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In September 2021, severe leaf spots were observed on Cucurbita argyrosperma plants in nine commercial fields in Cocula, Guerrero, Mexico. Conidia were similar to Curvularia, and morphological and molecular analyses of five monoconidial isolates confirmed them to be Curvularia brachyspora. Pathogenicity tests confirmed the isolates as the cause of the leaf spot. This report is the first worldwide of this pathogen causing leaf spot on C. argyrosperma. [ABSTRACT FROM AUTHOR]

The sugarcane aphid, Melanaphis sacchari (Zehntner), is a major pest in diverse sorghum-growing regions, affecting yields if no effective control measures are implemented. The objective of this study was to evaluate the field efficacy of commercial formulations of biorational insecticides against this pest. All the evaluated biorational insecticides exerted acceptable biological efficacy for at least 7 days after application. The insecticides based on fatty acid potassium salts (Ultralux® S and Impide®) maintained aphid density below the established threshold of 50 aphids per leaf up to 14 days after application. The results obtained suggest that biorational insecticides can be included in the integrated management of M. sacchari. [ABSTRACT FROM AUTHOR]

Onion seedlings with wilt symptoms were collected from the state of Guerrero, Mexico, from which Fusarium oxysporum f. sp. cepae was isolated and identified, based on the colony and conidia structure's morphological characteristics. A pathogenicity test was conducted, inoculating healthy onion seedlings with the isolated pathogen, while the control seedlings were sprayed with sterile distilled water only. Control seedlings remained healthy while inoculated ones developed wilt symptoms seven days after inoculation, similar to those observed in the production area. F. oxysporum f. sp. cepae was re-isolated and the genomic DNA extraction, PCR, and sequencing test were carried out. Based on morphological identification and pathogenicity tests, it was determined that F. oxysporum f. sp. cepae was the causal agent of wilt in onion, although the molecular identification was only carried out on a genus level. Additionally, different biocontrol products were evaluated in vitro including fungicides and phyto-extracts in order to determine the inhibition of the pathogen. The products used were as follows: Trichoderma asperellum strain obtained at CSAEGro (100%), T. harzianum (100%), prozycar (100%), cupravit (100%) manzate (100%), busan (100%), Q-2000 (60%), neem extract (51%) and garlic extract (27%). [ABSTRACT FROM AUTHOR]

Canavalia ensiformis is a Fabaceae used for soil conservation and control of weeds. The objective of this study was to identify gall wasps of C. ensiformis at Guerrero, Mexico. A survey was done in June 2022 in a crop of C. ensiformis planted to provide cover for Zea mays L. plots at Anahuac, San Marcos, Guerrero, México. Abnormal galls were found on several organs of the plants, especially the branches. Three branches from 10 plants were gathered, put into paper bags, labelled, and transported in polystyrene containers to Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) for rearing wasps. Adults were identified based on morphological characteristics. C. ensiformis was reported for the first time as an alternate host of wasps of the genus Eurytoma. Further studies of the genus and species identification using molecular techniques are needed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

El pulgón amarillo, Melanaphis sacchari (Zehntner), se detectó en México en 2013 y se ha dispersado a diversas regiones productoras de sorgo, Sorghum bicolor (L.) Moench, causando daños del 30 al 100%. Se evaluaron en campo insecticidas de diferente modo de acción en dos experimentos que mantuvieron la densidad por abajo del umbral económico establecido de 50 pulgones por hoja. A los 28 días después de la aplicación, imidacloprid sulfoxaflor, flupyradifurone, pymetrozine, spirotetramat, y afidopyropen presentaron las menores densidades de pulgón amarillo. Esta información es relevante, ya que conocer la efectividad de insecticidas con diferente modo de acción permite utilizar los más efectivos y que puedan integrarse con otras medidas que se implementen en el manejo de M. sacchari. The sugarcane aphid, Melanaphis sacchari (Zehntner), was detected in Mexico during 2013 and has dispersed to various sorghum ( Sorghum bicolor (L.) Moench)-producing regions, causing damage from 30 to 100%. Insecticides with different modes of action were evaluated in two experiments in the field, maintaining abundance below the established economic threshold of 50 aphids per leaf. Fewest sugarcane aphids were found 28 days after treatment with imidacloprid, sulfoxaflor, flupyradifurone, pymetrozine, spirotetramat, and afidopyropen. This information is relevant, because knowing the effectiveness of insecticides with different modes of action allows use of the most effective controls that can be integrated with other tools to manage M. sacchari. [ABSTRACT FROM AUTHOR]