Evaluation on the Cultural Characteristics and Antagonistic Activities of Cladobotryum semicirculare Against Ganoderma boninense in vitro

The objectives of this preliminary study were to identify the Cladobotryum-like isolate and assess the antagonistic activity of this fungus against G. boninense and other fungal pathogens. Based on both morphological and molecular approaches, the unknown fungus was later described as Cladobotryum semicirculare. Under dual-culture assays, Cladobotryum semicirculare was observed to suppress radial mycelial growth of all the tested fungi with G. lucidum and G. boninense G37s growth being inhibited the most, 74.8 % and 74.7 %, respectively. Clonostachys sp. inhibited the least (12.7 %). Through poison agar test, filtrates from C. semicirculare at 50 % concentration were observed to suppress the mycelial growth of G. boninense G14 (35 % inhibition) and G. lucidum (25 % suppression), and with 100 % filtrate concentration both Ganoderma species were showing more than 49 % inhibition. Growth of all tested Ganoderma isolates and C. semicirculare, was faster under aerobic (2.2 to 3.8 mm per day for Ganoderma isolates and 4.3 mm for Cladobotryum) compared to anaerobic (1.6 to 2.2 mm per day for Ganoderma isolates and 1.4 mm per day for Cladobotryum) condition. In vitro mycoparasitism test confirmed that C. sem circulare reduced the re-isolation of G. lucidum (33.3 %) and G. boninense (66.7 %) mycelia. This study also provided the first report of G. boninense as the host for C. semicirculare. (author)