Thursday, August 11, 2016
Pecan scab causes nut drop
previous post, I explained how scab impacts nut grown and kernel fill. But in the photo above I was able to document how scab can cause nut abortion. The orange arrow points to a small scab-infected nut that is just about to fall from the tree. In fact, after taking the photo, the nut fell in a gust of wind.
By cutting open the nuts that had fallen from the tree, I came to understand that scab causes nuts to abort when the infection starts early during the fruit expansion period. All the nuts I've found on the ground ceased growing before kernels reached the 1/2 water stage. This tells me that the scab infection on these nuts started right after nut fertilization and advanced to full shuck coverage by early July. Nuts that become covered with scab lesions later in the season usually remain attached to the tree and fall during harvest as blackened stick-tight.