Alternaria black leaf spot disease appeared to be wide spread in
cabbage fields of El-Sharkia governorate, Egypt during 2010-
2011 growing season. Alternaria brassicicola was the most frequently
isolated fungus. Different bioagent microorganisms, isolated from the
phyllosphere of the resistant cabbage cultivar (OS-Cross) were
investigated microscopically for their antagonistic effect against the
pathogen in vitro. Trichoderma spp., Bacillus subtilis and B1 bacterial
isolates as well as their culture filtrates proved to be highly effective
in inhibiting A. brassicicola spore germination as well as causing
mycelium and spore malformation subsequently reducing the disease
incidence and severity when applied in vivo.