Use of Radioisotopes in Selecting “Crisphead” Lettuce for Harvesting

A method has been developed for obtaining indications of the diameter and density of lettuce heads prior to harvest without physically contacting them. As a head passes through a collimated beam, the reduction in transmission is integrated to indicate mass. The interval of reduced signal is used to indicate size. The method offers improved selection for mechanical harvesting, higher speeds of operation, and less damage than with mechanical selection.