During the 2019-2020 Florida strawberry season (October to April), a strawberry fruit rot was observed in two fields (Plant City and Wimauma, FL) with up to 5% incidence on short-day cultivars SensationTM Florida127, and Florida Brilliance.
Symptoms on pink and ripe fruit consisted of softening, discoloration, watery rot with white fuzzy mycelium, and initial sclerotium formation. Diseased tissues were collected and a fungus, producing spreading cottony white colonies with dark sclerotia, was isolated.
Based on the morphological features, the pathogen was tentatively identified as Sclerotinia sclerotiorum, then it was confirmed by DNA sequencing and pathogenicity tests.
Symptoms of Sclerotinia fruit rot of strawberry, caused by Sclerotinia sclerotiorum, at three (A), six (B), ten (C), and fifteen (D) days after inoculation.
"Sclerotinia sclerotiorum has been previously reported causing strawberry fruit rot in Washington state in the United States, England, Israel, and Scotland - the pathologists of Florida University explained. It has also been listed among plant diseases from Florida, North Carolina, and California as causing crown rot.
To our knowledge, this is the first report of S. sclerotiorum causing strawberry fruit rot in Florida. The pathogen is an aggressive necrotroph with prolonged survival and affects several vegetable crops grown in Florida. Because only the strawberry beds are fumigated, sclerotia remaining in the alleys could serve as inoculum sources. Currently, the disease is rare and of minor significance to strawberry production. However, efforts should be implemented to monitor its occurrence and spread".
Source: Marin Marcus Vinicius, Peres Natalia A., 'First Report of Sclerotinia sclerotiorum Causing Strawberry Fruit Rot in Florida', 2020, Plant Disease.