The grapefruit (Citrus paradisi) is an important crop for citrus farming in Mexico. During June 2019, in a plantation in Iguala, Guerrero, Mexico, symptoms of anthracnose on grapefruit fruits were observed. Based on morphological and molecular characterisation, the fungus isolated from the anthracnose was identified as Colletotrichum gloeosporioides. Koch's postulates were verified and fulfilled. To our knowledge, this is the first report of C. gloeosporioides causing anthracnose on grapefruit fruits in Mexico.

El conocimiento de factores externos a los que se exponen los frutos durante el manejo postcosecha son importantes. Estos pueden ser determinantes en el tiempo de vida de anaquel hasta llegar al consumo. Se realizó caracterización física-mecánica en frutos de guayaba en etapa de madurez fisiológica (50 % verde) y madurez de consumo (amarilla), esto con la finalidad de obtener parámetros de referencia en las variables de diámetro geométrico (), esfericidad (), área superficial (), carga de compresión, esfuerzo y módulo de Young. Se evaluaron los efectos de pruebas de impacto realizadas con frutos de guayaba, sobre dos superficies (madera y concreto) y a dos alturas (50 cm y 100 cm), a partir de los cambios en la velocidad de respiración, color en la epidermis, pérdida de peso y porcentaje de daño. Se realizó un modelado solido tridimensional de fruto de guayaba mediante el mallador automático de Solidworks Simulation, con el fin de obtener, por simulación de impacto, el esfuerzo máximo que es capaz de soportar un fruto en la zona de impacto a diferentes alturas.

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The agave (Agave spp.) is an important crop in México, with 120,897 ha grown mainly for alcoholic beverage production (SIAP, 2019). In September 2020, in the municipality of Huitzuco de los Figueroa (18.328692 N; 99.3998 W), Guerrero State, México, a serious disease was observed affecting Agave angustifolia. Disease incidence was 8% of 150 plants sampled over an approximate area of 2.5 ha. Initial symptoms of soft rot of the bud developed and produced an abundant exudate which appeared from the apical part to the base of the plant. In severe infections, the plants showed total maceration of the bud, and consequently death of the plants was observed. Symptomatic plant tissue was superficially disinfected with 1% NaOCl for 30 s, and rinsed in sterile water three times. The disinfected tissues were macerated and with a loop spread in Nutrient Agar. The plates were incubated at 28 ° C for 2 days. Yellowish bacterial colonies were isolated, and eight colonies were selected for characterization. The bacterial strains were gram negative and rod-shaped, negative for fluorescent pigment tests and Kovacs' oxidase. Two isolates designated AGA1 and AGA2 were identified by PCR amplification and sequencing of the partial 16S rRNA gene with the primer 27F / 1492R (Lane 1991), and partial fusA, rpoB, and gyrB genes (Delétoile et al. 2009). Sequences were deposited in GenBank, with the accession numbers for 16S rRNA, AGA1 as MW548406 and AGA2 as MW548407; for specific genes fusA (AGA1 = MW558445, AGA2 = MW558446), rpoB (AGA1 = MW558447, AGA2 = MW558448) and gyrB (AGA1 = MW558449, AGA2 = MW558450), and they were compared with the sequences available in GenBank using BLASTn. 16S rRNA gene sequences for AGA1 and AGA2 aligned with Pantoea dispersa (MT921704.1, 99.9% identity). Housekeeping genes also aligned 99 to 100% to P. dispersa (fusA = 100%, CP045216.1; rpoB = 99.8% MH015167.1 and gyrB = 99%, MK928270.1). Phylogenetic analysis of concatenated genes showed that strains AGA1 and AGA2 cluster with P. dispersa. To confirm pathogenicity, eight plants of six-month-old A. angustifolia were inoculated with strain AGA1 using sterile toothpicks dipped in 108 CFU/ml bacterial suspension. The toothpicks were inserted in the middle part of the bud. Four plants were inoculated with sterile water as control. The plants were covered with plastic bags and housed in a greenhouse (average temperature and relative humidity of 25 ° C and 85%, respectively). Pathogenicity tests were repeated two times. After seven days, all inoculated plants developed symptoms similar to those observed in the field. Control plants did not show symptoms. From the plants that showed symptoms, the pathogen was reisolated again and was identified by morphological and molecular characterization, following the method previously described, fulfilling Koch's postulates. In México, Erwinia cacticida and Pantoea ananatis has been previously reported on A. tequilana that as causing soft rot and red leaf ring, respectively (Jimenez-Hidalgo et al. 2004; Fucikovsky and Aranda 2006). To our knowledge, this is the first report of P. dispersa causing bud soft rot on A. angustifolia in México. More studies monitoring and control strategies of bud soft rot on A. angustifolia are required.

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