A three way trees-fungi-bacteria interactions (Olea europaea, Epicoccum nigrum and Pseudomonas savastanoi pv. savastanoi (Psv)) mathematical model for the “olive knot” disease eradication

The bacterium Pseudomonas savastanoi pv. savastanoi [Psv), is responsible for the 'olive knot' disease producing tumorous galls mostiy on stems and branches of olive trees. This endangers olive harvest, reducing tree strength and ultimately killing them. Interaction of Psv at infection sites with other microorganisms, mainly epiphytic but in the knots as well, cause disease spread. In olive knots some of the latter either depress Psv growth or increase knot sizes. Preventíon strategies appear the better way to contrai olive knot. Naturally occurring antagonistíc microorganisms able to suppress Psv constitute biological agents, that can reduce olive knot incidence. The endophytic fungal community associated to Psv in the phyllosphere of olive tree cultivars is able to antagonize Psv following experiments in vitro. This antagonistíc activity againts Psv was particularly displayed by the fungus Epícoccum nigrum, that was showed the capacity to inhibited the Psv growth/biomass on 96%, after 48 hours ofinteraction. A nonlinear mathematical system is introduced for understanding the action of this resident fungus [E. nigrum) in Psv development. It accounts for interactions between o\ive-Psv-E. nígrum and increases our knowledge on the olive knot disease spreading.