Ceratocystis fimbriata causing canker and wilt disease on West Indian mahogany trees in Indonesia

Abstract

Between 2021 and 2023, a new disease affecting West Indian mahogany plants emerged in South Sumatra, Indonesia. The disease's incidence steadily increased, particularly in Palembang (Jakabaring), where it rose from 0.27–0.46%, and in Bukit Siguntang, increasing from 0–0.73%. In Ogan Ilir Regency (Universitas Sriwijaya), the incidence increased from 2.07–4.71%, and in Ogan Komering Ilir Regency (Celika) the incidence rose from 6.77–15.25%. Initial symptoms of this disease on the plant's stem included canker formation, gum exudation, vascular tissue discoloration, leaf wilting, and eventual plant death. The fungus was isolated from symptomatic vascular tree tissue and confirmed as a pathogen following Koch's postulates. Pathogen identification used a polyphasic approach, combining morphological and molecular characteristics from specific genomic regions (ITS and β-tubulin). Morphological traits and phylogenetic analysis identified the isolate as Ceratocystis fimbriata. Genomic sequences based on ITS revealed that the MHC2 isolate belonged to haplotype ITS7b, while the other four isolates (MHC1, MHC3, MHC4, and MHC5) were in haplotype ITS5. Thus far, C. fimbriata has not been identified as the cause of cankers and wilting in West Indian mahogany trees in Indonesia. Pathogenicity tests have demonstrated that the pathogen causes death in mahogany trees, as well as in Acacia, bullet wood, and jackfruit plants, indicating its potential to affect other agroforestry plants and pose a threat to the biodiversity of indigenous plants in South Sumatra, Indonesia.