Phytophthora fungi are the leading cause of diseases infecting numerous crop plants and especially potted flowers. These fungi spread within the substrate and water; plants are infected through their root systems and basal parts. The infection manifests itself in the impaired growth and wilting of the plant. Moreover, the infected plant roots and butts turn brown. Occasionally, the pathogen may remain dormant in the plant for a long period of time but the symptoms manifest themselves as soon as conditions become more favourable to the disease.In fact, symptoms often become visible in the summer heat and as potted plants begin to lower. Phytophthora fungi especially infect plants where the substrate is damp and oxygen poor.

Sudden wilting of gerbera caused by a species of Phytophthora fungus.