Control of Powdery Scab of Potato: Towards Integrated Disease Management

Abstract

Powdery scab of potato, caused by the plasmodiophorid pathogen Spongospora subterranea f. sp. subterranea, is an increasingly important disease where potatoes are grown in cool/temperate regions. Powdery scab lesions on tubers downgrade their quality as seed, fresh vegetable or processing potatoes, and the disease can severely harm crop productivity. Aspects of the biology of S. subterranea, including long-term persistence in soil, high and rapid reproductive potential, and, possibly, ability to infect alternative hosts, pose considerable problems for development of effective control of powdery scab. Methods shown to reduce the incidence and severity of the disease are reviewed. These include field choice and crop rotation, pathogen detection, use of resistant cultivars, planting disease- and pathogen-free seed tubers, appropriate pesticide treatments for seed tubers and/or infested soil, adjustment of soil nutrient status, and use of suitable management practices during crop growth. No single method is likely to give complete control of powdery scab, particularly where S. subterranea inoculum levels are high on seed tubers or in soil. Effective disease management will therefore depend on implementation of several appropriate methods, using an integrated approach to powdery scab control. This requires understanding of the biology of S. subterranea, and comprehensive and conscientious adherence to appropriate disease control methods during most stages of the potato crop management cycle.