ABSTRACT In Mexico, Creole corn has presented problems related to seed rot. Therefore, the objective of this study was to determine the frequency of fungi associated with Creole corn seeds. From January to February 2019, 13 Creole corn samples were collected from several localities in Guerrero, Mexico. The samples were processed in PDA culture medium and the frequency of each fungus was estimated based on cultural characteristics and taxonomic keys. Considering symptomatic corn seed samples, Fusarium oxysporum was recorded in eight samples at 97.2%, followed by F. graminearum, isolated from race “Olotillo 1” at 94.4% and from race “Cónico pepitilla” at 58.3%. Phomopsis sp. was isolated at 100% from race “Olotillo 2”. Gibberella moniliformis was isolated from “Elotes Occidental 1” at 83.3%, while the least frequent isolate (19.4%) from “Pepitilla” was Sarocladium strictum, which was recorded in three samples at the low values of 11.1% and 2.8% for races “Arrocillo 2” and “Pepitilla”, respectively; Talaromyces variabilis was found in two samples at 11.1% and 2.8% from “Arrocillo 2” and “Cónico pepitilla”, respectively; Stenocarpella macrospora was isolated at 72.2% from “Pepitilla”. Aspergillus flavus was obtained from “Cónico Pepitilla” at 16.7%, while Setosphaeria turcica and Emericella sp. were less frequently isolated. Considering asymptomatic seeds of race “Cónico pepitilla”, F. oxysporum was isolated at 8.3%, Fusarium acuminatum at 8.3% and Gibberella moniliformis at 41.7%; from asymptomatic seeds of “Olotillo 1” and “Olotillo 2”, Phomopsis sp. was isolated at 50% and Rhizoctonia solani at 50%, respectively. In the present study, the fungi F. oxysporum, Phomopsis sp., G. moniliformis and F. graminearum were most frequently associated with Creole corn seeds.

RESUMO No México, o milho crioulo apresenta problemas de podridão das sementes. Portanto, o objetivo desta pesquisa foi determinar a frequência de fungos associados a sementes de milho crioulo. De janeiro e fevereiro de 2019, 13 amostras de milho crioulo foram coletadas em localidades de Guerrero, México. As amostras foram processadas em meio de cultura BDA e a frequência de cada fungo foi estimada com base nas características culturais e chaves taxonômicas. Nas amostras sintomáticas de sementes de milho, Fusarium oxysporum foi registrado em oito amostras com 97,2%, seguido por F. graminearum isolado na raça de milho “Olotillo 1” com 94,4% e na raça “Cónico pepitilla” com 58,3%. Phomopsis sp., foi isolado 100% na raça “Olotillo 2”. Gibberella moniliformis, foran isolados de “Elotes Occidental 1” com 83,3% e o menos frequente (19,4%) em “Pepitilla” foi Sarocladium strictum registrado em três amostras com valores baixos de 11,1% e 2,8% na raça de milho “Arrocillo 2” e “Pepitilla”, Talaromyces variabilis em duas amostras com 11,1% e 2,8% em “Arrocillo 2” e “Cónico pepitilla”. Stenocarpella macrospora foi isolado em 72,2% da raça de milho “Pepitilla”. Aspergillus flavus em “Cónico Pepitilla” com 16,7%, Setosphaeria turcica e Emericella sp., foi isolado com menor frequência. Em sementes assintomáticas da raça “Cónico pepitilla” foi isolado F. oxysporum com 8,3%, Fusarium acuminatum 8,3%, Gibberella moniliformis em 41,7%, em sementes assintomáticas de “Olotillo 1” e “Olotillo 2” Phomopsis sp., foi isolado em 50% e Rhizoctonia solani com 50%. Neste estudo, os fungos F. oxysporum, Phomopsis sp., G. moniliformis e F. graminearum foram os mais frequentemente associados às sementes de milho crioulo.

Summary: The prickly pear cactus “tuna pelona” (Stenocereus zopilotensis), is an endemic cactus species from the state of Guerrero, Mexico, it develops in semi-arid areas and has great ecological importance as it houses and forms part of the diet of multiple species in its niche. There is a constant threat to natural populations of this species due to the overexploitation of seedling collections in the field by unregulated trade. In order to design an alternative for the conservation management of these species, the objective of the work was to evaluate treatments for the imbibition of “hairless tuna” seeds to promote germination and the successful establishment of seedlings with economic technologies for the farmers of the area. Fruits of "tuna pelona" (S. zopilotensis) were collected, near the community of Xalitla, municipality of Tepecoacuilco de Trujano, Guerrero; the seeds were stored for 70 and 273 days after collection (dac) at room temperature in order to maintain adequate conditions for the conservation of viability until reaching dormancy. In the stored seeds, the effect of soaking treatments was evaluated: 0, 6, 12, 24 and 12 hours in water plus another treatment that consisted of immersion in a plant-based hormonal stimulant. The germination percentage per treatment was evaluated, it was found that the control treatment (zero hours in water) of seeds stored at 70 dac only obtained 2.4% of germination. The treatment of soaking in water and in the hormonal stimulant both for 6 h presented the highest germination values with 48.6 and 44.4% respectively when using seeds of 273 dac at 14 days after the application of the treatments. These results will allow the massive production of seedlings of the species for reforestation and regional marketing purposes.

Resumen: La “tuna pelona” (Stenocereus zopilotensis), es una especie cactácea endémica del estado de Guerrero, México, se desarrolla en zonas semiáridas y tiene una gran importancia ecológica al albergar y formar parte de la dieta alimenticia de múltiples especies de su nicho. Existe una amenaza constante de poblaciones naturales de esta especie debido a la sobreexplotación de colectas de plántulas en campo por comercio no regulado. Con el fin de diseñar una alternativa para el manejo conservacionista de estas especies, el objetivo del trabajo fue evaluar tratamientos de imbibición de semillas de “tuna pelona” para promover la germinación y el establecimiento exitoso de plántulas con tecnologías económicas para los campesinos del área. Se colectaron frutos de “tuna pelona” (S. zopilotensis), cerca de la comunidad de Xalitla, municipio de Tepecoacuilco de Trujano, Guerrero; se almacenaron las semillas por 70 y 273 días después de la colecta (ddc) a temperatura ambiente con el objetivo de mantener condiciones adecuadas para la conservación de viabilidad hasta alcanzar la latencia. En las semillas almacenadas se evaluó el efecto de tratamientos de remojo: 0, 6, 12, 24 y 12 h en agua más otro tratamiento que consistió en inmersión en un estimulante hormonal de origen vegetal. Se evaluó el porcentaje de germinación por tratamiento, se encontró que en el tratamiento control (cero horas en agua) de semillas almacenadas a los 70 ddc, solo se obtuvo 2.4% de germinación. El tratamiento de remojo en agua y en el estimulante hormonal ambas por 6 h presentaron los valores más altos de germinación con 48.6 y 44.4% respectivamente al utilizar semillas de 273 ddc a los 14 días después de la aplicación de los tratamientos. Estos resultados permitirán la producción masiva de plántulas de la especie para fines de reforestación y comercialización regional.

Abstract The objective of this research was to identify the families of mites associated with blackberry (Rubus fruticosus L.), know its space distribution and population fluctuation in the Municipality of Sayula. A total of 5 937 mites were collected, corresponding to three orders and 13 families, the most abundant were Eriophyidae, Tetranychidae, Diptilomiopidae and Phytoseiidae, which contributed 86% of the total collected mites. The Parasitidae, Bdellidae, Cunaxidae, Iolinidae families are new records of association with blackberry plants in Mexico. Most of the families were distributed in the middle stratum of the plants. Population fluctuation increased from February, with the highest peak in May. It was observed that the number of predatory families increased as the number of phytophagous families increased. This constitutes an antecedent to carry out research on how to use more effective management strategies towards this crop.

Resumen El objetivo de la presente investigación fue identificar las familias de ácaros asociadas a zarzamora (Rubus fruticosus L.), conocer su distribución espacial y su fluctuación poblacional en el municipio de Sayula. Se colectaron 5 937 ácaros que correspondieron a tres órdenes y 13 familias, siendo las más abundantes Eriophyidae, Tetranychidae, Diptilomiopidae y Phytoseiidae, las cuales aportaron el 86% del total de los ácaros colectados. Las familias Parasitidae, Bdellidae, Cunaxidae, Iolinidae, son nuevos registros de asociación a plantas de zarzamora en México. La mayor parte de las familias se distribuyeron en el estrato medio de las plantas. La fluctuación poblacional aumentó a partir de febrero, con el mayor pico en mayo. Se observó que el número de familias depredadoras aumentó conforme se incrementó el de familias fitófagas. Esto constituye un antecedente para realizar investigaciones acerca de estrategias de manejo en este cultivo.