News release issued February 12. 2001, effective immediately.
For media inquiries, contact Caroline Booth Lara, Communications Specialist, (580) 224-6379.
  email: cblara@noble.org

Is It a Forb, a Weed, or Both?

By definition, a weed is an unwanted plant or a plant out of place. To many livestock producers, a weed is any plant other than grass. Although grass is the maintenance portion of a cow's diet, it may or may not be the preferred portion, depending upon the species of weed or time of year.

"Let's be careful to not be too hasty to kill those pesky weeds until we know what we are eliminating and evaluate the cost benefits of doing so," advised Chuck Coffey, a forage specialist with the Noble Foundation in Ardmore, Oklahoma. "For example, according to research at Oklahoma State University, we need a threshold level of 30 percent Western ragweed on native range before it is cost effective to chemically spray for removal. An even bigger question should be, If ragweed populations are 30 percent or higher, what is happening to cause this increased population, and is spraying really the answer to the problem?"

So what are forbs? They are broad-leaved, nonwoody, herbaceous plants that differ from grasses in that the latter have narrow, linear leaves. Many forbs have significant food value for livestock as well as wildlife, and livestock even prefer them to grasses. Even Western ragweed will be used by livestock during certain times of the year.

Some examples of forbs that livestock highly prefer, at least seasonally, include Maximilian sunflower, compassplant, Engelmann daisy, and Ashy sunflower.

"All four of these plants are rarely found in pastures where animals are grazing," Coffey said. "They are typically found only along roadsides and well-managed pastures or in hay meadows. Protein content can be as high as 20 percent in May and June and 12 to 14 percent even in August."

Giant ragweed, redroot pigweed, and lambsquarters typically grow in waste places, disturbed sites, fields, and monocultures of pastures such as bermudagrass. Although livestock may not prefer these plants twelve months of the year, they will definitely graze them seasonally and often prefer them to bermudagrass.

Some of our more inconspicuous legumes that are typically preferred by livestock but susceptible to weed spray include hairy vetch, tick clover, Korean lespedeza, black medic, hop clover and white clover.

"Too often we pull the trigger without clearly focusing on the target or focus on the target but use a shotgun to hit a bull's-eye," Coffey said. "In other words, we weed-spray to remove anything but grass, or we spray in an effort to eliminate a known target species without regard to other species that might be beneficial. Either approach could prove costly as well as undesirable!"

Photos of the plants mentioned above can be found in the Noble Foundation website at www.noble.org/WebApps/PlantImageGallery/index.aspx.

Thought for the day: Most weeds are forbs, but most forbs are not weeds.

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The Samuel Roberts Noble Foundation, headquartered in Ardmore, Okla., is a non-profit organization conducting agricultural, forage biotechnological, and plant biology research; providing grants to numerous non-profit charitable, educational and health organizations; and assisting farmers and ranchers through educational and consultative agricultural programs.

To learn more, check out the Noble Foundation Web site at http://www.noble.org.

More news releases available at www.noble.org/Press_Release