Himalayan Balsam Arrives in Nova Scotia

 

 Himalayan balsam (Impatiens glandulifera Royle), otherwise known as Poor Man’s Orchid or Policeman’s Helmet, has been ‘escaping’ from gardens since 1839, when John Forbes Royle, the former curator of the East India Company’s botanical gardens in Saharanpur, northern India, gave his specimens to the Royal Botanic Gardens at Kew in London. Fifteen years later, the fast-growing bamboo-like annual with purple and reddish stalks and pink, purple, or white flowers was found throughout the English countryside; by the turn of the century it had infested wide swathes of of Europe and had begun to spread across the United States and Canada. Some five years ago, it arrived in my garden in Cow Bay, Nova Scotia.

The elegant import from India became a staple of the ‘wild woodland gardens’ promoted by William Robinson, the celebrity gardener who rebelled against manicured British flowerbeds and promoted gardens with broad expanses of bright flowers growing together in a less tidy and more natural manner (the precursor of today’s English cottage gardens).

Exotic plants, including goldenrod and asters from North America, Chinese lilies and wild roses, Japanese knotweed and anemones, rhododendrons from Spain and Sikkim, giant hogweed from the Caucasus, and Himalayan balsam from the central and western Himalayas, were all part of the horticultural extravaganzas which 19th century Victorians created around their country homes. Seeds were obtained either directly or indirectly (via commercial nurseries) from the Horticultural Society of London, which imported seeds from, among others, the East India Company. Unfortunately, some of the imported exotics grew too well; Himalayan balsam literally exploded into the areas surrounding the country gardens where it had been planted. Impatiens glandulifera reproduces through seed-pods that pop when they are ripe and throw seeds up to seven meters (the plant belongs to the Touch-Me-Not family). A single plant, which can reach heights of three meters,  produces on average 700-800 (up to 2500!) seeds, so that a thick patch of young seedlings emerges early the following spring and crowds out other plants.

Where Impatiens glandulifera comes into contact with water currents, the spread is even faster.  The seeds are negatively buoyant and are carried downstream, sometimes for long distances, before becoming lodged and germinating in a muddy bank, starting the cycle all over again. Himalayan balsam thus rapidly establishes itself along waterways, where it is the greatest threat. Not only does it out-compete native species; when dense stands of Impatiens glandulifera die off in the fall, the hollow stalks quickly rot and leave large areas of river and lake banks exposed and highly susceptible to erosion.

By 1855 Himalayan balsam was already found throughout the English countryside; it continued to spread so rapidly that it was given weed status in 1898. Today, it is completely naturalized throughout riparian and open-wooded habitats in most of lowland England and Wales and in many parts of Scotland and Ireland and is even found in the Channel Islands. In 2010 Impatiens glandulifera was included in Schedule 9 of the 1981 Wildlife and Countryside Act, making it illegal to allow or cause the plant to grow in the British countryside.

Himalayan balsam does have its defenders, though – in particular British beekeepers, who value its high levels of sugar nectar, which honey bees gorge on late in the fall when they have difficuty finding other sources. Proponents claim that Himalayan balsam can be crucial in helping honey bees survive over winter. The British Beekeepers Assocation has advised its members to keep a few bushes in their gardens. being careful to ensure that seeds don’t escape to the countryside – the history of the plant makes it doubtful that this is possible.

Himalayan balsam did not stop at the UK border, but quickly spread to Europe. By the 1900s it was common in southwest Germany, where it spread via the Rhine River; by the mid-1900s, it was found throughout the Scandinavian countries. Today, it is found  in 27 European countries, and in New Zealand, Japan, and the Russian Far East. It is present in 11 states of the United States and invasive in 6. In Connecticut, for example, it has been illegal since October 2004 to move, sell, purchase, transplant, cultivate, or distribute the plant, according to Public Act 04-203.

Impatiens glandulifera was likely introduced to Canada as an ornamental garden plant. The first documented sighting in Canada was in 1901 in Ottawa, Ontario, but the plant quickly escaped the gardens and spread to much of southern Ontario, where it has gained a foothold in many watersheds. It is listed in Ontario as a Category 1 'invasive species that can dominate a site to exclude all other species’.

Himalayan balsam is now established in eight Canadian provinces: British Columbia, Manitoba, Ontario, Quebec, Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland. However, it is far from reaching its potential climatic range in Canada, given the plant’s ability to thrive in a wide range of soil and light conditions and in relatively cool climates (there are frequent sightings in Alaska). Beginning in the 1990s, there have been large-scale attempts to remove it, particularly in British Columbia, Alberta, and Ontario.

In British Columbia, Himalayan balsam is found predominantly in the southern part of the province, including southern Vancouver Island, the Fraser Valley, and Metro Vancouver, where it is spreading rapidly and potentially threatening many sensitive riparian habitats important for salmon. Impatiens glandulifera is listed on British Columbia’s Invasive Plant Alert List. 

In Alberta there are thick patches along water courses within the urban areas of Edmonton, Red Deer, and Parkland County. Between 2014 and 2018, the City of Edmonton aided by over 100 volunteers pulled nearly 8000 square meters of Himalayan balsam from the Kennedale Ravine.  However, the biggest infestation of escaped plants in Alberta was in Pigeon Lake, where the local community launched a campaign in 2009 to remove the plants that had spread halfway around the lake, a distance of around 25 kilometers.

Himalayan balsam is listed as prohibited noxious weed under the Alberta Weed Control Act and as a prohibited species under the Fisheries (Alberta) Act, making it illegal to sell, import, transport, or possess. Penalties can be up to $100,000 and/or a year in prison.

The first recorded sighting of Himalayan balsam in the Maritimes was in 1937, in vacant lots in New Glasgow, Nova Scotia. The plant was found in St. John, New Brunswick in 1943, where the seeds may have arrived attached to ships’ ballast. According to data collected by the Atlantic Canada Conservation Data Centre, the plant was repeatedly found in southern New Brunswick during the 1960, 70s, and 80s – in Fredericton, Deer Island, St. Andrews, Campobello Island, and Blacks Harbour, among other places.

Although there is a data gap in 1990s, the 2000s show more sightings in New Brunswick and a couple in Nova Scotia, along the Middle River and in Hammonds Plains. The data for the last five years, primarily from the smart phone app iNaturalist, show that the plant has now fully arrived in Nova Scotia;[1] it has been sighted in, among other places, Sydney, Inverness, Pictou, Amherst, Truro, Wolfville, Annapolis Royal, Digby, Brier Island, St. Margaret’s Bay, the McIntosh Run watershed, and  throughout greater Halifax, where it is listed as an invasive species.[2]  

I had never heard of Himalayan balsam until my neighbor purposefully strode into my field in mid-July and yanked out a two-meter-tall blooming plant. ‘The dreaded Himalayan balsam’, he announced. Say what? I had been on the lookout for ‘dreaded’ goutweed and Japanese knotweed since I had moved in a few months previously but Himalayan balsam?

Discussions with other neighbors revealed that the plant has been spreading from garden to garden in our corner of Cow Bay for the last 10 years or so. I needed to move on it immediately, as it was in bloom and would soon be forming seed pods that would spew their contents meters from each plant. So, I donned my gloves (the plant can induce an allergic reaction) and, with the help of my neighbor, began to pull and pulled and pulled for days on end. You have to pull Himalayan balsam, I learned; if you simply cut it, the plants will form new shoots with new flowers and new seed pods at one of the lower stem nodes.

The official recommendation is to place all the pulled plants into black bags, leave them in the sun so as to kill off the seeds, and then place the remains into normal garbage (NOT into the organic waste) – or burn the remains. That turned out to be highly impractical, as I had literally thousands of plants to dispose of.

The good people of Pigeon Lake, Alberta who removed Himalayan balsam from 25 kilometers of their shoreline came to the same conclusion. They pulled the plants up by the roots – quite easy to do, as the roots are only 10-20 cm deep – broke the stems a couple times and let them lie where they had pulled them. They found that this worked quite well; by and large, the plants did not reemerge the following year at the site where they had been dropped.[3]

All this assumes you reach the plants before seed pods have formed – if you are too late, you have to carefully place a bag over the seedpods before you pull. The weather also plays a role. It is best to pull when there is no rain in the forecast, because the pulled stems can actually form new adventitious roots along the lower stem nodes if there is some moisture near the ground.

So, if Himalayan balsam has now reached Cow Bay, how bad is it in the rest of Nova Scotia? Not so bad, it turns out – as of yet. According to Prof. Jeremy Lundholm, Chair of the Biology Department at St. Mary’s University and an expert on plant ecology at the community level, several other invasive plant species, including Japanese knotweed, rosa multiflora, and phragmites comprise far more serious problems for the province at present. Having said that, however, he notes that he and his family personally pulled Himalayan balsam from a 20 x 20 meter area of  Point Pleasant Park in Halifax some 10 years ago – because it is easy to remove a small infestation and it will grow to a big problem if you don’t. He has since been monitoring the spot and pulls out any newcomers that emerge.

But, I wondered, is anybody actually tracking the spread of invasive plant species like Himalayan balsam in Nova Scotia and doing something about the spread? Turns out that information and sporadic eradication attempts are scattered across various agencies. The Nova Scotia Department of Agriculture is responsible for the 10 noxious weeds that are listed under the province’s Agricultural Weed Control Act (Himalayan balsam is not on the list).[4]

The Department of Land and Forestry, on the other hand, deals with invasive plants on provincial crown land, particularly plants that pose a risk to human health such as giant hogweed. Halifax Regional Municipality, in turn, is responsible for invasive plants (like Himalayan balsam) on municipal parks, trails, and playgrounds. And for help identifying and advice about managing invasive species on private land, the municipality refers residents to the Nova Scotia Museum or the E.C. Smith Herbarium.

However, behind the scenes, there is an informal network of biologists, botanists, and conservationists in these government agencies and in academic and non-profit organizations in Nova Scotia who are the first responders for invasive species issues in the province. This group recently organized a volunteer brigade in Kentville to pull out dog-strangling vine, an invasive weed that has been virtually unknown in Nova Scotia up to now and needs to be stopped before it becomes established.

The network is in the process of setting up the Nova Scotia Invasive Species Council (NSISC). According to Claire Wilson, one of the coordinators of the new group, the vision of the NSISC is to serve as a one-stop shop for people seeking information and advice regarding the identification and management of all invasive species in the province. Modelled on invasive species councils of other provinces like Alberta, the volunteer-based NSISC aims to coordinate information flows between government departments and promote coordinated management activities, including early detection, rapid response, distribution/mapping, control and eradication.

The NSISC will also promote public education and undertake activities to raise awareness about invasive species. For more information or to submit an invasive species sighting, see the Council’s website.[5]

As for me in Cow Bay, after clearing out all the Himalayan balsam I could find on my land, I now only have to patrol the pulled sites and the rest of the garden for stragglers – small plants I missed because they had not yet emerged from underneath the alders, spirea, wild roses, and winterberry that fill much of the garden. These are easy to spot as they inevitably have pink, helmet-shaped flowers poking through the brush. The ones surrounded by wild roses or brambles are the worst, but I know that if I don’t get them, there will be a major outbreak of Himalayan balsam at that spot next year instead of the small patch I see now. 

--An edited version of this article first appeared in the Halifax Field Naturalist Newsletter, No. 182, (March to May 2021):10-12.

Sources:

Cartoon by Russ Brown

David R. Clements, Kathleen R. Feenstra, Karen Jones, and Richard Staniforth, The Biology of Invasive Alien Plants in Canada. 9.Impatiens glanduliferaRoyle, Canadian Journal of Plant Sciences. 88, 2008, p. 403-417, https://www.nrcresearchpress.com/doi/pdf/10.4141/CJPS06040

Fred Pearce The New Wild: Why Invasive Species Will Be Nature's Salvation, Beacon Press, 2016

Robert A. Tanner, An Ecological Assessment of Impatiens glandulifera in its Introduced and Native Range and the Potential for its Classical Biological Control, PhD thesis, University of London, 2011, https://core.ac.uk/download/pdf/78863851.pdf

To report an invasive plant sighting:

• Call the municipal Citizen Contact Centre at 311 if it is on municipal property Call the Provincial Department of Natural Resources at 902 861 2560 if it is on a property that is not owned by the municipality
• Upload a picture of it onto the iNaturalist app Submit a report on the website of the Nova Scotia Invasive Species Council:  http://nsinvasives.ca
• For help identifying and advice about managing invasive species on private land
• Call the Nova Scotia Museum at 902 424 3564
• Call the E.C. Smith Herbarium, Acadia University at 902 585 1335

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[1] https://inaturalist.ca/observations?place_id=6853&taxon_id=47892

[2] https://www.halifax.ca/sites/default/files/documents/about-the-city/energy-environment/InvasiveSpeciesinHalifax.pdf

[3] https://www.himalayanbalsam.ca, make sure to listen to the recording of the Himalayan Balsam Blues

[4] https://novascotia.ca/just/regulations/regs/WControl.htm

[5] http://nsinvasives.ca