Optimizing the use of copper bactericides for control of citrus canker and evaluation of copper resistance in Xanthomonas citri subsp. citri from Southern Brazil

Abstract

The recent increase in the incidence of citrus canker in the São Paulo State (SPS) after significant changes in the eradication program has worried citrus growers. The current situation is favorable for disease progression in the state to endemic levels. In this new scenario, the improvement of control measures and mitigation of citrus canker is essential to minimize the impact of this disease in SPS citrus industry. One of the most used control measures for this is application of copper bactericides. Thus, this project aims at promoting a thorough and comprehensive study to improve the use of copper bactericides for control citrus canker. This proposal is divided into subprojects that will specifically study different aspects relevant to the proposed theme namely: 1) Evaluation of different formulations and rates of copper bactericides for control of citrus canker, 2) Influence of copper particle size in the formulation on citrus canker control, 3) Spray volume of copper bactericides for control of citrus canker, 4) Residual of different formulations of cupric bactericides on treated plants, and 5) Assessment of copper resistance of Xanthomonas citri subsp. citri (Xcc) from Paraná. Preliminary results obtained in our laboratory demonstrated different bactericidal activity on Xcc of the tested copper formulations reinforcing the need to conduct a comprehensive study on this subject. This study will contribute to a more sustainable use of copper bactericides for the control of citrus canker, maximizing the relationship between copper rate and level of disease control and minimizing the side-effects of copper products on the environment. (AU)