Susceptibility of rubber genotypes [Hevea brasiliensis Muell. Arg. (Euphorbiaceae)] to Corynespora Leaf Fall disease in graft wood gardens in southwestern Côte d'Ivoire

Abstract

Objective: This work to determine the susceptibility of 20 rubber genotypes to leaf fall disease caused by Corynespora cassiicola (CLF) was conducted in the San Pedro Rubber Sector in southwestern Côte d'Ivoire. Methods and Results: These rubber genotypes were selected in large-scale clone fields and tested for susceptibility to CLF disease under natural infection in the transplant garden. In a clonal plot, the rubber plants were planted in line, with a spacing of 1 m x 1 m between the lines. Overall, the results showed that the susceptibility of rubber genotypes fluctuated over the past five years. In addition, some rubber genotypes such as IRCA 430, IRCA 101, IRCA 733, IRCA 321, IRCA 523, IRCA 41, IRCA 230, IRCA 323 and IRCA 229, once resistant or tolerant, showed over time a susceptibility to CLF disease. On the other hand, three genotypes: PB 217, IRCA 101 and IRCA 538 expressed a good level of resistance to C. cassiicola, unlike the sensitive control IRCA 18 which showed a high susceptibility throughout the 5 years of observation. Conclusion and Recommendation: Of the 20 rubber genotypes tested, only three (PB 217, IRCA 101 and IRCA 538) are good candidates for large-scale rubber crop referrals to minimize the impact of CLF disease in the South-West Côte d’Ivoire rubber orchard. Keywords: susceptibility, Corynespora cassiicola, Hevea brasiliensis, graft wood garden, CLF disease, Côte d’Ivoire 18998