Over the past two weeks I've been trying to make a photographic record of when pecan cultivars ripen at the Pecan Experiment Field. But when it came to determine a shuck-split date for Hirschi, the susceptibility of this cultivar to pecan scab makes it nearly impossible to tell when the shuck opens normally. In the photo at right a cluster of Hirschi nuts is covered with scab lesions. two of the nuts have tightly held shucks while the third appears to be opening up.
On the same tree, this cluster of Hirschi nuts has less scab covering the shuck but the shucks have yet to open (photo at left).
Five days later I went back to look over Hirschi to see if the nuts had opened up and I found at least one nut cluster with normal looking shuck split (photo at right).
Pecan scab interferes with normal shuck opening. Based on what I've found by watching Hirschi this fall, scab can both delay and inhibit shuck split. From past experience I know that Hirschi ripens early, but this year's true shuck-split date for this cultivar was masked by scab covered shucks.