Ceratocystis wilt and canker disease has severely compromised the profitability of Acacia mangium plantations in Southeast Asia. The focus of this review is on Ceratocystis wilt and canker disease in Acacia trees. Its aim is to synthesise information about this fungal pathogen that can be used to inform development of suitable disease-control strategies in forest plantations. The last 20 years have seen many taxonomic changes in Ceratocystis, with some disagreement as to species boundaries. Therefore, an understanding of the origins and development of this disease requires reference to other species, particularly in the context of the biology and fungal taxonomy, disease symptoms and mechanisms of fungal dispersal. The risks and impacts of the disease on the sustainability of Acacia wood production are examined. Observing or surveying disease symptoms in plantations, selecting and planting tolerant or resistant Acacia trees, and the potential of endophytic bacteria as biological control agents are also included in this review.

Red root rot disease caused by Ganoderma philippii is one of the most economically important diseases of tropicalAcacia species. Research on field control of the disease has to date focused on inoculum reduction, silviculture practices and application of biological control agents. Incorporation of tolerant genotypes, a key component of integrated disease management, has not been adequately explored because of a lack of reliable and quick screening protocols. Recently, we developed a more rapid method of screening for red root rot tolerance in Acacia mangium, A. crassicarpa and A. mangium  A. auriculiformis hybrid planting stock, in which groups of five, 6-week-old plants were subjected to inoculum consisting of a rubber (Hevea brasiliensis) wood block culture of the pathogen held within a polythene bag. As symptoms start to appear 10 weeks after inoculation, experiments can be completed in a six-month period instead of the years needed by the traditional pot system. Using this technique we were able to identify variations in tolerance and/or susceptibility to G. philippii in A. mangium, A. crassicarpa and A. mangium  A. auriculiformis hybrid planting stock in a more consistent manner. Tolerant and susceptible genotypes subsequently have been selected for further experiments or crosses. While the ultimate goal of this study was to develop and deploy high-yielding Acacia genotypes that are also tolerant to red root rot disease, results of the current screening studies may also be used to investigate the basis for tolerance to G. philippii in Acacia species.

Ganoderma philippii is the causal agent of root rot disease causing economic losses to Acacia plantations. In an effort to control the Ganoderma root-rot disease, we isolated and screened white-rot fungi as biological control agents. We collected 107 samples from forestry plantations in Riau Province. The fungi were isolated from rotten wood including trunks and twigs, and fruiting bodies. Out of the 107 samples, 28 from rotten woods and 51 from fruiting bodies were successfully isolated. Screening of the isolated fungi was done on wood block, wood disc, and wood-powder-containing agar. Eleven isolates showed fast growth on wood block and in subsequent second screening in dual culture on wood disc, three isolates showed fast growth and were capable of overgrowing G. philippii. The third screening was to examine quantitative growth rate of selected fungal isolates on malt extract agar wood powder (MEA-WP) two isolates were selected. These two isolates have shown potential as biological control agents of the root-rot pathogen, G. philippii.

Ceratocystis wilt and canker disease has devastated Acacia mangium plantations in south-east Asia. Current screening methodologies to identify resistant or tolerant germplasm use potted plants in a greenhouse as a preliminary screening to select material for field trials, but these tests are time-consuming, motivating a search for rapid screening protocols. In this study, inoculation procedures were tested on three species of Acacia, viz. A. mangium, A. crassicarpa and a hybrid of A. auriculiformis and A. mangium, using three isolates of Ceratocystis manginecans. Mycelial plugs were compared with spore suspensions as inoculum to infect artificial wounds on the stems of A. mangium potted plants. The rapid screening protocols involved inoculation of stem segments with mycelial plugs and detached phyllodes with a spore suspension, with susceptibility measured by lesion length on the stems or necrosis length on the phyllodes. Both mycelial plugs and spore suspensions produced a similar level of disease incidence, so either inoculum form can be used for an assay. The stem segments were prone to contamination by other fungi and to desiccation, while results from the potted plant and phyllode protocols showed similar trends of susceptibility among the Acacia clones and species. The ease, rapidity, and reproducibility of the phyllode inoculation protocol makes it a potential replacement for inoculation of potted plants as a preliminary screening protocol to identify disease tolerant A. mangium germplasm prior to field screening.