Thursday, March 17, 2016

The first signs of pecan tree bud growth

Surecrop, 17 March 2106
    This year we've been experiencing a warm and early spring. Over the past week, I've been watching pecan buds carefully to detect the first signs of bud expansion and growth. At this point only some trees are showing signs of bud swell while other are quite dormant.
   This morning I collected some terminal branches from several cultivars which will help me illustrate the first event in pecan bud development -- outer scale split. The twig I collected from a Surecrop tree (photo at right) had buds that were fully dormant. Each primary bud appears to be encased in a smooth, hard shell offically known as the outer scale.
Kanza, 17 March 2016

    The Kanza twig pictured at right shows the very first sign of bud swell. The outer bud scale on the upper-most bud has cracked open. (The shriveled stem above this bud is last years pedicle that held a cluster of nuts).

Peruque, 17 March 2016


  Once the outer scale cracks open, the scale drops off to reveal an expanding pecan bud covered by an inner scale. The photo of the Peruque terminal (at right) demonstrates that the outer scale split process begins with the terminal bud and continues sequentially down the stem.

Greenriver, 17 March 2016

   The photo at right of a Greenriver terminal shows what is revealed when the outer scale separates from the bud. Each bud contains a primary vegetative bud in the center surrounded on each side by smaller axillary buds containing catkins. The vegetative bud will eventually grow out into a new shoot that terminates in a cluster of pistillate flowers.