Oil Palm (Elaeis guineensis Jacq.) is an important agricultural commodity for many developing countries in South East Asia including Papua New Guinea and the Solomon Islands. Currently basal stem rot (BSR) disease caused by Ganoderma boninense is the major disease of economic importance causing severe crop losses. BSR disease has been known for over 100 years however, progress in disease control and management has been hampered by lack of understanding of Ganoderma-oil palm interaction which is essential in developing better strategies to control BSR incidence. To date, there are no effective control methods to manage BSR disease. The viable long term alternative would be to breed for resistant germplasm. However, this strategy is dependent on improved understanding of the factors associated with resistance/tolerance and susceptibility.
Pathogenicity assays were performed under controlled environmental conditions with oil palm seedlings inoculated at the bole (lower stem). Bright field and fluorescence microscopy was used to follow Ganoderma infection of oil palm seedlings. Microscopy revealed that Ganoderma appears to have a preference for colonising root tissue as opposed to bole tissue, even though the bole was the sight of inoculation. Hyphae were observed in the sub epidermal highly lignified corky cell layer found in primary and lateral roots. Other plant tissues colonised by Ganoderma included lateral roots emerging from primary roots, and the root-bole interface region and dead tissue areas associated with roots and bole. The tissue regions where Ganoderma has been observed did not fluoresce under fluorescence microscopy when stained with calcofluor white indicating that these were either dead or so highly lignified that these could not be stained. No specialized hyphal structures were observed during this early infection study. This study describes for the first time an account of early processes of Ganoderma colonisation and infection on oil palm seedlings.