First Report of Ganoderma ryvardenii causing Basal Stem Rot (BSR) disease on oil palm (Elaeis guineensis Jacq.) in Ghana

<ns3:p> Backgrounds Oil palm ( <ns3:italic>Elaeis guineensis</ns3:italic> Jacq.), is the most significant and highest-yielding crop among oil-producing crops worldwide. In 2020/2022, Basal stem rot (BSR) disease was observed in six oil palm growing Districts in Ghana. Methods Field study and laboratory analysis were conducted. A random sampling technique was used to select five plantation blocks from each District. Single-point disease assessments were done using Standard Operating Procedure (SOP) with a severity scale of 0-4. Molecular assays were performed on each sample using nucleic acid as a template. ITS and GanET sequence analysis were performed along with the formation of a phylogenetic tree using the FASTA algorithm with the Fungus database from EBI and NCBI GenBank. Koch’s postulate was followed to confirm the disease. Results The disease incidence was 11.3 % with the highest severity score of 4. BSR is characterised by stem decay large-perennial, woody brackets basidiocarps of average measurement of 2-65 cm in diameter on infected palms. Culture colonies were white, striated, undulating, woolly-cottony, and creamish pigment on the reverse depicting attributes of <ns3:italic>Ganoderma</ns3:italic> fungus. Molecular confirmation was done by combining ITS sequence of top matches of >97% to members of the genus <ns3:italic>Ganoderma</ns3:italic> , >98% and 99.3% identity to three sequences of <ns3:italic>Ganoderma</ns3:italic> sp. (HM138671; HM138670 and HM138672) generated from strains assigned to <ns3:italic>Ganoderma ryvardenii</ns3:italic> and compared with 132 published sequences of <ns3:italic>Ganoderma</ns3:italic> isolates. Conclusion This is the first report of <ns3:italic>Ganoderma ryvardenii</ns3:italic> causing BSR disease on oil palm in Ghana and possibly the second report in Africa. However, the pathogen was first reported to cause similar diseases in oil palm in Cameroon. </ns3:p>