As our weather warms, alfalfa producers are reminded to eliminate weeds in their fields before plants break dormancy. Herbicides for controlling winter annual weeds such as pennycress, mustards, and shepherd's purse should be applied before alfalfa regrowth reaches 2 inches of height. If alfalfa shoots are green when sprayed, its growth may be set back a couple weeks.
Broadleaf weeds can lower yields, reduce hay quality; and slow first-cutting alfalfa dry-down. Grassy weeds such as downy brome, cheatgrass and bromegrass can have even higher impact on lowering hay quality.
If your alfalfa variety is Roundup Ready, then glyphosate can be applied to the alfalfa almost any time without harming the fields. Fortunately, if you treat your alfalfa soon; you can have cleaner, healthier alfalfa at first cutting.
Before spraying these weeds, be sure they are causing economic damage to your crop. Spraying will provide a purer alfalfa stand; but may reduce your overall total tonnage.
Our new Nebraska Extension Weed Guide, EC 130, lists herbicides labelled to control weeds in alfalfa. To be most successful, apply herbicides before alfalfa shoots green-up this spring to avoid alfalfa injury. If it does get late, use either Raptor or Pursuit; because they tend to cause less injury to your alfalfa.
Get ready to control unwanted weeds now before alfalfa plants break dormancy. Spray timing is critical.