Sensitivity of Potato Cultivars to Potato mop-top virus-Induced Tuber Necrosis.

Potato (Solanum tuberosum) cultivars representing four market classes were assessed for sensitivity to Potato mop-top virus (PMTV)-induced tuber necrosis in three separate trials in a field in North Dakota known to be infested with PMTV. Reverse-transcription polymerase chain reaction confirmed the presence of PMTV in randomly selected samples. Results of tuber necrosis assessments conducted during storage demonstrated that sensitivity to PMTV-induced tuber necrosis among cultivars follows a continuum of tolerant to sensitive. As a group, the russet-skinned cultivars had a lower incidence of tuber necrosis than red-, yellow-, and white-skinned cultivars. The incidence and severity of PMTV-induced tuber necrosis in trial 1 were significantly correlated with those parameters in trial 2 across years. Significant correlations also existed between the incidence of powdery scab on tubers and the incidence of PMTV-induced tuber necrosis in trial 1 across years. A significant correlation was also found between root gall numbers and powdery scab incidence and severity on tubers as well as PMTV-induced tuber necrosis incidence in trial 2. The results of this study provide growers with disease management options by avoiding cultivars highly sensitive to PMTV-induced tuber necrosis development and potentially replacing them with tolerant cultivars in the same market class. It is apparent from these studies that field assessments can be used for the development of PMTV-resistant germplasm for use in future breeding strategies.