Common Scab Trials of Potato Varieties and Advanced Selections at Three U.S. Locations

Abstract

Common scab (CS), caused by Streptomyces spp., is a soil-borne bacterial disease of potato tubers which may cause superficial, raised, or pitted lesions. The results of screening potato germplasm for severity of CS can be variable, necessitating testing over multiple environments. The purposes of this study were to evaluate advanced germplasm from public potato breeding programs in different regions of the United States for their reaction to CS, estimate broad-sense heritability for resistance, and identify clones with stable resistance. Seventeen to 23 clones per year were evaluated at each of three locations (ID, ME, MN) from 2002 to 2007. After harvest, each tuber was scored for the percent of surface area covered with lesions and the type of lesion. These scores were converted to an area index (AI) and a lesion index (LI). AI, LI, and the arcsine √ proportion scabby tubers (PS) were analyzed as normally distributed responses. There were significant differences among clones for AI in 2 years, LI in 5 years, and PS in 3 years. There were significant clone x location interactions for AI and PS all 6 years, and LI in 5 years. Broad-sense heritability for AI, LI, and PS ranged from 0 to 0.78, 0.49 to 0.90, and 0.30 to 0.80, respectively. Evaluation at multiple sites remains important for characterizing the reaction of potato germplasm to CS.Resumen La roña común (CS), causada por Streptomyces spp., es una enfermedad bacteriana de los tubérculos de la papa, que puede causar lesiones superficiales, elevadas o punteadas. Los resultados en las evaluaciones del germoplasma de papa pueden variar en severidad de CS, requiriéndose pruebas en múltiples ambientes. Los propó-sitos de este estudio fueron evaluar germoplasma avanzado de programas públicos de mejoramiento de papa en diferentes regiones de Estados Unidos para su reacción a CS, estimar la heredabilidad para la resistencia en un sentido amplio, e identificar clones con resistencia estable. Se evaluaron anualmente de 17 a 23 clones en cada una de tres localidades (ID, ME, MN) del 2002 al 2007. Después de la cosecha, cada tubérculo fue cuantificado en porcentaje de área de la superficie cubierta con lesiones y de qué tipo. Estas evaluaciones se convirtieron a un índice de área (AI) y a un índice de lesión (LI). Se analizaron AI, LI, y la proporción √ arcoseno de tubérculos con roña (PS) como respuestas en una distribución normal. Hubo diferencias significativas entre clones para AI en dos años, LI en cinco años, y PS en tres años. Hubo interacciones significativas de clon x localidad para AI y PS en los seis años, y LI en Funded in part by the USDA/ARS Potato Special Grants Program. Electronic supplementary material The online version of this article (

Aggressiveness of Streptomyces on Four Potato Cultivars and Implications for Common Scab Resistance Breeding

“…The mechanism of pathogenicity, based on the phytotoxin thaxtomin, is presumably conserved in all plant pathogenic Streptomyces, but there are well-documented and consistent regional differences in CS severity in North America (Haynes et al 1997;Haynes et al 2006;Hill and Lazarovits 2005), and year-to-year variation in CS severity is also regularly noted. It has long been recognized that potato cultivars differ in CS susceptibility (Caligari and Wastie 1985;Haynes et al 1997;McKee 1958).…”

Cumulative and residual effects of different potato cropping system management strategies on soilborne diseases and soil microbial communities over time

“…Even so, although the irrigation applied may not have been sufficient to reduce scab, it would not be expected to increase scab. However, scab has been reported as a problem wherever potatoes are grown and under all conditions, including wet and dry soils, and even fields that are carefully irrigated (Haynes et al, 2010). In research in Maine soils over the past 15 years, the authors have consistently observed at least comparable, if not greater, scab in irrigated versus nonirrigated plots.…”

Mountain Gem Russet: a Potato Variety with High Early and Full Season Yield Potential and Excellent Fresh Market and Early Processing Characteristics

“…Common scab (Streptomyces scabies) was evaluated on tubers collected from three replicates from field trials arranged in a randomized complete block (RCB) using naturally occurring inocula at Aberdeen, Idaho. Mountain Gem Russet also was evaluated in the national common scab trial in 2012-2013 and in 2012-2014 for common scab response at Aberdeen, Idaho, Becker, Minnesota and Rock Springs, Pennsylvania as described by Haynes et al (2010). Early blight (Alternaria solani) foliar evaluations were conducted at Aberdeen, Idaho and were based on visual estimates of the amount of leaf area infected in three replicate plots of a RCB design.…”