Over the past 30 years, Heterobasidion root disease has increased its distribution and impact across in South-West France. This study describes a model for simulating the infection, spread and protective treatment impacts of Heterobasidion spp. in stands of Pinus pinaster (L.). The model includes two submodels; one for stand dynamics with a distance dependant tree growth model and one for disease dynamics: (i) level of air-borne spores and spore infection, (ii) stump and root colonization, (iii) vegetative transfer to tree roots, (iv) spread of disease in tree roots of healthy tree, and (vi) disease effect on tree growth and survival. Two specific processes were studied. First of all, the prediction of high risk season is based on air-borne survey in order to investigate climate impact. Another key point concerns growth losses in trees. For accurate impact assessment, diameter growth loss was investigated by analyzing annual growth increment of pairs of healthy trees vs. trees infected by H. annosum using dendrochronological techniques To illustrate the model, simulations were carried out with different levels of infected stumps as initial disease centers, use of stump treatment and impacts of site fertility on the rate of transfer of the disease. The model provides a means of incorporating the impact of root disease into forest planning.