The cartoon to the right shows some important phases of the basic life cycle of P. sojae . Oospores germinate to form zoosporangia . Zoospores are formed within zoosporangia and then released.
Zoospores are biflagellate and chemotactic .
Sensing exudates from soybean roots, they swim towards them. Zoosporangia may also be formed directly from mycelium to provide secondary inoculum in epiphytotics.