Leafy Spruge Biocontrol | South Dakota Department of Agriculture

Leafy Spruge Biocontrol

Redistribution Application

Leafy spurge (Euphorbia esula) is a perennial, up to 3 feet tall; reproducing by vigorous rootstocks and seed. Leaves are alternate, narrow, 1 to 4 inches long. Stems are thickly clustered. Flowers are yellowish-green, small, arranged in numerous small clusters and enclosed by paired heart-shaped yellow-green bracts. Roots are brown, containing numerous pink buds, which may produce new shoots or roots.

The entire plant contains a milky juice. The weed, a native to Eurasia, was brought into the United States as a seed impurity about 1827. However, it seems to be a serious problem only in North America where it infests in excess of 2.5 million acres, mostly in southern Canada and the northcentral United States. Seed capsules explode when dry; often projecting seeds as far as 15 feet. Seeds may be viable in the soil for up to eight years. An extensive root system containing large nutrient reserves and numerous buds makes leafy spurge extremely difficult to control.

Since 1988, several species of flea beetles (Aphthona spp.) have been released in South Dakota cooperatively by the South Dakota Department of Agriculture, the United States Department of Agriculture and County Weed and Pest Boards. The adults of these species feed on the foliage and flowers while larval stages feed on the roots of spurge.

The first collection and redistribution of Aphthona spp. from existing release sites occurred in 1993. Since then, collection and redistribution of flea beetles has greatly expanded and includes several multi-state efforts. As a result, multiple Aphthona spp. are now available as several insectary sites are reaching levels adequate for collection and redistribution. Other biological control agents including a stem borer (Oberea crythrocephala) and tip gall midge (Spurgia esula) have also been recently released. The establishment and efficacy of these additional bioagents is currently being evaluated.