Venturia inaequalis (Cke.) Wint, is the fungus which causes ``scab'' disease of apple. Its perithecia develop in fallen apple leaves late in winter, and ascospores mature during spring. Various workers, for example, Hirst and Stedman1, have established that the ascospores are not released unless the leaves are wetted. I have found that greater numbers of ascospores are released when the wetted apple leaves are in the light than when they are in darkness2. Results reported here are from an investigation of release of ascospores by V. inaequalis in light of different spectral bands.