Pythium infects roots via motile zoospores and is favoured by wet, poorly drained soils and is closely related to Phytophthora. Pythium tends to nibble root tips but can cause serious losses in production nurseries and hydroponic systems as a root rot and damping off pathogen.
Plants can often appear as though they have a nutrient deficiency and fail to thrive. Roots may have necrotic tip dieback, appear ‘glassy’ or sometimes may not have any noticeable symptoms.
Preventative management actions are recommended as plants that are infected with Pythium are likely to always be infected. It is particularly important to use irrigation water from a clean source (e.g. town water or disinfested dam water).
Photo caption: Coriander infected with Pythium root rot.