Biocontrol potential of rhizospheric fungi against Rigidoporus microporus, the causal agent of white root rot disease in tea plants

White root rot disease (WRD), caused by Rigidoporus microporus, poses a serious threat to various tropical trees, resulting in substantial crop damage and even plant death. However, there is still a lack of information regarding WRD in tea plants. Due to soil-borne in nature, synthetic fungicide is not recommended to control WRD. Therefore, biocontrol using natural microorganisms found in the tea's rhizosphere has been explored as a potential solution. This study aimed to identify rhizospheric fungi of tea plants with antagonistic properties that can be used as a biocontrol agent against R. microporus. The study involved a field survey and laboratory works had been conducted in a tea plantation at Rancabali, West Java and the Phytopathology Laboratory, Faculty of Agriculture, Universitas Padjadjaran from March to October 2021. The disease incidence and severity were assessed in three blocks of land representing different topographic conditions of the plantation while antagonism tests were conducted using the completely randomized design and dual culture method. The results showed that the highest occurrence of WRD was in the central part of the hill with the disease incidence and severity of 70 and 50%, respectively. Thirteen fungal isolates were obtained from the rhizosphere of tea plants, all of which were found to inhibit the growth of R. microporus. These isolates belonged to the genera of Trichoderma, Gliocladium, Paecilomyces, Penicillium, Aureobasidium, Acremonium and Rhizopus. The considerable inhibition of R. microporus colony growth was performed by the isolates of Aureobasidium sp. (51.23%), Rhizopus sp. (50%), and Trichoderma sp. (43.96%). The results suggested that rhizospheric fungi of tea plants have the potential as biocontrol agents against R. microporus.