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Analysis of seed potato certification data for limiting potato disease incidence in Colorado

Yuan Zeng: Colorado State University

<div>Seed potato certification programs aim to limit disease incidence in planting material to levels below a threshold that causes significant losses to seed potato buyers. Records maintained for seed potato certification also can be analyzed for trends in seed potato varietal mixture and disease incidences over time. In the present study, generalized linear models (GLM) were conducted to analyze effects of year, potato variety, and their interaction on the incidence of potato diseases and disorders, and to determine the effect of seed generation of important varieties on the incidence of common potato diseases based on seed potato certification data collected in San Luis Valley, Colorado from 2012 to 2016. Among documented diseases, mosaic and blackleg have been persistent problems leading to high percentage of seed lot rejection. The GLM demonstrated year, potato variety, and their interaction were key factors contributing to incidence of varietal mixture, or one or more potato diseases and disorders. Our models also predicted 49, 54, and 4 varieties were susceptible to mosaic, blackleg, and leafroll, respectively, whereas there were 12, 6, and 5 varieties that were disease tolerant or resistant regardless of pathogen pressures in the environment. Seed generation effects on mosaic and blackleg was not consistent. In addition, we observed a significantly positive correlation between disease incidence of leafroll and the relative abundance of the green peach aphid, <em>Myzus persicae</em>. Mosaic incidence was not influenced by common aphid species captured in the valley and leafroll was not influenced by other common aphid species captured in the valley. These results identify the major causes of seed potato losses, identification of susceptible and resistant varieties, and provide suggestions for improving integrated crop management practices in Colorado.</div>