Antimicrobial potential of Salvia karwinskii Benth. exudate against plant pathogens

Significant losses in the agricultural sector are caused by phytopathogenic fungi and bacteria, which harm food production and cause health problems. While synthetic pesticides offer control, they are associated with environmental concerns and issues of resistance [ 1 ]. Given these challenges, we investigated the biological activity and phytochemical composition of dichloromethane surface extracts from the aerial parts of Salvia karwinskii . The exudate yielded several known clerodane-type diterpenoids and exhibited strong antifungal and moderate antibacterial activity. In vitro antifungal activity was evaluated against nine phytopathogens and compared to synthetic fungicides [ 2 ]. Notably, at a concentration of 1 mg/mL, the extract completely inhibited the mycelial growth of Phaemoniella chlamydospora , with efficacy statistically comparable to the synthetic fungicide Score ®​ 25 EC. At 750 μg/mL, it significantly inhibited Pythium dissotocum growth by 86.7%, while Stemphylium sp. inhibition reached 94.3%, a level comparable to Ridomil Gold ®​ WG. The extract showed moderate inhibition against Fusarium oxysporum f.sp. lactucae race 1 and strong activity against Alternaria solani, Fusarium solani, Phoma betae, and Colletotrichum lindemuthianum . Furthermore, at 1000 μg/mL, the extract inhibited Botrytis cinerea mycelial growth by 97.2%, similar to the commercial fungicide Switch ®​ . Its efficacy was also tested against gray mold disease in tomato fruits caused by B. cinerea , where curative treatments at just 100 μg/mL provided complete decay control, comparable to peracetic acid. These findings highlight the potential of S. karwinskii exudate as a natural alternative for agricultural pest and disease management. Ongoing phytochemical studies aim to identify novel bioactive compounds that could further enhance its applications. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany