Checking for cold injury

     This winter in SE Kansas has been exceptionally cold and snowy. Earlier this month, the temperature dropped to -16 F (-26 C)  with several days below 0 F (-18 C). Since that week of bitter cold, I've been wondering if my pecan trees suffered any cold injury.

   Today was a beautiful day with spring-like high temperatures. It was the first day in a long time that I've been able to get outside into the pecan grove (photo at left). As I walked through the orchard, I stopped by several trees and multiple cultivars to take a close look at the health of the cambial layer underneath the bark of one-year-old twigs.

   Checking the health of the cambium layer is easy. I just use my pocket knife to peel back a small section of bark (photo at right). Healthy stem tissue is green in color as shown in the photo. Cold damage is expressed by the appearance of brown streaks under the bark and a brown cambium layer. I checked at least 10 cultivars and all were in perfect condition.

  

    Sometimes, a young, vigorously-growing graft suffers cold injury when mature trees in the same orchard are untouched.  The Kanza graft pictured at left made almost five feet of new growth last year. I also checked this tree and found beautifully green tissue under the bark.

   Pecan trees can be exceptionally cold hardy if the trees get a chance to harden off properly in the fall and it stays cold throughout the winter months. This year it looks like my trees have survived the cold just fine.