Characterization of the Pathogenic Fungus Fusarium oxysporum Causing Root Rot in Avocado Plants (Persea americana Mill.) in Buleleng Regency

Abstract

Avocado (Persea americana Mill.) is one of the horticultural commodities with significant economic value, and its production has increased in Buleleng Regency. Root rot disease is of major constraint in avocado production, alongside weather and climate factors. This study aims to determine the species of pathogenic fungi causing root rot that infect avocado plants in Buleleng Regency, based on morphological characteristics, molecular analysis, and phylogenetics. The methods used in this study include: (1) observation and sampling of plants; (2) isolation of pathogenic fungi; (3) pathogenicity tests; (4) macroscopic and microscopic morphological identification; (5) molecular identification through PCR using ITS1–ITS4 primers; and (6) phylogenetic analysis using MEGA 11 software version 11.0.13. We successfully obtained isolates from symptomatic avocado root samples collected from five locations, namely Wanagiri, Gesing, and Madenan. The results of the pathogenicity tests showed that the Gesing isolate was able to produce symptoms similar to root rot in the field on healthy avocado seedlings. Based on morphological characteristics, as well as molecular and phylogenetic analyses, we identified the isolate as Fusarium oxysporum. This study is the first scientific report on the characterization of pathogenic fungi associated with root rot disease in avocado plants in Buleleng Regency. The information obtained can serve as a reference for diagnosing and monitoring of root rot disease in avocado plants, as well as a basis for developing appropriate disease management strategies.