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

Abstract

Rubber plants are subjected to serious fungal diseases and among them, the losses caused by
foliar diseases play an important role. The frequent use of chemical fungicides to control
causative pathogens leads to environmental pollution, hazardous to human and may lead to
the development of new chemical resist pathogenic strains. Trichoderma species are
ubiquitous soil-borne Ascomycetes noted for their biocontrol capabilities against many
economically important plant pathogens. Hence, an attempt was made to investigate the
antagonistic effect of some native Trichoderma isolates on the plant pathogenic fungi;
Colletotrichum sp., Corynespora cassiicola, Phytophthora sp. and Drechslera heveae. Foliar
pathogens were isolated from Rubber Research Institute, Dartonfield, Agalawaththa and
identified based on the symptoms, cultural and reproductive characteristics. Five
Trichoderma isolates isolated from different habitats in Sri Lanka were tested in vitro for
their antagonistic effects against the four foliar pathogens. The results obtained from dual
culture tests showed that all the five Trichoderma isolates effectively checked the growth of
the four foliar pathogens. The test antagonists grew faster than the pathogen limiting their
growth. Trichoderma isolate A was the best antagonist against Drechslera heveae,
Corynespora cassiicola and Colletotrichum sp. showing inhibition of 75.63%, 51.34% and
74.46% 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 tested
Trichoderma isolates showed antagonistic effect on the four foliar pathogens under
investigation. Therefore, the fungal isolates under investigation can be used for further
greenhouse and field studies to confirm the feasibility of using for the management of rubber
foliar pathogens.
Keywords: Trichoderma spp., Drechslera heveae, Corynespora cassiicola, Colletotrichum
spp., Phytopthora spp, Bio-control agents