Searching for sustainable strategies for reducing the use of copper in the management of citrus canker: biological control and use of sun blockers

Abstract

Citrus canker is one of the most important diseases for citriculture. The continuous use of copper-based bactericides is the main strategy for controlling citrus canker. However, this practice may be harmful to the environment as a result of the accumulation of copper in the soil, phytotoxicity to citrus plants, and selection of bacterial populations with copper-resistance genes. Moreover, large consumer markets of the Brazilian orange juice may require reductions or restrictions on the use of copper in production systems in the future. This project aims to enable the use of biological products and kaolin-based sun blockers, at different stages of development (new promising microbiological agent isolates, non-commercial technologies in development, and commercial or registered formulations), in the control of citrus canker, seeking to establish a more sustainable management of the disease. This proposal will encompass laboratory, greenhouse, and field tests. Bactericidal and curative effects and the ability of each treatment to induce resistance will be assessed in the laboratory. The capacity to protect vegetative flush, colonize the plant endo and epiphytically (for microbiological products), and act systemically (plant extracts) will be assessed in greenhouse trials. The most promising formulations for disease suppression will be assessed in commercial sweet orange orchards. At the end of this project, it is expected that new products and technologies will be made available for the management of citrus canker (and possibly similar bacterial diseases in other crops), allowing the reduction of copper used annually or even its replacement for a more sustainable alternative. What makes the present proposal distinct and applied is the ability of Fundecitrus, along with key partners (in this case ESALQ/USP, FFCLRP/USP and EMBRAPII) to develop the research at all levels, through the laboratory, greenhouse, and especially the field, the greatest limiting factor in projects of the same scope. A proposal focused only on the evaluation of new microorganisms in the control of citrus canker does not meet the immediate needs of the citrus sector, due to the long time required for the development of a commercial product. Thus, conducting studies with scientific rigor, involving technologies under development or that are already available to growers is fundamental for generating information that guides and enables the implementation of more sustainable measures in the short term. (AU)