Optimal management of witches’ broom disease of lime in presence of extreme environmental factors using stochastic dynamic modelling

One of the major diseases affecting lime trees in Oman is witches’ broom (WBDL). The occurrence, prevalence and severity of the disease are influenced by climate conditions. This study derives a stochastic dynamic model to determine the optimal management of witches’ broom disease of lime while considering extreme environmental variables. The factors considered in the model include disease incidence, severity, spread, and weather conditions. The results indicate that increasing investment in disease management is the best way to reduce the risk of WBDL and the damage it causes to citrus fruits. However, scenario analysis reveals that the current disease management measures implemented by the government are insufficient to maximize the net benefit of citrus cultivation. Furthermore, adverse climate conditions have a significant negative impact on the economic and social value of citrus cultivation. These findings suggest that the government could introduce more effective educational programs to ensure that all citrus growers understand the damages due to WBDL and make socially and privately optimal decisions, thus reducing external costs.