English walnut (Juglans regia) has become an important crop in Chile, representing 11.5% of the total area of fruit trees, surpassed only by grapevine. As the Chilean walnut industry rapidly expands, young orchards are at risk from the emergence of new fungal diseases. Botryosphaeriaceae and Diaporthaceae fungi have been recognized as main causes of wood diseases in walnut, with symptoms of dieback, canker, and blight. In winter 2017, samples were collected from different orchards in Valparaíso and Maule regions. Fungal isolates recovered were cultured, characterized morphologically, and identified using DNA sequence analyses. Three species (Neofusicoccum parvum, Diplodia mutila, Diplodia seriata) were characterized in Botryosphaeriaceae and two (Diaporthe cynaroidis, Diaporthe australafricana) in Diaporthaceae. Pathogenicity tests showed that N. parvum was the most aggressive species to walnut. This study confirmed the presence of pathogenic Botryosphaeriaceae and Diaporthaceae in J. regia that should be considered an increasing risk for the growing Chilean walnut industry.

Las universidades cumplen un rol social, por tanto, son objetos y sujetos de las políticas públicas de los países, las cuales ejercen distintas influencias sobre aquellas. Este debate ha sido especialmente hostil hacia las universidades con identidad católica; de hecho, es reducido el número de investigaciones que den cuenta del modo como influyen tales políticas en el ejercicio de sus funciones universitarias, pese a la presencia que han mantenido en la historia de las instituciones occidentales. Recientemente, la vinculación o tercera misión como función institucional se ha intencionado y cabe preguntarse cómo la catolicidad influye en las formas de vinculación con el medio, o si las disposiciones institucionales están solo mediadas por los contextos en que estas se desenvuelven. Para intentar dar respuesta a los anteriores interrogantes, se analizó el discurso institucional a través de un corpus documental, entendiendo este como constructor de una matriz de inteligibilidad para la acción de los sujetos. Se analizaron dos contextos disímiles: el alemán y el chileno. Esta comparación hizo posible reconocer que, aunque los contextos ejercen diferencias importantes en las formas como se responde a sus particularidades, la catolicidad posibilita un discurso que trasciende el contexto, sin antagonizar con la función universitaria.

Excessive nitrogen (N) use in agriculture has been associated with increased severity of the damage caused by Phytophthora species. In this study, we investigated the impact in vitro and in vivo of N about Phytophthora cinnamomi. The preliminary in vitro assay showed the effect of different N sources on the mycelial growth of P. cinnamomi. This assay indicated that ammonium nitrate (NH4NO3) and ammonium sulfate [(NH4)2SO4] allowed for greater control of P. cinnamomi mycelia in comparison with calcium nitrate [Ca(NO3)2] and potassium nitrate (KNO3) when used with 1000 ppm N. The in vivo assay showed the severity of P. cinnamomi in 5-month-old Juglans regia saplings grown under greenhouse conditions. We selected NH4NH3 as the source for N for the greenhouse assay, considering the inhibitory effect on the ingrowth of P. cinnamomi and the intensive use of this fertilizer in agriculture. Walnut saplings were fertilized with 0, 35, 70, 140, 210, and 1050 ppm N and were inoculated with zoospores of P. cinnamomi 45 d after the application of nitrogen treatment (DAA). They were harvested at 90 DAA. We found that a 70-ppm N fertilization reduced the development of P. cinnamomi, resulting in lower root and canopy damage indices (DIs) than the unfertilized inoculated treatments and fertilized treatments greater than 140 ppm. The results of the in vitro and in vivo assay agree that increased N concentrations were associated with reduced mycelium growth of P. cinnamomi, providing further evidence that N fertilization can mitigate this disease. Greater root and canopy damage was observed in saplings fertilized with 1050 ppm N, regardless of whether they were inoculated with P. cinnamomi, as a result of N phytotoxicity (verified through foliar analysis). In contrast, inoculated and unfertilized saplings (N0) also showed high root and canopy DIs associated either with the inoculation with P. cinnamomi or the no fertilization treatment. We postulate that 70 ppm N is the best fertilization rate for J. regia saplings because the positive effects of N on growth are maximized and the damage caused by P. cinnamomi is mitigated.

Clonal rootstocks are one alternative used by the walnut industry to control damage caused by Phytophthora species, traditionally using plants grafted on susceptible Juglans regia rootstock. Vlach, VX211, and RX1 are clonal rootstocks with a degree of resistance to Phytophthora species. The resistance to pathogens in these rootstocks depends on the resistance mechanisms activated by the presence of the pathogen and subsequent development of responses in the host. In this work, we analyzed how plants of J. regia, Vlach, VX211, and RX1 responded to inoculation with Phytophthora cinnamomi or Phytophthora citrophthora isolates obtained from diseased English walnut plants from Chilean orchards. After inoculation, plants of Vlach, VX211, and RX1 showed canopy and root damage indexes that did not differ from noninoculated control plants. In contrast, plants of J. regia, which is susceptible to P. cinnamomi and P. citrophthora, died after inoculation. Vlach, VX211, and RX1 plants inoculated with P. cinnamomi or P. citrophthora showed greater root weight and volume and greater root growth rates than their respective controls. These results suggest that short-term carbohydrate dynamics may be related to the defense mechanisms of plants; they are immediately activated after inoculation through the production of phenolic compounds, which support the further growth and development of roots in walnut clonal rootstocks. To our knowledge, this is the first study that comprehensively characterizes vegetative and radicular growth and the dynamics of sugars and phenols in response to infection with P. cinnamomi or P. citrophthora in walnut rootstocks.