Two methods for detecting dead plant tissue before visual symptoms appear were evaluated. In one method, the rate of recovery of the bioelectrical potential of tissue to its original level after passage of an electric current was tested as an indicator of dead tissue and found unsatisfactory; in the other method, the change in wave form of a square wave electrical pulse passed through plant tissue was the indicator. With this method, leaf tissue from Doublas-fir (PseudotsugamenziesiiMirb. (Franco)) that had been killed by freezing, steaming, or treatment with an herbicide could be detected. Dead leaf tissue of other species could also be detected, but the damaged tissue had to be compared with undamaged tissue of the same species.