PUTATIVE DISEASE AGENTS ON Manglietia conifera Dandy IN NORTHERN VIETNAM

Abstract

Manglietia conifera Dandy is a native tree species of high economic value, widely planted in the northern mountainous provinces of Vietnam. However, the rapid expansion of plantation areas in recent years has increased the risk of disease outbreaks, particularly those caused by fungi, algae, and several members of the class Oomycetes. This study was conducted to identify the causal agents and assessed disease incidence and severity on four-year-old M. conifera trees across four provinces: Lao Cai, Yen Bai, Tuyen Quang, and Bac Kan. A total of 16 pathogenic taxa were identified through morphological examination combined with ITS rDNA sequencing, spanning nine orders and 12 families. These pathogens affected multiple plant parts, including leaves, shoots, stems, roots, and branches. Among them, Pestalotiopsis vismiae was the most virulent, causing severe tip blight with disease incidence ranging from 17.5 to 57.5% and disease severity values between 6.6% and 30.0%. Other notable pathogens included Colletotrichum fructicola, Phytophthora × vanyenensis, Fusarium oxysporum, Phoma sp., Meliola sp., and the green alga Cephaleuros virescens. Although most diseases had low severity indices (R %) ranging from 2.2 to 5.3%, the co - occurrence of multiple pathogens across all surveyed sites indicates a high risk of epidemics under favourable environmental conditions. This study provides an important basis for further research on pathogen virulence, disease development conditions, and the formulation of appropriate management strategies in Vietnam.