It was a long and difficult summer, but with the fall rains will come new grass… and weeds.
Compounding the problem is the lack of competition from forage grasses. Many pastures in the region were devastated by the drought. Tim Schnackenberg, University of Missouri Cooperative Extension Service agronomy specialist at the Stone County office in Galena, told Ozarks Farm & Neighbor, “In many cases we need to be evaluating these pastures right now and determining whether or not we’re going to be reseeding and adding more forage in there. If we don’t do anything, something else will take its place, and that will be weeds.”
“Weed control is going to be a big issue this fall and on into next spring,” Dr. John Jennings, University of Arkansas Cooperative Extension Service animal science professor and forage specialist, told OFN. “We’re already seeing a lot of weeds coming up that were sitting there at a small size through the summer, and they’re responding very well to the rain. In some of those cases those weeds are shading the grass right now. So if we want some continued fall growth, that’s going to have to be controlled.”
Among the problem weeds that over-summered and will germinate this fall are woolly croton (Croton capitatus), horsenettle (Solanum carolinense) and pigweed (genus Amaranthus). Jennings said, “Coming into next spring, buttercup (genus Ranunculus) is going to be a big issue, and cheat (Bromus secalinus), little barley (Hordeum pusillum), and weedy grasses such as those. Buttercup is very easy to control, and so is woolly croton; it’s just a matter of getting out there and getting it done.”
Jennings said producers need to watch for germinating weed seedlings through early December. “They can make control efforts then, when the fields are still dry enough to spray and the wind is generally not that bad,” he said. “If they wait until February and March, they may have wet fields. It may be too windy; you can’t get into fields, and the weeds end up taking over the pasture.”
Schnackenberg said bare spots in the field will be filled with winter annuals like chickweed and henbit, and next spring with foxtail (genus Seteria), purpletop (Tridens flavus) and crabgrass (genus Digitaria). “Crabgrass is not necessarily a bad weed and is a good quality forage, but it can settle in with ragweed and other kinds of broadleaves as well,” he noted. One broadleaf herbicide may not be enough; Schnackenberg said while one chemistry may control many annual, herbaceous-type weeds, the brushier species often require specialized, higher-priced herbicides. And, he added, options are even more limited for grasses: “There are really not any herbicides that kill grassy weeds in grass pastures.”
There are also weeds with acute toxicity to cattle, but Schnackenberg said they rarely pose a mortal threat. “Cattle have been around them for decades or centuries,” he pointed out. “It’s usually a worse situation when you have a drought, because sometimes cattle do not have anything else to eat in that scenario. When the grass starts growing again, the toxins seem to be less of a concern, but then once in a while we’ll run into problems in the winter.”
Instead of poisonous plants, his biggest concern is with toxic accumulations of nitrate and prussic acid in weeds.
