Resumen
Foreign market opportunities and domestic oversupply of navel oranges (Citrus sinensis (L.) Osbeck) in Chile has motivated growers to delay Navel orange harvest. This has been possible due to the introduction of late maturing cultivars. Nevertheless, an excessive late harvest may result in a loss of quality and the onset of physiological disorders such as granulation, particularly important due to its impact on quality and its possible development during postharvest. In order to compare on-tree storage and cold storage effects at 5°C, on fruit quality and granulation, this study was carried out in two orchards of Lane Late and Navelate navel oranges from two growing areas of Chile. Fruit under cold storage had slightly lower soluble solids, similar acidity and higher color index than fruit stored on the tree for an equivalent period of time. On Lane Late oranges, granulation incidence was higher for fruit held on the tree than fruit under cold storage for a similar period of time, reaching levels over 80% in the november harvest. Granulation incidence increased during postharvest; in fact, low levels of granulation of cold stored fruits were only obtained when fruits presented less than 5% granulation at harvest. Although granulation severity was generally rated as mild, its severity increased in all storage treatments even that they induced higher granulation incidence. Se determinaron las enfermedades virosas e insectos vectores presentes en malezas adyacentes a cultivos de tomate, pimiento, melón, sandía y zapallo, en las Regiones V y Metropolitana de Chile. Se analizaron 211 muestras de malezas que presentaban síntomas visibles de virosis, provenientes de 50 potreros, para determinar la presencia de virus utilizando la prueba serológica DAS-ELISA y transmisión mecánica a plantas indicadoras así como también a pimiento. Se determinó el índice de importancia relativa de las 13 especies de malezas que presentaron infección viral. De mayor a menor importancia fueron: Datura stramonium, Amaranthus spp., Raphanus sativus, Chenopodium album, Galega officinalis, Conium maculatum, Sonchus asper, Malva spp., Urtica urens, Bidens spp., Brassica campestris, Sorghum halepense y Solanum spp.. En estas malezas se encontraron uno a cinco virus, siendo los principales: el virus del mosaico de la alfalfa (AMV), el virus del mosaico del pepino (CMV), el virus del marchitamiento manchado del tomate (TSWV), virus Y de la papa (PVY), virus del mosaico del tomate (ToMV) y el virus del mosaico de la sandia (WMV-2). Se describe su sintomatología preidentificatoria que producen en malezas, plantas indicadoras y plantas de pimiento (Capsicum annum var. grossum). Se colectaron e identificaron afidos, trips y algunos lepidópteros en las mismas especies de malezas en estudio. Myzus persicae es vector de CMV, WMV-2, AMV y PVY; y Thrips tabaci es vector de TSWV, ambos insectos frecuentemente encontrados. Esta información permite afirmar que las malezas adyacentes a estos cultivos hortícolas son fuentes de inóculo de estos virus y de sus vectores.