In Vitro Evaluation of the Antagonistic Effect of Some Native Trichoderma Strains Against Economically Important Foliar Pathogens of Rubber

Rubber plants are subjected to serious fungal diseases and among them, the losses caused byfoliar diseases play an important role. The frequent use of chemical fungicides to controlcausative pathogens leads to environmental pollution, hazardous to human and may lead tothe development of new chemical resist pathogenic strains. Trichoderma species areubiquitous soil-borne Ascomycetes noted for their biocontrol capabilities against manyeconomically important plant pathogens. Hence, an attempt was made to investigate theantagonistic effect of some native Trichoderma isolates on the plant pathogenic fungi;Colletotrichum sp., Corynespora cassiicola, Phytophthora sp. and Drechslera heveae. Foliarpathogens were isolated from Rubber Research Institute, Dartonfield, Agalawaththa andidentified based on the symptoms, cultural and reproductive characteristics. FiveTrichoderma isolates isolated from different habitats in Sri Lanka were tested in vitro fortheir antagonistic effects against the four foliar pathogens. The results obtained from dualculture tests showed that all the five Trichoderma isolates effectively checked the growth ofthe four foliar pathogens. The test antagonists grew faster than the pathogen limiting theirgrowth. Trichoderma isolate A was the best antagonist against Drechslera heveae,Corynespora cassiicola and Colletotrichum sp. showing inhibition of 75.63%, 51.34% and74.46% respectively. Isolate B showed the best inhibition (70.99%) against Phytophthora sp.All antagonists showed their lowest inhibition against D. heveae. In conclusion, all the testedTrichoderma isolates showed antagonistic effect on the four foliar pathogens underinvestigation. Therefore, the fungal isolates under investigation can be used for furthergreenhouse and field studies to confirm the feasibility of using for the management of rubberfoliar pathogens.Keywords: Trichoderma spp., Drechslera heveae, Corynespora cassiicola, Colletotrichumspp., Phytopthora spp, Bio-control agent