Monday, December 4, 2017

WHY ARE THERE LEAVES STILL ON THE TREES?

    Why are some of the trees holding on to their leaves this deep into fall?  I am being asked this question quite often.
 
     This year a cold snap came on so suddenly that leaves were killed by frost.  This sudden cold snap came on the heels of an exceptionally warm spell mid Autumn.
      In a more normal years, trees gradually prepare for winter by creating a corky layer in the petiole that releases the leaves from their moorings after nutrients have been moved into the stem for storage.
Although most leaves had fallen, many trees were still holding onto leaves in the lower part of the crown.  This is most commonly seen in oak, beech, flowering pear and sometimes sugar maple.

     Here is what happened here in our neck of the woods: the corky layer that causes the leaves to detach failed to completely grow because of the cold snap, and any leaves still attached at that time died and remained tight to the tree. The Oaks and Pears are notorious anyway for hanging on deep into the winter, and sometimes don't even drop off until the new leaves push them off. But this year exacerbated this in the Oaks and Maples.The cold snap caught those few Maples and Beech out there that are chronically late, by surprise. I have one of those in my yard, we will probably have a messy leaf-littered winter this year.

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