THE DYNAMICS OF INFECTIOUS-DISEASES IN ORCHARDS WITH ROGUING AND REPLANTING AS CONTROL STRATEGY

Roguing and replanting is a widely adopted control strategy of infecti ous diseases in orchards. Little is known about the effect of this typ e of management on the dynamics of the infectious disease. In this pap er we analyze a structured population model for the dynamics of an S-I -R type epidemic under roguing and replanting management. The model is structured with respect to the total number of infections and the num ber of post-infectious infections on a tree. Trees are assumed to be r ogued, and replaced by uninfected trees, when the total number of infe ctions on the tree reaches a threshold value. Stability analysis and n umerical exploration of the model show that for specific parameter com binations the internal equilibrium can become unstable and large ampli tude periodic fluctuations arise. Several hypothesis on the mechanism causing the destabilisation of the steady-state are considered. The me chanism leading to the large amplitude fluctuations is identified and biologically interpreted.