Infection of one leaf of a plant with virulent or avirulent pathogens that cause localized necrotic lesions often results in physiological and biochemical changes in the plant that enhance the resistance of the plant to further infection. The induced resistance response is characterized by nonspecificity with regard to the inducing agent and the pathogens against which resistance develops. Induced resistance in cucumber and other Species has been reviewed extensively by R. Hammerschmidt and P. Yang-Cashman and by Hammerschmidt and J. Smith Becker. The literature concerning the induced disease resistance response in graminaceous monocots has been extensively reviewed by U. Steiner and F. Schonbeck. Incompatible reactions of plants to pathogens often result in a rapid and very localized death of one or a few cells at the infection site. R. A. Dean and J. Kuc were able to demonstrate that the infected leaf was the source of the signal. The first reported molecular candidate for the systemic signal was salicylic acid.