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Noxious Weed Alert - Myrtle Spurge

Post Date:05/07/2020

Noxious Weed Alert - Myrtle Spurge or Donkey Tail (Euphorbia myrsinites)

Myrtle spurge is a Utah Class 3 perennial noxious weed native to Eastern Europe and Western Asia. It reached the United States through the gardening industry and was advertised by the gardening community as an ideal water wise planting. It quickly escaped gardens and began taking over large areas of open space earning itself a place on the noxious weed lists of many states. It is now illegal to sell this plant and landowners are required to remove it if they have it on their property.

Myrtle spurge is a beautiful plant, but do not let that beautiful flower and interesting leaf pattern fool you. With the ability to shoot, yes, literally shoot its seed 15 feet, this plant can quickly overtake sunny slopes and displace native plants wildlife rely on. The seeds can remain dormant for 8 years and entirely new plants can establish from small root fragments. As Myrtle spurge forms monocultures (large areas with only one plant species), it also leaves substantial bare ground between plants. This increase in bare ground can result in higher rates of erosion and ultimately reaches waterways and reduces water quality.  In Salt Lake County alone, thousands of acres are dominated by Myrtle Spurge and it is moving up Parley’s Canyon rapidly. While it is knocking on our door here in Summit County, there are only a few known populations in our open space. The greatest concern, however, is how common Myrtle Spurge is in residential gardens. These gardens are a seed source that could result in its spread into Park City open space and threaten wildlife habitat, water quality and human health.

In addition to the environmental impacts, Myrtle spurge poses a health hazard. When damaged, the stem, leaves and roots of this plant leak a milky, white sap that can cause skin irritation, burns and blistering. The entire plant is toxic. If ingested, it can cause nausea, vomiting and diarrhea. More serious reactions to this plant include anaphylactic shock and, if sap reaches the eyes, blindness. The most common victims of Myrtle spurge reactions are children who pick or ingest the plants not knowing they are toxic. 

How to identify it: 

Myrtle is a creeping, bluish green succulent that stays low to the ground. The entire plant reaches up to 6 inches in height. The leaves are teardrop shaped and clasp around the stem. Flowering can begin late April and continue into October in cooler, higher elevations or where they are receiving supplemental water. Flowers are initially greenish yellow then transition to bright yellow. As seed pods form the flowers and some leaves may become pink to reddish in color. 

What to do if you have it:

There are no biological control agents for this plant so mechanical and chemical control are the only options. Myrtle Spurge can be controlled by digging up or hand pulling when the populations are relatively small and have not been present more than a couple years. The plant has a deep taproot and requires that you get as much root as possible to prevent new sprouting. They are easiest to pull at the seedling stage. Once the plants develop seed pods, they must be pulled and thrown away. Myrtle spurge reproduces mainly by seed so preventing seed is the most important management option. When pulling this plant, ALWAYS WEAR GLOVES, LONG SLEEVES, PANTS AND GLASSES! 

Myrtle Spurge can be controlled with many herbicides, but all herbicides should be applied prior to the plants developing seed. It is best to use a broadleaf selective herbicide to prevent impacts to grasses or grass like plants nearby, however, a non-selective herbicide will also work but requires more care to prevent damaging adjacent plants. Before selecting an herbicide, contact your local county weed supervisor, David Bingham (dbingham@summitcounty.org) for assistance and possibly less expensive and more effective herbicides than available at the local hardware stores.

Once you have removed Myrtle Spurge and no new sprouts are appearing, it is best to replant with native or non-invasive plants to prevent the spurge from reinvading. The following are a few replacement options that have a somewhat similar look to Myrtle Spurge: Sun Rose (Heliantheum ssp., Sulfur flower (Erogonum umbellatum), showy Cinquefoil (Potentilla gracilis) or Dwarf Silver Evening Primrose (Oenothera macrocarpa) and there are many Stonecrop species (Sedum ssp.) available at any local gardening center.

Myrtle Spurge Grid