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The Food and Agriculture Organization has reflected the importance of predicting yield response to water by developing the AquaCrop model. During three growing seasons (2007)(2008)(2009)), a field experiment was conducted in the South-East of Damascus (Syria) to assess the response of drip irrigated cotton grown under full (FI) and deficit irrigation (80, 65, 50% of FI). Input data and comparisons between simulated and observed canopy cover (CC), biomass production at harvesting, final seed cotton yield, and soil water content using data sets of the 2007 season, were used for model calibration. The calibrated model was validated using data sets of the 2008 and 2009 seasons, getting accurate simulation results for CC [root mean square error (RMSE) = 6.5%] and actual evapotranspirationETa (RMSE = 25 mm, index of agreement = 0.99). The predicted seed cotton yields were within 6% of measurements. The model predictions of soil water content in the 0.60 m profile were close in the general trend to the measurements. In spite of the good prediction of ETa and seed cotton yield for each treatment, there is an apparent tendency for AquaCrop to over-estimate water use efficiency (WUE) under water-deficit conditions. Therefore, in cases of limited input data, the AquaCrop could be a promising model for estimating crop productivity under deficit irrigation conditions. Additional key words: canopy cover; crop yield modeling; water productivity; water stress. ResumenSimulación de la respuesta del rendimiento del algodón al riego deficitario con el modelo AquaCrop de la FAO Por lo importante que es predecir la respuesta del rendimiento al riego, la FAO ha desarrollado el modelo AquaCrop. Se llevó a cabo durante tres temporadas (2007-2009) un experimento de campo en el sureste de Damasco (Siria) para evaluar la respuesta del algodón cultivado con riego por goteo, bajo riego total (FI) y deficitario (80, 65, 50% del FI). Para la calibración del modelo se utilizaron los datos input y las comparaciones entre los valores simulados y observados de cobertura del dosel (CC), producción de biomasa en la cosecha, rendimiento final de semilla de algodón, y contenido de agua en el suelo, utilizando conjuntos de datos de la temporada 2007. Se validó el modelo calibrado utilizando conjuntos de datos de las temporadas 2008 y 2009, obteniéndose resultados precisos de simulación para CC [error cuadrático medio (RMSE) = 6,5%] y la evapotranspiración real ETa (RMSE =25 mm; índice de concordancia = 0,99). Los rendimientos de semilla previstos estuvieron dentro del 6% de las mediciones. Las predicciones del modelo para el contenido de agua en el perfil de 0,60 m se acercaron a la tendencia general de las mediciones. A pesar de la buena predicción de la ETa y del rendimiento de las semillas para cada tratamiento, hay una clara tendencia de AquaCrop a sobreestimar el uso eficiente del agua (WUE) en condiciones de déficit hídrico. Por lo tanto, en los casos de datos input limitados, el AquaCrop podría ser un modelo prometedor para estimar la p...

In 2011, common symptoms of grapevine dieback were frequently observed in 2- to 5-year-old table grape (Vitis vinifera L.) cvs. in four vineyards located in northern Tunisia. The symptoms included dead spur and cordons, shoot dieback, and sunken necrotic bark lesions, which progressed into the trunk resulting in the death of large sections of the vine. Longitudinal and transversal sections of cordons and spurs from symptomatic vines revealed brown wedge-shaped cankers of hard consistency. Twelve symptomatic samples from spur and cordons were collected, surface disinfected by dipping into 5% (v/v) sodium hypochlorite for 2 min, and small pieces from the edge of necrotic and healthy tissue were removed and plated onto potato dextrose agar (PDA) at 25°C in the dark. Based on colony and conidia morphological characteristics, isolates were divided in three species, named Diplodia seriata, Botryosphaeria dothidea, and Neofusicoccum luteum. D. seriata colonies were gray-brown with dense aerial mycelium producing brown cylindric to ellipsoid conidia rounded at both ends and averaged 22.4 × 11.7 μm (n = 50). B. dothidea colonies were initially white with abundant aerial mycelium, gradually becoming dark green olivaceous. Conidia were fusiform to fusiform elliptical with a subobtuse apex and averaged 24.8 × 4.7 μm (n = 50). N. luteum colonies were initially pale to colorless, gradually darkening with age and becoming gray to dark gray producing a yellow pigment that diffuses into the agar. Conidia were hyaline, thin-walled, aseptate, fusiform to fusiform elliptical, and averaged 19.8 × 5.5 μm (n = 50). Identity of the different taxa was confirmed by sequence analyses of the internal transcribed spacer (ITS1-5.8S-ITS2) region of the rDNA and part of the elongation factor 1-alpha (EF1-α) gene. BLAST analysis of sequences indicated that six isolates were identified as D. seriata (GenBank: AY259094, AY343353), one isolate as B. dothidea (AY236949, AY786319) and one isolate as N. luteum (AY259091, AY573217). Sequences were deposited in GenBank under accessions from KC178817 to KC178824 and from KF546829 to KF546836 for ITS region and EF1-α gene, respectively. A pathogenicity test was conducted on detached green shoots cv. Italia for the eight Botryosphaeriaceae isolates. Shoots were inoculated by placing a colonized agar plug (5 mm diameter) from the margin of a 7-day-old colony on fresh wound sites made with a sterilized scalpel. Each wound was covered with moisturized cotton and sealed with Parafilm. Control shoots were inoculated using non-colonized PDA plugs. After 6 weeks, discoloration of xylem and phloem and necrosis with average length of 38.8, 17.6, and 11.2 mm were observed from inoculated shoots with D. seriata, N. luteum, and B. dothidea, respectively, and all three fungi were re-isolated from necrotic tissue, satisfying Koch's postulates. Control shoots showed no symptoms of the disease and no fungus was re-isolated. In Tunisia, Botryosphaeria-related dieback was reported only on citrus tree caused by B. ribis (2), on Pinus spp. caused by D. pinea (4), on Quercus spp. caused by D. corticola (3), and on olive tree (Olea europea) caused by D. seriata (1). To our knowledge, this is the first report of D. seriata, B. dothidea, and N. luteum associated with grapevine dieback in Tunisia. References: (1) M. Chattaoui et al. Plant Dis. 96:905, 2012. (2) H. S. Fawcett. Calif. Citrogr. 16:208, 1931. (3) B. T. Linaldeddu et al. J. Plant Pathol. 91:234. 2009. (4) B. T. Linaldeddu et al. Phytopathol. Mediterr. 47:258, 2008.