Observations on oospore production by Plasmopara viticola in floating leaf discs in artifii cal culture

Oospore formation by the grape downy mildew fungus, Plasmopara viticola (BERK. et CURT.) BERL. et de TONI was observed for the first time in inoculated leafdiscs floated on chemically pure water. The technique described here should prove useful in the resolution of problems c oncerning oospore formation which are presently not clearly understood