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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Plant Pathology Research » Research » Publications at this Location » Publication #162940
Title: CITRUS CANKER SYMPTOM ASSESSMENT USING IMAGE ANALYSIS

Author
item PARKER, P. E. - USDA-APHIS
item BOCK, C. H. - USDA, ARS, USHRL
item Gottwald, Timothy

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 9/9/2003
Publication Date: 6/1/2004
Citation: Parker, P., Bock, C., Gottwald, T.R. 2004. Citrus canker symptom assessment using image analysis. Phytopathology. 94:S81.

Interpretive Summary:

Technical Abstract: Images of 214 citrus leaves with symptoms of citrus canker (Xanthomonas axonopodis pv citri) were analyzed using image analysis (IA). In addition, several plant pathologists visually assessed (VA) each image for number of lesions, % area necrotic and the % area necrotic + chlorotic. There was a consistent positive correlation (r=0.683-0.916, P<0.0001) between these three VA symptoms and the IA estimates. Although mean number of lesions estimated per leaf was similar (16.2-18.7), there was some discrepancy between the IA estimate and among assessors: for example, the number of leaves with no symptoms was 17 using IA, and 18-24 when visually assessed. The mean % area necrotic was 3.4 (IA) and 3.5-5.4 (VA), respectively, and mean area necrotic + chlorotic was 10.7 (IA) and 8.9-11.0 (VA), respectively. Minor discrepancy was found within other lesion number categories, and % area diseased estimates, although frequency counts in each category were not dramatically different. IA appears to provide a reliable way to assess canker infected leaves for disease severity.