Resumen. Se determinó el efecto sobre la incidencia del moho gris en postcosecha de uchuva de las aplicaciones en campo de tres bioproductos a base de Trichoderma koningiopsis, Rhodotorula mucilaginosa y Bacillus amyloliquefaciens, la alternancia del bioestimulante Kendal® y el extracto vegetal EcoSwing® y las rotaciones de fungicidas a base de Azoxistrobina - Difenoconazole y Thiram - Pyrimethanil. Semanalmente se cosechó la fruta, disponiendo en cámaras húmedas frutos con cáliz y sin este, incubadas durante siete días a 20 °C para promover el desarrollo de la enfermedad y determinar la eficacia en su control. Se realizó el seguimiento de las poblaciones de los antagonistas entre aplicaciones, mediante colecta de foliolos y el lavado en Tween 80 al 0.1%, sembrando alícuotas en medios específicos. En los frutos con cáliz la menor incidencia de la enfermedad con medias de 48 y 51% se presentó con las aplicaciones del hongo y la levadura respectivamente, mientras que en los frutos sin cáliz la incidencia no supero el 1.4% en todos los tratamientos. La población de antagonistas en la filósfera permaneció constante entre aplicaciones con recuentos de 1x103 UFC g-1 para T. koningiopsis y de 1x105 UFC g-1 para R. mucilaginosa y B. amyloliquefaciens.

Abstract. The effect of the field applications of three bioproducts (based on Trichoderma koningiopsis, Rhodotorula mucilaginosa, and Bacillus amyloliquefaciens), the alternation of the biostimulant Kendal® and the Swinglea glutinosa extract and the rotations of two fungicides (based on Azoxystrobin-Difenoconazole and Thiram-Pyrimethanol), on the incidence of gray mold in cape gooseberry postharvest was evaluated. For this purpose, the fruit was harvested weekly in the field, arranged in wet chambers with fruits with and without calyx, and incubated for seven days at 20 °C in laboratory conditions to promote the development of B. cinerea and determine the efficacy in its control. In addition, the populations of the microbial antagonists were monitored between applications by collecting the leaflets and washing them in 0.1% Tween 80 and sowing aliquots in specific culture media. In fruits with calyx, the lowest incidence of the gray mold, with averages of 48 and 51%, occurred with the applications of the bioproducts based on T. koningiopsis and R. mucilaginosa, respectively. In contrast, the incidence did not exceed 1.4% in fruits without calyx in all treatments. Furthermore, the population of microbial antagonists in the phyllosphere remained constant between applications, with counts of 1x103 CFU g-1 for T. koningiopsis and 1x105 CFU g-1 for R. mucilaginosa and B. amyloliquefaciens.

Resumen El cultivo de cacao es parte de la actividad económica campesina y de sistemas de agroforestería en muchas regiones de Colombia y del mundo. Su rendimiento se ve disminuido por problemas fitosanitarios, siendo la monilia causada por el hongo Moniliophthora roreri, la enfermedad más limitante causando disminuciones de producción de más del 90%. En este estudio, se caracterizaron muestras de lixiviados de cacao de fincas comerciales y la actividad antifúngica de estos lixiviados esterilizados, no esterilizados, y filtrados contra M. roreri fue evaluada bajo condiciones in vitro en concentraciones de 1, 2, 5, 10, y 15%. Aislamientos monospóricos del patógeno fueron obtenidos a partir de frutos enfermos colectados en fincas productoras de cacao del municipio de Yacopí en Cundinamarca, Colombia. El efecto de los lixiviados se evaluó sobre la germinación conidial de M. roreri, el crecimiento micelial, y la producción de inóculo. Se encontró que los lixiviados de cacao no esterilizados en todas las concentraciones generaron 100% de reducción de las tres variables evaluadas, mientras que los lixiviados esterilizados generaron el mismo efecto a concentraciones de 10 y 15%. Los lixiviados filtrados no mostraron efecto inhibitorio sobre el crecimiento radial del patógeno, pero una reducción de la germinación conidial de 89,9; 90,5 y 95,9% a las concentraciones de 5, 10, y 15%, respectivamente. La presencia de ácido málico, cítrico, y ascórbico, compuestos como NH4, PO4, y NO3, y elementos como Ca, K, Na, Mg, y Cl fue identificada en los lixiviados evaluados usando cromatografía líquida de alta eficiencia y análisis fisicoquímicos. Esta investigación mostró el potencial de los lixiviados de cacao, aún a bajas concentraciones para el control de M. roreri, el cual puede ser atribuido a la acción de compuestos específicos como los encontrados en las evaluaciones cromatográficas.

Abstract The cocoa crop is part of the peasant’s economic activity and agroforestry systems in many regions of Colombia and the world. Its yields are diminished by phytosanitary problems, being the frosty pod rot caused by the fungus Moniliophthora roreri, the most limiting disease with decreases in production of over 90%. In this study, samples of cocoa leachates from commercial producing farms were characterized and the antifungal activity of sterilized, non-sterilized, and filtered cocoa leachates against M. roreri was evaluated under in vitro conditions, at concentrations of 1, 2, 5, 10, and 15%. Monosporic isolates of the pathogen were obtained from diseased fruits collected from cocoa-producing farms in the municipality of Yacopi in Cundinamarca, Colombia. The effect of leachates on M. roreri conidial germination, mycelial growth, and inoculum production was evaluated. It was found that non-sterilized cocoa leachates at all concentrations caused 100% reduction on the three variables evaluated, while sterilized leachates generated the same effect at concentrations of 10 and 15%. Filtered leachates showed no inhibitory effect on the radial growth of the pathogen, but they caused a reduction of conidial germination of 89.9, 90.5 and 95.9% at concentrations of 5, 10, and 15%. The presence of malic, citric, and ascorbic acids, compounds such as NH4, PO4, and NO3, and elements such as Ca, K, Na, Mg, and Cl in the evaluated leachates was identified using high-efficiency liquid chromatography and physicochemical analysis. This research showed the potential of cocoa leachates, even at low concentrations, for the control of M. roreri, which can be attributed to the action of specific compounds such as those found in chromatographic tests.

Resumen El chancro del tallo y la sarna negra de la papa son enfermedades ocasionadas por el hongo Rhizoctonia solani grupo de anastomosis tres (GA-3PT), el cual afecta raíces, tallos y tubérculos de papa y reduce el rendimiento de los cultivos. El objetivo de la presente investigación fue determinar la diversidad genética de R. solani GA-3PT presente en los departamentos colombianos de Antioquia, Boyacá y Cundinamarca. La restricción enzimática de la región ribosomal (RFLP, por sus siglas en inglés) ITS-5.8S permitió la diferenciación e identificación específica de los grupos de anastomosis GA-3PT y GA2-1 y confirmó que el GA-3PT es el principal agente causal y origen etiológico de la enfermedad en Colombia. Mediante amplificación aleatoria de marcadores microsatélites (RAMs), por sus siglas en inglés), se observaron dos agrupamientos dentro de R. solani GA-3PT; el GA-3PT (A) comparte un índice de similitud del 78 % entre sí, en comparación con el GA-3PT (B) que presenta una similitud del 79 % entre sus aislamientos. Los agrupamientos no están relacionados con su origen geográfico, sino con el grupo de anastomosis al que pertenecen. La diversidad genética de Nei [D] de 0,25 confirma una alta diversidad genética para el GA-3PT mediante análisis RAMs, relacionada con un alto potencial evolutivo al interior del grupo GA3PT en Colombia. Finalmente, el hongo R. solani GA-3PT que se obtuvo en Cundinamarca tiene potencial adaptativo para emerger como patógeno de la papa criolla (Solanum phureja) en Colombia, posiblemente, debido a la semejanza de los patosistemas.

Abstract Stem canker and black scurf are potato diseases caused by the fungus Rhizoctonia solani, anastomosis group 3 (AG-3PT). This fungus affects potato roots, stems, and tubers, reducing crop yields. This study aims to determine the genetic diversity of R. solani AG-3PT obtained from the Colombian departments of Antioquia, Boyacá, and Cundinamarca. Restriction fragment length polymorphism (RFLP) analysis of the ITS-5.8S ribosomal DNA region allowed the differentiation and specific identification of AG-3PT and AG2-1 anastomosis groups. These results confirm that AG-3PT is the primary causative agent and etiological origin of stem canker and black scurf in Colombia. Two distinct subgroups within R. solani AG-3PT were identified using random amplified microsatellite markers (RAMs); AG-3PT (A) shares a similarity index of 78 %, and AG-3PT (B) shares a similarity of 79 % among its isolates. These subgroups were not linked to a geographical origin but to the AG group to which they belong. Nei’s genetic diversity [D] of 0.25 confirmed the high genetic diversity for AG-3PT through RAMs analysis, related to a high evolutive potential within the AG-3PT group in Colombia. Finally, the R. solani AG-3PT fungus obtained from Cundinamarca had the adaptative potential to emerge as a pathogen of Solanum phureja in Colombia, possibly due to the similarity between pathosystems.

Abstract. The efficacy in the control of mango cv. Azúcar anthracnose in postharvest was determined by subjecting the fruit to a hydrothermal treatment at 53 °C; later two wounds of 2 mm deep were made and the fruits were immersed in suspensions of the antagonists or chitin in different concentrations. After, each wound was inoculated with a drop of 5 µL of the pathogen, and the fruits were storage at 23 °C. From this trial, Lysinibacillus xylaniticus Ap282, Rhodotorula glutinis Lv316, and chitin 10 mg L-1 were selected for showing an efficacy in the disease control of 49% to 69%. The bioassay was repeated, but adding the chitin to the hydrothermal treatment and evaluating the control of the disease from pathogen’s quiescent infections, storage the fruit at 13 °C. The combination of hydrothermal treatment and tempered of the fruit in the AP282 suspension presented the highest efficacy in the control of anthracnose (84%) in fruits inoculated with the pathogen, while, in the disease control from the quiescent infections, the combination of hydrothermal treatment adding the chitin or tempering in the microbial suspensions showed an efficacy of 83% to 89%.

Resumen. Se determinó la eficacia en el control de la antracnosis en la poscosecha de mango cv. Azúcar sometiendo la fruta a un tratamiento hidrotérmico a 53 °C, realizando posteriormente dos heridas de 2 mm de profundidad, luego se realizó la inmersión en suspensiones de los antagonistas o quitina en diferentes concentraciones, posteriormente en cada herida se inoculó una gota de 5 µL del patógeno, almacenando la fruta a 23 °C. De este ensayo se seleccionó a Lysinibacillus xylaniticus Ap282, Rhodotorula glutinis Lv316 y quitina (10 mg L-1) por presentar una eficacia del 49% al 69% en el control de la enfermedad. El bioensayo se repitió, adicionando la quitina al tratamiento hidrotérmico y evaluando el control de la enfermedad a partir de infecciones quiescentes del patógeno, almacenando la fruta a 13 °C. La combinación del tratamiento hidrotérmico y el temperado de la fruta en la suspensión de AP282 presentó la mayor eficacia en el control de la antracnosis (84%) en frutos inoculados con el patógeno, mientras que, en el control de la enfermedad a partir de las infecciones quiescentes la combinación del tratamiento hidrotérmico adicionando la quitina o el temperado en suspensiones microbianas presentó una eficacia del 83 al 89%.

Resumo A produção de amora na Colômbia é uma fonte de renda e emprego rural em 18 estados; no entanto, a planta é afetada por doenças como mofo cinzento, antracnose e oídio, que podem causar perdas superiores a 70%. Seu controle é realizado principalmente com fungicidas químicos como benomil, carbendazim ou mancozeb, aplicados a cada 7 ou 15 dias. No entanto, por ser uma planta de frutificação contínua e colheita semanal, a proximidade temporal entre a aplicação de pesticidas, a colheita e seu consumo representa um risco à saúde devido à residualidade dessas moléculas, condição que afeta sua segurança e sustentabilidade. Nesse sentido, este trabalho teve como objetivo desenvolver uma estratégia de gestão integrada para essas doenças. Para isso, duas estratégias foram propostas, integrando o trabalho agronômico com as aplicações de Tricotec®-Kendal® ou Tricotec®-EcoSwing®, e três fungicidas aplicados de acordo com a incidência de cada doença, comparando-os com o manejo convencional do produtor. Durante um período de 77 dias, sua eficácia foi determinada na redução da incidência, produção de frutas, seu impacto ambiental, calculando o coeficiente de impacto ambiental no campo (CIAc) e na redução de resíduos de pesticidas nas frutas. De acordo com os resultados obtidos, foi estabelecido que a estratégia Tricotec®-Kendal®, com aplicações de fungicida à base de azoxistrobina e difeconazol, apresentou a menor incidência para cada doença, com média de 3% para mofo cinzento, 11% para antracnose e 21% para oídio e a maior quantidade de frutas colhidas em média 5.668 g. Além disso, apresentou o menor CIAc com 5,3 comparado a um valor de 81,50 do manejo convencional do produtor, bem como a menor quantidade de vestígios de pesticidas, correspondendo a azoxistrobina (0,10 mg / kg) e difeconazol (0,046 mg / kg); no entanto, estes estavam dentro dos limites máximos de resíduos de pesticidas autorizados pela União Europeia por amoras.

Abstract The production of blackberry in Colombia is a source of income and rural employment in 18 departments; however, the plant is affected by diseases such as gray mold, anthracnose and powdery mildew that can cause losses of up to 70%. The control of these diseases is mainly carried out with chemical fungicides such as benomyl, carbendazim and mancozeb applied every 7 or 15 days. Nevertheless, being a continuous fructification plant of weekly harvest, the proximity between the application of the pesticides, the harvest, and its consumption represents a health risk due to the residually of these molecules, condition that affects its innocuousness and sustainability. Accordingly, this work aimed to develop an integrated management strategy for these diseases. Two strategies were proposed integrating agricultural labors with applications of Tricotec®-Kendal® or Tricotec®-EcoSwing®, and three fungicides applied according to the incidence of each disease, compared with the diseases producer management. In 77 evaluation days the effectiveness of the strategies was assessed according diseases incidence reduction, on fruit production, environmental impact, using the environmental impact quotient in the field (EIQf), and the reduction of fruit pesticides residues. According to the results obtained, the strategy Tricotec®-Kendal® with applications of a fungicide based on azoxystrobin + difeconazole showed the lowest diseases incidence, averaging 3% for gray mold, 11% for anthracnose, and 21% for powdery mildew and the highest amount of fruit harvested averaging 5,668 g. The strategy showed the lowest EIQf (5.3) compared with a value of 81.50 obtained with the traditional producer management, as well as the least amount of pesticides residues, corresponding to azoxystrobin (0.10 mg/kg) and difeconazole (0.046 mg/kg); these, however, remained within the maximum residue limits for pesticides stated by the European Union for blackberry.