Time To Evaluate Over-Wintering Alfalfa

Time To Evaluate Over-Wintering Alfalfa

Iowa had a mild winter, but you should still take time to check alfalfa stands and other perennial forages, for signs of injury and to get a stand count.

There are no particular concerns with over-wintering alfalfa at this time, says Iowa State University Extension field agronomist Brian Lang. However, you need to consider that older stands eventually do thin out from disease, wheel traffic damage and inherent aging issues. So alfalfa stands, particularly older stands should still be evaluated for plant health. It's worth your time to evaluate your stand and the time to do it is now.

Time To Evaluate Over-Wintering Alfalfa

Steve Barnhart, ISU Extension forage specialist, posted information on stand evaluation of alfalfa and other forages in the ICM News at:  http://www.extension.iastate.edu/CropNews/2012/0307barnhart.htm  A UW publication that also helps assess alfalfa stands and root health is available at:  http://learningstore.uwex.edu/assets/pdfs/A3620.pdf

Now is the time to control winter annual weeds in alfalfa stands

"Every May I get phone calls on outbreaks of weeds in alfalfa fields," says Lang. "Farmers want to know what they can do to control weeds like Shepherds purse, Field pennycress, and/or Pepperweed. However, by that time there isn't much of anything that we can do about it. These are among the most common winter annual weeds that show up in alfalfa fields. They are not very palatable to cattle and they are not high in quality for cattle to eat along with the hay."

Winter annuals germinate in the fall, develop a rosette-type growth (a flat growth, like you see with dandelions leaves), overwinter as the rosette, and then bolt (rapid growth of upright stems) in early spring producing seed for next fall. Once these plants bolt, herbicides are not very effective. The time to control these weeds is after alfalfa becomes dormant and before new growth begins in spring using herbicides such as Pursuit, Raptor, or Velpar. Velpar is a stronger choice for dandelion control. 

The only way to know if these weeds are present is to scout the fields, says Lang. This is not easy since weed growth at this time is still in the flat rosette stage. Concentrate scouting the fields that have a history of winter annual weed problems. However, you need to realize that most winter annual weed situations are not heavy enough to significantly interfere with yield and quality of the overall forage, so herbicides aren't usually recommended. Granted, with $6 per bushel corn, if the alfalfa field is marginal with weed problems, rotating to corn may be the best option.

Timely tips on planting small grains (such as oats) and alfalfa

If you are planting a pure stand of small grains, plant as soon as spring soil conditions permit, advises Lang. "However, for alfalfa we prefer to wait until April to minimize the chance of a late spring killing frost on early emerged alfalfa seedlings. If planting small grains with alfalfa, hold off for another 2 weeks, but within the next 4 weeks." Lang gave that advice to farmers on March 12.

On average, after mid-April oats and wheat lose an average of 10% yield per week, and after May 1 about 15% yield per week. Seeding rates for a pure small grain stands should be about 30 seeds per square foot, which is about 3 bushel per acre for oats, 2 bushel per acre for barley, and 2 bushel per acre for wheat. As a companion crop with alfalfa, reduce your small grain seeding rates by about one-third to reduce the amount of competition on the alfalfa seedlings, he advises. 

Oats should be seeded at about 1 inch deep, and alfalfa and other forages at about ¼-inch to ½-inch deep followed by soil firming, preferably with press wheels or a cultipacker. A harrow is better than nothing, and a good rain following seeding can achieve the same thing, but don't bet on getting the "good" rain. It is best to make a soil firming pass. Steve Barnhart, ISU Extension forage specialist, provides additional tips on spring forage seedings at  http://www.extension.iastate.edu/CropNews/2011/0307barnhart.htm

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