African Rue, poisonous to cattle, arrives in New Mexico

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The African Rue, a weed that is poisonous to cattle, is taking root in many parts of the Southwest, including New Mexico, where it got its start in the U.S.A.

It is displacing other weeds and plants and is poisonous to cattle.

The good news is that it smells and tastes bad, so cattle don’t like it. They’ll only eat it if they’re starving and there’s nothing else around, according to researchers at New Mexico State University.

The weed originated in Africa and migrated east. It first appeared in the United States in Deming. No one is sure how it got to Deming. One theory is it came on camels that were introduced into the area.

Another theory is it came on the tires of airplanes.

Valencia County Extension Agent Frank Holguin said there have been no confirmed sightings of African Rue in Valencia County, but it is in Socorro County.

Laurie Abbott, assistant professor of range science at New Mexico State University, is researching the plant.

“It’s a difficult plant to get rid of, that’s why I’m studying it. It’s a problem in New Mexico. It’s found in other places, but not to the degree it’s found here. It’s found in disturbed areas, areas that have seen some sort of activity. Sometimes it’s on roadsides.”

She said people should not mow the weed because it will sprout and more will grow. Instead, they should dig it out.

“If it’s found, dig down, cut it off at least a foot under the ground. If there’s a lot of them, they may be connected by lateral roots. Try to get rid of them before the fruits come out. The fruits are a small capsule, small and round, about the size of chickpeas or a jelly bean. They’re green to brown, and they break open.

“The plant also sprouts from a root below ground. The bud sends up a new shoot. If it’s growing there, and some other plant is there, it takes up space. They have to dig several feet to get at all of the roots.”

The African Rue “is related to the creosote plant. It’s in the same family. We don’t know very much about it. To be able to control a plant, you have to know how it works, under what conditions it thrives, how its vulnerable, the basic requirements for germination, how many seeds it produces in a year,” Abbott said.

In order to find out more about the plant, Abbott is doing field studies, lab studies and greenhouse work, she said.

“I’m focusing on its basic ecology and biology. It’s a perennial plant. It dies in winter. Then, you won’t see it, except for its stems. It starts to green up in March.”

Abbott said she recently visited an area of Deming where the plant is found.

“It’s the greenest thing around,” she said. “It has a slightly fleshy leaf, is vaguely succulent, has a slightly fleshy stem and leaves. It has pretty white flowers. It’s a low-growing plant that comes up from a woody stem. It grows back every year. Cattle can eat it and get sick. It smells bad. In general, livestock won’t eat it. It’s not palatable.”

Abbott said she was not aware of any cattle in New Mexico getting sick from the plant and she did not know whether the weed is in Valencia County.

“The African Rue was first introduced in the United States in Deming. It was a low population for a while, then it spread. We’re seeing the populations increasing in the southern part of the state. It gives me an opportunity to study the plant and make recommendations about how it grows. Other people are looking at herbicides.”

A few years ago, the African Rue was found in all southern counties of the state, including Lincoln and San Juan, she said.

“I’m interested in disturbances. Invasive species are becoming a problem in a lot of our landscapes because they are taking up resources and displace organisms.”

This is especially noticeable in the northwest, she said, where “hundreds of thousands of acres have been taken up. They’re no longer productive.”

An herbicide, Velpar, has been shown to be effective against the African Rue.

“You may kill the plant that kills the sprouts, but if you’ve got seeds you’ll get more of them (the plants),” Abbott said.