植物病理学および微生物学ジャーナル

概要

Management of Powdery Scab (Spongospora subterranea) of Potato in Dailekh, Nepal

Roman Pandey*, Ritesh KumarYadav, Dipesh Giri, Bibek Budhathoki, Ram Chandra Neupane, Sudan Gautam

Powdery scab caused by Spongospora subterranea (Wallroth) Lagerheim f.sp. subterranea is a serious disease of potato worldwide. The disease has been reported in a severe form in different potato growing areas of Nepal, particularly western hills. At present, it is a major problem for fresh and seed tuber producer as it reduces substandard appearance and marketability of tuber which makes it as a quarantine potato disease in Nepal. The disease is a major reason for limiting the export potato from western hills. The infected tubers were planted in same field year after year. When the monsoon brings abundant rain during growing season, condition was often favourable for the development of powdery scab. The disease causes powdery lesion on the surface which appears like scab containing mass of powdery spore balls. The initial visible symptom is the development of purple to brown pimple like swellings at the rose end of the tuber later on the pustules can increase in size and rupture the epidermis. The individual circular scab lesions can develop to approximately 10 mm in size and the shapes may become irregular when the lesions become large and merge together. Other symptoms may include galls and cankers which develop on the roots. The gall formations are seen in roots where there is no drainage facility and swampy field conditions. But, in hot dry condition of field no gall formation in roots. Galls may also develop on potato stolons and roots which become dark brown as they mature. The pathogen may be seed borne or soil borne prevalent in both cool temperate and hot dry climatic regions.