Sunday, June 27, 2010

Hand to hand combat.

There is a growing battlefield out there. Fields and gardens in our area (Southern Ontario) are being invaded by a insidious green enemy: Dog-Strangling Vine or Black (or Louis’s) Swallowwort (Vincetoxicum rossicum or Cynanchum louiseae).

It reproduces by seed and also by runners under the soil. In the wild, it sneaks up and begins to twine itself over shrubs, trees, beloved perennials and peace loving wildflowers. About this time of year, it blooms with seemingly insignificant pinkish-brown flowers but once fertilized, the plant makes narrow pods that will later release milkweed-like puffy pods and burst with airborne seeds when the time comes. Unsurprisingly, it is a cousin of the common milkweed. However this enemy is proving to be almost unstoppable.Trying to yank it up through weeding can cause breaks in the root system -- and each break can encourage a new growth top. It can cover large areas in a frighteningly short time.

The energy, discipline and hard work needed to build beauty into our gardens are the sane qualities needed to stop such a focused and insidious foe as Dog Strangling Vine. Like any serious battle, we need to marshal our resources. The best, most earth-friendly thing to do is to cut the stem(s) off at, or just below, the soil level. Repeatedly mowing over throughout the growing season will eventually wear the plant out but farmers and forest managers are dealing with thousands of hectares where a home lawn mower simply won't do.

Will a well built dry stone wall hold back the botanical deluge? Probably not — though I have clients willing to find out. Walls of stone can be the demarkation zone between lawn and bushland, garden and wilderness, or just your proeprty and the neighbours. Weeds and other garden enemies tend to quickly occupy any well intended buffer zone, so eliminating the no man's land with a wall is generally a good idea. An engineered wood or wire fence will not do as good a job and will definitely not look as nice. Stone walls give the landscape less of a modernday 'battlefield' look. They add character and create a sense of time and place to the battlezone which at least makes it seem more like an historic re-enactment.


  1. We have the same sort of problem with Bracken.It has to be cut three times a year. The old saying was cut in May it grows another day ,cut in June ,it grows again soon,cut in July it will surely die. Hard work is the only world friendly answer.

  2. Apparently Dog-Strangling Vine was introduced to Ontario from Eurasia via the Ottawa Experimental Farm as research was being done on it's possible use for life jacket filling. I wonder was Bracken imported to Scotland from somewhere exotic, sometime back in history and if so for what - brackish water purification perhaps?