When environmental conditions are suitable, the chlamydospores germinate, producing mycelia (or hyphae) and sporangia. The sporangia ripen and release zoospores, which infect plant roots by entering the root behind the root tip. Zoospores need water to swim through the soil, therefore infection is most likely in moist soils. Mycelia grow throughout the root absorbing carbohydrates and nutrients, destroying the structure of the root tissues, "rotting" the root, and preventing the plant from absorbing water and nutrients.
Early symptoms of infection include wilting, yellowing and retention of dried foliage and darkening of root color. Infection often leads to death of the plant, especially in dry summer conditions when plants may be water stressed.