This paper describes a new hybrid MPI-thread implementation of a parallel simulator for the propagation of a parasite in a vineyard. The model also considers the structure, the growth and the susceptibility of the plant. Two spatial scales are distinguished for the dispersal of the fungus. A realistic discrete model was used for the local and neighbouring dispersal, and a stochastic model integrates distribution laws for the long-range dispersal over the parcel. An algorithmic description of the new parallel simulator is given and real life numerical experiments on an IBM SP5 are provided, using up to 128 processors.