BIOCONTROL OF Cryptosporiopsis eucalypti CAUSING LEAF SPOT OF EUCALYPTS USING ENDOPHYTIC FUNGI

Abstract

Eucalyptus leaf spot disease, caused by Cryptosporiopsis eucalypti, is identified as a significant threat to eucalyptus forests in Vietnam. This study aimed to screen and select endophytic fungal isolates with potential antifungal activities against C. eucalypti, as a basis for developing microbial production and biocontrol agents. Endophytic fungi were isolated from Eucalyptus hybrid in both healthy trees and susceptible trees. The antifungal activity of endophytic fungi was assessed using a dual culture test. From the isolation process, 60 endophytic fungal isolates were obtained, with variations in their hosts across different tree organs. Results from the antifungal activity screening indicated that 17 isolates exhibited antifungal activities, with the inhibition rates against the fungal pathogen ranging from 47.78% to 66.04%. Specifically, 11 isolates were isolated from healthy trees, while 6 isolates originated from symptomatic trees. Further evaluation of antifungal activity using a culture filtrate test revealed that three isolates: BD7.07, BD3.06, and BD7.03 showed the most potent antifungal effects, with inhibition rates of 100%, 87.5% and 71.2%, respectively. Identification of these fungal isolates confirmed their scientific names as Penicillium sclerotiorum (BD3.06), Nigrospora aurantiaca (BD7.07) and Diaporthe liquidambaris (BD7.03). These endophytic fungi have potential as biocontrol agents for managing eucalyptus leaf spot disease in Vietnam.