First report of <i>Fusarium acacia‐mearnsii</i> causing leaf blight on pumpkin in Mauritius

Pumpkin (Cucurbita maxima) is an important crop in Mauritius that cultivated throughout the island. The annual production was 7,412 tonnes 2019 and pumpkin also exported to foreign countries (Food Agricultural Research Extension Institute, 2020). In November 2020, on a plantation super-humid zone Cluny, plants showing yellow lesions with pale pink fungal growth upper leaves were observed (Figure 1). Disease incidence estimated be 40% over area of c. 15 ha. Small pieces (1 cm2) infected foliar tissues excised from five plants, surface-disinfected 1% NaOCl, air-dried placed onto potato dextrose agar (PDA). After incubation at 23°C for seven days, obtained isolates uniform white-pink fluffy colonies intensive red pigment visible underside 2). All formed falcate, three- six-septate macroconidia (33.3 × 6 μm; Figure 3) numerous chlamydospores (12.5 μm diameter). DNA extracted mycelium one selected isolate (designated FSI) using modified CTAB protocol (Day & Shattock, 1997). PCR amplification sequencing tef-1α gene ITS region rDNA done EF1/EF2 (O'Donnell et al., 1998) ITS5/ITS4 primer pairs (White 1990), respectively. resultant sequences deposited GenBank (Accession Nos. OP651779 ON738580, respectively). BLAST analyses consensus revealed >99% nucleotide identity several F. graminearum including KJ705291 MW965280 MT482509 LT222056 ITS. Similarly, analysis FusariumID database species complex, Fusarium acacia-mearnsii (CBS110255 LC13787 ITS). morphological characteristics (Leslie Summerell, 2006) coupled demonstrated FSI belongs complex. Species-level identification phylogenetic representative resulted construction neighbour joining tree well-supported branch 4). To demonstrate pathogenicity, grown PDA 24°C days used inoculate roots cv. Olinka seedlings phenophase two true leaves. Five inoculated by spraying spore suspension (102 spores/ml) sprayed sterile distilled water as control plants. Another set placing mycelial plugs wounded stem tissue ground level, while plugs. 20 24°C, all had one-two necrotic spots similar those naturally stem-inoculated developed symptoms wilting 5). both experiments asymptomatic. From symptomatic morphology resembling original recovered. our knowledge, this first study confirming causing blight Mauritius. complex comprises toxigenic known cause fruit rots (Babadoost Zitter, 2009), disease can lead considerable financial losses if not controlled effectively. Thus, hoped provide better understanding affecting pumpkins so proper timely measures taken. This jointly funded Higher Education Commission Government Republic Serbia.