Development of an Integrated Management of Tomato Bacterial Spot - A Strategy That Lives in Practice

Tomato bacterial spot, caused by Xanthomonas spp. complex, is a constant threat to tomato (Solanum lycopersicum)commercial production, but is especially severe in Florida and the southeastern US when weather conditions become conducive for disease development. In an effort to develop more sustainable strategies for reducing severity of the disease, we investigated various combinations of PGPR strains, bacterial antagonists, bacteriophages and SAR inducers (harpin, acibenzolar- S-methyl)in greenhouse and field trials. The idea was to search for alternative treatments that could be integrated with conventional practices, in order to improve disease control and yield responses. After screening single treatments and their combinations for efficacy in a series of greenhouse experiments, acibenzolar-S-methyl (ASM)and phage treatment provided the most promising results. In field trials, carried out in three consecutive seasons, ASM significantly reduced disease severity compared to the untreated control. However, the combination of ASM and formulated host-specific phages provided an additional reduction in disease pressure and resulted in more efficient foliar disease control than ASM, phage, or copper-macozeb alone. Integrated application of phages, ASM and other practices is currently widely used in greenhouses and production fields in Florida as a part of a standard integrated management strategy for tomato bacterial spot control.