Wednesday, October 23, 2013

Heavy pecan crop + poor limb structure = limb breakage

    The photo at right is a great example of what can happen if a young tree doesn't receive proper training early in its life. This 'Gardner' pecan tree is only 11 years old  but was loaded down with nuts. Under the strain of a heavy crop, one large limb simply couldn't support the additional weight and broke from the tree. This tree has now lost nearly one third of its nut bearing area and it will take several years to fill out the canopy again.
     A close-up photo of the limb's breaking point reveals exactly why the limb couldn't support a heavy crop load (at left). You can clearly see evidence of a bark inclusion, a key characteristic of a narrow crotch angle. This type of branch attachment is structurally weak and prone to breakage under the stresses of wind, ice, or heavy crop load. In a series of blog posts on training young trees, I give tips on how to avoid growing trees with narrow branch angles by a process I call directive pruning and some simple pruning guidelines I call the 2-foot rule. The training young trees series starts here.