A method was developed using scanned computer images and software programs to measure the lesion area on leaves with cucumber anthracnose caused by Colletotrichum orbiculare. After cucumber plants were inoculated with various concentrations of conidia, lesions on diseased leaves were scanned, manipulated with Adobe Photoshop 6.0, and measured using the blob analysis feature in Matrox Inspector 2.2. The method requires relatively low-cost equipment including a scanner, a personal computer, and two programs: Adobe Photoshop 6.0 and Matrox Inspector 2.2. Because stored images are used, the lesion area can be measured as time permits. Processing the images requires about 3min per sample. The image assessment accurately detected anthracnose lesions on cucumber leaves and could be applied to other foliar necrotic or spot diseases.
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Fig. 3. Diseased leaf area on second leaves inoculated with various concentrations of conidial suspensions (103, 104, 105, 5 ¥ 105, 106, and 107 conidia/ml) of Colletotrichum orbiculare 5 days (A) and 7 days (B) after inoculation. The water control did not have anthracnose on treated leaves. Anthracnose on leaves of ca. 23-day-old cucumber plants was estimated by visual and image assessment with computer programs (Adobe Photoshop 6.0 and Matrox Inspector 2.2). Arc sine square root-transformed data of percent diseased leaf area were used for statistical analysis; however, untransformed data are presented. Different capital or small letters indicate significant differences between inoculum concentrations at P = 0.05. Asterisks indicate significant (P = 0.05) differences between visual and image assessment at a given concentration Acknowledgment This research was financially supported by special research grant 299119-3 from the Ministry of Agriculture and Forestry of Korea from 1999 to 2002.
Copyright 2008 Elsevier B.V., All rights reserved.
- Colletotrichum orbiculare
- Disease quantification
- Image analysis
- Lesion area
ASJC Scopus subject areas
- Agronomy and Crop Science
- Plant Science