Symptom Expression of Mainstream and Specialty Potato Cultivars to Bacterial Ring Rot (Clavibacter sepedonicus) and Evaluation of in-Field Detection

Abstract

Bacterial ring rot caused by Clavibacter sepedonicus is a zero-tolerance disease in seed potato certification and can cause crop loss and substantial economic damage for affected growers. To address symptom expression and time of expression, 28 cultivars and advanced breeding lines were inoculated with C. sepedonicus and grown in North Dakota and Idaho. Cultivars included russet, chip, and specialty types. Foliar ratings were taken, and first symptoms were observed as early as 91 days after planting in Idaho and 55 days in North Dakota. Symptom characteristics were noted for each cultivar. This information is useful to growers and certification officials. Samples of stems, petioles, stolons, and tubers were also collected at different pre-harvest intervals to determine if C. sepedonicus can be reliably detected in the lab. The ability to detect C. sepedonicus before harvest allows an affected grower to make harvest and management decisions that limit damage caused by bacterial ring rot.