LAUSR

Basal and upper stem rot of oil palm is caused by the agaricomycete Ganoderma boninense. This study investigated the transmission of basal stem rot from Ganoderma-infected oil palm stumps to young oil palm seedlings. Low seedling mortalities (2.5%) were observed in a field trial after 24 months, but G. boninense could be detected in the rachis, bole and roots of a significant proportion of seedlings that were outwardly healthy. A high level of genetic heterogeneity amongst G. boninense isolates within the trial area was revealed. Furthermore, germinated seedlings growing in close proximity to infected palms in a mature oil palm field contained multiple isolates of G. boninense indicating that colonization of roots by basidiospores and dikaryons, arising from mating between basidiospores, is a common occurrence in oil palm plantations. The probability that basidiospores are a direct source of inoculum in addition to diseased trunk tissue is discussed as a means of explaining the observed heterogeneity in populations of G. boninense on oil palm. Such a scenario presents challenges for the long-term management of basal stem rot.