Although recent rains have helped some Arkansas pastures recover from drought, Dr. John Jennings, University of Arkansas professor of animal science and Extension forage specialist said a lot of fields were grazed so heavily before the rain resumed, the cows left a lot of open space for weed populations to take over.
If you control weeds in your pasture, the cows will thank you for it.
Dr. Kevin Bradley, University of Missouri professor and researcher in the Department of Plant Science, told Ozarks Farm & Neighbor their studies have found if half a field is treated with herbicide, that’s where the cows will congregate. “The cows preferred to stay on an herbicide treated portion of a pasture anywhere from 1.5-5 times more than they stayed on the portion of the pasture that was not treated,” he said. The researchers ran their test at three Missouri sites, monitoring the animals with GPS tracking collars. “That’s a first step for us in being able to say you can show a lot of things on paper,” said Bradley.
Bradley said there isn’t objective data on when grassland is so weedy that it needs to be treated. “Everybody has their own trigger on what they think will justify weed removal,” he said. “There’s just not a whole lot of research data out there that says, ‘if there’s this many, then you should remove them.’ It’s something that’s desperately needed.”
He’s also studied the nutritional value of weeds. “Common Ragweed, when it’s less than knee high and in that vegetative state of growth, has a protein content that would rival Alfalfa in a lot of years,” he said. The nutritive value becomes very poor when the plant matures, and in any event the plant is of no benefit if the animal refuses it. “Our next step in all of that research has been to try to show whether cattle will eat it or not,” Bradley said. “I’m not arguing the fact that there’s certainly situations where cattle will eat Common Ragweed, but the cattle will prefer that weed-free grass, in my opinion, day in and day out.”
There are other weeds the cattle won’t take at all, noted Jennings. “Buttercup might be one; the cattle might eat those when they’re small, but when they get large and start to bloom cattle refuse them, and they produce a huge amount of shade that can reduce the growth of the pasture,” he told OFN. Woolly Croton causes similar problems; the weed appeared after some Arkansas fields got a flush of rain last August. “In a lot of areas the Bermudagrass was able to respond to the rain and grew well, but where the Woolly Croton came up it shaded the Bermuda and got virtually no growth underneath it,” Jennings said.
While the weeds are still small and relatively easy to control, Jennings said 2, 4-D (2,4-Dichlorophenoxyacetic acid) will do a good and inexpensive job on common spring weeds like Buttercup and Chickweed. “In Bermudagrass pastures that are still dormant, a good application of glyphosate herbicide across those will clean up weedy grasses and broadleaves,” he said.
Producers also again have the option of planting Roundup Ready Alfalfa, which carries Monsanto’s gene for glyphosate tolerance. A three-year court battle prevented new sowings until last year. Jennings said county agents are reporting interest from producers, and the biotech crop will fit with a lot of forage programs. “We had a small field down in Cleveland County near Rison for several years we planted when Roundup Ready first came on the market, and its performance was excellent,” he said. “The recommendation from the company is to spray glyphosate across that field within the first 4-6 weeks after emergence; the idea is 5 percent of the seedlings might not be tolerant, and that cleans those out early.”
Jennings said yields are comparable to those of conventional varieties, and unlike eastern Arkansas and other row crop areas, glyphosate resistant weeds haven’t yet appeared in grazing regions. He believes resistance may be slower to take hold there because treatments will be less frequent. “The main time we need weed control in Alfalfa is that first establishment period; you get a good, healthy stand established, and then the stand is really competitive and there are very few weed problems after that,” Jennings said. “After that stand of Alfalfa gets to be a few years old and it starts to thin a little bit, we can start using some weed control again.” In addition, Alfalfa is cut frequently enough that fewer resistant weeds will reach maturity and go to seed.
