The stability of host-pathogen interactions of plant disease in relation to biological weed control

A theoretical analysis was conducted to investigate the dynamics of plant-pathogen interactions for biological weed control. Computer simulation showed that the dynamics of plant-pathogen interactions can be determined by the properties of the pathogen. Pathogens with high levels of virulence may exist in nature in low frequencies due to high extinction rates. Pathogens of this type are suitable for the mycoherbicide strategy. Pathogens with a low level of virulence are frequent and may coexist stably with their host. Good candidates for the classical strategy may be the pathogens with intermediate pathogenicity, which maintain a stable interaction and a high control efficiency. The probability of extinction of a pathogen increases when pathogenicity is greater than a critical value at the intermediate range. The regulation of plant populations through reducing host reproductivity and increasing host mortality has similar results.