Identification and characterization of Neopestalotiopsis fungi associated with a novel leaf fall disease of rubber trees (Hevea brasiliensis) in Thailand

Abstract A novel leaf fall disease of rubber trees ( Hevea brasiliensis ) has been recently noted in Thailand. The fungal pathogens of this disease were identified based on both morphological and molecular characteristics as Neopestalotiopsis cubana and N . formicarum . Portions of internal transcribed spacer (ITS) region and the large subunit (LSU), translation elongation factor 1‐α ( TEF1‐α ) and β‐tubulin ( TUB ) genes were PCR amplified with the primer pairs ITS1/ITS4, LR0R/LR5, EF1‐728F/EF2 and T1/Bt2b, respectively. Sequencing of the PCR products and a phylogenetic tree based on the combined ITS, TEF1‐α and TUB confirmed these pathogens as N. cubana and N. formicarum . Pathogenicity test results showed that the pathogens cause leaf spot and leaf fall similar to that observed in natural infections. This is the first report on the novel leaf fall disease of rubber trees in Thailand, with the results demonstrating that it is associated with N. cubana and N. formicarum .