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Matilde Tenorio Dominguez - One of the best experts on this subject based on the ideXlab platform.
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flavonoides extraidos de la cascara de naranja tangelo citrus reticulata x citrus paradisi y su aplicacion como antioxidante natural en el aceite vegetal sacha inchi plukenetia volubilis
Scientia Agropecuaria, 2016Co-Authors: Matilde Tenorio DominguezAbstract:The purpose of this research was to obtain extracts of flavonoids from orange tangelo peelings (Citrus reticulata x Citrus paradisi) and apply them as natural antioxidant to the vegetable oil Sacha inchi (Plukenetia volubilis). The information was obtained from experimental tests which were made in seven steps: physical and chemical characterization of the orange tangelo and the sacha inchi oil; extraction of flavonoids by the Soxhlet extractor; detection of flavonoids in each extract through fine layer chromatography and paper chromatography; identification and quantification of flavonoids by high resolution chromatography liquid (HPLC); determination of the antioxidant capacity of each extract of flavonoid, and finally evaluation of the antioxidant activity in oil sacha inchi, of the extract with the higher level of antioxidant capacity using a multifactorial design with two factors: extracts of flavonoids and concentration at three levels: 0.05%; 0.1% and 0.15%, and 16 blocks which are the times. The results showed that the liquid extract had the greatest quantity of flavonoids: 100.3724 mg/g, being naringine with 81.1727 mg/g, the flavonoid found in greatest proportion. At a concentration of 0.1%, the extract of flavonoid showed the lowest index of peroxide at 384 hours. It is concluded that the flavonoids present in the orange tangelo peeling can be used as raw extracts, without needing partial or total purification, to increase the sacha inchi oil life.
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flavonoides extraidos de la cascara de naranja tangelo citrus reticulata x citrus paradisi y su aplicacion como antioxidante natural en el aceite vegetal sacha inchi plukenetia volubilis
Scientia Agropecuaria, 2016Co-Authors: Matilde Tenorio DominguezAbstract:La investigacion tuvo como objetivo obtener extractos de flavonoides de la cascara de naranja tangelo (Citrus reticulata x Citrus paradisi) y aplicarlos como, antioxidante natural en el aceite vegetal Sacha inchi (Plukenetia volubilis). La informacion se obtuvo de las pruebas experimentales, que se realizo en siete etapas: caracterizacion fisica y quimica de la naranja tangelo y del aceite vegetal sacha inchi, obtencion de los extractos de flavonoides por soxhlet , deteccion de los flavonoides de cada extracto por cromatografia de capa fina y cromatografia de papel, identificacion y cuantificacion de los flavonoides por cromatografia liquida de alta resolucion (HPLC), determinacion de la capacidad antioxidante de cada extracto de flavonoide y finalmente se evaluo la actividad antioxidante en el aceite sacha inchi, del extracto que tuvo la mayor capacidad antioxidante, para lo cual se utilizo un diseno multifactorial con dos factores : extractos de flavonoides y concentracion con tres niveles: 0,05%; 0,1% y 0,15% y 16 bloques que son los tiempos. Los resultados mostraron que en el extracto acuoso se encontro la mayor cantidad de flavonoides: 100,3724 mg/g, siendo la naringina con 81,1727 mg/g el flavonoide que se encontro en mayor proporcion. A la concentracion del 0,1% el extracto de flavonoide presento el menor indice de peroxido a las 384 horas. Se concluye que los flavonoides presentes en la cascara de naranja tangelo pueden ser utilizados como extractos crudos sin necesidad de purificaciones parciales o totales, para conseguir aumentar la vida util del aceite sacha inchi.
Simone Rodrigues Da Silva - One of the best experts on this subject based on the ideXlab platform.
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tree performance and fruit yield and quality of okitsu satsuma mandarin grafted on 12 rootstocks
Scientia Horticulturae, 2010Co-Authors: Tatiana Cantuariasaviles, Francisco De Assis Alves Mourao Filho, Eduardo Sanches Stuchi, Simone Rodrigues Da Silva, Erick EspinozanunezAbstract:Abstract The citriculture in Brazil, as well as in other important regions in the world, is based on very few mandarin cultivars. This fact leads to a short harvest period and higher prices for off-season fruit. The ‘Okitsu’ Satsuma (Citrus unshiu Marc.) is among the earliest ripening mandarin cultivars, and it is considered to be tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.) and to citrus variegated chlorosis (Xylella fastidiosa Wells et al.). Despite having regular fruit quality under hot climate conditions, the early fruit maturation and absence of seeds of ‘Okitsu’ fruits are well suited for the local market in the summer (December through March), when the availability of citrus fruits for fresh consumption is limited. Yet, only a few studies have been conducted in Brazil on rootstocks for ‘Okitsu’. Consequently, a field trial was carried out in Bebedouro, Sao Paulo State, to evaluate the horticultural performance of ‘Okitsu’ Satsuma mandarin budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin (Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid Rangpur lime (Citrus limonia Osbeck) × ‘Swingle’ citrumelo (P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’ and ‘Flying Dragon’ (P. trifoliata var. monstrosa); the mandarins ‘Sun Chu Sha Kat’ (C. reticulata Blanco) and ‘Sunki’ (Citrus sunki (Hayata) Hort. ex. Tanaka); the Rangpur limes (C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange (Citrus sinensis × P. trifoliata), ‘Swingle’ citrumelo (P. trifoliata × C. paradisi), and ‘Orlando’ tangelo (C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 6 m × 3 m spacing, in a randomized block design. No supplementary irrigation was applied. Fruit yield, canopy volume, and fruit quality were assessed for each rootstock. A cluster multivariate analysis identified three different rootstock pairs with similar effects on plant growth, yield and fruit quality of ‘Okitsu’ mandarin. The ‘Flying Dragon’ trifoliate had a unique effect over the ‘Okitsu’ trees performance, inducing lower canopy volume and higher yield efficiency and fruit quality, and might be suitable for high-density plantings. The ‘Cravo Limeira’ and ‘Cravo FCAV’ Rangpur limes induced early-ripening of fruits, with low fruit quality. ‘Sun Chu Sha Kat’ and ‘Sunki’ mandarins and the ‘Orlando’ tangelo conferred lower yield efficiency and less content of soluble solids for the latter rootstock.
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Qualidade e maturação de tangerinas e seus híbridos em São Paulo
Sociedade Brasileira de Fruticultura, 2009Co-Authors: Simone Rodrigues Da Silva, João Carlos De Oliveira, Stuchi, Eduardo Sanches, Reiff, Eduardo TollerAbstract:A ampliação da oferta de tangerinas tanto no mercado interno como no externo é limitada pela grande quantidade de sementes nos frutos das principais cultivares, danos na casca resultante de doenças e pela pequena produção nas épocas mais quentes do ano. O presente trabalho teve como objetivo caracterizar a qualidade dos frutos e a época de maturação de 46 tangerinas e híbridos em condições de campo na Estação Experimental de Citricultura de Bebedouro (EECB), Bebedouro-SP. As variedades de tangerinas e híbridos (tangores e Tangelos) foram introduzidas de bancos de germoplasma da Itália, Portugal, Espanha e França, e a pesquisa desenvolveu-se durante os anos agrícolas de 2001/2002 e 2002/2003. Foram avaliadas características externas de qualidade, como altura e diâmetro dos frutos, massa dos frutos, facilidade em descascar com a mão e características internas como: número de sementes, teor de sólidos solúveis totais, acidez total titulável, rendimento em suco, ratio e rendimento em polpa. Duas cultivares apresentaram frutos de boa qualidade e época de maturação precoce, podendo ser disponibilizadas no mercado, num período de escassez deste tipo de citros, e serem alternativas à tangerina-'Cravo'. Quatro cultivares que apresentaram boa qualidade e maturação mediana poderão ser alternativas à 'Poncã'.The extension of tangerine offering both for internal and external markets is limited by the large amount of seeds present in the main cultivars, the occurrence of peel injures caused by diseases and the small fruit production during the hottest periods of the year. This work was aimed to characterize the fruit quality and maturation period of 46 tangerines and hybrids grown in the field at the Estação Experimental de Citricultura de Bebedouro (EECB), located in Bebedouro county, in São Paulo State, Brazil. Tangerines and their hybrids (tangors and Tangelos) were introduced from germplasm banks of Italy, Portugal, Spain and France, and the study was conducted during the years of 2001/2002 and 2002/2003. External fruit quality was assessed by measurements of fruit height and diameter, fruit mass and peeling facility, as well as the internal quality characteristics, such as seed number, total soluble solids content, total titrable acidity, juice content, ratio and pulp content. Two cultivars produced good quality and early ripening fruits that may be offered in the local marketinperiods oflow fruitoffer,asalternatives to the 'Cravo'tangerine.Fourcultivars that presented good quality and a moderate maturation precocity may be introduced as alternatives for the 'Ponkan' cultivar
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Quality and maturation of tangerines and their hybrids in São Paulo
Sociedade Brasileira de Fruticultura, 2009Co-Authors: Simone Rodrigues Da Silva, Stuchi, Eduardo Sanches, Oliveira, João Carlos De [unesp], Reiff, Eduardo TollerAbstract:A ampliação da oferta de tangerinas tanto no mercado interno como no externo é limitada pela grande quantidade de sementes nos frutos das principais cultivares, danos na casca resultante de doenças e pela pequena produção nas épocas mais quentes do ano. O presente trabalho teve como objetivo caracterizar a qualidade dos frutos e a época de maturação de 46 tangerinas e híbridos em condições de campo na Estação Experimental de Citricultura de Bebedouro (EECB), Bebedouro-SP. As variedades de tangerinas e híbridos (tangores e Tangelos) foram introduzidas de bancos de germoplasma da Itália, Portugal, Espanha e França, e a pesquisa desenvolveu-se durante os anos agrícolas de 2001/2002 e 2002/2003. Foram avaliadas características externas de qualidade, como altura e diâmetro dos frutos, massa dos frutos, facilidade em descascar com a mão e características internas como: número de sementes, teor de sólidos solúveis totais, acidez total titulável, rendimento em suco, ratio e rendimento em polpa. Duas cultivares apresentaram frutos de boa qualidade e época de maturação precoce, podendo ser disponibilizadas no mercado, num período de escassez deste tipo de citros, e serem alternativas à tangerina-'Cravo'. Quatro cultivares que apresentaram boa qualidade e maturação mediana poderão ser alternativas à 'Poncã'.The extension of tangerine offering both for internal and external markets is limited by the large amount of seeds present in the main cultivars, the occurrence of peel injures caused by diseases and the small fruit production during the hottest periods of the year. This work was aimed to characterize the fruit quality and maturation period of 46 tangerines and hybrids grown in the field at the Estação Experimental de Citricultura de Bebedouro (EECB), located in Bebedouro county, in São Paulo State, Brazil. Tangerines and their hybrids (tangors and Tangelos) were introduced from germplasm banks of Italy, Portugal, Spain and France, and the study was conducted during the years of 2001/2002 and 2002/2003. External fruit quality was assessed by measurements of fruit height and diameter, fruit mass and peeling facility, as well as the internal quality characteristics, such as seed number, total soluble solids content, total titrable acidity, juice content, ratio and pulp content. Two cultivars produced good quality and early ripening fruits that may be offered in the local marketinperiods oflow fruitoffer,asalternatives to the 'Cravo'tangerine.Fourcultivars that presented good quality and a moderate maturation precocity may be introduced as alternatives for the 'Ponkan' cultivar
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Qualidade e maturação de tangerinas e seus híbridos em São Paulo
Sociedade Brasileira de Fruticultura, 2009Co-Authors: Simone Rodrigues Da Silva, João Carlos De Oliveira, Stuchi, Eduardo Sanches, Reiff, Eduardo TollerAbstract:A ampliação da oferta de tangerinas tanto no mercado interno como no externo é limitada pela grande quantidade de sementes nos frutos das principais cultivares, danos na casca resultante de doenças e pela pequena produção nas épocas mais quentes do ano. O presente trabalho teve como objetivo caracterizar a qualidade dos frutos e a época de maturação de 46 tangerinas e híbridos em condições de campo na Estação Experimental de Citricultura de Bebedouro (EECB), Bebedouro-SP. As variedades de tangerinas e híbridos (tangores e Tangelos) foram introduzidas de bancos de germoplasma da Itália, Portugal, Espanha e França, e a pesquisa desenvolveu-se durante os anos agrícolas de 2001/2002 e 2002/2003. Foram avaliadas características externas de qualidade, como altura e diâmetro dos frutos, massa dos frutos, facilidade em descascar com a mão e características internas como: número de sementes, teor de sólidos solúveis totais, acidez total titulável, rendimento em suco, "ratio" e rendimento em polpa. Duas cultivares apresentaram frutos de boa qualidade e época de maturação precoce, podendo ser disponibilizadas no mercado, num período de escassez deste tipo de citros, e serem alternativas à tangerina-'Cravo'. Quatro cultivares que apresentaram boa qualidade e maturação mediana poderão ser alternativas à 'Poncã'
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Qualidade e maturação de tangerinas e seus híbridos em São Paulo Quality and maturation of tangerines and their hybrids in São Paulo
Sociedade Brasileira de Fruticultura, 2009Co-Authors: Simone Rodrigues Da Silva, Eduardo Sanches Stuchi, João Carlos De Oliveira, Eduardo Toller ReiffAbstract:A ampliação da oferta de tangerinas tanto no mercado interno como no externo é limitada pela grande quantidade de sementes nos frutos das principais cultivares, danos na casca resultante de doenças e pela pequena produção nas épocas mais quentes do ano. O presente trabalho teve como objetivo caracterizar a qualidade dos frutos e a época de maturação de 46 tangerinas e híbridos em condições de campo na Estação Experimental de Citricultura de Bebedouro (EECB), Bebedouro-SP. As variedades de tangerinas e híbridos (tangores e Tangelos) foram introduzidas de bancos de germoplasma da Itália, Portugal, Espanha e França, e a pesquisa desenvolveu-se durante os anos agrícolas de 2001/2002 e 2002/2003. Foram avaliadas características externas de qualidade, como altura e diâmetro dos frutos, massa dos frutos, facilidade em descascar com a mão e características internas como: número de sementes, teor de sólidos solúveis totais, acidez total titulável, rendimento em suco, "ratio" e rendimento em polpa. Duas cultivares apresentaram frutos de boa qualidade e época de maturação precoce, podendo ser disponibilizadas no mercado, num período de escassez deste tipo de citros, e serem alternativas à tangerina-'Cravo'. Quatro cultivares que apresentaram boa qualidade e maturação mediana poderão ser alternativas à 'Poncã'.The extension of tangerine offering both for internal and external markets is limited by the large amount of seeds present in the main cultivars, the occurrence of peel injures caused by diseases and the small fruit production during the hottest periods of the year. This work was aimed to characterize the fruit quality and maturation period of 46 tangerines and hybrids grown in the field at the Estação Experimental de Citricultura de Bebedouro (EECB), located in Bebedouro county, in São Paulo State, Brazil. Tangerines and their hybrids (tangors and Tangelos) were introduced from germplasm banks of Italy, Portugal, Spain and France, and the study was conducted during the years of 2001/2002 and 2002/2003. External fruit quality was assessed by measurements of fruit height and diameter, fruit mass and peeling facility, as well as the internal quality characteristics, such as seed number, total soluble solids content, total titrable acidity, juice content, ratio and pulp content. Two cultivars produced good quality and early ripening fruits that may be offered in the local marketinperiods oflow fruitoffer,asalternatives to the 'Cravo'tangerine.Fourcultivars that presented good quality and a moderate maturation precocity may be introduced as alternatives for the 'Ponkan' cultivar
M Kimchi - One of the best experts on this subject based on the ideXlab platform.
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susceptibility and resistance of citrus genotypes to alternaria alternata pv citri
Journal of Phytopathology, 1997Co-Authors: Z Solel, M KimchiAbstract:A survey of citrus cultivars in Israel in orchards where Alternaria brown spot was common on Minneola Tangelos (mandarin × grapefruit), revealed the occurrence of the disease as typical foliar and fruit lesions on Dancy and Ellendale (mandarins), on Murcott tangor (mandarin × sweet orange), on Nova and Idith (mandarin hybrids), on Calamondin, and on Sunrise and Redblush (grapefruit). Isolates of Alternaria alternata from each of these hosts were proven to be pathogenic to Minneola tangelo. The host range of A. alternata pv. citri from Israel was assayed by inoculating leaves of diverse citrus genotypes. Several mandarins and their hybrids (Dancy, Kara, King, Wilking, Satsuma, Minneola, Orlando, Mikhal, Idith, Nova, Page, Murcott), grapefruit (Marsh seedless), grapefruit × pummelo (Oroblanco), sweet orange (Shamouti, Valencia, Washington navel) Calamondin, and Volkamer citrus were susceptible. Several mandarins and their hybrids (Clementine, Avana, Yafit, Ortanique), Cleopatra, one sweet orange cultivar (Newhall), pummelo (Chandler), lemon (Eureka), Rough lemon, Rangpur lime, sweet lime, citron, limequat, sour orange, Troyer citrange and Alemow were resistant.
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iprodione resistance of alternaria alternata pv citri from minneola tangelo in israel and florida
Plant Disease, 1996Co-Authors: Z Solel, L W Timmer, M KimchiAbstract:In an orchard of Minneola tangelo at Suffa, Israel, where iprodione had been used in the preceding 3 years, iprodione treatments in the current season failed to control Alternaria brown spot, caused by Alternaria alternata pv. citri. All 200 A. a. pv. citri isolates from this orchard were iprodione resistant, as evidenced by growth on potato-dextrose agar (PDA) amended with 25 mg of iprodione per liter. The average ED 50 of 10 resistant isolates was 280 mg of iprodione per liter. In addition, in Florida and Israel, many isolates of A. a. pv. citri were recovered from brown spot lesions of Minneola tangelo in randomly selected orchards differing in iprodione history. The average ED 50 of these iprodione-sensitive isolates ranged from 0.20 to 0.62 mg of iprodione per liter. All Florida isolates of A. a. pv. citri were iprodione sensitive, with ED 50 values of 0.20 to 0.62 mg of iprodione per liter. When plates with mycelial plugs were incubated for 7 to 14 days on PDA amended with 6 to 200 mg/liter, most isolates from Florida and Israel developed resistant colonies as sectors. The subcultures from these sectors, designated as laboratory-selected iprodione-resistant isolates, grew well on PDA supplemented with 100 mg of iprodione per liter. Detached leaves of Minneola tangelo that had been sprayed with iprodione at 250 or 500 mg/liter were well-protected from infection by iprodione-sensitive isolates of A. a. pv. citri. However, when leaves were inoculated with an iprodione-resistant isolate from Suffa, disease was not controlled. The severity of infection of leaves inoculated with laboratory-selected resistant isolates from Florida or Israel was not affected by spraying iprodione at 250 mg/liter, but was reduced slightly at 500 mg/liter.
Patrick Ollitrault - One of the best experts on this subject based on the ideXlab platform.
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genotyping by sequencing reveals the interspecific c maxima c reticulata admixture along the genomes of modern citrus varieties of mandarins tangors Tangelos orangelos and grapefruits
PLOS ONE, 2017Co-Authors: Amel Oueslati, François Luro, Hélène Vignes, Pierre Mournet, Amel Salhihannachi, Patrick OllitraultAbstract:The mandarin horticultural group is an important component of world citrus production for the fresh fruit market. This group formerly classified as C. reticulata is highly polymorphic and recent molecular studies have suggested that numerous cultivated mandarins were introgressed by C. maxima (the pummelos). C. maxima and C. reticulata are also the ancestors of sweet and sour oranges, grapefruit, and therefore of all the “small citrus” modern varieties (mandarins, tangors, Tangelos) derived from sexual hybridization between these horticultural groups. Recently, NGS technologies have greatly modified how plant evolution and genomic structure are analyzed, moving from phylogenetics to phylogenomics. The objective of this work was to develop a workflow for phylogenomic inference from Genotyping By Sequencing (GBS) data and to analyze the interspecific admixture along the nine citrus chromosomes for horticultural groups and recent varieties resulting from the combination of the C. reticulata and C. maxima gene pools. A GBS library was established from 55 citrus varieties, using the ApekI restriction enzyme and selective PCR to improve the read depth. Diagnostic polymorphisms (DPs) of C. reticulata/C. maxima differentiation were identified and used to decipher the phylogenomic structure of the 55 varieties. The GBS approach was powerful and revealed 30,289 SNPs and 8,794 Indels with 12.6% of missing data. 11,133 DPs were selected covering the nine chromosomes with a higher density in genic regions. GBS combined with the detection of DPs was powerful for deciphering the “phylogenomic karyotypes” of cultivars derived from admixture of the two ancestral species after a limited number of interspecific recombinations. All the mandarins, mandarin hybrids, Tangelos and tangors analyzed displayed introgression of C. maxima in different parts of the genome. C. reticulata/C. maxima admixture should be a major component of the high phenotypic variability of this germplasm opening up the way for association studies based on phylogenomics. (Resume d'auteur)
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Genotyping by sequencing reveals the interspecific C. maxima / C. reticulata admixture along the genomes of modern citrus varieties of mandarins, tangors, Tangelos, orangelos and grapefruits
PLoS ONE, 2017Co-Authors: Amel Oueslati, Amel Salhi-hannachi, François Luro, Hélène Vignes, Pierre Mournet, Patrick OllitraultAbstract:The mandarin horticultural group is an important component of world citrus production for the fresh fruit market. This group formerly classified as C. reticulata is highly polymorphic and recent molecular studies have suggested that numerous cultivated mandarins were introgressed by C. maxima (the pummelos). C. maxima and C. reticulata are also the ancestors of sweet and sour oranges, grapefruit, and therefore of all the "small citrus" modern varieties (mandarins, tangors, Tangelos) derived from sexual hybridization between these horticultural groups. Recently, NGS technologies have greatly modified how plant evolution and genomic structure are analyzed, moving from phylogenetics to phylogenomics. The objective of this work was to develop a workflow for phylogenomic inference from Genotyping By Sequencing (GBS) data and to analyze the interspecific admixture along the nine citrus chromosomes for horticultural groups and recent varieties resulting from the combination of the C. reticulata and C. maxima gene pools. A GBS library was established from 55 citrus varieties, using the ApekI restriction enzyme and selective PCR to improve the read depth. Diagnostic polymorphisms (DPs) of C. reticulata/C. maxima differentiation were identified and used to decipher the phylogenomic structure of the 55 varieties. The GBS approach was powerful and revealed 30,289 SNPs and 8,794 Indels with 12.6% of missing data. 11,133 DPs were selected covering the nine chromosomes with a higher density in genic regions. GBS combined with the detection of DPs was powerful for deciphering the "phylogenomic karyotypes" of cultivars derived from admixture of the two ancestral species after a limited number of interspecific recombinations. All the mandarins, mandarin hybrids, Tangelos and tangors analyzed displayed introgression of C. maxima in different parts of the genome. C. reticulata/C. maxima admixture should be a major component of the high phenotypic variability of this germplasm opening up the way for association studies based on phylogenomics.
L W Timmer - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the alter rater model for timing of fungicide applications for control of alternaria brown spot of citrus
Plant Disease, 2003Co-Authors: Alka Bhatia, Pamela D Roberts, L W TimmerAbstract:ABSTRACT Alternaria brown spot, caused by Alternaria alternata, results in serious yield losses of tangerines and their hybrids in Florida. The Alter-Rater model predicts the need for fungicide applications based on daily cumulative points that are assigned on the basis of rainfall, leaf wetness, and temperature. Previously, Alter-Rater threshold or trigger values of 50, 75, 100, and 150 points for application of copper fungicides were suggested for groves with different cultivars and disease histories. In this study, we evaluated thresholds of 50, 100, and 150 points in four Minneola tangelo and Murcott tangor groves in 2000 and 2001. For comparison, copper fungicides were applied according to the DISC Copper Model in 2000 and according to calendar sprays in 2001. Use of the Alter-Rater model resulted in fewer sprays in three of the four groves in 2000 and better fruit quality in the other grove than the Copper Model. Compared to a calendar spray schedule in 2001, use of the Alter-Rater model resulted in...
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Population Genetic Structure and Host Specificity of Alternaria spp. Causing Brown Spot of Minneola Tangelo and Rough Lemon in Florida.
Phytopathology®, 1999Co-Authors: Tobin L. Peever, Y. Canihos, L. Olsen, A. M. Ibáñez, Y.-c. Liu, L W TimmerAbstract:ABSTRACT Alternaria spp. were sampled from two rough lemon (RL) and two Minneola tangelo (MIN) groves in a limited geographic area in central Florida to test for host-specialized forms of the pathogen. Isolates of Alternaria spp. were scored for variation at 16 putative random amplified polymorphic DNA (RAPD) loci and for pathogenicity on both hosts. Subpopulations on each host were differentiated genetically and pathogenically, which was consistent with the hypothesis of host specialization. Highly significant genetic differentiation was detected among all four subpopulations (Nei's coefficient of gene differentiation [GST] = 0.292, P = 0.000); most of the differentiation occurred between hosts (GST = 0.278, P = 0.000). Phenograms of qualitative similarities among isolates within subpopulations revealed two or three distinct clusters of isolates within each subpopulation. The majority of isolates sampled from RL were pathogenic on RL and not on MIN, although a few RL isolates were able to induce disease ...
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iprodione resistance of alternaria alternata pv citri from minneola tangelo in israel and florida
Plant Disease, 1996Co-Authors: Z Solel, L W Timmer, M KimchiAbstract:In an orchard of Minneola tangelo at Suffa, Israel, where iprodione had been used in the preceding 3 years, iprodione treatments in the current season failed to control Alternaria brown spot, caused by Alternaria alternata pv. citri. All 200 A. a. pv. citri isolates from this orchard were iprodione resistant, as evidenced by growth on potato-dextrose agar (PDA) amended with 25 mg of iprodione per liter. The average ED 50 of 10 resistant isolates was 280 mg of iprodione per liter. In addition, in Florida and Israel, many isolates of A. a. pv. citri were recovered from brown spot lesions of Minneola tangelo in randomly selected orchards differing in iprodione history. The average ED 50 of these iprodione-sensitive isolates ranged from 0.20 to 0.62 mg of iprodione per liter. All Florida isolates of A. a. pv. citri were iprodione sensitive, with ED 50 values of 0.20 to 0.62 mg of iprodione per liter. When plates with mycelial plugs were incubated for 7 to 14 days on PDA amended with 6 to 200 mg/liter, most isolates from Florida and Israel developed resistant colonies as sectors. The subcultures from these sectors, designated as laboratory-selected iprodione-resistant isolates, grew well on PDA supplemented with 100 mg of iprodione per liter. Detached leaves of Minneola tangelo that had been sprayed with iprodione at 250 or 500 mg/liter were well-protected from infection by iprodione-sensitive isolates of A. a. pv. citri. However, when leaves were inoculated with an iprodione-resistant isolate from Suffa, disease was not controlled. The severity of infection of leaves inoculated with laboratory-selected resistant isolates from Florida or Israel was not affected by spraying iprodione at 250 mg/liter, but was reduced slightly at 500 mg/liter.
