Resumen La melina (Gmelina arborea Roxb) es una especie de amplia distribución mundial y de elevado valor comercial por su crecimiento rápido y las excelentes propiedades físicas y mecánicas de su madera; sin embargo, constantemente se ve amenazada por diversos factores físicos, químicos y biológicos, siendo los hongos y las bacterias los microorganismos que más pueden afectar su producción. El presente estudio tuvo como objetivo aislar e identificar hongos y bacterias asociados con fustes enfermos de G. arborea en plantaciones ubicadas en el departamento del Tolima (Colombia). La caracterización morfológica de las colonias fúngicas se realizó en el medio Papa-Dextrosa-Agar (PDA) con posterior identificación microscópica, después de inducir la producción de las estructuras reproductivas. El aislamiento de las bacterias se realizó en Agar Nutritivo (AN), con posterior caracterización bioquímica. La identificación molecular fue realizada mediante la amplificación de la región ITS para hongos y 16S para bacterias. Se identificaron los hongos Lasiodiplodia theobromae, Coniothyrium aleuritis, Curvularia geniculata, Chaetomium globosum, Phomopsis columnaris, Diaporthe sp y un aislamiento perteneciente a la clase Dothideomycetes. Las bacterias correspondieron a Bacillus cereus, Pseudomonas alcaligenes y Pantoea dispersa. Mediante pruebas de patogenicidad se determinó que los microorganismos causantes de la pudrición del tejido vascular en fustes jóvenes de melina fueron L. theobromae y C. geniculata.

Abstract Gmelina (Gmelina arborea Roxb) is a species of global distribution with a high commercial value due to its rapid growth and excellent physical, chemical, and biological features. Fungi and bacteria are the most important microorganisms that can affect its production. The present study aimed at isolating and identifying fungi and bacteria associated with G. arborea stem diseases in plantations located in the department of Tolima (Colombia). The morphological characterization of the fungal colonies was carried out in Potato Dextrose Agar medium (PDA) with subsequent microscopic identification after inducing the reproductive structures. Bacteria isolation was conducted in nutrient agar with subsequent biochemical characterization. The molecular identification was made by the amplification of the ITS region for fungi and the 16S for bacteria. We identified the fungi Lasiodiplodia theobromae, Coniothyrium aleuritis, Curvularia geniculata, Chaetomium globosum, Phomopsis columnaris, Diaporthe sp, as well as an isolate belonging to the Dothideomycetes class. The bacteria corresponded to Bacillus cereus, Pseudomonas alcaligenes, and Pantoea dispersa. The pathogenicity tests determined that L. theobromae and C. geniculate caused rot of vascular tissue in young candahar stems.

RESUMO Entre as infecções fúngicas que afetam a pós-colheita da videira se destacam a podridão seca ocasionada por Lasiodiplodia theobromae que provoca perdas superiores as perdas no campo, pelo fato de serem adicionados aos custos de colheita, transporte e armazenamento. Produtos naturais vêm sendo utilizados no controle de doenças de plantas, apresentando eficiência na redução do uso de defensivos agrícolas. Desta forma, o presente trabalho teve por objetivo obter o controle da podridão seca pela utilização de produtos alternativos. Foi analisado o crescimento micelial de L. theobromae em placas de Petri contendo o meio BDA suplementado com os seguintes produtos: óleo de citronela, cravo e menta, nas concentrações de 1,0% e 1,5% e quitosana (1,5%). A testemunha foi placa com meio BDA sem adição de produto. Para avaliação do efeito curativo dos óleos sobre o desenvolvimento da podridão seca, cachos da cv Itália foram inoculados com o patógeno e, após 4 h, aspergidos com concentrações 1,0% e 1,5% de solução de óleos de cravo, citronela e menta e de Quitosana a 1,5% e água (testemunha). Posteriormente, para avaliar o efeito protetor dos cachos da cv Itália foram submetidos aos mesmos tratamentos e, inoculados após 4 horas com L. theobromae. Na avaliação do tempo de inoculação, cachos da cv. Itália foram aspergidos com solução de óleos essenciais: cravo (1,5%) e citronela (1,0% e 1,5%), e água (testemunha) e, inoculados após 24, 48, 72 ou 96 h com o fungo L. theobromae. Os óleos de Citronela e Menta, em todas as concentrações foram capazes de inibir o crescimento micelial de L. theobromae. Os óleos essenciais e Quitosana foram eficientes em reduzirem a incidência da podridão seca em cachos da videira cv Itália. No entanto, em relação à severidade apenas os óleos de citronela e menta, na concentração de 1,5% mantiveram a capacidade de reduzir a doença em 30 e 29,2%, respectivamente. O tempo de inoculação influenciou a incidência e a severidade da doença. Quanto mais tempo o material esperou para ser inoculado, maior foi à incidência e a severidade da doença.

ABSTRACT Among fungal infections that affect the grapevine post-harvest is dry rot caused by Lasiodiplodia theobromae, which leads to losses greater than those in the field since they are added to the costs of harvest, transport and storage. Natural products have been used to control plant diseases, showing efficiency in reducing the use of pesticides. Thus, this study aimed to obtain control of dry rot by using alternative products. Mycelial growth of L. theobromae was analyzed on Petri plates containing PDA medium supplemented with the following products: citronella, clove and mint oil at the concentrations of 1.0% and 1.5%, and chitosan (1.5%). Control was a plate with PDA medium with no product addition. To evaluate the healing effect of oils on dry rot development, bunches of grapevine cv Itália were inoculated with the pathogen and, after 4 h, sprayed with the concentrations of 1.0% and 1.5% clove, citronella and mint oil solution; 1.5% chitosan solution, and water (control). Subsequently, to evaluate the protective potential, bunches of grapevine cv. Itália were subjected to the same treatments and inoculated, after 4 hours, with L. theobromae. For the assessment of inoculation time, bunches of grapevine cv. Itália were sprayed with solution of the essential oils: clove (1.5%) and citronella (1.0% and 1.5%), and water (control), and inoculated after 24, 48, 72 or 96 h with the fungus L. theobromae. Mint and citronella oils, at all concentrations, were capable of inhibiting the mycelial growth of L. theobromae. Essential oils and chitosan were effective in reducing the incidence of dry rot in bunches of grapevine cv. Itália. However, regarding the severity alone, citronella and mint oils, at the concentration of 1.5%, retained the ability to reduce the disease by 30 and 29.2%, respectively. The inoculation time influenced the disease incidence and severity. The longer the time for the material to be inoculated, the higher the incidence and the severity of the disease.

A series of fungi diseases severe is disseminated by avocado seeds and they can decrease the production in approximately 14% and a reduction of quality in 10%. The present investigation consisted in to isolate and identify pathogens fungal present in the avocado seeds mexican race used for patron. The fotopatogenos fungi were isolated in culture medium Sucrose Agar Potato from the embryo and cotyledon of 200 seeds of avocado and to identify with taxonomic keys also was carried out Pathogenicity test on avocado plants with the most frequent phytopathogenic fungi. The pathogens fungal isolated and identified from embryo and cotyledon of seeds were Lasiodiplodia sp. with 0.5% and 1.00%, and Fusarium sp with 1.50% and 2.50% of frecuency respectively. The pathogenicity test allowed confirming that Lasiodiplodia theobromae and Fusarium verticillioides affect to seedlings of avocado, being the source of primary inoculum and means of dissemination infected seeds by these pathogens.

Una serie de enfermedades severas de origen fungoso son diseminadas por semillas de palto, y pueden causar una disminución de la producción en aproximadamente el 14 % y una reducción de calidad en un 10 %. El presente trabajo consistió en aislar e identificar hongos fitopatógenos presentes en las semillas de palto (Persea americana Mill.) raza mexicana utilizadas para patrón. A partir del embrión y cotiledón de 200 semillas de palto, se aislo los hongos fotopatogenos en medio de cultivo Papa Sacarosa Agar e identifico utilizando claves taxonómicas; asimismo, se realizo la prueba de patogencidad en plantones de palto con los hongos fitopatógenos de mayor frecuencia. Los hongos fitopatógenos aislados e identificados a partir del embrión y cotiledón de semillas fueron Lasiodiplodia sp. con 0.5 % y 1.00 %, y Fusarium sp. con 1.50 % y 2.50 % de frecuencia respectivamente. La prueba de patogenicidad permitió confirmar que Lasiodiplodia theobromae y Fusarium verticillioides afectan a plantones de palto, siendo la fuente de inoculo primario y un medio de diseminación las semillas infectadas por estos patógenos.

The aim of this work was to study the phytochemical and antifungal activity of anthraquinones and root and leaf extracts of Coccoloba mollis on phytopathogens. The chemical analysis of ethanolic extracts showed a mixture of long-chain hydrocarbons, carboxyl esters and 3-taraxerone in the leaf extract. Two anthraquinones (emodin and physcion) were isolated and identified from the root extract. Phytochemical screening using the pharmacognostic methods revealed the presence of flavonoids and tannins in the leaves and roots. Anthraquinones were only found in the root extract, no alkaloids, coumarins, saponins and simple phenolics were present. The antifungal activity of C. mollis extracts and anthraquinones isolated from the root of this plant against Botryospheria ribis, B. rhodina, Lasiodiplodia theobromae and Fusarium sp showed promising results for their use as fungicides, where emodin was the most active compound, which inhibited the microorganisms tested up to 44%.

El estado Mérida es el mayor productor de cacao en la zona occidental, aunque con rendimientos que representan el 50% del promedio mundial, debido al predominio de plantaciones viejas e improductivas que por mucho tiempo no han recibido el manejo agronómico que el cultivo requiere. Por la ausencia de manejo fitosanitario en las plantaciones se presentan diversas enfermedades que afectan el follaje, flores, frutos y raíces, y ante esta problemática se realizó la identificación de la micobiota del filoplano de las hojas del cacaotero con la finalidad de determinar la diversidad de hongos que están presentes en el follaje de este cultivo. Durante el período septiembre - noviembre del año 2002 se realizaron tres muestreos para cada una de las cinco fincas seleccionadas. Se recolectaron hojas sanas y secciones de estas hojas se colocaron durante 5-15 días en cámara húmeda en cajas de Petri con papel de filtro estéril y a temperatura ambiente promedio de 28ºC. De los análisis microscópicos de los diversos hongos aislados y con el uso de claves taxonómicas se logró identificar 48 hongos. Las especies más abundantes fueron Curvularia lunata (67-100%), Nigrospora sphaerica (53-100%) y Colletotrichum gloeosporioides (67-93%). Se confirma la presencia de los hongos Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Moniliophthora roreri y Phytophthora spp. como agentes causales de enfermedades de importancia en la zona del sur del Lago de Maracaibo y la presencia de los hongos Penicillium sp. y Gliocladium sp. con posible potencial como biocontroladores.

Merida state is the major cocoa producer in the western zone with yields that represent 50% of mean world due to the predominance of old and unproductive plantations that for a long time have not received the agricultural management that crop requires. Due to the absence of plant health management there are some diseases that affect the foliage, flowers, fruits and roots. The identification of cocoa leaves phylloplane mycobiota it was made with the purpose of establishing the fungi diversity that are present in the crop foliage. In period Sept Nov 2002 were accomplished three samplings for each of five farms selected. Healthy leaves and sections of these leaves were collected and placed by 5-15 days inside a moist chamber made with Petri dishes with sterilized filter paper and at mean temperature of 28 ºC. From the microscopically analysis of various isolated fungi and by using taxonomic keys it was possible to identify 48 fungi. The more abounding species were Curvularia lunata (67-100%), Nigrospora sphaerica (53-100%) and Colletotrichum gloesporioides (67-93%). It is confirm the Colletotrichum gloesporioides; Lasiodiplodia theobromae, Moniliophthora roreri and Phytophthora spp presence, as causal agents of important diseases in the Maracaibo Lake region, so the Penicillium sp. and Gliocladium sp fungi acting as possible bio controllers.