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POSTERS: New and emerging diseases

Fitness, virulence and fungicide sensitivity of a newly reported pome fruit pathogen Phacidium lacerum
Kutay Ozturk - Washington State University. Laxmi Pandit- Washington State University, Achour Amiri- Washington State University

Phacidium lacerum (Ceuthospora pinastri) is a recently reported quarantine fungal pathogen responsible for postharvest rot in apples and pears. Very little is known about its epidemiology and best management practices. We tested a representative sample of P. lacerum isolates for their ability to grow and sporulate under various conditions and their ability to cause decay on several apple cultivars. While Phacidium in vitro growth was established on all six media tested, sporulation was only observed on oatmeal agar. Among nine cultivars tested, Honeycrisp and Gala were the most susceptible, whereas WA 38 (Cosmic CrispTM) was the least susceptible (P<0.01). Detached fruit assays were used to assess the sensitivity of P. lacerum to six pre and postharvest fungicides. After 6 months of storage at 1°C, fludioxonil (FDL) and difenoconazole (DIF) provided full control followed by pyrimethanil (PYR) and boscalid (BOSC) + pyraclostrobin (PYRA) with 70% control on non-wounded apples. On wounded fruits, FDL, DIF and PYR were as effective as on non-wounded fruits, whereas the efficacy BOSC+PYRA decreased to 7%. Thiabendazole was the least effective fungicide regardless of the inoculation method. Findings of this project will provide basis for development of efficient control strategies against Phacidium rot.