BIOPEST

LEAFY SPURGE

Spurgia esulae

Leafy spurge was introduced into North America in the 19th century probably from seed grain such as wheat with the spurge seeds contaminating the planting. It now infests millions of acres in the United States and is a serious pest across the northern Great Plains where it displaces desirable grasses normally consumed by cattle, deer, elk or other grazing animals. Cattle and horses usually avoid leafy spurge, but of they do eat it, the milky latex-like sap can cause sickness and death. Annual losses due to leafy spurge infestation in Montana, South Dakota, North Dakota, and Wyoming total several hundred millions of dollars. Leafy spurge frequently grows in monocultures that often displace native plants and degrade wildlife habitats. Leafy Spurge is a serious plant pest causing harm to the native ecological systems of North America. See below for a map of current infestation areas.


Map of Leafy Spurge infestation in North America from magi.com

Leafy spurge is difficult to control with herbicides, burning, hand-weeding, or other traditional methods. A number of biological methods are underway to attempt to control this serious pest. One of these, grazing by goats, will work (the goats will eat leafy spurge without serious illness) but the spurge comes right back as soon as the goats are removed from the pasture. Leafy spurge spreads though its roots and through its seeds. The seeds actually "shoot" from the seed pod to a distance of up to 15 feet. When hand-pulled, any portion of the root remaining in the ground (and there will be some root break off every time) will regrow more leafy spurge, often creating even more spurge plants than prior to weeding. Burning alone will cause all the plants of the pasture to die back. Unfortunately, leafy spurge is the most aggressive in returning and will put up multiple shoots from it's root system, making the problem worse. Herbicides required are simply so strong that virtually everything in the field is killed. When that happens, the only survivor is usually a few roots of Leafy Spurge and the pasture quickly is recovered with the pest worse than before.


Range infested with Leafy Spurge. Photo from cornell.edu

Biological solutions (such as the goats or insects) combined with burning, herbicides, replanting, and weeding seem to provide the only solution for the future. According to the U.S.G.S. (U.S.Geological Survey), there are at least 5 leafy spurge insect enemies currently used to begin to control this "scourge of the west" and recover some of the destroyed ecological system to a more native habitat. Each of these were tested extensively in Europe (where leafy spurge is a native) prior to bringing the insects to North America for release. So far, none of these insects alone are sufficient. Working with a combination of insects, burning, herbicides, and replanting seems to be the only way to combat this highly invasive plant. We will obviously never be rid of leafy spurge but we must regain some of the environment for the native plants and animals (also for farming and ranching).

The reasons for leafy spurge's widespread proliferation in North America as a noxious pest is not understood and may not be due simply to the lack of natural enemies but may extend to differences in agricultural practices, climate or other factors. The adult flea beetle, Aphthona abdominalis, small, flea-like in appearance, and eats leafy spurge was released in 1993. However, the jury is still out on this insect as it is with as many as 10 european insects released to help control leafy spurge.

Agricultural methods do work to some extent in holding down the continued spread of Leafy Spurge. For example, closely planted soybeans will eliminate as much as 95 percent of the leafy spurge in a field. A number of other crops will do the same. However, none of them are North America natives and the spurge grows back quickly when farming techniques are stopped. In non-farmed areas such as natural meadows, un-tilled prairie, open woodlands, or wetlands, the leafy spurge chokes out all (ALL) native vegitation, destroying the ecology for many insects, small mammals, birds, and the list could go on. Not a good thing at all and virtually impossible to control unless some suitable insect controls are found so the non-farmed areas can be brought back to a reasonable native character.

If you live in the infested area, keep a watch for leafy spurge and assist in removing this pest. When insect control is finally found, try to get insects to release in infected areas. Leafy Spurge costs all of us more for food and harms the North American ecological system.

Thanks for listening.