Exploring the Biocontrol Efficacy of spp. against , the Causal Agent of White Root Rot Disease in Rubber Trees ().

which causes white root rot disease (WRD) in is a looming threat to rubber plantation in Malaysia. The current study was conducted to determine and evaluate the efficiency of fungal antagonists (Ascomycota) against in rubber trees under laboratory and nursery conditions. A total of 35 fungal isolates established from the rubber tree rhizosphere soil were assessed for their antagonism against by the dual culture technique. isolates can inhibit the radial growth of by 75% or more in the dual culture test. Strains of , and were selected to assess the metabolites involved in their antifungal activity. Results indicated that exhibited an inhibitory effect against in both volatile and non-volatile metabolite tests. All isolates were then tested for their ability in producing hydrolytic enzymes such as chitinase, cellulase and glucanase, indole acetic acid (IAA), siderophores production, and phosphate solubilization. From the positive results of the biochemical assays, and were selected as the biocontrol candidates to be further tested in vivo against . The nursery assessments revealed that rubber tree clone RRIM600 pretreated with only or with the combination of and was able to reduce the disease severity index (DSI) and exert higher suppression of compared to other pretreated samples, with the average DSI below 30%. Collectively, the present study demonstrates that represents a potential biocontrol agent that should be further explored to control infection on rubber trees.