Pseudoperonospora Cubensis - Pathogen Biology

Pathogen Biology

P. cubensis is an obligate parasite or biotroph, meaning that it requires live host tissue in order to survive and reproduce. Because of this characteristic, the pathogen must overwinter in an area that does not experience a hard frost, such as southern Florida, and where wild or cultivated cucurbits are present. The spores are dispersed via wind to neighboring plants and fields and often over long distances. Symptoms appear 4 to 12 days after infection. The pathogen thrives under cool and moist conditions, but can do well under a wide range of conditions. Optimum conditions for sporulation are 59° F (15° C) with 6 to 12 hours of moisture present, often in the form of morning dew. Even when high daytime temperatures are not favorable for the pathogen (>95° F or >35° C), nighttime temperatures may be very suitable. Oospores (thick-walled, resting spores) of P. cubensis are rare and their role in nature is unknown.