Abstract:
Rubber foliar diseases play an important role in latex yield losses of rubber plantations in Sri Lanka. 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 the most widely studied bio control agent against many economically important plant pathogens. Hence, an attempt was made to investigate the antagonistic effect of five native Trichoderma strains on the plant pathogenic fungi; Colletotrichum spp., Corynespora cassiicola, Phytophthora spp. and Drechslera heveae. Foliar pathogens were isolated, identified and confirmed based on the symptoms, cultural and reproductive characteristics. Five Trichoderma strains isolated from different rubber growing soils in Sri Lanka were tested in vitro for their antagonistic effects against four foliar pathogens. The results obtained from dual culture tests showed that all 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 spp. showing percentage inhibition of 75.63 %, 51.34 % and 74.46 % respectively. Isolate B showed the best inhibition rate (70.99 %) against Phytophthora spp. All antagonists showed their lowest inhibition rates against Drechslera heveae. All the tested Trichoderma isolates showed antagonistic effects against four foliar pathogens under investigation. Therefore, the fungal strains can be used for further greenhouse and field studies to confirm the feasibility of using for the management of rubber foliar pathogens.
Key Words: Trichoderma spp., Drechslera heveae, Corynespora cassiicola, Colletotrichuin spp., Phytophthora spp.
