Leafy Spurge

Wolf’s milk

Leafy spurge is a long living perennial with an incredibly vigorous root system. The extensive roots of the plant can reach depths of 30 feet and contain nutrients that will sustain the plant for long periods of time. The brownish roots have pink buds on them and each develops into new shoots. This plant will reproduce by seeds or the roots. Seedlings resemble Yellow toadflax seedlings. When the plant is broken anywhere the plant will produce a milky sap. The stems of Leafy spurge can grow up to 3 feet in heights and have alternate, narrow, smooth margined leaves. Leaves and stems are a bluish-green in color. The flowers are yellow-green in color and arranged in clusters contains seven to ten flowers. The showy, heart shaped yellow bracts surround the flower. The plant will go to seed and produces three-celled capsules and at maturity; these capsules explode launching the seed up to 15 feet from the parent plant. Flowers resemble Spotted knapweed in that they are pink to purple and ray-like. Each plant produces both female and male flowers. One plant is capable of producing over 3,000 seeds annually. This plant reproduces by both seed and the roots, but primarily by the roots.

Break any part of this plant and you see milky white latex this is Leafy spurge. When looking at the roots they will be dark and have pink buds on them. Also, once recognized Leafy spurge is easy to identify by its distinctive yellow-green flowers. 

Leafy spurge is a flexible plant that tolerates extremely dry to extremely wet soil conditions. It can often be found along waterways and irrigation ditches, but also found in draws and sagebrush. This plant will grow in a wide variety of soil types but is mostly found in sandy or gravelly soils and in arid conditions. 

There are only a few herbicides and other control methods that effectively control leafy spurge. Tordon is the most common and often considered the most effective, but is a restricted use product - meaning an applicator’s license is required to purchase and use. Other herbicides that have shown some level of control are: Dicamba, 2,4-D, Plateau, Quinclorac, and Method. For more information on these herbicides and other control methods contact the Weed and Pest office. 

There are also a few biological control options that provide some control on leafy spurge. Apthona flea beetles feed on the plants and have been shown to reduce stand density and slow spread. Hawk moth caterpillars feed on plants and slow spread, but less effective than beetles.These insects work better in certain climate conditions and habitats, and also need a large enough spurge infestation in order to establish and maintain insect populations. While they are an alternative to herbicides, it is important to understand they are not going to eradicate infestations, or control infestations as fast as herbicides. 

Selective grazing is also a viable form of control for leafy spurge, using the certain species of animals. Leafy spurge is toxic to cattle and horses, but goats and sheep have shown to be able to digest it at most levels. Goats have shown to pass less viable seed than sheep through their digestive system, and additionally carry less seeds around on their bodies as sheep do in their wool. Intensive short interval grazing has been shown to have the best measure of control. Grazing weakens the root system and can lower stand density and slow the spread of seeds. Combining grazing and herbicides would be a great option - treating with herbicides after an intensive grazing and allowing plants to grow again. 

Leafy spurge is toxic to cattle and horses, giving mouth sores and intestinal irritation. Leafy spurge first arrived in the U.S.A. around 1820’s and has doubled its coverage every decade for the past 100 years. Stories in Crook County have been told that the initial population was started on a homestead up Left Creek when a woman thought it was a pretty ornamental plant and it then escaped and spread all over. It is estimated that over 75% of townships in Crook County have leafy spurge infestations - including small isolated infestations. Considering that, over 1.2 million acres in the county are invaded by leafy spurge on a township scale.