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Fadel A.L.,University of Sao Paulo | Stuchi E.S.,Estacao Experimental de Citricultura de Bebedouro | Alves de Carvalho S.,Anhanguera | Della Coletta-Filho H.,Anhanguera
Crop Protection | Year: 2014

Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa, is a bacterial disease of great importance to the Brazilian citrus industry. CVC is transmitted by grafting and by leafhoppers of the Cicadellidae and Cercopidae families. There is little information about CVC tolerant sweet orange cultivars (Citrus sinensis L. Osbeck). However, previous studies have indicated some resistance to CVC in the 'Navelina ISA 315' cultivar. Based on such information, this study has been carried out to determine the resistance of 'Navelina ISA 315' to CVC observing disease symptoms in the field and in the greenhouse, associated with the presence and quantitation of X.fastidiosa in plant tissue by PCR and quantitative real time PCR (qPCR). In agreement with previous information, the results show that 'Navelina ISA 315' is resistant to CVC, on the grounds that almost no symptoms and low bacterial concentrations were found. © 2014 Elsevier Ltd.

Santos L.O.,Paulista University | Durigan J.F.,Paulista University | Martins R.N.,Paulista University | Durigan M.F.B.,Paulista University | Stuchi E.S.,Estacao Experimental de Citricultura de Bebedouro
Acta Horticulturae | Year: 2012

Fruit of 'Satsuma Okitsu' tangerine are similar to 'Ponkan', with a maturation period starting in January, and supplying the Brazilian market during the off-season. Fruits of this cultivar have to be harvested with green peel, which is not well accepted by the market. This study aimed to evaluate the degreening of 'Satsuma Okitsu' tangerine using ethephon (2-chloroethyl phosphonic acid). The fruits were harvested with stems when they reached soluble solids:acidity ratio of >7. After selection, the fruits were treated with the Imazalil fungicide (200 ml 100 L-1) for two min and after 24 hours fruits were dipped in different concentrations of ethephon (Ethrel 240): control, 250, 500 and 1000 ppm. The fruits were analyzed every 3 days during 9 days of storage at 18±2°C, 85±5% RH for appearance, weight loss, rind color, soluble solids, acidity and ascorbic acid content. The experiment was conducted as a factorial in a completely randomized design. The treatment with Ethrel provided the best flavedo or rind degreening which made these fruits turn orange with greater intensity and showed good quality during 9 days at 18°C, besides increase in weight loss.

Santos L.O.,Sao Paulo State University | Durigan J.F.,Sao Paulo State University | Martins R.N.,Sao Paulo State University | Durigan M.F.B.,Sao Paulo State University | Stuchi E.S.,Estacao Experimental de Citricultura de Bebedouro
Acta Horticulturae | Year: 2012

This study aimed to evaluate the postharvest conservation of tangerines 'Fremont', 'Satsuma Okitsu' and 'Ponkan' when stored at different conditions, as well as the quality of the minimally processed product. Fruit were harvested when a sugar:acid ratio of 10.0 to 12.0 for 'S. Okitsu' and 'Fremont' and 16.0 to 19.0 for 'Ponkan' was reached, selected for uniformity of color, size, and absence of injuries. Whole fruits were stored at 3°C, 85% RH and 7°C, 95% RH, and after each storage period, fruits were brought to ambient conditions (22°C, 65% RH) for 3 days before evaluation. The minimally processed products (peeled) were packed in polystyrene trays (22.4×14.8×3.7 cm) coated with polyvinyl chloride (PVC) stretchable, with 0.014 mm thickness, and in lidded packages (500 ml) of transparent polyethylene terephthalate. Fruit were analyzed for appearance, weight loss, respiratory rate, package atmosphere, rind and pulp color, soluble solids, titratable acidity and ascorbic acid content. Shelf life of tangerine 'Fremont' was limited to 42 days based on freshness. Its minimally processed product had a 9 day shelf-life for products packaged in PVC film. The mandarins 'S. Okitsu' had 35 days shelf-life at 7°C, which was reduced to 28 days at 3°C. Its fresh-cut product had a shelf-life of 15 days, stored in PVC or PET. 'Ponkan' fruit stored at 3°C had a shelf life of 35 days, which was reduced to 28 days at 7°C. When minimally processed, its shelf-life lasted for 15 days, whether packaged in PVC or PET. The 'Ponkan' had a shelf-life of 35 days at 3°C and 28 days at 7°C, also limited by loss of freshness. When minimally processed and stored in PVC or PET, its shelf life reached 15 days.

Goncalves F.P.,University of Sao Paulo | Stuchi E.S.,Estacao Experimental de Citricultura de Bebedouro | Lourenco S.A.,University of Sao Paulo | Hau B.,Leibniz University of Hanover | Amorim L.,University of Sao Paulo
Plant Pathology | Year: 2012

Citrus Variegated Chlorosis (CVC) is currently present in approximately 40% of citrus plants in Brazil and causes an annual loss of around 120million US dollars to the Brazilian citrus industry. Despite the fact that CVC has been present in Brazil for over 20years, a relationship between disease intensity and yield loss has not been established. In order to achieve this, an experiment was carried out in a randomized block design in a 3×2 factorial scheme with 10-year-old Natal sweet orange. The following treatments were applied: irrigation with 0, 50 or 100% of the evapotranspiration of the crop, combined with natural infection or artificial inoculation with Xylella fastidiosa, the causal agent of CVC. The experiment was evaluated during three seasons. A negative exponential model was fitted to the relationships between yield versus CVC severity and yield versus Area Under Disease Progress Curve (AUDPC). In addition, the relationship between yield versus CVC severity and canopy volume was fitted by a multivariate exponential model. The use of the AUDPC variable showed practical limitations when compared with the variable CVC severity. The parameter values in the relationship of yield-CVC severity were similar for all treatments unlike in the multivariate model. Consequently, the yield-CVC intensity relationship (with 432 data points) could be described by one single model: y=114·07 exp(-0·017 x), where y is yield (symptomless fruit weight in kg) and x is disease severity (R 2=0·45; P<0·01). © 2011 The Authors. Plant Pathology © 2011 BSPP.

Girardi E.A.,Estacao Experimental de Citricultura de Bebedouro | Filho F.A.A.M.,University of Sao Paulo | Alves A.S.R.,Casa do Cafe Rua Agua Santa
Revista Brasileira de Fruticultura | Year: 2010

The fertilizer program is a major practice for screened citrus nursery tree production. The effect of six fertilizer programs commercially recommended was evaluated on the production of 'Valencia' sweet orange [Citrus sinensis (L.) Osbeck] nursery trees budded on rootstocks 'Rangpur' lime (Citrus limonia Osbeck) and 'Swingle' citrumelo [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.]. Experimental work was carried out from rootstock transplant until 180 days after budding, in a citrus nursery in Conchal, SP, Brazil. Fertilizer managements consisted of two soluble fertilizers solutions applied isolated, soluble fertilizers associated with control release fertilizer and control release fertilizer alone. Experimental design was factorial 2 × 6 (rootstock × fertilizer program) in randomized blocks, with three replicates and 12 plants in the unit. 'Rangpur' lime induced higher vigor to the scion. Plant growth was similar among fertilizer managements, even though nutrient amounts applied varied significantly. Therefore, nurserymen can choose the most practical or economic management depending on local conditions.

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