The effect of organic amendments on stem canker and black scurf (Rhizoctonia solani) of potatoes

摘要

Stem canker and black scurf are diseases of potato caused by Rhizoctonia solani, which are increasingly important in organic systems as high quality produce is required to meet market requirements. Soil amendments have potential to suppress soil-borne diseases, but are not widely exploited in commercial production. This paper reports an evaluation of a range of organic amendments on stem canker and black scurf. Treatments were used at realistic commercial rates and timings in a naturally-infested soil in a glasshouse experiment. Chitin, cabbage, vetch and rye amendments reduced the severity of black scurf, whilst seaweed and manure increased its severity. No treatments reduced the length of canker lesions. Straw reduced vigour and tuber number. Care should be taken in choosing amendments and cropping systems in organic disease management programmes as some have potential to aggravate rather than suppress soil-borne pathogens.