Evaluating the Efficacy of Hymexazol in Controlling Globisporangium spinosum , the Newly Identified Pathogen Causing Root Rot in Houttuynia cordata .

Houttuynia cordata is a prevalent vegetable in several Asian countries and is commonly used as a traditional Chinese medicinal herb for treating various diseases in China. Unfortunately, its yield and quality are adversely affected by root rot. However, the pathogen responsible for the losses remains unidentified, and effective fungicides for its management have not been thoroughly explored. In this work, we demonstrate the first report of Globisporangium spinosum as the causative agent causing root rot of H. cordata . Moreover, we evaluated the efficacy of hymexazol to manage the disease, which displayed remarkable inhibitory effects against mycelial growth of G. spinosum in vitro, with EC 50 values as low as 1.336 μg/ml. Furthermore, hymexazol completely inhibited sporangia in G. spinosum at a concentration of 0.3125 μg/ml. Specifically, we observed that hymexazol was highly efficacious in reducing the incidence of H. cordata root rot caused by G. spinosum in a greenhouse setting. These findings offer a potential management tool for utilization of hymexazol in controlling H. cordata root rot in field production.