First report of Botryosphaeria dothidea causing Bot Rot in Figs ( Ficus carica L.) in Spain

The Jerte Valley (Cáceres, Spain) is a leading European region for dried fig (Ficus carica L.) production (cv. Picholetera). During 2023-2024, growers reported losses (up to 75% of fruit) due to brown stains, reducing commercial quality. To identify the causal agent, 100 symptomatic fruit discarded by growers after post-harvest sun-drying, before shipment to industry, were collected from four orchards. Fungi were isolated on acidified PDA (1.5 mL L⁻¹ 85% lactic acid), and hyphal tips subcultured (5 days, 25ºC, darkness) for morphological classification. Of these, Botryosphaeria was the most frequent genus (35%), followed by Alternaria (10%), Aspergillus (2%), and Penicillium, Fusarium, Neofusicoccum, and Stemphylium (1% each). Ten representative isolates were grouped morphologically into seven genera: B. dothidea (3), Neofusicoccum sp. (2), Aspergillus sp. (1), Penicillium sp. (1), Fusarium sp. (1), Alternaria sp. (1), and Stemphylium sp. (1). Only B. dothidea was confirmed molecularly. Three B. dothidea isolates (FIT25001, FIT25002, FIT25005) were sequenced at the ITS (ITS1/ITS4), TEF1-α (EF1-728F/EF1-986R), and TUB2 (Bt2a/Bt2b) loci (GenBank: ITS PX682909, PZ011015–6; TEF1-α PX687340, PZ016944–5; TUB2 PX687339, PZ016946–7), with 100% BLASTn similarity and clustering with B. dothidea reference strains (bootstrap 99) (Zhang et al. 2021; Fiorenza et al. 2022). The three isolates produced fusiform conidia (18.3–26.8 × 4.3–6.5 μm, n = 150); the isolate FIT25001 developed bitunicate asci with eight ascospores (23.8–31.6 × 9.2–11.8 μm, n = 50), consistent with Moral et al. (2010). Koch’s postulates were fulfilled with isolate FIT25001. Ripe ‘Picholetera’ fruit were surface disinfected (10% NaOCl, 1 min), rinsed, and incubated at 24-26 °C; 21 fruit were inoculated with a conidial suspension (1 × 10⁵ conidia mL⁻¹) and 21 with mycelial plugs; controls received water or PDA plugs. After 5 days (12h light/12h dark), rot developed in 76% and 66% of fruit, respectively (controls symptomless). Field inoculations (5 × 10⁴ conidia mL⁻¹, three branches/tree, three trees) resulted in 45% rot after 20 days. The pathogen was re-isolated and confirmed by ITS and morphology. B. dothidea was reported on fig in China (Wang et al. 2020), but this is the first record on fig in Spain. Unusual rainfall in late May-June 2024 and a summer heat wave likely favored infection. Given the high value of ‘Picholetera’ figs, this disease poses an economic threat requiring targeted management strategies.