March 18, 2016
ALFALFA - The Forgotten Crop
Too often alfalfa can be the forgotten farm crop... we take care of alfalfa when we’re caught up on everything else. I’d like to suggest you move alfalfa higher on your priority list... and one of the first things you need to do with your alfalfa fields should be done in the next few weeks.
With warmer temperatures, your alfalfa will be greening up soon. Before that happens, you should control weeds if they are a problem. Weeds like pennycress, downy brome, mustards, cheatgrass, and shepherd's purse are common in first cutting alfalfa. They lower yields, reduce quality, lessen palatability, and slow hay drydown. Now that the snow is gone, you should be able to see their small, green, over-wintering growth if they are present in your fields.
Once alfalfa starts growing, you can't control these weeds very well without injuring your alfalfa. However, if you treat your alfalfa as soon as possible during this spring-like weather, you can have cleaner, healthier alfalfa at your first cutting.
Several herbicides can help control winter annual grasses and weeds in alfalfa. They include Metribuzin, Velpar, Sinbar, Pursuit, Raptor, and Karmex as well as Roundup and Gramoxone. They all control mustards and pennycress but Karmex and Pursuit do not control downy brome very well.
To be most successful, though, you must apply most of these herbicides before alfalfa shoots green-up this spring to avoid much injury to your alfalfa. The exception would be you can use Roundup on Roundup Ready Alfalfa after it has greened up this spring. When the snow has melted and fields are dry enough that you don’t leave ruts is a great time to spray. If you wait and alfalfa shoots are green when you spray, your alfalfa growth might be set back a couple weeks. If it does get late, use Pursuit or Raptor because they tend to cause less injury to your alfalfa.
Another consideration is if you are planning to plant alfalfa this spring. Should you use oats or another companion crop? There are the advantages and disadvantages to both options. Alfalfa often is seeded with a companion crop like oats to control weeds and prevent erosion.
In contrast, clear seeding alfalfa alone, without a companion crop also works well. A preplant herbicide like Balan or Eptam often is pre-plant incorporated to control weeds in a clear seeding, but herbicide isn't always necessary.
Your own situation will determine whether a companion crop or a clear seeding is better for you. Where erosion isn’t a problem, clear seeding has the advantage because alfalfa production begins much sooner, with 2 to 4 tons possible the seeding year. Companion crops lower alfalfa yield the first year, and they often cause thinner stands which can lower yields in following years.
Oats are a companion crop, not a nurse crop, because companion crops like oats don’t nurse... they act like weeds, robbing alfalfa seedlings of moisture, sunlight, and nutrients during the seeding year. However, on erosive ground a companion crop may be necessary.
So if you want alfalfa, plant only alfalfa. But, if erosion is a problem, include just half a bushel of oats with your alfalfa. Then kill oats early using Poast Plus or Select herbicide, or Roundup if your alfalfa is Roundup Ready. Next best is to hay oats early rather than taking grain. Otherwise, if you want oats, plant only oats. Then seed alfalfa into oat stubble next August if soil moisture is good. Your alfalfa stand will be better because of it.
For more information on establishing alfalfa or weed control in alfalfa, contact your local Nebraska Extension office.