First Report of Root Rot on <i>Belamcanda chinensis</i> Caused by <i>Fusarium equiseti</i> in China

Belamcanda chinensis, commonly known as “she gan”, is an herbaceous plant known for its medicinal properties and is distributed throughout China (Tang et al. 2025). In August 2025, root rot were observed on B. chinense plants in Chengde (40.57°N, 117.51°E) , Hebei Province, China (incidence rate 70%), plants in 350 ha were observed to be severely affected by the disease, causing a yield loss of 60%. Infected plants displayed the leaves gradually turn yellow and wither, accompanied by the root bark turns brown and separates from the pith, progressing to deep brown rot of the root, ultimately leading to plant mortality. To isolate the causal agent, tissues (5×5 mm) from four symptomatic plants were removed from the border of lesions, surface sterilized in 75% ethanol for 30 s and 0.1% HgCl2 for 1 min, then rinsed three times with sterile distilled water, plated on potato dextrose agar (PDA) at 25℃, and incubated in the dark for 7 days. Two representative isolates, 202507 and 202508, were cultivated on carnation leaf ager (CLA) medium. Macroconidia of the isolates had five to seven septa, and were very long and slender, apical cell were tapered and elongate or even whip-like, basal cell were prominent foot shape that may be elongated in appearance. The morphological characteristics were consistent with the description of Fusarium species (Leslie and summerell 2006). DNA was extracted from the isolate using the cetyltrimethylammonium bromide method. The translation elongation factor (TEF-1α), and partial RNA polymerase second largest subunit (RPB2) were amplified (accession nos. TEF-1α: PX549680 and RPB2: PX549685) (Crous et al. 2009). When compared with other Fusarium species in GenBank, the isolate exhibited 100% (TEF-1α, PV779594) and 100% (RBP2, OR425261) similarity with Fusarium equiseti (query coverage=100%, per-centage identity=100%). A phylogenetic tree was constructed in MEGA software (version 11.0.10) (Tamura et al. 2021) using the partial concatenated gene sequences. Maximum likelihood analysis revealed that the isolates were closely related to F. equiseti (99% bootstrap). To test pathogenicity, a conidial suspension of 202507 and 202508 with a concentration of 1×106 conidia/mL was inoculated on 36 plants per isolate. For the control treatment, 36 plants were treated with an equivalent volume of sterile water. The experiment was repeated three times. The plants were placed in a greenhouse from 26 to 30℃ and 95% relative humidity. The typical symptom were observed 10 days after inoculation, except on the control samples where no symptoms were observed. The same fungus was successfully reisolated from the symptomatic plant tissue and was reidentified as F. equiseti through morphological characteristics, TEF-1α and RBP2 sequencing analysis (accession nos. TEF-1α: PX926519 and RPB2: PX926520), thereby fulfilling Koch’s postulates. The pathogen could reportedly infect white clover (Zhang et al. 2024) and Salvia miltiorrhiza (Yuan et al. 2024). To the best of our knowledge, this is the first report of F. equiseti causing B. chinensis root rot in China. This study paves the way for developing and implementing strategic approaches to managing this disease in China.