Basal Stem Rot of Oil Palm - The Pathogen, Disease Incidence, and Control Methods.

Abstract

Basal stem rot of oil palm caused by Ganoderma boninense is the most serious disease of oil palm in Malaysia, Indonesia, and other oil palm producing countries. Economic losses caused by the disease can be up to USD500 million a year. For many years, basal stem rot was found to infect older palms of over 25 - 30 years. Only in the 1950s, the disease began to appear in much younger palms (10 to 15 years old) and in the last decade or so, palms as young as 1 year were infected by the disease. The highest incidence occurs in coastal areas of Southeast Asia but the disease has now infected oil palm in inland areas, mainly oil palm planted in peat soils. Disease incidence is also high in areas previously growing coconut or forest. Basal stem rot infection and spread occur through root-to-root contact, and basidiospores that colonize the roots also play a role. In the early stages of infection by G. boninense, the pathogen behaves as a biotroph and later as a necrotroph, secreting cell wall-degrading enzymes and triggering host defense responses. Genes, gene products and metabolic pathways involved in oil palm defense mechanisms against G. boninense have been identified, and these metabolites have the potential to be used as markers for early detection of the disease. Integrated disease management used to control basal stem rot includes cultural practices, chemical control, and application of biocontrol agents or fertilizers. Early detection tools have also been developed which could assist in management of basal stem rot infections. Development of resistant or tolerant oil palm is still at an early stage, so the existing integrated disease management practices remain the most appropriate methods for managing basal stem rot of oil palm.