Development of a Chitosan Biogel for Carrying Eugenol in Combating Citrus Canker: Scale Production and Field Evaluation

Abstract

Brazil is the largest exporter of sweet orange juice in the world, and citrus growing is therefore an important economic activity for the country. However, there are difficulties in citrus growing involving losses due to pests and diseases that affect crops, especially citrus canker. This bacterial disease affects all aerial parts of plants and, in severe cases, causes leaf and fruit drop. In addition to the loss caused by the disease, there are international restrictions on the marketing of oranges from countries where the canker is present, in an attempt to prevent the spread of the disease. The control of the disease is carried out with the application of metallic copper, which is effective in reducing the spread of the cancer, but has no curative effect. Copper is a heavy metal that can have several undesirable effects on humans and the environment. In an attempt to minimize or even replace the massive use of copper in crops, alternatives have been sought, such as the use of natural oils capable of inhibiting the growth of phytopathogens. Although these products already exist and are effective in disease control, they have little adherence to the substrate and are easily degraded by weathering. For an efficient application of these compounds, it is necessary to develop carriers capable of attaching to the substrate and protecting the compounds. Thus, this project proposes to evaluate the properties of chitosan gels (and modification) and their interference with the physiology of orange trees in order to use this polymer as a carrier of compounds in the form of biogel. This project will contribute to the specific objectives of the Fapesp Thematic Project (process 2021/10839-4), evaluating the biogel formulation for carrying eugenol for application in orange trees. The best formulations will be produced on an industrial scale and applied in the field.