Gabriola's invasive plants

Invasive plants are spreading agressively across all of British Columbia, and Gabriola is no different. The Invasive Plant Council of BC web site states: "Often mistaken for wildflowers, invasive plants are spreading through our natural ecosystems, urban landscapes, and agricultural lands at an alarming rate. Invasive plants are spread through several key pathways of invasion including increased international, national, and regional travel and trade; horticulture, gardening, and ornamentals; transportation and utility corridors; seed mixtures (re-revegetation, birdseed, wildflower); recreation; and wildlife, livestock, humans, and pets."

The Coastal Invasive Plant Committee web site asks: "Did you know that invasive species are considered to be one of the greatest threats to biodiversity world-wide, second only to habitat loss? Or that in Coastal BC existing invasive non-native (alien) plant infestations are estimated to be in the tens of thousands?"

The four worst invasive plants on Gabriola are scotch broom (Cytisus scoparius) in open sunny places, daphne, or spurge laurel (Daphne laureola) in the forest understorey, tansy ragwort (Senecio jacobeae) in sunny spots and along roadsides, and giant hogweed (Heracleum mantegazzianum) in moist areas. Others include beloved plants like Himalayan blackberry, periwinkle, and yellow flag iris, and familiar garden pests such as thistles. This page offer some advice on how to identify and safely remove a few of the worst invaders from public parks, roadsides, and our own land.

Scotch broom (Cytisus scoparius)

GaLTT member Rufus Churcher has compiled all you need to know about one of Gabriola's worst invasive species. Click here to read about the plant, how it spreads so rapidly, and how to eradicate it.

Gabriola's regular broom-bashing

It's always a pleasure to see the lovely spread of blue Camas lilies (Camassia quamash) and yellow Spring Gold (Lomatium utriculatum) blooming on the broom-free meadow. Also, a few garry oak (Quercus garryana) seedlings can be found in the grass where broom was pulled over the last few years. New broom seedlings are there too though, so it's a constant battle.

All broom contains toxins that kill other plants, allowing it to take over areas. Wherever you see Scotch broom on public land, do the whole island a favour and remove it before it goes to seed. In May and June it's easy to see because of its beautiful yellow blooms. Please remove it from your own property too.

GaLTT has special tools called Extractigators that help to pull larger plants up by the roots. There are two sizes, depending on the job. You may borrow one by calling Rob Brockley at 247-9467.

Joanne Sales from Nanaimo Broombusters gave Gabriola's Gardening Club this advice in April 2013: Main message—It's best to cut the broom while it is flowering.

Condition Process Disposal
Mature broom in full bloom (April to June) Use geared loppers to cut as close to the ground as possible. Pile on other invasives such as blackberry, or put through chipper.
Mature broom in full bloom with seedpods (July to August) Use geared loppers and cut close to the ground, but this is NOT a good time to cut in most places because of the danger of spreading seeds. If you cut, try to catch the seeds and destroy them. Avoid spreading them.
Mature green broom the rest of the year

Pull with Extractigators. Pull grass back over the exposed dirt to prevent light reaching seeds in the soil.
Lopping can produce fan-shaped plants that are more difficult to pull later.

Place broom without seedpods in piles or use a chipper. Dry broom is a fire hazard.
Small seedlings in wet periods Hand pull and tamp down bare or disturbed soil. Disperse on ground or place in piles.
Small seedlings in dry conditions or where hand-pulling is difficult. Use small "Junior" Extractigators and tamp down bare or disturbed soil. Disperse on ground or place in piles.
Medium sized green broom that's unlikely to bloom. Use either size of Extractigator but take care to tamp down disturbed soil and cover with grass. Place on piles or over other invasives such as blackberry.
Mature broom trees Saw down at any time. Probably best left where it falls.

Daphne or spurge laurel (Daphne laureola)

To remove daphne, use gloves and try to pull it up from the roots. If you snip small plants, they will continue to grow and branch into a sturdy bush, but if a large plant has all its branches snipped off in late summer, the stress may be enough to kill it. Pulling large daphne is best done with a tool called an extractigator—Randy Young says "you can borrow a GaLTT extractigator at no charge… just give me a call at 250-247-8541, and come and pick it up."

The Commons team has done sterling work pulling invasive Daphne Laureola from their land, some of it really large. And they've discovered an added problem—horizontal branches can put down new roots and then send up a new shoot, as you can see in Don Smardon's photo at right.

For more pictures and advice on managing invasive Daphne laureola click here.

Tansy ragwort (Senecio jacobeae)

Help eradicate it by uprooting and removing the plants before they go to seed. Use protective gloves and make sure you pull out all the root system so that it doesn't regenerate. Bag the culled plants for removal. Do NOT leave the pulled plants on the ground where animals could eat them. They are toxic to cows, horses, and even goats.

A great way to deal with culled tansy ragwort plants is to just stuff them into a black plastic garbage bag and seal it. Leave them to compost in the sealed bag for a few months (to make sure no seeds escape) and you'll get some good, pest-free soil for your garden.

Giant hogweed (Heracleum mantegazzianum)

It spreads easily and is hard to eradicate. It reproduces by seeds and from perennial buds at its crown. The seeds are adundant and long-lasting in the soil. This plant is a persistent problem in Drumbeg Park in the fenced area behind the public toilets, and can be found elsewhere on Gabriola.

WARNING—DO NOT HANDLE THIS PLANT! Its sap on exposed skin causes hypersensitivity to sunlight, resulting in blistering and dermatitis. Scarring and blindness may result.

Management strategy: Use protective clothing and eyewear. Cut off the flowerheads to prevent seed formation. Excavate the plants by severing the roots at least 8 cm below the soil surface. Dispose of plants in strong garbage bags. DO NOT COMPOST. Return to the site to check for regrowth—followup may be needed for 3 to 5 years. Chemical controls can be effective using foliar application in both spring and summer, or stem injection during heavy sap flow in spring.

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