Submitted to: Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2012
Publication Date: 5/4/2012
Publication URL: http://handle.nal.usda.gov/10113/58947
Citation: Dees, M.W., Wanner, L.A. 2012. In search of better management of potato common scab. Potato Research. 55:249-268. Interpretive Summary: There are currently no adequate practices to control potato common scab, which decreases potato quality and marketability because of the wart-like or pitted lesions on the potato skin. We have conducted research to understand the soil bacteria that cause the disease and how the disease develops in potatoes. In this paper we show that Streptomyces can cause common scab lesions on all types of underground stem tissue and not only potato tubers, and that there is a continuous range in severity of the disease in many different potato cultivars. No single measure is sufficient for managing common scab, but development of potato varieties with greater resistance to the disease integrated with best agricultural practices is presently the best option for control. This research will benefit potato breeders and potato growers.
Technical Abstract: Common scab (CS) is an important disease and quality problem in potato crops worldwide. It degrades the appearance of the potato tubers and thereby the market value. Knowledge of CS has expanded considerably over recent years. This knowledge has enabled improved detection of the pathogens, increased understanding of mechanisms of pathogenicity, and provided potential methods of modulating pathogen response for disease resistance. However, effective control of this disease remains elusive and depends on greater understanding of both the host and the pathogen. Factors that have hampered the development of CS-resistant potato cultivars include variable effects of environmental conditions, need for better sources of resistance, genetic variation in pathogen populations, and the variability in CS severity from year to year and location to location. Traditional control strategies like irrigation and reduced soil pH are insufficient and often fail. Recent research has focused on two areas that should help in controlling CS: (1) developing rational, research based measures based on understanding the pathogen, its distribution, and under what circumstances it causes disease; and (2) developing reliable disease-resistant cultivars. No single measure is sufficient for managing CS. Integrated use of the available methods, especially planting cultivars with the best CS resistance for a region, is presently the best option for control.