Abstract:

Abstract: The influencing factors on the mycelial growth, sporulation , sporangia germination and infection of Peronophthora litchtii were primarily studied. The result showed that the optimum conditions for the mycelia growth and spores formation of P. litchii were at 24℃ and under light for 20h. The optimum illumination on the mycelial growth and spores formation were under light for 20h and 16h separate. The lethal temperature of the sporangia was 45 ℃, keeping for 10 min. The results also showed that the germination form and rate of sporangia were different when they in various temperatures, illumination, pH values and nutrient compositions. The best germination rate of the sporangia was from the sporangia which were produced from the fungus cultured on PDA medium (pH7.0) at 24℃ and under light for 20h. And the disease was most serious when the fungus infested the lychee fruit at 24-28℃. The results got a better understanding this pathogen and provided the theoretical basis for understanding the occurrence and damage of the Litchi downy mildew disease.