The rapid expansion of oil palm (OP) has led to its emergence as a commodity of strategic global importance. Palm oil is used extensively in food and as a precursor for biodiesel. The oil generates export earnings and bolsters the economy of many countries, particularly Indonesia and Malaysia. However, oil palms are prone to basal stem rot (BSR) caused by Ganoderma boninense which is the most threatening disease of OP. The current control measures for BSR management including cultural practices, mechanical and chemical treatment have not proved satisfactory. Alternative control measures to overcome the G. boninense problem are focused on the use of biological control agents and many potential bioagents were identified with little proven practical application. Planting OP varieties resistant to G. boninense could provide the ideal long-term solution to basal stem rot. The total resistance of palms to G. boninense has not yet been reported, and few examples of partial resistances have been observed. Importantly, basidiospores are now recognized as the method by which the disease is spread, and control methods require to be revaluated because of this phenomenon. Many methods developed to prevent the spread of the disease effectively are only tested at nursery levels and are only reported in national journals inhibiting the development of useful techniques globally. The initial procedures employed by the fungus to infect the OP require consideration in terms of the physiology of the growth of the fungus and its possible control. This review assesses critically the progress that has been made in BSR development and management in OP.

Latex production from Hevea brasiliensis rubber tree is the second most important commodity in Malaysia, but this industry is threatened by the white root rot disease (WRD) caused by Rigidoporus microporus that leads to considerable latex yield loss and tree death. This study aimed to characterize and compare the virulence of five R. microporus isolates obtained from infected rubber trees located at different states in Malaysia. These isolates were subjected to morphological and molecular characterization for species confirmation and pathogenicity test for the determination of virulence level. BLAST search showed that the ITS sequences of all the pathogen isolates were 99% identical to R. microporus isolate SEG (accession number: MG199553) from Malaysia. The pathogenicity test of R. microporus isolates conducted in a nursery with 24 seedlings per isolate showed that isolate RL21 from Sarawak has developed the most severe above- and below-ground symptoms of WRD on the rubber clone RRIM600 as host. Six months after being infected with R. microporus, RL21 was evaluated with the highest average of disease severity index of 80.52% for above- and below-ground symptoms, followed by RL22 (68.65%), RL20 (66.04%), RL26 (54.38%), and RL25 (43.13%). The in vitro growth condition tests showed that isolate RL21 of R. microporus has optimum growth at 25–30 °C, with the preference of weakly acidic to neutral environments (pH 6–7). This study revealed that different virulence levels are possessed among different R. microporus isolates even though they were isolated from the same host species under the same climate region. Taken together, field evaluation through visual observation and laboratory assays have led to screening of the most virulent isolate. Determination of the most virulent isolate in the present study is vital and shall be taken into consideration for the selection of suitable pathogen isolate in the development of more effective control measures in combating tenacious R. microporus.

The pathogenic fungi, Rigidoporus microporus and Corynespora cassiicola are among the major agents of root and leaf disease of rubber tree (Hevea brasiliensis). In this study, endophytic fungi were isolated from seeds of H. brasiliensis obtained from different regions of Malaysia to determine the diversity of endophytes inhabiting the seeds and to select a potential biocontrol agent against selected Hevea pathogens. Through morphological observation and molecular identification, six genera were identified namely Aspergillus, Colletotrichum, Diaporthe, Lasiodiplodia, Mucor and Pseudofusicoccum. Isolate PN3 which showed 99.82% identity to Aspergillus terreus was selected as a candidate to evaluate its biocontrol potential against R. microporus and C. cassiicola as it displayed promising inhibitory potential in preliminary experiments. A. terreus showed inhibition of 81.24%, 70.35% and 64.19% against R. microporus and two races of C. cassiicola namely CLN 16 and CSB 16 respectively in dual culture assay. In dipped stick inhibition assay, A. terreus showed 100% inhibition to the growth of R. microporus. A. terreus also reduced infection of leaves cultured with C. cassiicola CLN 16 and CSB 16 by 93.33% and 86.67% respectively. This study has identified some of the fungal species inhabiting the seeds of H. brasiliensis which may have potential as biocontrol agents.