ABSTRACT
Pathometry is a major tool for developing resistant varieties. Disease management through breeding resistant cultivars at forefront in countries where resource limitations do not permit high cost plant protection technology. Description of disease symptoms in standard diagrams, color plates and in words are essential for disease appraisal. Besides measuring diseased area, the counting of spores has been tried as an alternative method, especially for fungal diseases. Several workers have employed video image analysis for assessment of plant disease severity. Disease incidence, severity, and spatial pattern depend on data obtained from field samples. Linear regression equations often are used to characterize critical-point models where the independent variable is disease measurement and percentage loss in yield is the dependent variable. Plants can be evaluated for incidence or severity. Such models provide loss estimates for a given amount of disease at a given point in time or for any point in time when a given amount of disease is present.
