is easily detectable and entire DSV plants are yellowing in response to insect feeding on just a few leaves. In one year the caterpillars have spread over 100 meters.
Is anything eating the caterpillars, or will we have another foreign invader replacing the DSV? I’m still battling the stink bug invasion.
The Ontario Government issued these guidelines for the general public to help eradicate and control DSV.
Preventing the Spread
Everyone can help prevent the spread of dog-strangling vine by following these tips:
If you think you see dog-strangling vine, take a picture, record the location and contact the authorities to report it. In our case email@example.com
Watch for it.
Learn what dog-strangling vine looks like. Monitor hedges, property boundaries, fence lines and trails.
Early detection of invasive plants can increase the success of control and removal efforts.
Stay on trails.
Avoid traveling off-trail and in areas known to have dog-strangling vine or other invasive species.
Stop the spread.
Inspect, clean and remove mud, seeds and plant parts from clothing, pets (and horses), vehicles (including bicycles), and equipment such as mowers and tools. Clean vehicles and equipment in an area where plant seeds or parts aren’t likely to spread (e.g., wash vehicles in a driveway or at a car wash) before travelling to a new area.
Keep it natural.
Try to avoid disturbing soil and never remove native plants from natural areas. This leaves the soil bare and disturbed, which makes it more vulnerable to invasive species.
Use native species.
Try to use local native species in your garden. Don’t buy or transplant invasive species such as dog-strangling vine and encourage your local garden centre to sell native species. Plant Milkweed for the Monarch butterfly.
When looking at these alternatives, the prime objective seems to be ‘reduce seed population’’ by whatever means.
Note that ‘pulling’ will leave parts of the root in the soil which will regrow, but the flip side is that you have removed potentially over 10000 seeds from spreading. It is better to cut the plant at ground level as this weakens the plant and the seeds are removed.
As with most invasive plants, the swallow-worts are ecologically threatening because they can easily dominate areas and do not allow native plants to grow. Swallow-worts are extremely competitive, and grow and spread quickly. This causes a loss in biodiversity which can also harm animals who depend on the native plants for food or habitat. Pale swallow-wort’s increase in given areas has been shown to coincide with a decrease in the population of native birds. Black swallow-wort’s similarity to milkweed causes monarch butterflies to lay their eggs on the plant, but the larvae die.