Existence of Phytophthora Cinnamomi as Chlamydospores and Oospores in Roots and Soil

Persistence of the avocado root-rot fungus Phytophthora cinnamami Rands in soil for 6 years without a living host was reported by Zentmyer and Mircetich (8). The authors suggested that the fungus may survive in dead avocado roots as inactive mycelia, chlamydospores or oospores. Blackwell (1) considers chlamydospores of Phytophthora spp. to be resistant structures which allow these fungi to persist during adverse conditions, although she presented no experimental evidence to support this claim. According to Hawker (2), a fungus frequently survives adverse conditions temporarily by the production of thick-walled bodies, the simplest being mycelial chlamydospores. However, the literature contains little data on the exact conditions leading to morphogenesis of these structures.