rom 1987 to 1991.an intensive investigation on the ecology of Larch leaf cast was madein 17 forest farms of Panshi and two other counties in jilin province. The data analysis ofthree hundred plots of larch plantations Larix olginsis revealed that the disease index of larchneedle cast had a close relation with density. type,height of clearance, soil, age and topogra-phy.The ecological model of larch needle cast was thus tstablished as follows:Y=15-23C_(11)-15C_(12)-C_(13)+21C_(21)+6C_(32)+9C_(23)+19C_(31)+9C...