|Parker, P. E. - USDA-APHIS|
|Bock, C. H. - USDA, ARS, USHRL|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: September 9, 2003
Publication Date: June 1, 2004
Citation: Parker, P., Bock, C., Gottwald, T.R. 2004. Citrus canker symptom assessment using image analysis. Phytopathology. 94:S81. Technical Abstract: Images of 214 citrus leaves with symptoms of citrus canker (<i>Xanthomonas axonopodis pv citri</i>) 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.