Leafy spurge, Euphorbia esula, is a herbaceous perennial plant in the spurge family (Euphorbiaceae).
Leafy spurge is a Eurasian native that was first introduced to North America in 1826 (Massachusetts).
It is believed to have had multiple introductions through the disposal of ship ballast water, contaminated agricultural shipments, and as an ornamental plant.
Leafy spurge has been in Canada (Ontario) since at least 1889 and is believed to have been introduced in contaminated spelt (wheat) from Germany.
Today, Leafy spurge is found throughout the western half of the continent and much of the eastern half as well.
In 2005, it was estimated that leafy spurge had infested 4.6 million acres of land in the United States (mainly in agricultural land).
Leafy spurge distribution is unknown on PEI. It is currently listed by the Atlantic Conservation Data Centre as “Absent False Report”.
Here are some key features that may help to positively identify Leafy spurge:
Can reach 1m in height.
Stems are smooth, hairless, and grow in clumps.
Leaves are small with waxy smooth edges, arranged alternately or spirally, and are ~7cm long.
Leaves are bluish-green in colour, turning to reddish-orange in late summer-early fall.
Greenish-yellow heart-shaped bracts form under flowers.
Reproduces through lateral root buds and seeds; mature fruit explodes, spreading seeds up to 5m.
Has a lookalike, Cypress spurge (Euphorbia cyparissias), which is also considered invasive.
Leafy spurge is taller and more robust than Cypress Spurge and has fewer and wide leaves (3-8mm).
What it does in the ecosystem
Leafy spurge emerges early in the spring before most native plants.
Where it invades, it forms monocultures, displacing native species and preventing their growth.
Leafy spurge is not an adequate nutritional replacement for most wildlife species, meaning that its presence degrades wildlife habitat where native species are displaced.
Leafy spurge prefers full sun, and dominates in pastures, meadows, roadsides and other disturbed areas with dry, sandy soil.
Drought tolerance adds to leafy spurge’s competitive ability.
The plant is a prolific seed producer, producing as many as 2,500 seeds per square metre per year in an established patch.
The seed bank itself will pose an additional challenge for management, as leafy spurge seeds have been proven to remain viable in the soil for as long as seven years.
Reduces the value of pasturelands as cows and horses will not graze the plant due to it causing severe diarrhea.
Livestock and humans may also be affected by a milky latex sap that causes severe skin irritation and blistering.
If you see any leafy spurge on PEI it is crucial that you report your sighting. Early detection is absolutely essential in the management of this species.
Before selecting a control method, consider:
The size of the infestation.
The amount of effort you are willing and/or able to expend.
Often, multiple control methods are used simultaneously.
Consider the local ecosystem and what other organisms or ecological processes may be affected by management.
Leafy Spurge management will require time, labour, and diligence.
Focus on smaller, satellite populations first before tackling larger patches.
Leafy spurge emerges early in spring and begins to flower in May (continuing until October!). With this in mind, it is important to begin Leafy Spurge management as early as possible in its growing season.
Preventing seed formation is very important in limiting the plant’s spread.
Any management program will require repeated visits to the management site (at least annually) to remove any plants that sprout from dormant seeds or lef-behind rhizome pieces.
Physical removal of leafy spurge is a challenging task.
This challenge is, in part, due to its ability to regrow from any rhizomes left behind in the soil. Even root pieces buried three metres deep can regenerate to form new plants.
The plant secretes a milky latex sap that causes skin irritation and blistering. Wear protective equipment when handling the plant such as thick gloves, eye protection, long pants, tall boots, and a long shirt.
If hand pulling or digging leafy spurge, be sure to remove as much of the plant as you can, ideally the entire plant.
Plants will likely regrow quickly, so this must be repeated every 2-3 weeks to be effective.
Cutting or mowing Leafy spurge will prevent it from going to seed, but will not restrict vegetative growth below the soil level.
The latex sap can gum up equipment, making it less effective.
Mowing, like hand-pulling, will need to be repeated frequently.
These methods may prove ineffective if dealing with large infestations.
If you choose to remove leafy spurge physically, another option is to cover the treated area with a thick black tarp to “solarize” any new growth that appears.
Burning can be an effective control method, but not alone. If burning, you should do this in combination with other control methods, as burning alone may stimulate plant growth.
Burning may be prohibited seasonally or based on some other measured risk.
With any fire comes risks. Fire can spread quickly, especially during times of drought. It is important to assess the applicable safety risks associated with a burn before undertaking one.