Co-infection of two Ganoderma boninense strains on oil palm seedlings

Abstract

Ganoderma boninense is the basal stem rot disease (BSR) pathogen that devastates oil palm plantations. Disease infection generally occurs by a single strain of G. boninense, or co-infection of two strains arises as revealed by somatic incompatibility. This study aimed to determine the effects of co-infection of two somatically incompatible G. boninense strains on the BSR disease of oil palm seedlings. Two strains of G. boninense were from 2 oil palm plantations and had different aggressiveness. Co-infection of two G. boninense strains was performed by inoculating the Ganoderma rubber wood blocks to the 3-month-old oil palm seedling and examined for 7 months. The results showed that co-infection with two G. boninense strains had similar disease symptoms, decreased disease severity (score 1.5 compared to 2.0 for a single aggressive strain), and similar seedling growth retardation by the single aggressive strain. Higher fungal colonization (92%) of oil palm roots was exhibited in the co-infection compared to 85‒86% colonization of a single strain infection. This study revealed that co-infection with two somatically incompatible strains might favor host colonization by G. boninense.