Allelopathic potential of root exudates from edible perennial herbaceous (Canna indica, Maranta arundinacea, and Xanthosoma sagittifolium) against mycelium of Ganoderma boninense, basal stem rot pathogen of oil palm has been studied in vitro. Root exudates were extracted from 10-day old aseptically growing plants generated from surface-sterilized corm or rhizome on water agar. Allelopathic activity was tested based on inhibition of G. boninense mycelial growth on malt extract agar supplemented with 0.1 and 1.0 μL mL−1 ethyl acetate extract of root exudates. Root exudate from X. sagittifolium and C. indica was found to significantly inhibit the mycelial growth of G. boninense at 0.1 and 1.0 μL mL−1, respectively.

Basal stem rot (BSR) disease caused by Ganoderma boninense is the most destructive disease in oil palm plantations. Herbaceous plants such as arrowroot, cocoyam, and canna were reported to interfere with the Ganoderma disease of oil palm under mixed planting on non-sterilized soil. This study aimed to determine the role of the ligninolytic fungi isolated from herbaceous plants on wood decay, mycelial growth, and infection of Ganoderma boninense. A total of 24 ligninolytic fungal isolates were isolated from arrowroot, cocoyam, and canna plant and grouped into 6 types of wood decay interaction, namely (1) neutral, (2) negative interference to the herbaceous isolates, (3) negative interference to both fungi, (4) negative interference to Ganoderma, (5) negative interference to the herbaceous isolates and positive for Ganoderma, and (6) positive interference in both fungi. Ligninolytic fungi from cocoyam and canna plants were able to negatively interfere with the Ganoderma wood decay, inhibit the colony, and reduce the initial root infection of oil palm. Keywords: antagonistic in vitro, Ganoderma boninense, ligninolytic fungi, root necrosis, wood decay.