The essential oils of plants of the genus Piper have secondary metabolites that have antimicrobial activity related to their chemical composition. The objective of our work was to determine the chemical composition and evaluate the antifungal activity of the aerial part essential oil of P. auritum obtained by hydrodistillation on Fusarium oxysporum and Fusarium equiseti isolated from Capsicum chinense. The antifungal activity was evaluated by direct contact and poisoned food tests, and the minimum inhibitory concentration (MIC₅₀) and maximum radial growth inhibition (MGI) were determined. The identification of oil metabolites was carried out by direct analysis in real time mass spectrometry (DART-MS). By direct contact, the essential oil reached an inhibition of over 40% on Fusarium spp. The 8.4 mg/mL concentration showed the highest inhibition on F. oxysporum (40–60%) and F. equiseti (>50%). The MIC₅₀ was 6 mg/mL for F. oxysporum FCHA-T7 and 9 mg/mL for F. oxysporum FCHJ-T6 and F. equiseti FCHE-T8. DART-MS chemical analysis of the essential oil showed [2M-H]⁻ and [M-H]⁻ adducts of high relative intensity that were mainly attributed to eugenol and thymol/p-cimen-8-ol. The findings found in this study show a fungistatic effect of the essential oil of P. auritum on Fusarium spp.

The genus Crotalaria comprises about 600 species that are distributed throughout the tropics and subtropical regions of the world; they are antagonistic to nematodes in sustainable crop production systems, and have also shown antimicrobial capacity. Chipilín (C. longirostrata), which belongs to this genus, is a wild plant that grows in the state of Chiapas (Mexico) and is traditionally is used as food. Its leaves also have medicinal properties and are used as hypnotics and narcotics; however, the plant has received little research attention to date. In the experimental part of this study, dried leaves were macerated by ethanol. The extract obtained was fractionated with ethyl ether, dichloromethane, ethyl acetate, 2-propanone, and water. The extracts were evaluated against three bacteria—namely, Escherichia coli (Ec), Citrobacter freundii (Cf), and Staphylococcus epidermidis (Se)—and three fungi—Fusarium oxysporum A. comiteca (FoC), Fusarium oxysporum A. tequilana (FoT), and Fusarium solani A. comiteca (FSC). During this preliminary study, a statistical analysis of the data showed that there is a significant difference between the control ciprofloxacin (antibacterial), the antifungal activity experiments (water was used as a negative control), and the fractions used. The aqueous fraction (WF) was the most active against FoC, FsC, and FoT (30.65, 20.61, and 27.36% at 96 h, respectively) and the ethyl ether fraction (EEF) was the most active against Se (26.62% at 48 h).

Las enfermedades causadas por Fusarium en Agave aumentan, lo cual significa importantes pérdidas económicas. Es necesario entonces buscar alternativas en la prevención y control de pató­genos para reducir el uso de fungicidas químicos, y así promo­ver un tipo de control de enfermedades que sea amigable con el ambiente. Los aceites y extractos de hojas de algunas plantas son eficientes en el control de plagas y enfermedades. Piper auritum (“hierba santa”) contiene aceites esenciales que cumplen funcio­nes ecológicas, como las de atraer polinizadores y causar efectos alelopáticos. Baccharis glutinosa (“jarilla”) también se usa en el tratamiento de diversas enfermedades infecciosas. Hay diferentes extractos de plantas que tienen una actividad biológica contra microorganismos que afectan cultivos importantes. El objetivo de esta investigación fue evaluar la actividad antimicrobiana del aceite esencial y extractos de dos plantas con uso tradicional en el estado de Chiapas sobre los hongos fitopatógenos (Fusarium spp.) de Agave spp. Los extractos de P. auritum y B. glutinosa se probaron contra los hongos fitopatógenos, como parte de un di­seño experimental completamente aleatorizado. Un ANOVA se realizó con seis tratamientos y tres repeticiones por tratamiento, utilizados en tres especies de Fusarium. El aceite esencial extraí­do de las hojas de Piper auritum tuvo el mayor efecto inhibi­dor significativo (96 h) sobre Fusarium oxysporum f. sp. comiteca (75.32%), Fusarium oxysporum f. sp. tequilana (86.57%) y Fu­sarium solani f. sp. comiteca (63.36%). Por lo tanto, P. auritum mostró un claro efecto fungistático.

Background. Chili pepper (Capsicum spp.) cultivation extends throughout Mexico, hosting a wide variety worldwide. However, crop health is reduced by the incidence of pathogenic microorganisms such as those of the Fusarium genus, which is one of the main agents causing vascular wilt and mortality of plant species. The use of molecular tools allows for rapid and reliable identification of organisms at the species level and help characterize the symptoms and pathogenicity they cause in hosts, which is important for field management and control. Objective. To identify at the molecular level fungal strains isolated from Siete Caldos chili (C. frutescens) using ITS and evaluate their pathogenicity in C. frutescens and C. chinense. Methodology. Strains of Fusarium from chile Siete Caldos plants (C. frutescens L.) were isolated and identified using traditional techniques (humid chamber and isolation in specific culture media) and molecular techniques (ITS1 and ITS4), and their pathogenicity in C. chinense Jacq. and C. frutescens was evaluated. Results. Seven strains were identified using taxonomic keys denoted as: 44hp, 45ta, 46ta, 46hp, 47hp, 45hpssc and 45hpmcsc. From the amplified regions, the phylogenetic tree was obtained using the maximum-likelihood method based on the comparison of ITS sequences. The fungal isolates were identified and grouped, which corresponded to F. oxysporum strains reported in the NCBI database. The pathogenicity test showed the presence of symptoms in C. frutescens, with strain 45ta being the most virulent (80 % incidence in inoculated plants). However, under the evaluation techniques used, C. chinense plants did not present wilting symptoms. Implications. The higher incidence of strain 45ta in C. frutescens could be due to the affinity of F. oxysporum for its host (Siete Caldos chili), while the absence of symptoms in C. chinense could be due to an asymptomatic infection. Conclusions. The isolated strains showed no variability in their molecular identification, but not all showed the same infective capacity in the pathogenicity test. Therefore, it is necessary to perform tests with greater specificity to determine whether subspecies of the studied isolates exist.