Weed Control Options in Seedling Alfalfa September 21, 2016
Late summer plantings of alfalfa tend to have fewer weeds than spring plantings, but this year, fall weeds may be a problem in some fields.
You have several options to deal with weedy alfalfa plantings, and the option you select depends on the type of weed and how dense it is in your alfalfa. Perhaps the best option for many fields is to do nothing at all. Often doing nothing is best when weeds are annuals like foxtail, crabgrass, and pigweed that will be killed by frost. This works as long as the weed stand is thin enough to permit plenty of light to reach new alfalfa seedlings.
Clipping tall weeds is another option, but be careful to avoid cutting or smothering alfalfa seedlings. This works best on thick stands of tall broadleaf weeds; grassy weeds tend to branch out and thicken when clippped.
Herbicide options are somewhat limited. If herbicides are used, spray this fall because spring treatment usually is not effective. For grassy weeds, especially winter annual grasses like downy brome, cheatgrass, and volunteer wheat, use Poast Plus or Select Max herbicides before grasses are four inches tall. If, instead, your weeds are broadleaf weeds like pennycress and mustards, spray Buctril or Butyrac while weeds are small this fall. If both grasses and broadleaves are a problem, Pursuit or Raptor can be used, but this is a more expensive option.
Examine your weed problems closely before deciding how to treat your alfalfa. By selecting the best method of weed control, you can help your alfalfa be clean and productive for many years.