Optimal management of citrus disease and extreme climatic factors

Abstract

This study develops a dynamic bioeconomic model using the Bellman equation to derive the optimal management strategy for Witches’ Broom Disease of Lime (WBDL) and the optimal replanting age of citrus trees after the first attack under multiple scenarios of disease management options and climate conditions. In addition, the study investigates different scenarios of disease presence and spread given different climatic conditions of arid, semi-arid and tropical zones in Oman. Factors such as disease incidence, severity, spread, and specific climatic conditions of three growing regions are considered. The farmers' optimal disease mitigation decision is determined by the disease density and insect vector level on the farm, and adverse climate conditions have a significant negative impact on the economic value of citrus cultivation. Results indicate that management measures by citrus growers and policymakers should be based on the climatic conditions of the growing region with a high level of treatment frequency and intensity in the arid region, and lime production should be concentrated in the tropical and semi-arid regions of the country.