First report of Pilidium concavum causing tan-brown rot in strawberry fruits in Brazil

Between March and July 2009, a survey of diseases was conducted on strawberry fruits (Fragaria x ananassa in Venda Nova do Imigrante, in the state of Espírito Santo, Brazil.Sunken, yellowish brown lesions with the presence of sporodochia were observed in approximately 70% of fruits stored at 20-25^o C with high humidity (Fig. 1).A sample was stored in the herbarium at the Universidade Federal de Viçosa, Minas Gerais, Brazil (VIC 31215).Fungal structures were taken directly from the fruit and examined microscopically for morphological characteristics. Sporodochia were 273-354 x 86-121 µm (Fig. 2A) with long conidiophores, 13.7-47.5 µm in length (Fig. 2B). Conidia, 2.6-8.2 x 1.0-2.1 µm, were hyaline, filiform, aseptate, and allantoid to canoe-shaped, forming singly (Fig. 2C).The fungus fits the description of Pilidium concavum (Desm.) Höhn. [synanamorph: Hainesia lythri (Desm.) Höhn.] (Rossman et al., 2004), which is commonly associated with leaf spotting and postharvest diseases in strawberry (Opgenorth & White, 1991; Golebniak & Jarosz, 2004).

The fungus was isolated in pure culture on potato dextrose agar (PDA) (Fig. 3). Pathogenicity tests were conducted on fresh strawberry fruits that were either slightly wounded by a needle or not wounded.Strawberry fruits were submerged in a conidial suspension (2x10⁶ conidia/ml) obtained from rinsing a 15-day-old colony with water. Controls were submerged in sterile distilled water. The inoculated fruits were maintained in a moist chamber at 25^o C. Lesions typical of those described above were detected two days after inoculation on 100% of the wounded and 40% of the non-wounded fruits. Sporodochia appeared on the fruits three days after inoculation. The control fruits remained healthy. The original fungus was re-isolated from inoculated fruits showing the symptoms. In Brazil , this fungus is reported to cause leaf spot on eucalyptus (Krugner & Auer, 2005), but this is the first report of P. concavum causing tan-brown fruit rot of strawberry. It is important to document this finding in Brazil so as to promote research to screen chemical products and test cultivars for resistance to this disease.Currently, there are no registered chemical products to control this pathogen on strawberry in Brazil , where in tropical areas the climate is favourable for disease development.