A cool period is also essential in order to break dormancy; the climatic requirements vary with the variety. Harvesting Fallen nuts formerly harvested by hand. Hand harvesting now largely replaced by mechanization, including tree or limb shakers, shake and catch harvesters, windrowers, sweepers, vacuum harvesters, conveyers and trash separators. Post-harvest treatments Pecans harvested mechanically have a higher moisture content than nuts that have fallen naturally.