A method of inoculating seedling with the fungus (Ganoderma Boninense), the causal agent of Basal Stem ROT (BSR) an important problem in oil palm industry in South East Asia and elsewhere is described. Symptoms of BSR similar to those found in the field were reproduces on seedling and the fungus was re-isolated from them, fulfilling the third and fourth of Koch's postulates. In brief, plants were sprayed with a suspension of G. boninense fragments which were incubated before at 25 Celsius in darkness for 12 days. Oil palm seedling root were later sprayed with a finely blended suspension of 17.5 ml of mycelia mixed with 50ul of Tween 20, scrapped from the entire surface of an 8cm diameter petri dish up by 20ml of Potato Dextrose Broth (PDB). The severity of the disease was assessed based on Horsfall and Barratt, 1945 Disease Severity Scale in correlation with ergosterol analysis.