Harvest time is here. By this time in November, all the shucks have split open and most are dried down to a deep chocolate brown revealing the pecan inside. However, you might spot some nuts that have tight, green shucks still hanging on the tree (photo at right). Unfortunately, those green nuts will never open.
Shuck split in pecan is controlled by plant growth regulators that are manufactured by the maturing seed inside the nut. If the kernel never forms or is devoured by a pecan weevil larva, the shucks will never open. These damaged pecans will remain green and tight on the tree until a hard freeze turns them into black "sticktights".
This year, I've seen green nuts caused by both summer drought and pecan weevil. The green nuts caused by drought are typically 1/2 normal size and contain only a wafer of kernel. Pecan weevil infested nuts are normal sized but have no kernel inside (consumed by weevil larvae). Pecan weevil damaged pecan are easily recognized by a round exit hole created by the larva (photo at left).
If you spot numerous pecan weevil damaged nuts in your trees this fall, you can be certain that pecan weevil will back with a vengeance in 2013 (pecan weevil has a 2 year life cycle).
