Abstract
The citrus industry contributes with the volume of fruits produced in Brazilian, obtained with high productivity of orchards, a result of the adoption of technologies such as planting density, fertilization and irrigation. However, the incidence of phytosanitary problems that affect citrus farming has caused the increase of fruit production costs, which leads to a decrease in the sector's sustainability. Despite advances in the management of nutrients, little has been discussed about the relationship between nutritional status of plants and severity of such citrus diseases. Thus, it is necessary to characterize processes and relationships between nutritional status and the susceptibility of citrus plants to major diseases for the Brazilian citrus industry (citrus canker, huanglongbing, PFD, black and brown spot), and establish rational orchard management strategies that minimize the losses caused by these diseases to the quantity and quality of local production. The research proposal, supported by long-term field results and other developed by the research team, is organized in studies carried out in the field, for evaluation of plant responses to differential nutrient management with N, Ca and Mg, and some micronutrients on structure and integrity of tissues, biochemical responses (carbohydrate metabolism and oxidative stress) and physiological, and biomass partitioning that can result in increased tolerance and / or resistance of plants in different rootstocks to stresses and reduce the willingness of these to the progress of diseases in the citrus orchards. These studies are supported by other developed at greenhouses and laboratories. The definition of best management practices to minimize impacts of fertilization of these diseases can prolong the life of the orchards, and also contribute to reducing the use of pesticides and their environmental impacts. (AU)