Antifungal activity of zinc oxide (ZnO) and ZnO nanoparticles (ZnO NPs) was evaluated on the control of Fusarium oxysporum Schltdl. (Nectriaceae) under laboratory and greenhouse conditions. In vitro ...evaluation, poisoned culture media was prepared, and an explant was placed in the centre of solid medium. The experimental design was completely randomized with 18 treatments. Mycelial growth and conidia concentration were evaluated. Subsequently, three treatments (3,000, 1,500, 100 ppm) of ZnO NPs and ZnO were chosen for their evaluation in the greenhouse in tomato plants of Floradade variety under a randomized block design. Inoculation was carried out with a 1x107 conidia per mL suspension of F. oxysporum, when the plants presented the third pair of true leaves. Later, the application of different concentrations of ZnO and ZnO NPs was carried out; in this investigation, the incidence and severity and plant height were evaluated into account to determine the treatment effect on F. oxysporum. In vitro, the best treatments in mycelial growth inhibition were the high concentrations of ZnO NPs from 1,600 to 3,000 ppm with 81%–83%, and in the sporulation of the fungus, they were also those that inhibited from 82.57% to 83.85%. In greenhouse, the treatments that reached the highest plant height were ZnO NPs from 1,500 to 3,000 ppm, with a range of 166.0–175.40 cm, with a severity on the scale of 0.40–0.80 and an incidence of 20%–40%. ZnO NPs have a potential application as an antifungal agent and can be used to control the spread of F. oxysporum in tomato plants, in addition to improving the promoter effect related to the Zinc activity as a precursor in auxins synthesis, cytokinins and gibberellins biosynthesis, as well as the induction of higher activity of antioxidant enzymes useful in response to the pathogens attack.
In Mexico, the main states for garlic (Allium sativum L.) production are Zacatecas, Guanajuato, and Puebla. In the 2020 crop season, garlic cultivation encompassed 6,794 ha, yielding 85,505 tons ...(SIAP, 2021). In February 2020, 35 garlic samples showing basal rot symptoms were collected from the garlic-growing regions in the states of Zacatecas and Aguascalientes in the municipalities of San Antonio Tepezala 22°13'13.5''N, 102°15'55.3''W, Rincón de Romos 22°17'44.9''N, 102°13'06.8''W, and Calera 22°58'39.4''N and 102°41'29.9W, respectively. The sampling carried out was random sampling by conglomerates, dividing each field in groups with plants that showed similar symptoms. The infected plants were stunted in growth, with reddish dying leaves. The stalks and bulbs were soft, and their root system was poorly developed. The collected samples were placed in polyethylene bags and taken to laboratory. The roots and bulbs of 35 plants were cleaned, portions of the diseased tissue was cut into 0.5 cm pieces and disinfected in 1% sodium hypochlorite for 3 minutes. The samples were rinsed twice with sterile distilled water and dried on sterile paper towels. The tissues were cultured on Potato Dextrose Agar (PDA) medium and incubated in the dark at 25°C. Seven days after incubation, pure cultures were obtained using monoconidial cultures technique on Spezieller Nährstoffmmarmer agar (SNA) and subcultured on carnation leaf agar (CLA). Ten isolates were obtained that grew slowly, showing a white coloration, then turning yellow with abundant aerial mycelia. Microscopic traits of 30 characterized spores included slender macroconidia that were curved dorsiventrally, tapering towards both ends, with five to seven thin septa, measuring 36.4-56.6 µm × 4.0-4.9 µm in size and chlamydospores that were abundant, globose to oval, subhyaline and terminal or intercalary in chains measuring 8.8-4.5 µm in diameter. Microconidia, were single-celled, hyaline, nonseptate, and ovoid. The morphological traits matched the description of Fusarium clavum (Xia et al. 2019). To confirm the strain's identity, DNA was extracted from six monoconidial cultures and used as template to amplify translation elongation factor (TEF) gene 1α, RNA polymerase largest subunit (RPB1), and RNA polymerase second largest subunit (RPB2) (O'Donnell et al. 2010). The products were sequenced and deposited in GenBank as ON209360, OM640008 and OM640009, the homology analysis using BLASTn was similar to F. clavum with 99.46%, 99.49% and 98.82% respectively with E VALUE 0.0 in all cases with access numbers OP48709, HM347171 and OP486686. Koch postulate was performed to confirm the pathogenicity of the six isolates. Variegated garlic cloves were planted after being disinfected with sodium hypochlorite at 3% w/v in 2-kg pots under the greenhouse conditions. When the garlic plants developed 4 or 5 true leaves, their basal stalks were inoculated by pouring uniformly with 1 mL of a spore suspension at 108 conidia/mL prepared from 1-week-old colonies (Lai et al. 2020). Twenty-four plants were inoculated with six isolates (four plants per isolate), and four control plants were treated with sterile distilled water. Symptoms appeared 20 days post-inoculation. The leaves were reddish, and the stalks were soft. The leaves eventually developed foliar dieback disease symptoms, their root system showed brown lesions and rot, and all water-inoculated controls remained asymptomatic. Isolations were made on the diseased plants, and the inoculated pathogen was recovered and confirmed morphologically and molecularly by DNA extraction and PCR reactions. Koch's postulate was repeated twice, obtaining the same results. To our best knowledge, this is the first report of F. clavum infecting Allium sativum L. in Mexico. bulb rot caused by F. clavum is a severe threat to garlic cultivation, and identification of this pathogen is important for effective disease management and control.
Secondary metabolites produced by the fermentation of Streptomyces avermitilis bacterium are powerful antiparasitic agents used in animal health, agriculture and human infection treatments. ...Avermectin is a macrocyclic lactone with four structural components (A1, A2, B1, B2), each of them containing a major and a minor subcomponent, out of which avermectin B1a is the most effective parasitic control compound. Avermectin B1a produces two homologue avermectins (B1 and B2) that have been used in agriculture as pesticides and antiparasitic agents, since 1985. It has a great affinity with the Cl-channels of the glutamate receptor, allowing the constant flow of Cl- ions into the nerve cells, causing a phenomenon of hyperpolarization causing death by flaccid paralysis. The purpose of this work was to gather information on the production of avermectins and their biocidal effects, with special emphasis on their role in the control of pests and phytopathogenic diseases. The literature showed that S. avermitilis is an important producer of macrocyclic lactones with biocidal properties. In addition, avermectin contributes to the control of ectoparasites and endoparasites in human health care, veterinary medicine and agriculture. Importantly, avermectin is a compound that is harmless to the host (no side effects), non-target organisms and the environment.
Phytotoxicity caused by secondary metabolites of botanical extracts is a drawback in agriculture. The objective of this study was to evaluate the phytotoxic effects of methanolic extracts of ...Crotalaria longirostrata and Argemone mexicana on the germination and physiological variables of tomato seedlings. The results indicated that high doses of both extracts (Clong500 and Amex500) inhibited tomato seed germination, while their mixture (Cl50 + Am50) promoted germination by 100%. At 30 days after transplanting (dat), the plant height increased by 15.4% with a high dose of C. longirostrata (Clong500) compared to the control. At 30 dat, the vigor index displayed a notable increase with Cl50 + Am50, reaching 29.5%. The root length increased with the mean dose of A. mexicana (Amex95) at 10, 20, and 30 dat (59.7%, 15.1%, and 22.4%, respectively). The chlorophyll content increased with Amex95 by 66.1% in 10 dat, 22.6% at 20 dat, and 19.6% at 30 dat. On the other hand, Amex95 had a higher nitrogen content throughout the trial. Amex95 produced the greatest increase in root dry weight by 731.5% and 209.4% at 10 and 20 dat. The foliage dry weight increased by 85.7% at 10 dat with Amex95 and up to 209.7% with Amex50 at 30 dat. The present investigation reveals the ability of the extracts to stimulate tomato growth at low and medium doses, though at high doses they exhibit allelopathic effects.
Avocado tree wilt is a disease caused by Phytophthora cinnamomi Rands. Recently, this disease has been associated to Pythium amazonianum, another causal agent. Avocado tree wilt is being currently ...controlled with synthetic fungicides that kill beneficial microorganisms, polluting the environment and leading to resistance problems in plant pathogens. The current research work aims to provide alternative management using extracts from Proboscidea parviflora W. and Phaseolus lunatus L. to control the development of mycelia in P. amazonianum in vitro. Raw extracts were prepared at UAAAN Toxicology Laboratory, determining the inhibition percentages, inhibition concentrations and inhibition lethal times. Several concentrations of the plant extracts were evaluated using the poisoned medium methodology, showing that both extracts control and inhibit mycelial development, in particular P. lutatus, which inhibits mycelial growth at concentrations lower than 80 mg/L, being lower than P. parviflora extracts. These extracts are promising candidates for excellent control of Pythium amazonianum.
Resumen Objetivo: Detectar y cuantificar residuos de glifosato en cereales de desayuno comercializados en la ciudad de Saltillo, Coahuila. Materiales y Métodos: Se analizaron tres muestras de 12 ...marcas de cereal distintas. Para la extracción de plaguicidas se utilizó un equipo Soxhlet y la cuantificación se realizó por medio de Cromatografía Líquida de Alta Eficiencia (HPLC), utilizando un equipo marca Agillent modelo 1100 Series acoplado a un detector UV-Vis. Resultados: Se detectó glifosato en el 100% de las muestras analizadas, se obtuvieron concentraciones de entre 170 a 2 400 mg/kg, las muestras que presentaron mayores concentraciones fueron las de marcas internacionales. Conclusiones: Se detectaron residuos de glifosato en las 24 muestras analizadas de cereales de desayuno, las cuales sobrepasaron los LMR establecidos en el CODEX ALIMENTARIUS, por lo que es importante realizar más estudios con el fin de monitorear y asegurar la inocuidad de los productos procesados que son consumidos.
The nematicidal effect of Canavalia ensiformis seed extract combined with silicon dioxide nanoparticles was evaluated on second instar juveniles of Meloidogyne incognita, a phytopathogenic nematode ...that affects tomato crops. In the first experiment, concentrations of the extract were tested at 2, 4, 6, 6, 8 and 10%, observing that the most effective concentration was 10%, with 90% mortality at 24 hours. In the second experiment, concentrations of the extract at 1.5, 2.0, 2.5 and 3.0% were combined with silicon dioxide nanoparticles at 0.06, 0.08, 0.10, 0.12 and 0.14%, where the most effective was 1.5% extract with 0.14% nanoparticles, which showed a mortality of 94% at 72 hours. These results suggest that the combination of C. ensiformis extract with NP's can be a strategy for the management of M. incognita in tomato crops
Se evaluó el efecto nematicida del extracto de semillas de Canavalia ensiformis combinado con nanopartículas de dióxido de silicio, en juveniles de segundo estadio (J2) de Meloidogyne incognita, nematodo fitopatógeno que afecta el cultivo de tomate. En el primer experimento, se probaron concentraciones del extracto al 2, 4, 6, 8 y 10%, observando que la concentración más efectiva fue del 10%, con una mortalidad del 90% a las 24 horas. En el segundo experimento, se combinaron concentraciones del extracto al 1.5, 2.0, 2.5 y 3.0% con nanopartículas de dióxido de silicio al 0.06, 0.08, 0.10, 0.12 y 0.14%, donde la más eficaz fue la de 1.5% de extracto con 0.14% de nanopartículas, que mostró una mortalidad del 94% a las 72 horas. Estos resultados sugieren que la combinación de extracto de C. ensiformis con las NP’s puede ser una estrategia para el manejo de M. incognita en cultivos de tomate.
A new genetic variation and potential new haplotype of Bactericera cockerelli was identified based on the analysis of the mitochondrial region Cytochrome Oxidase subunit I of two populations from ...greenhouses in Villa Unión, Durango and Saltillo, Coahuila, Mexico. A variation was found in the base 247 of a 500 bp amplified of the mtCOI gene, this change implies the substitution of an adenine (A) to a Guanine (G), this mutation was detected in the insects collect from greenhouses and in their progeny obtained under laboratory conditions. This genetic variant has a great potential to be a new haplotype of B. cockerelli, therefore, it was designated Mexico Haplotype 1 (MXH1) with GenBank accession number KX130767. A total of ten insects from the original collection and then from laboratory cages were evaluated for Lso infection and all tested negative.
Resumen Las complicaciones ocasionadas por la generación de resistencia en el psílido Bactericera cockerelli por los plaguicidas químicos, plantean la necesidad del uso alternativo de productos que ...reduzcan la resistencia y garanticen un mejor control. La especie Crotalaria longirostrataes una fuente de metabolitos secundarios, que presentan posible actividad contra insectos plaga. El objetivo de la investigación fue identificar los compuestos del extracto metanólico crudo de hojas de C. longirostrata, así como evaluar su actividad biológica sobre ninfas de B. cockerelli. Se identificaron 25 compuestos por análisis de Cromatografía de Gases acoplada a Espectrometría de Masas (GC-MS); de los cuales, el de mayor abundancia fue el 1β,2β-epoxy-1α-metoximetil-8α-pirrolizidina; un alcaloide del grupo de las iminoazúcares, reportándose por primera vez en C. longirostrata, del cual se prepararon concentraciones desde 2 a 30 mg/mL del extracto metanólico para evaluar sobre ninfas de B. cockerelli. Observándose que a las 48 h se presentó una mortalidad de 73,2%-100% en los tratamientos de 8, 12, 16, 20 y 30 mg/mL. La concentración letal media (CL50) fue de 4,78 mg/mL y CL95 14,52 mg/mL. Los resultados obtenidos con el extracto metanólico de hojas de C. longirostrata para el control del insecto B. cockerelli sugieren que puede ser empleado como un insecticida de origen botánico alternativo al manejo del insecto.
