Identification and Pathogenicity of Ganoderma Causing Basal Stem Rot in Oil Palm in South Sumatra

Basal stem rot is a significant disease affecting oil palm (Elaeis guineensis Jacq.) in Indonesia, with occurrences reported in the Sumatra and Kalimantan regions. Understanding the pathogenic characteristics of fungal pathogens is essential for accurate diagnosis and effective disease management. This research was conducted with an aim to characterize the pathogenicity of three Ganoderma isolates and to identify them using molecular methods. The results showed that the KM8 isolate exhibited the highest pathogenicity, with a disease incidence of 73%, compared to 67% for B55 and 47% for B93. The mycelium of KM8 also demonstrated the fastest growth rate, averaging 0.5 cm day-1, followed by B93 at 0.4 cm day-1 and B55 at 0.15 cm day-1. Symptoms of basal stem rot began to appear three days after inoculation. Cross-sectional observations of the stem revealed brown discoloration in infected plants. Microscopic examination showed clear differences between healthy and Ganoderma-infected tissues, with infected plantlets displaying vascular shrinkage and abnormalities. The isolates were morphologically pre-identified as belonging to genus Ganoderma based on distinctive colony traits and pigmentation. Therefore, species specific primers targeting G. boninense (90F-443R and 90F-444R6) were used to confirm identity at the species level. PCR amplification produced a band of approximately 370 base pairs. All the three isolates were identified as Ganoderma boninense, with a sequence similarity of approximately 98–99%