DOMESTIC, EXOTIC, AND EMERGING DISEASES OF CITRUS, VEGETABLES, AND ORNAMENTALS (DEED)
Location: Subtropical Plant Pathology Research
Title: Efficacy of Cankerguard® Sprays for Effective Decontamination of Citrus Canker
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2008
Publication Date: October 1, 2008
Citation: Bock, C., Parker, P., Cook, A., Graham, J., Gottwald, T.R. 2008. Efficacy of Cankerguard® Sprays for Effective Decontamination of Citrus Canker. Phytopathology. 99:S13.
Citrus canker (Xanthomonas citri subsp. citri, Xcc) is endemic in Florida. We used grapefruit leaf surfaces to explore the efficacy of the personnel decontaminant Cankerguard® to kill inoculum. In three experiments plants in flush (leaves 3/4 expanded) were sprayed with inoculum (2x104-9x105 CFU/ml). Immediately after inoculation, plants were passed through standard personnel decontamination spray hoops (0, 1, 2, 3, and 6 times) with spray nozzles, ensuring good droplet coverage with each pass. Leaves were sampled at 0, 10 and 20 min after decontamination and tested for viable bacteria of Xcc by dilution plating. There was a large and rapid decline in the quantity of live bacteria with one pass through the spray hoop (5 to10 fold decrease in CFU), and multiple sprays (up to six) resulted in a 100 fold reduction in the population to complete decontamination. Presumably better coverage with multiple sprays killed remnant bacteria, although the first spray invariably killed the most bacteria. Inoculated plants were incubated and development of symptoms on plants from all treatments suggested that infection took place at, or very soon after, inoculation as decontamination did not reduce disease incidence or severity. Based on these results, decontamination with Cankerguard® is efficacious at reducing the quantity of surface inoculum, and even a single spray hoop can provide a high level of kill, but multiple sprays improve mortality of Xcc.