Citation: Salas-Gómez, A.L.; Espinoza Ahumada, C.A.; Castillo Godina, R.G.; Ascacio-Valdés, J.A.; Rodríguez-Herrera, R.; Segura Martínez, M.T.d.J.; Neri Ramírez, E.; Estrada Drouaillet, B.; Osorio-Hernández, E. Antifungal In Vitro Activity of Phoradendron sp. Extracts on Fungal Isolates from Tomato Crop. Plants 2023, 12, 672. https://doi.org/10.3390/ plants12030672 Academic Editor: Roxana Vidican Received: 31 December 2022 Revised: 25 January 2023 Accepted: 27 January 2023 Published: 3 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). plants Article Antifungal In Vitro Activity of Phoradendron sp. Extracts on Fungal Isolates from Tomato Crop Alma Leticia Salas-Gómez 1 ,César Alejandro Espinoza Ahumada 2 , Rocío Guadalupe Castillo Godina 3 , Juan Alberto Ascacio-Valdés 3 , Raúl Rodríguez-Herrera 3 , Ma. Teresa de Jesús Segura Martínez 1 , Efraín Neri Ramírez 1 , Benigno Estrada Drouaillet 1 and Eduardo Osorio-Hernández 1, * 1 Research and Postgraduate, Faculty of Engineering and Sciences, Autonomous University of Tamaulipas, University Center Adolfo Lopez Mateos. Cd., Victoria 87120, Tamaulipas, Mexico 2 El Mante Superior of Technological Institute, Km 6.7, Highway Mexico 85, Quintero 89930, Tamaulipas, Mexico 3 School of Chemistry, Autonomous University of Coahuila, Saltillo 25280, Coahuila, Mexico * Correspondence: eosorio@docentes.uat.edu.mx Abstract: Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for the control of these diseases, which is why the main objective of this research was to study an alternative biocontrol strategy for the management of plant diseases caused by fungi through obtaining polyphenol extracts from mistletoe plants growing on three different tree species—mesquite (Prosopis glandulosa), cedar (Cedrus), and oak (Quercus), which contain flavones, anthocyanins, and luteolin. The overall chemical structure of the obtained plant extracts was investigated by RP-HPLC-ESI-MS liquid chromatography. The antifungal effect of these extracts was examined. The target phytopathogenic fungi were isolated from tomato plantations located in Altamira, Tamaulipas, Mexico. The microorganisms were charac- terized by classical and molecular methods and identified as Alternaria alternata, Fusarium oxysporum, Fusarium sp., and Rhizoctonia solani. Keywords: cedar; ethanolic extracts; mesquite; mistletoe; oak; polyphenols 1. Introduction Tomato crop is one of the agricultural commodities with the highest economic impor- tance worldwide; in addition, it offers benefits to human health due to its high content of potassium and antioxidants such as ascorbic acid, vitamin A, lycopene, and tocopherols [1]. However, this crop is attacked by more than 200 pathogens that affect its yield and quality, the most important being Alternaria solani, causing early blight, and Rhizoctonia solani, Fusarium oxysporum, and Fusarium solani causing wilt. These pathogens may cause yield losses of more than 60% [2], whereby, they are mostly controlled through the use of syn- thetic chemicals [3], which may have some weaknesses such as being a risk to human health, the environment, and beneficial organisms. This is why ecologically safe alternatives are being explored to control these plant pathogens [4]. In this context, biological control is an alternative that has shown efficacy for the management of pathogens that affect tomato plants [5]. One strategy to reduce the spread of disease-causing fungi in vegetables is the use of plant extracts, which are characterized by the presence of secondary metabolites such as alkaloids, saponins, and terpenoids that have fungistatic activity and/or induce plant defenses [6]. Extracts of indigenous medicinal plants of Pakistan such as Justacia adhatoda, Azadriachta indica, Foeniculum vulgare, and Mentha spicata have been used and the presence of various functional groups such as alcohols, carboxylic acids, esters, alkanes, and alkenes were determined by Fourier transform infrared spectroscopy (FTIR), which suppressed the growth of Alternaria alternata [7]. The use of these extracts can be taken as an option for the Plants 2023, 12, 672. https://doi.org/10.3390/plants12030672 https://www.mdpi.com/journal/plants