Evaluating and Managing Forage Stands for Winter Injury

Heather Darby and Sid Bosworth, Extension Assistant Professor, UVM Extension - Northwest Region and Extension Associate Professor, Department of Plant and Soil Science, University of Vermont heather.darby@uvm.edu

Many conditions occuring in the fall, winter or spring can have an impact on the winter survival or injury of perennial forage stands, particularly alfalfa.  Therefore it is important to assess stands early in the spring and explore your options for dealing with winter injury.

How to diagnose winter injury
First and foremost it is most important to determine if your field(s) was impacted by the winter weather.  The most obvious sign of winter injury are stands that are slow to green up.  If other fields in your area are starting to grow and yours are still brown those stands should be checked for injury or death.  In addition to slow green up, fields with uneven growth patterns may also indicate damage.  The best way to diagnose damage is by examining the plant roots in a suspect field.  To do this walk diagonally across a field and at regular intervals (every 4 to 5 paces) dig up a shovel full of plants (4 to 6 inches deep) and examine their roots.  The roots of each plant should be firm and the interior color should be white or cream colored.  If the roots are soft and the interior yellow to brownish in color it most likely was wintered killed.  For alfalfa, the majority of crown buds should be white or pink and firm throughout the bud.  It is important to try and inspect as many plants as possible to determine the percentage of your stand and/or areas of your field that are injured.

Options for fields moderately affected by winter injury
Winter injured stands will require different management than healthy stands if they are to stay in production. If winter injury is evident consider the following:

Options for fields severely affected by winter injury
If your stand was over 50 % killed, you may want to consider replanting. Depending on your needs, there are several forage choices. For more information, contact Heather Darby in St. Albans at 524-6501 or 1-800-639-2130, Jeff Carter in Middlebury at 388-4969 or 1-800-956-1125, or Sid Bosworth, in Burlington at 656-0478.

This site is maintained by Sid.Bosworth@uvm.edu, Plant & Soil Science Department, University of Vermont.

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