Monitoring streptomycin resistance in Xanthomonas citri in support of FireWall registration for canker

Monitoring streptomycin resistance in Xanthomonas citri in support of FireWall registration for canker

Report Date: 01/19/2015
Project: 730   Year: 2015
Category: Horticultural & Management
Author: James Graham
Sponsor: Citrus Research and Development Foundation

FireWall 50WP (50% streptomycin; Agrosource, Inc.) was granted by an EPA section 18 registration for control of citrus canker in Florida grapefruit. The label for FireWall restricts use to no more than two applications per season. As a condition for FireWall registration, EPA requires monitoring of Xanthomonas citri subsp. citri (Xcc) for streptomycin resistance in treated groves. The objective of this survey was to apply our published protocol (Behlau et al., 2012) for sampling canker-infected grapefruit leaves for isolation and detection of streptomycin resistant Xcc. The survey for 2015 season applications was conducted in January 2016. After sprays with FireWall, no Xcc colonies resistant to streptomycin were detected from two grove locations that received two sprays of FireWall in spring- summer 2015. Xcc in one of the locations has been exposed to streptomycin for three seasons without development of resistance. A report of our findings will be submitted to FDACS.


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