This study describes and identifies the fungi associated with root-rot disease in Eucalyptus pellita, associated anecdotally with a species of Phellinus. Macro-and microscopic morphological observations and DNA analysis were used to identify sporocarps and fungal cultures growing from symptomatic root samples. Investigation of 12 sites in Central Sumatra revealed that red root-rot disease caused by species of Ganoderma (most commonly Ganoderma philippii) was as prevalent as root disease caused by Phellinus noxius. The study also detected the presence of several potential fungal agents of root rot at any one site. Fungal signs such as absence/presence of sporocarps were a poor indicator of root-rot incidence in stands. Instead, fungal isolation from infected roots was essential to obtain accurate identification of active pathogens.

An investigation of root rot in Acacia mangium plantations in Indonesia generated over 1000 fungal isolates from field surveys at six locations. The majority of isolates were identified as Ganoderma philippii or Ganoderma mastoporum by species-specific PCR, but this still left 274 isolates to be identified. As barcoding initiatives for fungi are still in the early stages, to assist identification of these isolates in this way we developed a database of sequences based on identified sporocarps and also searched public DNA sequence databases for sequences with high similarity. The database of sequences from sporocarp collections is more limited than public DNA databases. This resulted in more reliance on public DNA databases for a high proportion of taxa. Several pathogenic species were identified, with Phellinus noxius occurring at several locations and on both A. mangium and Eucalyptus pellita. Ganoderma steyaertanum was isolated from A. mangium roots and Rigidoporus microporus from E. pellita roots, each at a single location only. Potential pitfalls of using public DNA databases for fungal identification are discussed and methods to avoid these and increase confidence in the identification are presented.

DNA sequence variation in the rDNA internal transcribed spacers (ITS) was exploited to design species-specific primers for Ganoderma philippii and Ganoderma mastoporum, two fungi associated with red root rot in Acacia mangium and other perennial crops. Specificity was verified against five other Ganoderma species, 34 other basidiomycete species and two ascomycete species. The PCR tests assisted in the identification of 822 fungal isolates obtained from A. mangium and Eucalyptus pellita plantations in Indonesia. These tests have provided a high level of confidence in the identification of the major root rot pathogens, information that can be used to support the development of management options for their control in A. mangium plantations.

Ganoderma philippii causes root-rot disease in a wide range of commercial perennial woody crops such as rubber and tropical acacias. In terms of productivity loss, the disease is considered as the most economically damaging disease of Acacia mangium. Many strategies to manage root rot have been developed and applied, including application of biological control which has focused on species and strains of the ascomycete genus Trichoderma. This research aimed to test the potential of a wood-rotting basidiomycete as a biocontrol agent for root rot caused by Ganoderma philippii. This basidiomycete was isolated from a Eucalyptus pellita stump in a coppicing trial in Riau province, central Sumatra. DNA sequence analysis indicated that this isolate is most likely a Phlebiopsis sp. In vitro tests and microscopic morphological description of mycelial interactions between the Phlebiopsis and G. philippii isolates showed a mycoparasitic reaction. This result offered an alternative potential fungal isolate for root-rot management in Indonesia as Phlebiopsis gigantea is already successfully used as a biocontrol agent for managing root rot caused by Heterobasidion annosum throughout pine forests in Europe and North America.

The restoration of peat swamp forests in Sumatra island has become Indonesian government’s priority to restore ecological functions and their utilization. Indigenous. However, little information is available on the status of arbuscular mycorrhizal (AM) fungi in Sumatera. The objective of this research was to know AM fungi colonization in indigenous of tropical peat swamp forests. Root samples of 28 tree species in 14 families grown in a peat swamp forest of Jambi, Riau, and South Sumatera. All soil and tree roots were grown in zeolite media and trapped in Pueraria javanica and Shorgum bicolor as host plants for four months in a green house. Roots were stained with 0.1% trypan blue and vesicles, arbuscles and internal hyphae of AM fungi observed under a compound microscope. The results have shown that 20 tree species (72%) were colonized by AM fungi, 4 tree species of the dipterocarps family (14%) were colonized by ectomycorrhizal fungi (ECM), and four other tree species (14%) did not find FMA or ECM colonization. It is suggested that utilization of mycorrhizas can increase early growth of some tree species grown in peat swamp forests and mycorrhizal application will be expected as a key technology to restore degraded peatlands.