Walnuts and dog-strangling vine: a relationship in photos

by Sandy Garland

Once upon a time, 4-5 years ago, I pulled out the DSV that was growing under this walnut tree. I put down some newspapers to keep it from growing back (this doesn't really work) and forgot about it. This year, I noticed there is almost no DSV under this tree. The few DSV plants there are small and wilted.

Once upon a time, 4-5 years ago, I pulled out the DSV that was growing under this walnut tree. I put down some newspapers to keep it from growing back (we’ve learned subsequently that this doesn’t really work) and forgot about it. This year, I noticed there is almost no DSV under this tree. The few DSV plants there are small and wilted.

Another walnut tree, about the same age as the previous one, but this one has been ignored and is surrounded by DSV. A new volunteer has undertaken the job of pulling out this DSV in hopes of duplicating the experience just described, i.e., hoping the tree will inhibit regrowth of DSV.

Another walnut tree, about the same age as the previous one, but this one has been ignored and is surrounded by DSV. A new volunteer has undertaken the job of pulling out this DSV in hopes of duplicating the experience just described, i.e., hoping the tree will inhibit regrowth of DSV.

This walnut tree is probably about 20 years old, certainly old enough to be producing nuts.

Another walnut tree, this one is about 20 years old, certainly old enough to be producing nuts.

Under it, inside the "drip line," there is no DSV and, in fact some bare spots where nothing is growing.

Under it, inside the “drip line,” there is no DSV and, in fact some bare spots where nothing is growing.

Outside the drip line, there are patches of grass with no DSV, but the pattern is irregular.

Outside the drip line, there are patches of grass with no DSV, but the pattern is irregular.

A closer look at a DSV-free area next to the large walnut tree.

A closer look at a DSV-free area next to the large walnut tree. In this one, you can see that the green taller vegetation is DSV.

An area that was sprayed with Roundup last summer and again this spring. DSV is yellow and wilted, but most other vegetation has also been killed.

An area that was sprayed with Roundup last summer and again this spring. DSV is yellow and wilted, but most other vegetation has also been killed.

Looking in the opposite direction from the previous photo, this large walnut tree has successfully defeated DSV and grass is growing under the tree.

Looking in the opposite direction from the previous photo, this large walnut tree has successfully defeated DSV (except for that patch at the right of the trunk) and grass is growing under the tree.

Is this a relationship or just a lot of coincidences? Time to investigate it with some controlled experiments. Anyone interested?

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Scythes vs. dog-strangling vine

by Sandy Garland

Tuesday-in-the-woods day and my trusty crew of Catrina, Mirko, and Kate arrived right on time. Unfortunately, it looked like rain, so we stayed around the centre for a while watering (the plants that don’t get rained on) and potting up more seedlings: Gray Goldenrod and Upland White Goldenrod.

As the sky cleared a bit, we sharpened the scythes and set off for the field north of the woods to do battle with dog-strangling vine (DSV). This week, DSV was over two feet tall and mostly blooming. (Remember, the goal is not to let it set seed.)

Mirko and Catrina cutting DSV along the road north of the Old Woodlot

Mirko and Catrina cutting DSV along the road north of the Old Woodlot

We worked around the damp Red Osier Dogwood/Tamarack field, cutting around large clumps of goldenrod and along the narrow grassy area between the shrubs and the road (photo above). We’ve found that goldenrod competes with DSV somewhat, so we try to give this native species an advantage by damaging its competition (photo below).

Catrina scythed DSV around these clumps of goldenrods, while I pulled any DSV plants left at the edges and the few plants in the middle.

Catrina scythed DSV around these clumps of goldenrods, while I pulled any DSV plants left at the edges and the few plants in the middle.

Tiny Common Milkweed sprouts; hopefully we'll have a field full by the time Monarch butterflies arrive later this month.

Tiny milkweed sprouts; hopefully we’ll have a field full by the time Monarch butterflies arrive later this month.

In the milkweed field (still north of the woods but east of the centre trail), we again cut DSV along the road. In that field, a group of amazing high school students dug up a large area of DSV several weeks ago and planted Common Milkweed seeds, which are now sprouting. They turned the turf upside down on top of more DSV to double the damage and put down a tarpaulin south of the milkweed patch, in hopes of killing DSV there as well.

Questions we hope to answer

How many times do we have to cut DSV in various areas to keep it from setting seed? Will grass grow back faster than DSV, shading it and making it weaker? How effective is digging up the layer of sod that contains DSV roots? How effective is it to put down a thick layer of mulch after cutting DSV – a possible solution around shrubs?

Names of plants

False Solomon's Seal

False Solomon’s Seal


The woods are looking very lush this week as spring wildflowers take their turn adding splashes of colour to the shades of green. False Solomon’s Seal is still in bloom, as are wild Red Columbines and persistent pink ones that arrived many years ago in someone’s fall leaves.

Red Columbine

Red Columbine

Starry Solomon's Seal (right), just finished blooming and Canada Anemone just starting

Starry Solomon’s Seal (right), just finished blooming and Canada Anemone just starting

Interesting sightings
Dozens of Red Admiral caterpillars are eating their way through the nettles in the woods (below left). And Mirko found this tiny (2 cm diameter) mushroom growing in some mouldy wood chips (right).

Tuesday afternoons in the woods

by Sandy Garland

When our ash trees were taken down last spring, not only did they leave enormous “holes” in the Old Woodlot, but they also caused damage to other trees and plants when they fell and were dragged out of the area. Increased light means the ground vegetation is likely to change. All this prompted us to form a regular work group to restore this habitat and create a mixed woodlot full of a variety of native plants, shrubs, and trees.

A small group of us have been tackling this work, a bit at a time. Here are some successes and some things we’ve seen.

Over the last few weeks, a priority has been to remove Garlic Mustard, especially plants that are blooming as we want to prevent any more seeds from planting themselves. Garlic Mustard is an invasive species that is especially a problem in woods. See our fact sheet and photos.

Dog-strangling vine (DSV) is the most difficult invasive species to control. In fact, we don’t seem to be able to control it at all. Our goal is to at least keep the plants that are already in the woods from producing seeds. Mirko proved to be very adept with a scythe last Tuesday and cut a lot of DSV that was just starting to bloom. We’ll have to cut these same plants again in a month and probably once more in late summer as they grow back quickly. But if we can deplete the resources the plant stores in its roots, we might gain a few “points” in the battle. See our fact sheet and photos.

Newly scythed Dog-strangling Vine. Cutting gives grasses an advantage as they grow back faster than DSV.

Newly scythed Dog-strangling Vine. Cutting gives grasses an advantage as they grow back faster than DSV.

Glimpse of a gartersnake photographed by Kate Davis

Glimpse of a gartersnake photographed by Kate Davis

Kate chose to dig up DSV as that’s the only way to truly get rid of it. We dig it out around “good plants,” but it would take an army to do this all through the garden. In this area, goldenrods, blackberries, native clematis, and other wildflowers are competing with DSV. We’re on their side. While working, Kate found this gartersnake that seems to live on the south edge of the woods.

Another way to fight DSV is to cover thick patches of it with a tarpaulin. The tarp has to be left in place for more than a year to make sure the plant roots are killed. Last week, Catrina and I moved a tarp from this area to an adjacent one. I was very pleased to see that blackberries from nearby had grown runners under the tarp and were now sending up new shoots. You can just see blackberry flowers at the right of this photo. And you can just see the tarp in its new location in the background.

After killing DSV by covering it for more than a year, we were delighted to find blackberries growing into this now bare area

After killing DSV by covering it for more than a year, we were delighted to find blackberries spreading into this now bare area

Names of plants

A mass of Large-leaved Asters

A mass of Large-leaved Asters

In addition to invasive species, we’re all learning the names of the “good” plants. At the left are Large-leaved Asters (Eurybia macrophylla; see our database), a good ground cover in shady areas. They DO bloom, in late summer and early fall, usually just before Heart-leaved Asters.
Jack-in-the-Pulpit on the left growing right next to White Trilliums (right)

Jack-in-the-Pulpit on the left growing right next to White Trilliums (right)

At the left are two spring ephemerals, both of which have three-part leaves: Jack-in-the-Pulpit (Arisaema triphyllum; database) and White Trillium (Trillium grandiflorum; database).

Interesting sightings

We learned that Kate’s the one with sharp eyes – and a great cell-phone camera. She spotted and photographed a huge spider (not sure what species), a morel mushroom growing in our plant nursery, and a colourful American Toad (Anaxyrus americanus).

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Help wanted

With Ted off in Europe and Gene visiting grandchildren, we are down two valuable people from our Old Woods team. If you’d like to help, please come along any Tuesday afternoon at 1:30 pm. Even helping for one afternoon is important.

What is a Weed Ninja?

Invasive plants are the vegetative evil doers of the plant world. They slyly sneak in and wreak havoc on unsuspecting native plant colonies, displacing, damaging or downright killing our local flora. Such plants are also difficult to control or eradicate – this is the difference between the aggressive invader and a regular non-native plant.

Pesticides work for some invasive plants, and biological controls are researched for others – but the harsh truth is that sometimes the most effective, and only, plant control strategy is manual removal and monitoring. Considering the amount of natural green areas we have in Canada and even naturalised spaces in Ottawa, this equates to the need of an ARMY of weed pullers.

However, since we can’t always work together, even if you pull a garbage bag of weeds alone you are making a difference. Imagine if everyone did that! You are the Weed Ninja who clears the greenspace of Garlic Mustard along your favourite jogging path. A Weed Ninja identifies Dog-Strangling Vine in their child’s playground and eradicates it. When you brush off your dog between runs in natural areas to prevent the transport of weed seed, you are making a difference. You are the Weed Ninja when you educate your neighbours and encourage them to not throw their Periwinkle or Creeping Jenny over the fence.

You are that stealthy force for good, so arm yourself with education, garbage bags and gardening gloves, then go out and HI-YA the heck out of invasive plants!

Join us for a Weed Bee this summer to pitch in as part of the group, or organise your friends and tackle forgotten public lands further afield.

Weed Ninjas Unite! Your Target: Garlic Mustard

Garlic Mustard

This is the perfect time of year to tackle our first invasive foe of the season: Garlic Mustard (Alliaria petiolata). If you’re gazing out the window along the Transitway or parkways, you can’t miss this white-flowered plant standing out from the grass or other herbaceous plants around it. Rarely does one plant grow alone, so also noteworthy is its nature of having one tall plant in the middle surrounded by many of its smaller brethren (or children!) This group growth form is due to the way Garlic Mustard produces many seeds, which it then releases in the same location.

Garlic Mustard is a shade-tolerant biennial plant that thrives in woodland settings. It is considered a serious invasive pest of natural areas, particularly woodlands, displacing native flora and severely reducing species diversity. Its aggressive, rapid growth allows it to form dense carpets that prohibit growth of other species.

Recent research shows that Garlic Mustard can release chemicals that destroy the mycorrhizal fungi that many trees depend on for nutrients. This allelopathy means that when Garlic Mustard invades a site, growth of tree seedlings is reduced. Maple trees are particularly susceptible. Like many non-native plants, Garlic Mustard has few natural enemies to help keep it in check.

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Slender False Brome shows its face in Ontario

Brachypodium sylvaticum

Drat, another invader has crossed our border to the south.

“Slender False Brome (Brachypodium sylvaticum), an invasive Eurasian grass, is reported for the first time in Ontario and eastern Canada from Grey County, southern Ontario. The only previous Canadian record is from Vancouver Island, British Columbia. The species is widespread in the U.S. Pacific Northwest, where it is spreading aggressively throughout much of western Oregon. In the eastern U.S.A., known populations are few and localized, although the species will likely spread.  It should be watched for in southern Ontario and eastern Canada and controlled wherever possible in order to prevent the widespread invasion of the species in eastern North America.”

For more information, check out the full article at www.canadianfieldnaturalist.ca/index.php/cfn [Miller et al. 2011. Slender False Brome (Brachypodium sylvaticum, Poaceae), an Invasive Grass New to Ontario, Canada. Canadian Field-Naturalist 2011; 125(3)]. The article is very technical although it does have photos.

Some plants are…just evil. Learn how not to plant them.

dog-strangling vine, aka swallow wort

Some plants are the poster children of invasive species awareness campaigns. We’ve all heard about Purple Loosestrife (Lythrum salicaria), and FWG works hard to raise awareness about Dog-strangling Vine (Cynanchum rossicum /Vincetoxicum rossicum) and Buckthorn (both glossy Rhamnus frangula and common Rhamnus cathartica). However, some attractive lesser-known plants with invasive tendencies are still sold as ornamentals in nurseries or gifte­d between friends. They are no less invasive, but information campaigns in the garden industry aren’t always effective so these lovely plantes fatales are still grown and sold to consumers who plant them at home, perpetuating sources of invasive spread. There isn’t any malice involved, just a lack of information or even warnings on labels.

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