First report of <i>Pestalotiopsis macadamiae</i> causing leaf blight on <i>Pongamia pinnata</i> in India

Pongamia pinnata (Indian beech tree, karanja) is important for its diverse medicinal properties and potential insecticidal nematocidal (Parmar et al., 1976). In July 2022, a severe outbreak of leaf spot disease was observed in 15 trees Hardaspur, Punjab, India. Disease incidence the canopy 30–35%. The symptoms were spots (0.8 to 1.3 cm diameter), light brown ash-coloured surrounded by dark black irregular, zonate margins (Figure 1). eventually coalesced, becoming large, blighted areas. During humid conditions, black, sessile conidiomata developed exuding conidial masses. Twenty diseased leaves collected from ten plants 4–5 mm disks cut spots. discs disinfected 70% ethanol one minute, rinsed twice sterilised distilled water allowed dry inside laminar flow hood before placing Petri dish containing agar. After 48 hours incubation, 20 isolates sub-cultured onto potato dextrose agar (PDA). Actively growing mycelial tips transferred fresh PDA plates incubated seven days at 26 ±1°C. colonies produced white aerial mycelia 2) with acervuli five-celled conidia (n = 50) measuring 18.5-24.5 × 5.3-7.0 μm basal appendages 12.0-18.5 long 3). Based on morpho-cultural characteristics, identified as Pestalotiopsis sp. (Sutton, 1980). Sequencing rDNA ITS region β-tubulin gene, described Prasannath al. (2023), undertaken confirm species identity. resulting sequences gene (GenBank Acession Nos. OP363152 OP378566, respectively) identical macadamiae isolate BRIP 63738b (KX186588 KX186680, this supported phylogenetic tree constructed using MEGA software 4). Pathogenicity determined inoculating healthy each three different 30 μl suspension fungus (1-4 104 conidia/ml). Leaves sprayed control. incubation ±1°C alternate periods 12 95% relative humidity, typical all inoculated leaves, but only remained disease-free 5). A reisolated symptomatic morphologically P. microscopy. genus has wide host range, infecting both monocots dicots causing including blight, twig dieback (Maharachchikumbura 2014). There also record flower Macadamia Australia (Akinsanmi 2017). To our knowledge, first report blight caused India worldwide. impact pathogen not known it may become major threat future.