What causes "shake" in pine?

The cause of this defect, which significantly impacts lumber grade. June 20, 2000

I would like to know if a kiln operator has any control over the amount of "shake" that appears after drying frozen, green, eastern white pine. If so, which variables would lead to increased shake? Does more shake invariably appear after kiln drying than after air drying?

Shake is caused nearly 100 percent of the time by bacterial infections in the tree.

If you over-dry white pine (or any pine), it will shake when machined if the machine is not set-up well (and the knives pound the lumber). In fact, pounding will result in ring separation of almost any species that has well defined rings. Pounding is how thin chair cane reeds are made from larger pieces of wood.
Gene Wengert, forum moderator