Shaker-clamp stresses on fruit and nut trees during mechanical harvesting, which can result in bark injury and susceptibility to disease, were measured under a variety of conditions in these continuing studies. Some of the variables found to affect bark injuries include moisture in both soil and bark, varietal differences, and tree age.

These tests were conducted by the University of California in cooperation with USDA at the request of the California Prune Advisory Board. The California Prune Advisory Board, the Cling Peach Advisory Board, and the Almond Industry provided financial assistance; Delbert Henderson and James De Vay contributed technical assistance; and Jim Rumsey and Clarence Wong, U. C., Davis, aided in collection of data.