Fluctuating Spring Temps Create “Wild Ride” for Alfalfa

by Corey Catt

What our alfalfa plants have experienced this spring reminds me of my experience as a kid riding with my grandmother in a car.  She drove with both feet: one the gas pedal, the other on the brake.  Grandma would speed way up and then apply the brakes, continuing this pattern for the duration of the ride.

Similarly to the wild ride I had with Grandma, alfalfa is getting “jerked around” this spring:

  1. Quick Speed Up –The abnormal early season warmth made the alfalfa want to grow, which broke winter dormancy early and began the seasonal growth cycle.  Fortunately, alfalfa’s unique growing style will initiate new buds from the crown to help recover from this event.
  2. Quick Slow Down – The freezing conditions experienced in areas last week may have caused some damage to the plants.  Some growers report that not all areas of the fields were affected.  Low lying areas, such as hollows and valleys, received the full effect of Mother Nature’s crispy spring chill.

Although this type of cold injury event doesn’t occur often with alfalfa, universities have responded quickly.  Recent publications by the University of Wisconsin Extension and by Iowa State University Extension provide some good stand evaluators that will help growers make decisions in the days and weeks ahead.

There will likely be leaf damage in areas where overnight temperatures dipped to 27 degrees Fahrenheit  or below for several hours.   Well established, developing forage plants have lost their winter cold hardiness, so exposed tissue is susceptible to cold temperature injury.  Alfalfa and most legume seedlings have good cold tolerance at emergence, but spring cold snaps can hurt new seedings.  Slope position, soil temperature, companion crop of oats, wind, snow cover, all will influence what occurs in a particular field or part of a field.

We’ll have to take a “wait and see approach” for about a week before we can determine the extent of the damage.  The severity of damage with obviously effect yield and quality.  Be aware this may alter the PEAQ forage evaluation, as well, as it’s dependent on plant height.