Aspects of the Biology of Phytophthora cryptogea

Abstract

Laboratory studies of Phytophthora cryptogea showed that the fungus was able to colonize dead organic matter in soil in competition with other soil microorganisms. When mycelium of the fungus was pre-exposed to various temperatures, the optimum pre-exposure temperatures for subsequent production of sporangia under sterile and non-sterile conditions were 15° and 5°C respectively. Production of sporangia by P. cryptogea was also influenced by aeration; numbers of sporangia decreased sharply when the depth of liquid above culture discs of the fungus was increased from 6 mm to 13 mm. Encysted zoospores of P. cryptogea were able to germinate after 14 days in a forest soil.