Compositions of fungal pathogens causing longan fruit rot in Ba Ria - Vung Tau province

Abstract

Compositions of fungal pathogens causing fruit rot were investigated on three major longan varieties cultivated in Ba Ria - Vung Tau province in their commercial stages, i.e., xuong com vang, edor and tiêu da bo. Ninety diseased fruit samples with newly emerged symptoms during 12 - 16 days and 1 - 3 days before harvest were collected in three different orchards of each variety. Fungal pathogens were isolated to perform the Koch’s postulates for pathogen identification. Using morphological characteristics, five fungal genera corresponding to five typical fruit rot symptoms were identified from the collected samples including: Lasiodiplodia, Diaporthe, Calonectria, Pestalotiopsis and Fusarium. Pericarp brown rot symptoms caused by Lasiodiplodia spp. were found to be predominant on all three longan varieties. The Lasiodiplodia genus appeared in the highest frequency (62.96%) among the samples isolated. Appearance frequencies of the other four fungal genera Diaporthe, Calonectria, Pestalotiopsis and Fusarium were 26.30%, 18.52%, 4.81% and 1.85%, respectively. This is the first report on compositions of fungal pathogens causing longan fruit rot before harvest in Vietnam where the Calonectria genus was firstly reported as a causal agent of the disease.