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POSTERS: Fungicide and antibiotic resistance

Copper-resistant strains of Xanthomonas gardneri and X. perforans from Illinois tomato fields
Sabin Khanal - University of Illinois at Urbana Champaign. Sarah R. Hind- 259 E R Madigan Laboratory, Mohammad Babadoost- University of Illinois - Crop Sciences Dept

During 2017-2018, 159 Xanthomonas isolates were collected from symptomatic leaf and fruit samples from commercial tomato fields in Illinois. Among the 159 isolates, 102, 56, and 1 isolates were identified as X. gardneri, X. perforans, and X. euvesicatoria, respectively based on Sanger sequencing using hrp gene primers (RST65 and RST69). All the Xanthomonas isolates were grown on media containing 0.08 mM copper sulfate (CuSO4) to screen for copper resistance. Isolates that grew on the copper media were further evaluated using PCR to confirm the presence of two copper-resistance genes, copA and copM. Based on our phenotyping and genotyping analyses, 17 X. gardneri and 13 X. perforans isolates were identified as copper resistant. The efficacy of commonly used chemicals for management bacterial spot of tomato in Illinois are being investigated against a subset of these identified copper-resistant isolates. Commonly used chemicals for management of Xanthomonas spp. on tomatoes in Illinois are copper hydroxide (Kocide-3000), copper octanoate (Cueva), copper sulfate pentahydrate (Phyton 27AG), mancozeb (Manzate PRO Stick), quinoxyfen (Quintec 250SC), and an extract of Reynoutria sachalinensis (Regalia). The findings of this study are expected to help to develop effective management of bacterial spot of tomatoes.