Abstract The basal stem rot (BSR) disease caused by Ganoderma boninense has been affecting the health and productivity of oil palms for over seven decades. The disease incidences have been progressively on the rise due to multiple predisposing factors. The lack of understanding on the pathogen’s epidemiology leads to poor management of the disease in oil palm. An investigation was initiated on the survival and aggressiveness of the G. boninense isolates sampled across Peninsular Malaysia (Perak, Terengganu, Selangor and Johor) . For the first part, potential substrates were pre-inoculated with G. boninense PER71 to assess the survival ability of the pathogen in four different soil depths (5, 10, 20, and 30 cm). Over the six months of assessment, the highest survival rate of G. boninense PER71 was found on oil palm root (OPR), oil palm trunk (OPT) and rubberwood block (RWB) at 30 cm depth. The survival varied in different types of substrates, while depth and time were observed to be inversely related. The second part of the study investigated the spectrum of G. boninense isolates aggressiveness via a pathogenicity test. Based on the disease severity index (DSI), ET61 (Terengganu) was recorded as the most aggressive (58.75%), while SJ33 (Johor) was the least aggressive isolate (3.13%) under 70 and 90% shades. It was interesting to note that the isolates’ aggressiveness decreased as the age of the sampled palms increased, and this was also related to the soil type in which the isolates were sampled. We conclude that infection within younger palms in the field was due to a higher aggressive spectrum of the isolates. This is the first report associating the age of the palms with the aggressiveness of G. boninense isolates.
Periasamy et al. (Mon,) studied this question.