Springtime Reminders for Leafy Spurge Management

Leafy spurge is a creeping invasive perennial forb. Those who have been lucky enough to never see leafy spurge before, can learn to recognize it by the yellow-green, heart-shaped seed pods and bluish-green leaves and stems. 

When seeds have matured, the pods will burst open and “throw” seeds up to 15 feet from the parent plant, which stands one to three feet tall and has umbel flowers. Broken stems will exude a milky-white latex which can help distinguish it from other weeds prior to flowering. 

Belowground, leafy spurge produces extensive root systems. These rhizomatous roots can extend down, up to 15 feet and spread laterally, up to 15 feet per year, producing new shoots along the way. 

The extensive root system provides nutrient reserves allowing the plant to easily recover from environmental stresses. This makes effective control difficult to attain. 

Impacts

Leafy spurge is an extremely invasive species which outcompetes desirable native forage. 

It emerges early in the spring and utilizes limited water and nutrient resources before desirable vegetation. Flowering primarily occurs in early spring – April and May – but some plants will continue to flower throughout the fall. 

Without proper control, leafy spurge will reduce cattle grazing capacity by 50 to 75 percent. 

Besides reducing desirable forage, leafy spurge compounds grazing impacts as it contains a toxic substance called euphorbon, which is an alkaloid causing skin irritation in humans. When consumed by livestock, it can cause excessive salivation, vomiting, colic and diarrhea. 

Producers should simply remove livestock from leafy spurge if symptoms arise.

Sheep and goats are more resistant to the negative impacts of leafy spurge toxicity. 

Management

Prevention is the best form of control for leafy spurge. Having healthy native grasses and forbs can help prevent leafy spurge from establishing into new sites. 

Producers should be vigilant for hay and seed contaminants and continuously survey their land to find leafy spurge populations when they are small. 

Management is easier and cheaper when leafy spurge has not developed large root systems or extensive patches. 

Grazing leafy spurge will provide some control but will not remove all leafy spurge. 

Sheep and goats will eat spurge but may also lose weight without consuming other vegetation due to poor forage quality. Horses and cattle will avoid leafy spurge to avoid toxic impacts. 

Fire and mowing can reduce growth and help limit seed production. Both can cause stress to the plant and help deplete root reserves but will not provide complete control. 

Also, be aware of possible damage to desirable vegetation when burning or mowing. 

Chemical control requires proper timing of herbicide applications. Applications should be made in the spring when true flowers appear or in the fall. 

Spring applications will cause more damage to seed production and to plants while they are pulling nutrient reserves from the roots, leading to a lower chance of recovery. 

Fall applications can control vegetative regrowth and also allow for herbicides to translocate into the roots as the plants pull nutrient reserves underground for the winter. 

Several herbicides can be used to control leafy spurge with varying efficacy, including Tordon; Plateau; Paramount; 2,4-D; Roundup and Venue. Be sure to read the label for safety information, application rates and timing recommendations. 

A single herbicide application will not control spurge. Repeat applications and using different herbicide groups each year will improve leafy spurge control. 

For example, repeat Tordon applications may lead to rapid microbial breakdown of the herbicide leading to reduced efficacy. Changing herbicide applications between years can prevent this and improve control in the long term. 

There are numerous biological control methods for leafy spurge as well. 

The black flea beetle, black dot flea beetle, brown dot flea beetle, brown-legged flea beetle, copper flea beetle, leafy spurge tip gall midge, red-headed stem borer and hawk moth are known to control spurge via root feeding or foliar feeding. 

Producers should contact their local weed and pest office for guidelines and resources before considering these biological control insects. 

Integrated pest management will provide the best control of leafy spurge. 

Don’t be afraid to use multiple management strategies and continued monitoring to improve adaptive management long term. 

Jaycie Arndt is a University of Wyoming Extension educator. She can be reached at jarndt1@uwyo.edu.