Abstract:Root-rot of tung-oil tree caused by Fusarium solani f. sp aleuritidis Chen et xiao is a new root disease. The causative fungi mainly intrude into the root hairs and infect the lateral roots, thus causing root-rot and damaging the tree to death. The number of peroxidase isozymes decreased with the increase of severity of the disease, so that it can be taken as the intrinsic "biochemical symptom" of the infected tree. Within a year, four developmental stages of the disease were observed. In order to forecast the epidemic trend of disease, a simulated model of partial ifferential regression equation has been assembled:Y=0.623+0.457x1-0.391x2-0.02x3+0.005x4 A better result in application could be achieved when this model was used for forecasting.