Stevia is a semi-perennial crop grown to obtain the diterpene glycosides in its leaves, which are processed to manufacture non-caloric sweeteners. Anaerobic soil disinfestation (ASD) and fungicide application were evaluated for the management of stevia stem rot (SSR) and Septoria leaf spot (SLS) in lab and field experiments. In 2019 and 2021, experiments using carbon sources for ASD were carried out in microplots at NCSU (Clayton, NC, USA). In 2020/21 and 2021/22 seasons, field experiments were conducted at CSAEGRO, Mexico (MX) and CEDIT, Paraguay (PY) using a 2 × 3 factorial design with two ASD treatments and three fungicide treatments. ASD treatments included soil amended with cornmeal (MX) or wheat bran (PY) at a rate of 20.2 Mg ha⁻¹, molasses at 10.1 Mg ha⁻¹, and non-amended controls. Fungicide applications included chemical (azoxystrobin), organic (pyroligneous acid, PA), and a non-treated control. ASD was effective in reducing sclerotia viability of Sclerotium rolfsii in laboratory assays (p < 0.0001) and microplot trials (p < 0.0001) in NC. During field trials, the viability of sclerotia was significantly reduced (p < 0.0001) in soils amended with cornmeal + molasses or wheat bran + molasses as carbon sources for ASD. While there was no significant effectiveness of ASD in reducing SLS in 2020 and 2021 or SSR in MX 2020 field trials (p = 0.83), it did exhibit efficacy on SSR in 2021 (p < 0.001). The application of fungicides was significantly effective in reducing SSR (p = 0.01) and SLS (p = 0.001), with azoxystrobin being the most consistent and PA not being statistically different from the control or azoxystrobin. The effects of ASD on fresh yield were inconsistent, exhibiting significant effects in Mexican fields in 2020 but not in 2021. During Paraguayan field trials, ASD only significantly interacted with fungicide applications in the dry yield in 2022. In the 2020/21 MX and 2020 PY field trials, fungicides were significantly effective in enhancing dry leaf yields, with azoxystrobin showing the highest consistency among treatments and PA variable control. In conclusion, utilizing ASD alongside organic fungicides can be a valuable tool for stevia farmers when the use of chemical fungicides is limited. Further research is required to enhance consistency and reduce the costs associated with these treatments under diverse edaphoclimatic conditions.

La antracnosis causada por Colletotrichum gloeosporioides provoca defoliación, aborto de flores, lesiones en frutos y reduce la producción y calidad de maracuyá. Aunque es controlada con fungicidas químicos, éstos contaminan el medio ambiente y son peligrosos para la salud, por lo que se ha incrementado la investigación en el control biológico con Trichoderma spp. Los objetivos de la investigación fueron aislar, identificar, determinar la patogenicidad del agente causal de la antracnosis y evaluar el antagonismo frente a cepas nativas mexicanas: T. asperellum (TaCh y TaST), Trichoderma sp. (TsRV, TsCo, TsCh y TsLF); además, frente a especies foráneas: Trichoderma virens G-41^®, T. harzianum T-22^®, Trichoderma sp. (Bactiva^®) y Trichoderma sp. (Fithan^®), mediante la técnica de cultivo dual. Se evaluaron: el día del primer contacto entre hifas, el antagonismo y el porcentaje de esporulación e inhibición de Trichoderma spp., contra el hongo patógeno. De frutos de maracuyá infectados se aisló e identificó C. gloeosporioides, el cual provocó infección en los frutos sanos a los 10 días después de la inoculación del aislado fungoso. Trichoderma y el patógeno hicieron contacto entre 1,6 (TsLF) y 3,8 (TaST) días. Todas las cepas evaluadas excepto TsLF y Bactiva^®, presentaron entre 97,56 y 100 % de esporulación. TsRV, TsCh, Fithan^®, TaCh, G-41^® y T-22^® sobrecrecieron al patógeno y cubrieron toda la superficie del PDA (antagonismo 1). Asimismo, TsRV, Bactiva^®, Fithan^® y TaChinhibieron 88,1; 76,0; 73,5 y 72,8 % el crecimiento miceliar de C. gloeosporioidesy se consideran candidatas para el manejo integrado de la antracnosis en maracuyá.

Background. The chili is a cornerstone of Mexican culture and cuisine, deeply embedded in the country's history and identity. Objective. To identify genetically and phylogenetically the virus that affects the native Apaxtleco chili pepper in Guerrero, Mexico, and to recognize symptoms of virosis in plants. Methodology. Young leaves of native Apaxtleco chili pepper plants with typical virosis symptoms were collected. The alignment of 13 sequences of DNA nucleotides was carried out, 11 of which belong to the fragment of region that codifies for the gene of “capsid protein / nuclear exportation factor BR1” of PepGMV two of these were obtained in this study, Aymedi-02 (KX641201.1) and Aymedi-01 (KX641200.1), and the nine remaining sequences were obtained from the GenBank database. Two more sequences were included for the purpose of tree rooting; one corresponds to the chlorotic leaf curl virus (AF325497.1) and another to the mosaic virus of African cassava (J02057.1), obtained from GenBank. The alignment of 13 sequences consisted of a total extension of 541 bases. To obtain descriptive information about the PepGMV sequences, only the sequences corresponding to it (11 sequences) were used, with a total of 326 conserved sites and 211 variable sites; of these, 89 are parsimony informative sites and 120 Singleton. Results. The sequence analysis showed 99% of identity with sequences of the PepGMV and the phylogenetic analysis confirmed the identification. Implications. Our results highlight a significant opportunity to enhance the control of this pathogen in this crop. Conclusion. Pepper Golden Mosaic Virus (PepGMV) was identified in Guerrero, Mexico, the symptoms presented in plants infected by this pathogen were: chlorosis, deformation, and mosaics.

In Mexico, there are 29 native species of the genus Hymenocallis, including H. glauca, which is characterized by a bulb that stores carbohydrates, giving energy for the emergence of foliage and floral scapes; it is the most cultivated species and holds economic value as a potted plant and cut flower (Leszczyñska-Borys and Borys, 2001). In September 2024, a survey was conducted at the Center for Research in Horticulture and Native Plants (18°55'55.6"N 98°24'01.4"W) at UPAEP University, where there was an average temperature of 25 °C and 75% relative humidity (RH) for 10 consecutive days. Approximately 30-day old H. glauca seedlings exhibited symptoms of root and bulb rot in a 0.4 ha area, with a 45% disease incidence. Symptoms included root and bulb rot with constriction at the base of the bulb and the presence of brown mycelia. Symptomatic tissues from 50 seedlings were collected, cut into 5 mm pieces, sterilized with 3% NaClO for a minute, rinsed with sterile distilled water, and placed in Petri dishes with potato dextrose agar (PDA) medium. Samples were incubated in the dark for six days at 28 °C. An isolate was obtained from each diseased seedling using the hyphal tip method. After six days, the colonies consisted of white mycelium that turned brown with age. Right-angle branching hyphae were observed, with slight constriction at the base of the branches. The hyphae were multinucleate, containing four to nine nuclei per cell. After 15 days, some isolates produced dark brown sclerotia. Based on these morphological characteristics, isolates were tentatively identified as Rhizoctonia solani Kühn (Parmeter, 1970). To confirm the anastomosis group (AG), two isolates (RsHg4 and RsHg8) were selected for molecular identification. Genomic DNA was extracted using the CTAB protocol. The ITS region was amplified and sequenced (White et al. 1990) in both isolates, and the sequences were identical. Thus, only the sequence of isolate RsHg8 was deposited in GenBank (PQ524600). BLAST analysis of the partial ITS sequence (639 bp) showed 99.84% similarity with R. solani AG 2-1 isolate (GenBank: JF792354) (Mercado et al. 2012). Phylogenetic analysis of AGs sequences allowed assignment of the isolate RsHg8 to the AG 2-1 clade. Pathogenicity was confirmed by inoculating 50 30-day old H. glauca seedlings, grown in pots with sterile substrate. A 5 mm diameter PDA plug colonized with mycelium from the RsHg8 isolate was placed on each bulb, 10 mm below the soil surface. For control treatment, a PDA plug without fungal growth was placed on the bulb of 25 seedlings. The inoculated seedlings were incubated in a greenhouse at 28 °C and 90% RH. After six days, inoculated seedlings showed root and bulb rot with constriction at the base of the bulb. No symptoms were observed in controls. Fungus was re-isolated from the inoculated seedlings and characterized both morphologically and molecularly, yielding identical results as described above and identified as R. solani AG 2-1, thereby fulfilling Koch's postulates. Pathogenicity tests were repeated thrice. R. solani AG 2-1 has been reported infecting Allium tuberosum in Hokkaido, Japan (Misawa and Kuninaga, 2013), and Allium cepa in Morrow, Oregon (Patzek et al. 2013). To the best of our knowledge, this is the first report of R. solani AG 2-1 causing root and bulb rot in H. glauca in Mexico. Data on diseases affecting this plant is scarce, highlighting the importance of this research in developing integrated management strategies and preventing pathogen spread.

En México, lograr la autosuficiencia alimentaria sigue representando un desafío, particularmente en el cultivo de maíces nativos pigmentados, de alto valor nutricional y cultural. La dependencia de insumos agroquímicos ha generado efectos adversos sobre la salud humana y el ambiente, lo que ha impulsado la búsqueda de alternativas sustentables, incluyendo el uso de microorganismos rizosféricos con potencial como desestresantes, biofertilizantes y bioplaguicidas. En esta investigación se comparó el efecto de bacterias y hongos aplicados de forma individual frente a la fertilización con N-P-K, sobre variables de crecimiento y peso de plántulas de los maíces criollos azules: Las Mesas, Colima y Tecoanapa, en interacción con cinco tratamientos: testigo, fertilizante químico (120N-90P-00K), Grow Depot®, Bacillus subtilis Biojal® y Trichoderma spp. (consorcio de cepas nativas de Guerrero) distribuidos en bloques al azar con cinco repeticiones en invernadero. La unidad experimental fue una bolsa de polietileno con 5 kg de sustrato. Los tratamientos se aplicaron en la siembra y a los 7 y 15 días después de la siembra (d.d.s.). Se midieron semanalmente la altura, diámetro del cuello, número de hojas y cobertura foliar, a los 15 días de la emergencia (seis evaluaciones) y a los 49 d.d.s. se pesó la biomasa acumulada en follaje y raíz (materias fresca y seca). Los datos se analizaron mediante análisis de varianza, regresión, correlación y prueba de Tukey (α ≤ 0.05). Se comprobó que la fertilización química favoreció significativamente la altura, diámetro del cuello y peso de biomasa en las plantas de criollos Las Mesas y Tecoanapa, sin mostrar diferencias en el número de hojas entre tratamientos. Además, se registraron correlaciones positivas y altamente significativas entre las variables evaluadas. Se concluye que la respuesta a los bioinsumos depende del genotipo, recomendando considerar esta interacción en programas de nutrición sustentable.