Abstract: The Pinus armandi blister rust and the aphid Pineus armandicola were usually occurred during the same period within the harmful bioecosystem of armand pine forest,and there was conplex relationship between them.So,if the unitary object control threshold was applied under this condition,the outcome would be biased,the danger that the loss ratio of the timber volume exceeded the economical injury level would be occurred. In order to avoid this case,the compound damage of both the disease and the pest was studied on No.220 Forest Farm,Dongchuan District of Kunming City,Yunnan Province.The result showed that the interrelationship of both the representative value of the damage grade of the Pinus armandi blister rust and that of the aphid Pineus armandicola with the loss ratio of the volume was evident,which could be expressed in a regression equation:Y=10.574+8.11324X₁+7.01964X₂ X₁ —the representative value of damage grade of Pinus armandi blister rust,X₂ —the representative value of damage grade of Pineus armandicola On the basis of the regression equation,and taking the differences of the timber volume,log price,control cost and control effect into account future,the compound control threshold dynamic model of both the disease and the pest can be formulated as:8.11324X₁+7.01964X₂=[C/(D×J×E) ]×100-10.574　 C—control cost,D—checked volueme,J—log price,E—control effect This model provides the theoretical basis for the integrated control of the diseses and pests of the armand pine.

Key words: Pinus armandi blister rust, Pineus armandicola, Compound damage, Multiple regression, Compound control threshold