11 Colletotrichum Isolates were identified based on a polyphasic approach from avocado orchards in northern Thailand, and the pathogenicity was assessed for each species on avocado fruits and leaves.

Abstract

Avocado production is restricted globally by the anthracnose disease caused by Colletotrichum species. In Thailand, anthracnose symptoms can be found on avocado leaves and fruits, and it is an important postharvest disease, reducing the shelf life of the fruits and causing huge economic losses. Avocado leaves and fruits showing anthracnose disease were collected from Chiang Rai province, located in northern Thailand, and the Colletotrichum species isolated from the samples were identified based on morphological examination and multigene phylogenetic analyses. Phylogenetic analyses using five loci (ITS, ACT, CHS-1, GAPDH and TUB2) coupled with the morphology of 11 isolates showed that they belonged to four known species of Colletotrichum. Colletotrichum endophytica, C. fructicola and C. siamense are illustrated as new geographical records, and C. henanense is characterized as a new host record. Furthermore, the pathogenicity of these species in avocado fruits and leaves (West Indian variety) has been proven. In addition, this study provides further evidence for the synonymization of C. pandanicola and C. parvisporum with C. siamense.