Abstract:
Bacterial halo blight (BHB), caused by Pseudomonas syringae pv. garcae, has reemerged as an important disease in Brazil, especially in coffee cultivated at high altitude in the states of Minas Gerais and São Paulo. In this study we evaluated copper-based antimicrobial compounds (CBACs), the antibiotic kasugamycin and the resistant inducers acibenzolar-S-methyl (ASM) and phosphite for BHB management in four experiments carried out in coffee crops in the municipalities of Caconde and Altinópolis, São Paulo State, Brazil. Fungicides to control brown leaf spot (BLS), a disease caused by Boeremia exigua pv. coffea, were also included in two experiments, because both diseases frequently occur simultaneously. Copper oxychloride, copper hydroxide, antibiotic, and ASM mixture with copper hydroxide, and phosphite reduced BHB incidence and had no phytotoxic effects on flowers or pin-head berries. Mixtures of boscalid or pyraclostrobin with copper hydroxide were compatible and effective for the simultaneous control of BHB and BLS. In this study, we showed that August-September is the most important period to control BHB in Brazil and lasts until December, when disease incidence increases, and flowers and pin-head berries are being formed. The chemical management of BHB in this period can improve the coffee crop yield.
