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Researchers take fight to weeds

Invasive weeds offer 'essentially terrible' nutrition for animals


Capital Press

ORLAND, Calif. -- University of California researchers are making headway in their efforts to help ranchers fight two invasive weeds that take over pastures -- and that livestock won't eat.

A tropical grass called smutgrass has been cropping up in irrigated pastures in the Sacramento Valley, and no livestock, including goats, will eat mature plants unless there's no alternative feed.

"The quality is essentially terrible" with very little protein, said Josh Davy, a UC Cooperative Extension livestock advisor based in Red Bluff, Calif. "The stuff is basically (like) rice straw sitting out there in your field."

In addition, slender aster is becoming a common occurrence in the valley, often seen in heavier or finer textured soils, and is also not palatable to livestock. It is most recognizable by its "woody" plant base, Davy and other researchers noted in a recent newsletter.

Davy and others have been testing rotary wipers that spread Roundup over the unwelcome weeds after the other nutrients have been grazed. They're set to publish a peer-reviewed article on their findings later this month.

"When you push the button, it sprays onto a carpet," Davy told dairy producers during a workshop here Feb. 6. "The carpet spins backwards and grabs the plant and lifts it up, contacting it with the herbicide. Dragging it behind you wipes the whole plant."

The wipers are now available to ranchers and dairy farmers, but they're expensive; they start at about $3,000, Davy said. The Tehama County Resource Conservation District is renting a machine out to landowners for a day or a week.

Results are best when the spray is used in midsummer, Davy said. Users should be sure that desirable grass is grazed below the wiper level so it survives, he said.

Smutgrass, or Sporobolus indicus, is a perennial bunch grass native to tropical Asia. The plant can grow to 8 to 10 inches in diameter for small smutgrass or 12 to 18 inches for giant smutgrass, according to the University of Florida's Institute of Food and Agricultural Sciences. Seeds are spread by adhering to livestock and machinery or by movement in water or wind.

Infestations started showing up in the Sacramento and San Joaquin valleys in the mid-1990s, Glenn Nader, a UC Cooperative Extension farm advisor in Yuba City, has said.


Research Update on Using a Rotary Wiper: http://cetehama.ucdavis.edu/newsletters/Livestock_-_Range_News41691.pdf


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