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New Mexico State University

New Mexico State University

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Act Now to Prevent Spring Problems with Rayless Goldenrod

LAS CRUCES -- Before winter weather hits, livestock owners should protect their animals by treating poisonous rayless goldenrod plants.


Rayless goldenrod, also called jimmy weed, is toxic to all animals, but especially affects horses. It causes losses every year in New Mexico.

"Research at New Mexico State University has told us that the best time to control rayless goldenrod is in the fall, once it blooms," said Keith Duncan, brush and weed control specialist with NMSU's Cooperative Extension Service . "So you need to treat it between bloom and frost, which will kill the above-ground portions."

The plant is native, growing mainly along river valleys and drainage areas in eastern and central New Mexico. It is most abundant on alkali or gypsum soils.

"When cattle and horses and sheep want to get out of the winter weather, they go down in the lowlands in these river basins where the goldenrod grows," Duncan said. "That's why it's a problem."

To identify rayless goldenrod, look for a small shrub with several upright branches growing from a stout, woody crown. Stems will be two to four feet tall with clusters of yellow flowers on stem tips from August to October.

Most poisoning problems occur in late winter and early spring, although the above-ground part of the plant is nothing but dried stems, Duncan said. "We don't know why the animals will eat it at that time, but they do."

Both green and dry plants contain the toxin tremetol, which produces a condition called "trembles" in affected animals and causes death in large doses. There is no known antidote.

Until recently, no good control measures were available for the control of rayless goldenrod. NMSU research and demonstration trials have shown that rayless goldenrod can be controlled with herbicides that contain picloram, metsulfuron or tebuthiuron.

Herbicides can be applied aerially to dense stands covering large areas. Smaller areas can be treated with ground equipment such as four-wheelers or backpacks.

Picloram and metsulfuron should be sprayed after the plant blooms, but before frost. Tebuthiuron may be used any time during the year.

For more information, contact your local county Extension office.