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| Kanza nuts right after a deep freeze |
Last night we received our first killing freeze as temperatures dropped to 15 degrees F (-9.4 C). For pecan trees, temperatures need to drop below 26 degrees F (-3.3 C) to kill green plant tissues. During the final days of Fall a hard freeze results in the hastening of leaf fall and killing still-green pecan shucks.
Since the deep freeze forecast was made earlier in the week, I made plans to make a visual record of the impacts of sub-freezing temperatures on Kanza pecan trees. In the photo above, my Kanza tree was still holding a leaf crop up on November 9th. After a blast of cold weather, every leaf from the very same tree had dropped off by mid-afternoon.
The photo above shows that Kanza shucks were still very green before the freeze but turned dark and water soaked after being subjected to temperatures below 26 degrees F. When green shuck tissue freezes, cell walls are destroyed by the formation of ice crystals. At first the shucks look water soaked but they will dry out and turn black in just a few days. As the shuck dries, it pulls back away from the nut and will finally open enough to allow the nut to fall free.
