Effects of presprouting on potato diseases in organic farming

The effects of presprouting on potato diseases were examined during 3 years of field trials at two locations. The trials, running from 1991 to 1993, were carried our under the conditions of organic farming with the cvs. 'Agria', 'Granola', 'Linda' and 'Nicola'. Presprouted potatoes showed significantly higher areas under the disease progress curve (AUDPC) for early blight (Alternaria spp.) than not presprouted on cv. 'Agria' in all 3 years and on all cultivars in 1993. Presprouting did not have any influence on the first occurrence of late blight (Phytophthora infestans). In some cases, AUDPC for late blight were significantly reduced by presprouting, in another case it was increased. Presprouting significantly diminished common scab (Streptomyces scabies) on cv. 'Agria', which was more attacked than the other cultivars. In 1 year, hollow heart was detected in presprouted potatoes of cv. 'Agria' in considerable extent. Tuber rots, internal rust spot, black scurf (Rhizoctonia solani) and PVYNTN were not affected by presprouting.