Rice production experiences significant losses due to fungal diseases, particularly rice sheath blight caused by Rhizoctonia solani. Despite the intensive and continuous use of synthetic fungicides, diseases severity has not reduced and control has become increasingly challenging; therefore, the search for environmentally friendly and sustainable products has intensified. Here, we conducted a chemical characterization of Xylopia frutescens and using in silico analysis evaluated the interaction of their two major compounds with lectin protein site of R. solani. In vitro tests using increasing concentrations of essential oil against R. solani were performed. Subsequently, in four varieties of rice, five concentrations of X. frutescens essential oils were applied and evaluated the phytotoxicity effect as well the potential of Xylopia frutescens essential oil for controlling, both preventively and curatively, rice sheath blight. We further investigate the selectivity of this essential oil towards the non-target organism, Trichoderma asperellum. Our analysis revealed that trans-pinocarveol and myrtenal are the main compounds of X. frutescens essential oil and interact with the lectin of R. solani, supporting the antifungal properties of X. frutescens essential oil. In in vitro conditions, the highest tested concentrations of X. frutescens essential oil inhibited the pathogen’s sclerotia and mycelial growth. Under greenhouse conditions, the treatments caused low phytotoxicity and effectively reduced disease severity when applied, both preventively and curatively. Furthermore, the biocontrol agent T. asperellum exhibited tolerance to X. frutescens essential oil. Collectively, our findings demonstrate the potential of X. frutescens essential oil for the development of botanical fungicides capable of controlling R. solani without harming beneficial non-target organisms such as T. asperellum.

Adenium obesum (Forssk.) Roem. & Schult (desert rose) is one of the most popular ornamental species cultivated in residential gardens and as a potted plant for balconies and verandas in Brazil. However, Neocosmospora keratoplastica has recently been identified as one of the causal agents of rot disease in this species. Therefore, this study evaluated the antifungal potential of Ocimum tenuiflorum L. essential oil (EO) as a preventive and curative treatment against this pathogen, while assessing its phytotoxicity and selectivity toward beneficial fungi. The EO was obtained by hydrodistillation and chemically characterized. In vitro mycelial growth inhibition assays, in vivo evaluations on A. obesum seedlings, and selectivity tests against Trichoderma asperellum were performed. In addition, in silico molecular docking analyses were conducted to investigate the interaction of the major EO constituents with fungal target proteins. Eugenol (47.04%) and 1,8-cineole (29.47%) were identified as the predominant compounds in the EO. Mycelial growth inhibition reached a maximum of 59% at 100 μL mL⁻¹, but strong phytotoxicity was evident; while a concentration of 50 μL mL⁻¹ yielded an 18% inhibition rate representing an approximately three-fold greater effect than that of thiophanate methyl (7.68%) at the recommended dose, with a slight phytotoxicity. The lowest Area Under the Disease Progress Curve (AUDPC) was recorded when the EO was applied preventively, and intermediate concentrations were selective toward T. asperellum. Molecular docking analyses indicated that eugenol and 1,8-cineole exhibited greater affinity for CYP51A than for α/β-tubulin, whereas dehydroaromadendrane and α-copaene showed the strongest interactions with these target proteins. Overall, O. tenuiflorum EO exhibits promising potential as a preventive treatment against N. keratoplastica in desert rose, while preserving beneficial fungi at moderate concentrations.