Occurrence of bacterial spot in illinois tomato fields and characteristics of the causal agents

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Bacterial spot, caused by Xanthomonas spp., is one of the most important diseases of tomato in Illinois. Field surveys were conducted during 2017-19 to assess occurrence of bacterial spot in commercial tomato fields. Severity of foliage and fruit infection was recorded, and symptomatic samples were collected from three-to-five cultivars in three different farms in each of northern, central, and southern regions of Illinois. Severity of symptomatic foliage ranged from 0% to 91% (average 36.7%) and incidence of symptomatic fruit ranges from 0% to 30% (average 10.8%). During the surveys, 266 Xanthomonas isolates were collected and identified as Xanthomonas gardneri and X. perforans using Xanthomonas-specific hrp primers. Eighty-six percent of the isolates from the northern region were identified as X. gardneri, whereas 73% of the isolates from southern region were identified as X. perforans. Isolates from the central region were identified as X. perforans and X. gardneri 53% and 47% of the time, respectively. Multilocus sequence analysis using six housekeeping genes (fusA, gap-1, gltA, gyrB, lepA, and lacF) revealed the endemic population of X. gardneri and X. perforans. In addition to Xanthomonas, nine non-Xanthomonas bacterial genera were isolated from the samples, with most of the isolates classified as Microbacterium, Pantoea, and Pseudomonas.

Original languageEnglish (US)
Pages (from-to)8-12
Number of pages5
Issue number1
StatePublished - Jan 2021


  • Foliage disease
  • Fruit infection
  • Pathogen identification
  • Tomato
  • X. Gardneri
  • Xanthomonas perforans

ASJC Scopus subject areas

  • Horticulture


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