Tolerance of Trichoderma asperellum Isolates to Chemical Fungicide and Their Antagonistic Activity against Phytophthora infestans

Trichoderma constitute filamentous fungi which are frequently used as biocontrol agents against plant pathogenic fungi. The tolerance of these fungi to chemical fungicides is a prerequisite for biocontrol agents for their application to suppress the growth of some soil-borne pathogens. The objectives of this study were to evaluate tolerance of Trichoderma asperellum local isolates TK and TS from Batu-East Java, to mefenoxam fungicide, as well as to identify in-vitro the antagonistic activity of T. asperellum against the plant pathogen Phytophthora infestans by using dual-culture method. Thus, an integrated approach of chemical and biological methods was used to control the growth of P. infestans. This study was conducted at the Department of Biology, Faculty of Science and Technology Airlangga University, Indonesia, during March through December, 2012. T. asperellum isolates TK and TS were evaluated in-vitro for their efficacy against P. infestans and tolerance to 5000 ppm mefenoxam. The results showed that the growth of the two T. asperellum isolates on Potato Dextrose Agar (PDA) medium supplemented with 5 mL/L mefenoxam was up to 67%, while their antagonistic activity against P. infestans in dual-culture was 5,08% and 16,37%. The results are expected to help in selection of potential biocontrol agents.