Field screening of RRISL recommended rubber clones against Corynespora Leaf Fall Disease

Identification of resistant clones is of vital importance in the management of Corynespora leaf fall disease (CLFD) of rubber. The recommended and potential clones were screened in a bud wood nursery which was especially designed for screening purposes at Ratnapura, Kalutara, Moneragala and Padiyatalawa. The lesion types agreed with the symptoms observed in the field plants and new symptoms have been identified from Padiyatalawa, in non-traditional rubber growing areas. Analysis of results from test methods showed that 81% of the recommended clones by the Rubber Research Institute of Sri Lanka (RRISL) can be ranked as resistant. Among the clones screened, no clones were found to be severely susceptible, yet moderately or mildly susceptible clones have been identified. This information should be used in future breeding programmes and also should be considered by the growers while selecting clones for their own plantations. The cultivation of resistant clones with a wide genetic base is considered as the most reliable long-term solution in the management of CLFD.