Abstract: The incidence of Armillaria root rot was quantified based on temperature,rainfall,and soil moisture in New Zealand Pinus radiata plantations. The results showed that the disease incidence decreased with the increase of temperature,and increased with the increase of rainfall and soil moisture. A linear multiple regression model that predicts infection levels of Armillaria root rot was derived:Y=-0.8-1.5T1+15.1R1+43.2L1+11.1L2. This model might give a clue for the disease control.