El cacao es una planta nativa de américa tropical y el Perú ha expandido su área sembrada consideradamente, por lo que es necesario un manejo adecuado del cultivo para obtener rendimientos rentables. Así, el presente trabajo tuvo como objetivo validar la inclusión de Trichoderma endófito y micorrizas en la fertilización orgánica e inorgánica para mejorar el rendimiento y la tolerancia a enfermedades del cacao. El experimento fue localizado en dos zonas productivas del Departamento de San Martín (Juanjui y Lamas), cepas de Trichoderma (T) y hongos micorrízicos arbusculares (HMA) se inocularon en plantas de cacao de 6 a 12 años en conjunto con aplicación de fertilizantes (F) y Guano de isla (G), dispuestos en DBCA con 10 tratamientos (Aplicación de T; HMA; T+HMA; T+F; T+G; HMA+F; HMA+G; T; G). Se evaluó la dinámica de las principales enfermedades en cacao (Escoba de bruja, Moniliasis y Pudrición parda), número de frutos cherelles, número de mazorcas y peso de grano seco. A partir de los resultados, se puede concluir que las zonas de Juanjui y Lamas, presentaron mayor incidencia de Moniliasis y Pudrición parda, respectivamente; explicado por el posible desbalance nutricional en las plantas producido por el exceso y falta de calcio, respectivamente. De forma general, la localidad de Juanjui tuvo mayor rendimiento de granos de cacao en comparación a Lamas. Los tratamientos con mayores rendimientos fueron los que incluyeron la aplicación de HMA y fertilizante inorgánico indicando la sinergia entre factores.

The "gray mold" is one of the main diseases of the blueberry crop that causes economic losses, the causal agent is the fungus Botrytis cinerea. The application of fungicides is one of the main strategies for its management; however, the pathogen has developed resistance to groups of fungicides. In search of a new control alternative, the antagonistic activity of 40 strains of endophytic fungi (EF) on B. cinerea was evaluated at the National University of Cañete. Antibiosis tests were performed with the extraction of secondary metabolites from the strains of HE and mycoparasitism with the method pre-colonized plate by the pathogen, where the mycelial inhibition of the pathogen and HE colonization, respectively, were evaluated. The metabolites obtained from the genus Aspergillus (strain 111) completely inhibited the mycelial growth of pathogen, followed by the genera Nigrospora (58) and Aspergillus (117) with 89.82 % and 63.33 % respectively compared to Cladosporium (116) which had less effect towards the pathogen with 3.19 % mycelial inhibition. However, all the strains of the genus Trichoderma (1, 91, 93 and 94), Alternaria (5 and 78), Fusarium (106), Cladosporium (41) and Lasiodiplodia (49) completely colonized the pathogen and were considered as more aggressive mycoparasites followed of the 117 and 111 Aspergillus strains that colonized 83.33 % and 63.33 % to the pathogen respectively. These endophytic fungi with antagonistic activity towards B. cinerea could be used as an alternative for disease control in blueberry cultivation.

En el sector Atusparia, Tocache, de la Región de San Martín, Perú, plantas de Theobroma cacao L. (Malvaceae) clon CCN-51 de dos años de edad presentaron, por primera vez en enero de 2010, síntomas de amarillamiento en hojas, marchitez y muerte, e internamente obstrucción del sistema vascular. Para el aislamiento del agente causal, tejidos enfermos fueron sembrados en placas Petri que contenían medio papa dextrosa agar oxitetraciclina, cuya identificación fue con base en un análisis morfológico, microscópico y secuenciación de Sanger. Las pruebas de patogenicidad se hicieron en T. cacao clon ICS-1 con edad de tres meses, inoculadas con una suspensión de conidias de 1x107 ufc/mL por dos métodos de inoculación (Drench al suelo y punción en el tallo). La capacidad antagónica (micoparasitismo y antibiosis) se determinó in vitro con aislamientos de Trichoderma endófito sobre el patógeno. En ambos métodos de inoculación, se observaron síntomas de marchitez de diferentes grados de severidad y se confirmó que el agente causal de la muerte súbita del T. cacao fue el hongo Verticillium dahliae Kleb. El análisis de la secuencia blast reveló que el aislamiento mostró un 100 % de homología con las secuencias de V. dahliae en GenBank. El Trichoderma TE-91 fue identificado como el micoparásito más agresivo, debido a que sus metabolitos inhibieron completamente el crecimiento micelial del patógeno.

Análisis de la diversidad genética de 21 aislamientos del hongo Moniliophthora roreri basado en marcadores RAPD

The use of endophytic fungi is an effective alternative to control pathogens, improve plant metabolism and yield in crops. The objective of this study was to assess the effect of five different strains of Trichoderma sp. on the growth and yield of quinoa plants (Chenopodium quinoa Willd) by using two methods of inoculation: a) pelleted seed, and b) drenching with the endophytic fungi. A completely randomized design with a 2 x 5 factorial arrangement, plus a control with five repetitions was used. The 11 treatments were evaluated with five repetitions. Yield, and aerial and root growth variables were determined. There were no interactions between strains and inoculation methods for aerial plant growth, but there were for root growth and yield. The seed pelleting method produced a higher aerial growth compared to the drench method. In root length, the greatest values were found with the TE-7 and TE-126 strains combined with the pelleted seed method. Likewise, the TE-126 strain induced the greatest dry biomass of roots using the same method. The yield varied between 4147.6 and 3222.7 kg.ha-1 in most of the strain-method combinations, without significant differences between them. Statistically, the control always ranked last, indicating the importance of the seed inoculation. Trichoderma sp. produced increases in vegetative growth and quinoa yield, with TE-7 and TE-126 being the best strains. Furthermore, seed pelleting promoted vegetative growth of the plants, while grain yield was not affected by the inoculation method.

The excessive use of chemical fertilizers causes alterations in soil microbial activity, environmental pollution and high production costs in potato cultivation (Solanum tuberosum L.). One way to avoid this effect is with the use of beneficial microorganisms, due to their ability to capture atmospheric nitrogen, produce growth-promoting substances such as indole acetic acid and solubilize inorganic phosphorus from insoluble compounds, which in turn time improves crop yields. The objective of this research was to evaluate the effect of the beneficial microorganisms as biofertilizers on growth and yield of potato crop. In a population of 1,600 potato plants cv. “Bicentenaria” four treatments were evaluated: Trichoderma harzianum (0.5 g.L-1), Glomus spp. (30 g.plant-1), efficient microorganisms (EM) (50 mL.L-1) and a control treatment (no application of microorganisms). A completely randomized experimental design with four repetitions per treatment was used. The effect of the treatments was evaluated using vegetative and reproductive variables. It was evident that the treatment with T. harzianum significantly favored the rest of the treatments in plant height at 90 days (43.60 cm), tuber weight (154 g) and yield (57.13 t.ha-1). The use of Glomus spp. and EM, had only a partial effect on the growth of the plants. The treatment with T. harzianum could represent an ecological agricultural alternative for potato production.