Comparative incidence of Ganoderma basal stem rot and upper stem rot disease in oil palm in relation to soil type and geographical distribution

Abstract The greatest danger to oil palm sustainability in Indonesia is posed by basal stem rot (BSR) and upper stem rot (USR). However, information on their comparative incidence in relation to soil types and geo-distribution remains scarce. As such, data from annual surveys carried out over 95,000 ha of first-generation oil palms planted in Asian Agri estates was reviewed and analyzed. The highest infection levels occurred in North Sumatra, followed by Riau and Jambi. Likewise, infection levels were highest in peat (24.79 palms/ha), followed by alluvial (13.41 palms/ha), volcanic (7.25 palms/ha), and inland (0.07 palms/ha) soil types. Averaged over three provinces and all four soil types, infection due to USR was more dominant than BSR, comprising 52.3% and 47.7%, respectively. Molecular assays of infected tissue confirmed that both BSR and USR were caused by the genus Ganoderma with the major species being G. boninense. Longitudinal dissections of oil palm trunks infected by USR indicated no infection connectivity with the basal portion of the trunk, unlike BSR, where the infection is through root contact. Transmission through basidiospores is likely to play an essential role in USR epidemiology. Understanding pathogen distribution, species identity, and its transmission epidemiology are prerequisites to control diseases more effectively.