This year’s OIPC conference included many field trips that allowed participants to try out tools, such as the green Weeder and orange Extractigator to remove dog-strangling vine and small shrubs.

by Lynn Ovenden

The Ontario Invasive Plants Council hosted their 10th annual meeting and conference in Ottawa this year. The event began on October 10, 2017 with a field trip to the Leitrum wetland, Mud Lake and Macoun Marsh to view the invasive plant situation at each place. On Wednesday Oct. 11, a long 8am-5pm day, attendees were treated to 15 talks, lunch and ample chat time. OFNC’s donation in support of the event was gratefully acknowledged and our table display was prominent and looked good. The event was very well organized and the presentations excellent.

Here is a list of the talks and speakers, with my take-home messages.

David Phillips, Environment Canada and climate change: tomorrow’s weather forecast: warmer, wetter, and wilder
Fossil fuel emissions have increased variability of weather, energized the global climate system, and seem to be destabilizing it (e.g., looping of jet stream, slowing of North Atlantic current, ozone layer thinning, ocean acidification and warming). A rule of thumb prediction for future plant hardiness zones: up 1 zone by 2050, up 2 zones by 2100.

Genevieve Mercier, National Capital Commission: Restoring a natural habitat, Mud Lake vegetation management project
The NCC launched the project in fall 2015 with machines to remove large (>10 cm dbh) common and glossy buckthorn, honeysuckle, and Norway maple in the western part of the forest; more mechanical removal of shrubs in fall 2016. They enlisted the public and elementary school classes for manual/small tool removal of smaller shrubs, garlic mustard, and dog-strangling vine in spring 2016 and 2017.  They took Dan Brunton’s advice to first remove invasives from the most intact part of Mud Lake’s old forest, then remove invasives and restore native species on the periphery of this core, moving out. They are grateful to Tony Denton and the Fletcher Wildlife Garden for advice and loan of buckthorn wrenches in 2016. They bought new, easier-to-use tools in 2017: the Extractigator plus BigFoot for shrubs,  and the Field Gear Weeder for dog-strangling vine (pictured above). They will plant native species in the cleared areas in spring 2018.

Iola Price, Invasive plant management and control at McKay Lake
Since 2001, a neighbourhood group has pursued a management plan to replace the dense buckthorn understory in a white pine plantation with diverse native trees and shrubs. They removed some buckthorn with wrenches and winches; others were cut and the stumps covered with handmade toques made from heavy plastic bags.  Herb seeds were collected and broadcast. It worked.

Genevieve Raymond and Laila Gibbons, City of Ottawa wild parsnip strategy
In 2015, the city began a multi-year program to control wild parsnip in suburban and rural areas. Maps were prepared showing  the level of infestation (high/mid/low) on roadsides in early summer and again in fall, after application of  various mowing regimes and broadleaf herbicide applications. The process was repeated in 2016 and 2017 in areas not reached in 2015 and where abundant wild parsnip persisted. To be continued. Findings: mowing can only control the spread of wild parsnip,  doesn’t reduce or remove it once established. New rosettes appear on roadsides owing to seed dispersal and long seed dormancy in soil. Herbicide treatment leaves roadsides with more grass, less broadleaf herbs. Public support for the work was high owing to blanket distribution of information sheets and postcards saying “Caution! Avoid it.”

Erin Markham: Management of European water chestnut at Voyageur Provincial Park
Staff and volunteers have been trying since 2008 to control this aquatic plant that covers some bays of the park with a dense blanket of floating leafy rosettes. For the major infestations, they now use custom-made boats to cut the stems, collect the floating rosettes (and attached seeds) and deposit them onshore.  Floating barriers are placed across the mouth of the bay to keep loose rosettes from escaping. For smaller infestations elsewhere, people in canoes or hipwaders hand-pull individual plants by the submerged root. Result: the infested area is smaller each year and, so far, no spread elsewhere in Ottawa River. Water chestnut now occurs in Ontario at Wolf Island and near Blacks Rapids on the Rideau River; it also occurs in 44 New York counties.

Christine Villegas, CFIA: Progress on eradicating kudzu
Kudzu was found on a 0.5-ha site on the shoreline bluff of Lake Erie in 2009. In 2015, 9 plants including kudzu and wild parsnip, were added to Ontario’s schedule of noxious weeds to help minimize their threat to agriculture and horticulture. The 10-year kudzu eradication project began in spring 2015: 5 years to spray herbicide and replant shrubs, grass and forbes, 5 years monitoring with no kudzu to declare the site kudzu-free. Result after 3 seasons: the coverage of kudzu is reduced, kudzu is not spreading.

Meghan Grguric, University of Guelph: Management of giant hogweed
It grows along roadsides, streambanks, and forest edges in the GTA and is spreading. It produces abundant seed and a sap that causes photodermatitis. Bees love the flowers. Recommended control strategy: spray rosettes in May with a residual (reduce new seedlings), broadleaf (to retain grass) herbicide, like for wild parsnip in Ottawa. Kill full-grown plants in early August (when seeds set) by manual injection of herbicide into stems. Parsnip webmoth caterpillars can destroy the developing seed heads.

Richard Dickinson, University of Toronto: Mechanisms of invasion by dog-strangling vine
DSV makes soil inimical to other plants by producing a biochemical called antofine. Seeds and small DSV produce more antofine than mature DSV. For healthy growth, native plants depend on a network of diverse soil fungi, of many types, called the common mycorrhizal network. Richard Dickinson’s 4-year research included a survey of 56 DSV populations across Ontario (including at the FWG), an “invasion-in-progress” field study, and greenhouse experiments. Results suggest that, like native plants, growing DSV roots connect to the common mycorrhizal network. Their presence (probably via antofine) completely alters the composition of the common mycorrhizal network, so that it no longer supports native vegetation. To restore a site dominated by DSV, Richard suggests focusing first on removing the small DSV, then rehabilitating the soil fungal community by inoculating it with “healthy” soil from a non-DSV site, then adding native plants with as much soil from the transplant source as possible. He offers the example of soil inoculation experiments in the Netherlands as evidence that this approach might benefit restoration efforts.

Hypena opulenta moth caterpillar, is voarciously eating DSV leaves in test plots. Photo by Christine Hanrahan.

Robert Bourchier, AAFC: Biological control for invasive plants
It will take years to learn if larvae of a Ukrainian moth can be a good biocontrol agent for dog-strangling vine in North America. From 2006 to 2011, many researchers worked to prepare the petition to CFIA, who reviewed it from 2011 to 2013 and granted the release permit. The first open-field release of larvae was in 2015 on the Central Experimental Farm in Ottawa and two locations north of Toronto. Work since then includes monitoring, more releases and trials to improve protocols for rearing and release of the caterpillars. Results: initial releases have survived and slowly expanded, spread 700 m to Hogsback area in Ottawa.  If you find DSV with picture-window damage to leaves as pictured (below), send a photo of the leaf and location description to

Hypena opulenta moth caterpillar, early instar on a DSV leaf. Copyright free image provided by Agriculture and Agri-foods Canada.

James MacKay, City of London: Invasive plant management strategy
The strategy was recently endorsed by city Council with a budget of $500 thousand a year. Proponents used the strong environmental policies in the city’s official plan, the risk that unchecked invasive plants would be dangerous and costly, and partnership with the conservation authority to justify the need for the strategy. The strategy includes mapping, early detection and rapid response, management, restoration, and prevention. They will create, and encourage citizens to use, a native seed mix better suited to London area than commercial seed mixes.

Abby Wynia: Fish communities in invasive Phragmites australis versus native emergent species, St. Clair River Delta 

Erin Mallon & Dianne Watkins: Five-leaf aralia treatment and removal in an urban ravine

Dayna Laxton: Invasive plant management strategy for the York Regional Forest

Erling Armson & Kyle Borrowman, Ducks Unlimited: Habitat restoration projects across Canada
Projects include creation of carp exclusion areas in Manitoba’s Delta Marsh to increase vegetation, water quality, and fish diversity; emergency use permit for aerial application of glyphosate to 1700-ha marsh at Long Point, Ontario;  surveillance and removal of European Water Chestnut from Wolfe Island and Rideau River.

Ken Farr, Natural Resources Canada: Canada 150: national invasive species update