First report of the Fusarium arthrosporioides/avenaceum complex causing olive fruit rot in Italy

Abstract

Olive (Olea europaea) is affected by different fungal pathogens causing fruit rot which decrease the overall productivity in terms of oil quantity and/or quality (Lazzizera et al., 2008). In autumn 2022, rotting fruits bearing red-yellow mycelium and ochre sporodochia were observed in different olive batches of cultivars Leccino and Canino delivered to an oil mill in Viterbo province, Italy (Figures 1–3). To investigate the causal agent, the olives were surface sterilised in 2% NaOCl for two minures, rinsed three times with sterile distilled water and sectioned with a sterile scalpel. Sections were plated on potato dextrose agar (PDA) and incubated at 25◦C for 15 days. The fungal colonies produced abundant fluffy white aerial mycelium with a yellow to red pigmentation when viewed from the bottom (Figure 3). Macroconidia were slender, slightly curved, from 5 to 7 septate, with a tapering apical cell, a foot-shaped basal cell, and measured 46.8–64.6 × 3.9–4.5 μm (Figure 4). Microconidia produced on PDA were sporadic, unicellular, or with a single septum, and measured 8.5–13.5 × 3.5–5.0 μm.