Biological characterization and fungicide screening of a new pathogen of basal stem rot of in Jilin Province, China.

INTRODUCTION

(Turcz.) Baill. is a widely cultivated medicinal plant with significant economic value and serves as a major component of specialty agriculture in Jilin Province, China. In 2024, a novel basal stem rot disease was observed in Latai Village, Liudaogou Town, Linjiang City, Jilin Province, posing a potential threat to local production.

METHODS

Field symptoms were characterized by stem-base necrosis, vascular browning, wilting, and plant death, often accompanied by soft rot under high humidity. The causal pathogen was isolated and identified through morphological observation and sequencing of , -tubulin (), and genes. Pathogenicity was confirmed via Koch's postulates on detached stems, seedlings, whole plants, and tissue-cultured plantlets. Biological characteristics were evaluated under different media, temperatures, light conditions, pH levels, and carbon/nitrogen sources. Additionally, seven fungicides (three chemical and four botanical) were tested for inhibitory activity .

RESULTS

The pathogen was identified as , marking the first global report of this species causing basal stem rot on . Optimal growth conditions included CDA or CMA media, 25°C, continuous darkness, and pH 7. Sodium nitrate and lactose were the most favorable nitrogen and carbon sources, respectively. Among the fungicides tested, 98% fluazinam showed the strongest inhibitory effect with an EC₅₀ value of 5.658 mg/L.

DISCUSSION

This study confirms as a novel and virulent pathogen of in Jilin Province. The findings provide foundational data on its biology and pathogenicity and identify fluazinam as a promising candidate for integrated management of basal stem rot disease.