In this research, we aimed to isolate and identify native strains of Trichoderma spp. with potential activity against avocado pathogens (Neofusicoccum parvum, Colletotrichum gloeosporioides, Diaporthe sp., and Phomopsis perseae). Strains of Trichoderma spp. were isolated from roots and soil obtained from avocado orchards from different regions of Mexico. Twenty-five Trichoderma spp. strains were isolated, of which six (TSMICH7, TSMICH8, TRMICH9, TSMICH10, TSMICH15, and TRJAL25) showed greater antagonistic capacity in vitro (>80%) against avocado pathogens. After 96 h, the antagonistic strain undergoes a thickening of hyphae, while the phytopathogen tends to thin, except for Diaporthe sp., which tends to thicken. The characterization of these strains was carried out through morphological observations and the amplification and sequencing of rDNA fragments (ITS regions), as well as the translation elongation factor 1-alpha (Tef 1-α), achieving the identification of Trichoderma harzianum. However, in the in vivo evaluation (applying directly to the avocado fruit), the TSMICH7 strain maintained considerably high effectiveness (>90%) against the four phytopathogens tested, mainly with P. perseae, N. parvum, and Diaporthe sp., increasing the activity of glucanases and chitinases. Therefore, T. harzianum could be used as a biological control agent to inhibit post-harvest pathogens in avocados, thus avoiding significant losses of this fruit of international importance.

Avocado orchards in eight avocado-producing states of México were sampled to collect and identify the armored scale insect species (Hemiptera: Diaspididae) that attack the crop and their natural enemies. Sixteen species of armored scales were identified, 12 from the subfamily Aspidiotinae and four from Diaspidinae. A dichotomous key is provided for the identification of the 18 armored scale species associated with avocado in central México. Forty species of associated natural enemies were also recorded, the most important belonging to Hymenoptera: Aphelinidae, Encyrtidae, Eulophidae, and Signiphoridae, and to Coleoptera: Coccinellidae. For each species of armored scale, brief general information on its distribution, host varietal preferences and natural enemies is given.

This work describes the characterization of Trichoderma atroviride strain CMU-08, isolated from Michoacán, Mexico. CMU-08 demonstrated robust growth and conidiation across a temperature range from 16 to 32 °C and a pH range from 4 to 9 on potato dextrose agar (PDA) and malt extract agar (MEA) media. The strain is an efficient antagonist of six species of phytopathogenic fungi and oomycetes in PDA, MEA, and Vogel minimal medium (VMM). Antagonist mechanisms of CMU-08 included direct mycoparasitism observed in dual-culture assays, as well as antibiosis attributed to growth inhibition via both volatile and non-volatile metabolites, with the effectiveness varying depending on the test phytopathogen and culture medium. Extracellular filtrates (ECFs) recovered from liquid cultures of CMU-08 under basal and induced conditions using Botrytis cinerea cell walls significantly inhibited their growth at a concentration of 750 µg/mL. Moreover, in detached tomato leaf assays, these ECFs reduced foliar damage caused by B. cinerea by 24–34%. The volatile organic compounds (VOCs) produced by CMU-08 also exhibited substantial efficacy, reducing foliar damage by up to 50% in similar tests. Despite showing no basal extracellular chitinase enzymatic activity, CMU-08 demonstrated significant induction of this activity in cultures supplemented with B. cinerea and Fusarium sp. cell walls. Four genes encoding extracellular chitinases (chit33, chit36, ech42, and locus 217415) showed different dynamics of transcriptional regulation during the dual-culture confrontation of strain CMU-08 with B. cinerea and Fusarium sp., varying according to the phytopathogen and the interaction stage. The CMU-08 strain shows physiological versatility and employs a variety of antagonist mechanisms toward different species of phytopathogenic microorganisms, making it a good candidate for developing a biocontrol product for field application.

Mexico is the world’s leading producer of avocado (Persea americana); however, its productivity is threatened by various diseases, especially root rot caused by Phytophthora. While P. cinnamomi is the most commonly reported species worldwide, this study identified P. mengei for the first time as a causal agent of root rot and trunk canker in avocado orchards in the state of Michoacán, México. The morphological and molecular characterization of four isolates (three from canker and one from root rot) confirmed their identity: semi-papillate sporangia and plerotic oospores with paragynous antheridia, with sequence identities of 99.87% (ITS) and 100% (COI) with type sequences of P. mengei. Pathogenicity tests demonstrated the ability to infect roots, stems, and fruits, although with a low reisolation percentage in roots (10%), suggesting an opportunistic pathogen behavior. Sensitivity tests to potassium phosphite (EC₅₀ of 3.67 μg/mL⁻¹ a.i.) and metalaxyl-M (0.737 μg/mL⁻¹ a.i.) revealed possible limitations for chemical control. These findings position P. mengei as an emerging pathogen with important implications for integrated crop management. To the best of our knowledge, this is the first report of P. mengei causing root rot and trunk canker in avocado in Michoacán, Mexico.

Introducción: La identificación de las especies de Armillaria y Desarmillaria asociadas con la pudrición de raíces por Armillaria es importante para determinar estrategias de manejo, debido a su variación en patogenicidad y virulencia. Objetivo: Identificar las especies de Desarmillaria/Armillaria asociadas con árboles de litchi (Litchi chinensis Sonn.), aguacate (Persea americana Mill.) y pino (Pinus sp.) con síntomas y signos de la pudrición de raíces por Armillaria.Materiales y métodos: Se colectaron muestras con signos y síntomas de la pudrición de raíces por Armillaria en árboles de litchi en Veracruz, en tres huertos de aguacate y en una zona forestal en Michoacán. Ocho aislamientos fúngicos se identificaron mediante la secuenciación del gen factor de elongación 1-alpha (tef1).Resultados y Discusión: Con base en las secuencias de tef1, tres aislamientos de árboles de litchi en Veracruz se identificaron como Desarmillaria caespitosa; cuatro aislamientos de árboles de aguacate y uno de pino en Michoacán se identificaron como Armillaria mexicana. Los aislamientos fúngicos están depositados en la colección de hongos del Servicio Forestal del USDA, RMRS, Moscow, Idaho, EUA y las secuencias del tef1 están depositadas en el GenBank.Conclusion: Este trabajo constituye los primeros reportes de Desarmillaria caespitosa en litchi en Veracruz y Armillaria mexicana en aguacate y pino en Michoacán, México.