In vitro production of the teleomorph of Guignardia bidwellii, causal agent of black rot of grapevine

Abstract

The control of in vitro differentiation of perithecia of Guignardia bidwellii was made possible by the manipulation of the light and temperature of cultures grown on oatmeal agar medium. Perithecia were initiated during a 2-week period of growth at 25 °C in the dark, which was favorable for mycelial growth. Perithecial differentiation was dependent on light and temperature (5–15 °C) conditions. Under these conditions, perithecia were formed in sclerotia, which also contained pycnidia, at a minimum interval of 4 weeks. The ability of seventeen monoascospore cultures to differentiate mature perithecia demonstrates the homothallism of the fungus. Key words: Guignardia bidwellii, black rot, sexual cycle in vitro, homothallism, grapevine, Vitis vinifera.