Here it is, the dog days of summer. Temperatures exceed 100 degrees and harvest is still three months away. So why are we shaking pecans off the trees in August?
Pecans naturally produce a large crop every other year. It’s called alternate bearing. The reason older pecan trees fall into this alternate bearing cycle has to do with tree stress.
A large crop puts a significant demand on the tree for the “food” produced through photosynthesis. After spending six months maturing a large crop the tree is tired, it’s stressed when it goes dormant in the fall. There aren’t enough sugars stored in the sap to come back the following year with a second big crop so it produces a light crop instead. Because a light crop does not stress the tree it goes dormant that year with a huge energy reserve resulting in a large crop the following spring. And so the cycle perpetuates itself.
A commercial orchard needs to produce salable pecans every year so we implement a technique to help alleviate some of the stress caused by a big crop. We remove part of the crop in July and August.
We don’t do this to every variety. Most varieties can tolerate a large crop one year and come back with a reasonable crop the next. But other varieties need a little help. Without our intervention those varieties would have a large crop one year and NO crop the next. That just won’t do.
Managing an orchard for commercial purposes is different than what you might do for your yard trees so I don’t recommend crop thinning for homeowners. You’re better off taking what the tree can offer each year and be grateful for it.