These are chlamydospores and do not release zoospores. They germinate by producing germ tubes. These spores are able to survive in soil for many months in the absence of the host. Phytophthora nicotianae is heterothallic and has two mating types, A1 and A2. When both mating types are grown together, numerous sexual spores, called oospores are produced.
Oospores are also thick-walled.
This pathogen produces sporangia on the surface of diseased tissue. The sporangia release zoospores when water is present and zoospores or sporangia are splashed to healthy leaves or other plants. On the host, the germ tube produced by the zoospores will penetrate the host. Penetration of the host and growth of the fungus in the host begins the infection process. Continued feeding and growth of the microscopic fungus results in rots and disease symptoms.