Wednesday, July 25, 2012
Signs of drought stress on pecan trees
The other day, I drove past some native pecan trees that were growing along a small creek south of Chetopa. Among this small stand of natives, one tree showed the definite signs of drought damage (photo at right). The tree of the left has started to yellow with many leaves turning brown. This tree is shutting down just like it would in the fall in preparation for winter. Going dormant early is the pecan tree's last defense against severe drought.
Just like every other tree characteristic, reaction to drought varies widely among seedling trees in a native grove. The photo above demonstrates that fact. But soil depth is also a factor. Pecan trees growing along creek banks far removed from major river flood plains will be the first to suffer drought stress. Soils in these locations are relatively shallow (5-7 ft.) compared to the extremely deep soils found in major river bottom flood plains (20-25 ft.). Deep soils have a larger capacity to store water and trees growing in these soils seem to weather drought far better.
Tree age and drought stress). The photo at left shows a young tree suffering from lack of rainfall. By just looking at the tree, you can tell it is having a hard time. Leaves are light green with many internal leaves yellow or browning. To protect itself from drought this tree is starting to shed leaves.
Note that, in all the photos of this post, the ground cover is already crispy brown. Like I said before, pecan trees are pretty good at handling drought. Unfortunately, this summer looks to be among the top 5 driest on record and our trees are already suffering for it.