Sclerotinia Sclerotiorum Causes Decay And Forms Sclerotia In Potato Tubers In Idaho

Potato tubers (cultivar 'Austrian Crescent') displaying a dry rot decay symptom and internal sclerotia were received for diagnosis. Isolations were attempted from symptomatic material, and Sclerotinia sclerotiorum was frequently recovered. Pathogenicity tests for S. sclerotiorum in potato tubers were completed using agar plugs with S. sclerotiorum placed over tuber wounds and through injecting stolon end with a S. sclerotiorum hyphal suspension. Both inoculation methods induced decay symptoms, although these were observed less frequently with the agar plug inoculation (37.5%) compared with hyphal injection (100%). S. sclerotiorum was consistently reisolated from inoculated symptomatic tubers. This symptom is rare, but potato growers should be aware that tuber infection is possible when white mold is present.