A technique is described by which the firmness of apples, carrots and beets can be determined accurately and quantitatively. The method consists of measuring the load required to crush small cylinders (18 mm in diameter and 10 mm high) cut from the fleshy portion of the tissues. The crushing load was measured for samples irradiated with gamma rays from Co60 and compared with similar measurements on control (unirradiated) material. In the case of all three tissues there was a certain dosage below which no measurable softening occurred and above which there was progressive softening with increasing radiation dosage. In the softening phase there was a linear relationship between crushing load and log radiation dosage. This relationship made it possible to establish "threshold dosages" by extrapolation, which were 34,700, 166,000, and 316,000 r for Gravenstein apples, Chantenay carrots, and Detroit Dark Red beets, respectively.