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A method for determining the severity of sudden death syndrome in soybeans

Cui, D., Zhang, Q., Li, M., Slaminko, T., Hartman, G. L.
ARS USDA Submissions 2014 v.57 no.2 pp. 671
Fusarium, Glycine max, breeding lines, cameras, color, cultivars, death, foliar diseases, fungal diseases of plants, fungi, greenhouse experimentation, image analysis, leaf area, leaves, lesions (plant), solar radiation, soybeans
Sudden death syndrome (SDS), caused by the fungus Fusarium virguliforme, is a widespread mid- to late season soybean disease with distinctive foliar symptoms that in some extreme cases may cause nearly 100% yield loss. This article reports on the development of an image analysis method to quantify SDS severity using an RGB camera under natural light in a laboratory environment. An HSI (hue, saturation, and intensity) color space based image processing approach was developed. A lesion index (LI) was defined as the ratio of affected leaf area to healthy area for evaluating SDS severity levels on leaves of infected plants. A method of using the frequency distribution of hue values of whole leaf area to measure the severity of SDS was also investigated. Preliminary results obtained from laboratory-scale validation demonstrated that the developed method could provide a feasible means of recording SDS severity in situ that could potentially be used for high-throughput greenhouse evaluation of breeding lines or commercial soybean cultivars.