Warm early fall weather with only a few light frosts has kept most Nebraska alfalfa fields green. But it’s also been great for winter-annual weeds to get started in the crop, warns Bruce Anderson, University of Nebraska Extension forage agronomist.

“Check your fields and you might find lots of small henbit plants or mustard rosettes or short grass seedlings of downy brome,” says Anderson. “This density and robust start suggests heavy weed growth next spring. If left uncontrolled, they could grow rapidly, reducing alfalfa yield, thinning stands and lowering forage quality.”

To avoid next spring’s weed infestation, spray fields before soils freeze up, he advises, adding that Sencor, Sinbar and Velpar are probably the three best herbicide choices. All three do an excellent job of controlling pennycress, mustards and downy brome. Raptor might be a better choice, though, if henbit is your biggest problem.

You could wait and spray early next spring, he says. But spring spraying must be done before alfalfa greens up or you will injure the alfalfa plants. Usually, there are only a few days in spring when alfalfa is dormant, weeds are actively growing and it’s not too wet or windy. Most of the time, fields don’t get sprayed at all or they get sprayed late and alfalfa suffers some setback.

“Take advantage of opportunities now to control weeds in your alfalfa,” says Anderson. “That way you won't be plagued by them next spring.”