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Variabilidade e heran?a da resist?ncia de mangueira (Mangifera indica L.) aos fungos Lasiodiplodia theobromae e Neofusicoccum parvumCoelho, Washington Carvalho Pacheco 06 February 2018 (has links)
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Previous issue date: 2018-02-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The fungi Lasiodiplodia theobromae and Neofusicoccum parvum are pathogens responsible for reducing mango yield due to dieback, which both cause in the culture. Inheritance studies and variability in accessions for fungal diseases in mango, in general, are quite limited, despite their importance for the development of cultivars. The goals of this study were1) to evaluate the inheritance of resistance to dieback disease caused by L. theobromae and N. parvumin three crossings, and 2) evaluate 75mango accessions for resistance to these fungi to support mango breeding programs. Young branches containing young leaves were selected, and suspension of 103 conidia/mL of L. theobromae or N. parvum was sprayed, separately. After inoculation, leaves were protected in a plastic wet chamber for 48 hours. The infection was estimated by taking the branches without symptoms/total number of inoculated branches. Plants without disease symptoms in more than 90% of the brancheswere considered as resistant. Monogenic resistance, conferred by recessive alleles, was observed for L. theobromae for the three crossings evaluated, despite the 13:3 segregation detected for 'Keitt' x 'Tommy Atkins'. For N. parvum, recessive resistance with 3:1 monogenic segregation was observed in the crossing 'Keitt' x 'Tommy Atkins', and 9:7 epistatic segregation was observed in the crossing ?Haden? x ?Tommy Atkins? and ?Espada x ?Tommy Atkins?. ?Apple DCG?, ?Ataulfo?, ?Da porta?, ?Dashehari?, ?Espada?, ?Haden?, ?Haden 2H?, ?Heidi?, ?Irwin?, ?Keitt?, ?Kent?, ?N?ldica?, ?Recife? and ?Smith? were resistant to both pathogens, being promising for breeding programs. 'Rosa' are resistant to L. theobromae, and susceptible to N. parvum. 'Tommy Atkins', the most grown cultivar in the S?o Francisco valley, was susceptible to both pathogens.The mono or digenic inheritance observed in the present study indicates the possibility of selection in the F2 generation and identification of plants with double resistance to L. theobromae and N. parvum in mango trees. / Os fungos Lasiodiplodia theobromae e Neofusicoccum parvum s?o pat?genos que podem limitar a produ??o da mangueira devido a doen?a morte-descendente, que ambos ocasionam na cultura. Estudos de heran?a da resist?ncia e da variabilidade em acessos para doen?as f?ngicasem mangueira, em geral, s?o bastante limitados, apesar da sua import?ncia para o desenvolvimento de cultivares. Este estudo teve como objetivos 1) avaliar a heran?a da resist?ncia ? doen?a morte-descendente causadas por L. theobromae e N. parvumem tr?s cruzamentos, e 2) avaliar 75acessos de mangueira para resist?ncia aos dois fungos, para apoiar programas de melhoramento da cultura. Foram selecionados ramos jovens contendo folhas jovens para aplica??o, com aux?lio de pulverizador manual, de suspens?o de con?dios de 103 con?dios/mL de L. theobromae ou N. parvum. Ap?s a inocula??o, as folhas foram protegidas em c?mara ?mida de pl?stico durante 48 horas. A infec??o foi estimada tomando-se ramos sem sintomas / n?mero total de ramos inoculados. As plantas sem sintomas de doen?a em mais de 90% dos ramos, em diferentes per?odos de inocula??o, foram consideradas resistentes.Foi observada resist?ncia monog?nica conferida por alelos recessivos para L. theobromae, para os tr?s cruzamentos avaliados, apesar da segrega??o 13:3 para ?Keitt? x ?Tommy Atkins?. Para N. parvum foi observada resist?ncia recessiva com segrega??o monog?nica 3:1 no cruzamento ?Keitt? x ?Tommy Atkins? e segrega??o epist?tica 9:7 nos cruzamentos ?Haden? x ?Tommy Atkins? e ?Espada x ?Tommy Atkins?. Os acessos ?Apple DCG?, ?Ataulfo?, ?Da porta?, ?Dashehari?, ?Espada?, ?Haden?, ?Haden 2H?, ?Heidi?, ?Irwin?, ?Keitt?, ?Kent?, ?N?ldica?, ?Recife? e ?Smith?apresentaram resist?ncia aos dois pat?genos, sendo bastante promissoras para programas de melhoramento. ?Rosa? apresentou resist?ncia a L. theobromae, sendo considerada suscet?vel ao N. parvum. ?Tommy Atkins?, a mais cultivada no vale do S?o Francisco, foi suscept?vel a ambos os pat?genos. A heran?a mono ou dig?nica observada no presente estudo indica a possibilidade de sele??o na gera??o imediata aos cruzamentos, bem como a possibilidade da identifica??o de plantas com resist?ncia dupla a L. theobromae e N. parvum em mangueira.
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Efeitos de ferimento, umidade e temperatura na virulência de espécies de Lasiodiplodia em frutos de mangaSILVA, Soraya de Lima e 12 February 2016 (has links)
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Previous issue date: 2016-02-12 / Dieback and stem-end rot, caused by species of Botryosphaeriaceae, are important diseases of mango in the Brazilian Northeast. These diseases limit the production and drastically reduce fruit quality, directly affecting exports. In this study, was investigated the effects of wound, humidity and temperature in virulence of five Lasiodiplodia species prevalent in the orchards of northeastern Brazil (L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae and L. viticola). Lasiodiplodia hormozganensis, L. pseudotheobromae and L. theobromae did not induce symptoms in non-wounded fruits, but all Lasiodiplodia species induced symptoms in wounded fruits. There were differences between species in relation to virulence levels both in the absence and in the presence of wound. The wound age in fruits influenced the virulence of Lasiodiplodia species of all species has expressed increased virulence when inoculated immediately after the wound, reducing the virulence with increasing wound age. Lasiodiplodia pseudotheobromae was the most sensitive species to the wound age. The high relative humidity length influenced the virulence of the Lasiodiplodia species, with an increase in virulence with the lifting of the period under high humidity. Lasiodiplodia hormozganensis, L. iraniensis and L. theobromae induced symptoms in the absence of high humidity. The virulence of Lasiodiplodia species was significantly influenced by the time interval between the inoculation and beginning of high relative humidity. All species expressed increased virulence when exposed to high relative humidity immediately after inoculation and decreased virulence with increasing time interval to beginning of high humidity. Lasiodiplodia iraniensis and L. viticola were the species most sensitive to the delay in onset of high relative humidity. No Lasiodiplodia species induced symptoms in fruit stored at 5 ° C and only L. pseudotheobromae induced symptoms at 10 ° C. There was no significant difference between species in relation to the optimum temperature for maximum virulence expression, ranging between 29.6 and 31.3 ° C. In most experiments, the increased virulence was demonstrated by L. iraniensis while L. viticola was less virulent. / A morte descendente e a podridão peduncular, causadas por espécies de Botryosphaeriaceae, são importantes doenças da mangueira no Nordeste brasileiro. Essas doenças limitam a produção e reduzem drasticamente a qualidade dos frutos, afetando diretamente a exportação. Nesse estudo, foi investigado o efeito de ferimento, umidade e temperatura na virulência de cinco espécies de Lasiodiplodia prevalentes em pomares de mangueira do Nordeste brasileiro (L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae e L. viticola). Lasiodiplodia hormozganensis, L. pseudotheobromae e L. theobromae não induziram sintomas em frutos sem ferimento, mas todas as espécies de Lasiodiplodia induziram sintomas em frutos feridos. Houve diferença entre as espécies em relação aos níveis de virulência tanto na ausência como na presença de ferimento. A idade do ferimento nos frutos influenciou no nível de virulência das espécies de Lasiodiplodia e todas as espécies expressaram a maior virulência quando inoculadas imediatamente após a realização do ferimento, reduzindo a virulência com a elevação da idade do ferimento. Lasiodiplodia pseudotheobromae foi a espécie mais sensível à idade do ferimento. O tempo de duração da umidade relativa elevada influenciou na virulência das espécies de Lasiodiplodia, havendo um aumento na virulência com a elevação do período em umidade elevada. Lasiodiplodia hormozganensis, L. iraniensis e L. theobromae induziram sintomas na ausência de umidade elevada. A virulência das espécies de Lasiodiplodia foi influenciada significativamente pelo intervalo de tempo entre a inoculação e o início da umidade relativa elevada. Todas as espécies expressaram a maior virulência quando submetidas à umidade relativa elevada imediatamente após a inoculação e reduziram a virulência com o aumento do intervalo de tempo para início da umidade relativa elevada. Lasiodiplodia iraniensis e L. viticola foram as espécies mais sensíveis à demora para início da umidade relativa elevada. Nenhuma espécie de Lasiodiplodia induziu sintomas em frutos armazenados a 5 ºC e somente L. pseudotheobromae induziu sintomas a 10 ºC. Não houve diferença significativa entre as espécies em relação à temperatura ótima para expressão da máxima virulência, que variou entre 29,6 e 31,3 ºC. Na maioria dos experimentos, a maior virulência foi evidenciada por L. iraniensis, enquanto L. viticola foi a menos virulenta.
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Sensibilidade de isolados de Lasiodiplodia theobromae de mamoeiros do nordeste brasileiro a tiofanato metílicoCAVALCANTE, Rômulo Diniz 25 February 2013 (has links)
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Previous issue date: 2013-02-25 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Stem rot caused by Lasiodiplodia theobromae is an important postharvest disease of papaya in Brazil. The disease symptoms start on the stem region and then progressing around the fruit. The tissues remain with soaked aspect and with progression of symptoms, lesions become dark brown and depressed. The infected area becomes gradually devoid of parenchymal tissue and fruits lose their consistency and strength. It is recommended that the disease control starts in the field and continue until the commercialization phase since the symptoms are difficult to be perceived until an advanced stage of maturation. The use of Fungicides is one of the main disease management measures. However, there are no data available on the sensitivity of L. theobromae to thiophanate methyl, the most common fungicide used in papaya orchards in Northeastern Brazil. Thus, the EC50 of 109 isolates of the fungus, representing five populations of the pathogen was estimated in vitro for the fungicide. Of the 109 isolates, 20,2% were non-sensitive (NS) to the fungicide with EC50 values greater than 300 mg ml-1, for the remaining 79.8% sensitive (S) isolates the average EC50 was 1.87 μg ml−1. The EC50 values for the NS isolates were significantly (P≤0.05) higher than those for the sensitive isolates. Seven components of fitness were measured for the 10 isolates with lower and high values of EC50. When the fitness components were evaluated, the non-sensitive (NS) isolates showed sporulation capacity significantly lower than the sensitive isolates, indicating a fitness costs. / A podridão peduncular causada por Lasiodiplodia theobromae é uma doença em pós-colheita importante na cultura do mamoeiro no Brasil. Os sintomas da doença iniciam na região do pedúnculo e então progride para todo o fruto. Os tecidos permanecem com aspecto encharcado e com a progressão dos sintomas, as lesões se tornam marrom escura e deprimida. A área infectada torna-se gradualmente desprovida de tecido parenquimatoso e os frutos perdem sua consistência e vigor. É recomendado que o controle da doença seja iniciado no campo e continue até a fase de comercialização, uma vez que os sintomas são difíceis de serem percebidos até um estádio avançado de maturação. O uso de fungicidas é uma das principais medidas de manejo da doença. Todavia, dados sobre a sensibilidade de L. theobromae a tiofanato metílico, fungicida comumente empregado em pomares de mamoeiros no Nordeste brasileiro são inexistentes. Sendo assim, a CE50 de 109 isolados do fungo, representando cinco populações do patógeno foi estimada in vitro para o fungicida. Dos 109 isolados, 20,2% foram não sensíveis (NS) ao fungicida com valores de CE50 superiores a 300 μg ml-1, para 79,8% dos isolados remanescente denominados de sensíveis (S), a média de CE50 foi 1,87 μg ml-1. Os valores da CE50 dos isolados NS foram significativamente (P≤0.05) superiores quando comparados com os isolados S. Sete componentes de adaptabilidade foram mensurados para os 10 isolados com menores e maiores valores de CE50. Quando foram avaliados os componentes de adaptabilidade, os isolados não sensíveis apresentaram capacidade de esporulação significativamente inferior aos isolados sensíveis, indicando um custo de adaptabilidade.
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Etiología y control de las enfermedades fúngicas de la madera del almendro en la isla de MallorcaOlmo García, Diego 25 January 2016 (has links)
[EN] Almond is one of the main crops of Majorca Island. Since 2008, symptoms of severe decline of almond trees have been observed in several orchards from different areas of the Island. Disease symptoms are similar to those described by different authors in other parts of the world caused by fungal trunk pathogens. In order to study the etiology of this problem, surveys were conducted on almond orchards distributed throughout the main growing regions in Majorca for six consecutive years (2009-2014). Based on morphological and molecular identification, 14 fungal species were recovered from almond wood samples: Collophora hispanica, Diplodia olivarum, D. seriata, Eutypa lata, E. leptoplaca, Fomitiporia mediterranea, Neofusicoccum luteum, N. mediterraneum, N. parvum, Omphalotus olearius, Phaeoacremonium amygdalinum, Pm. iranianum, Phellinus pomaceus and Pleurostomophora richardsiae and two species were recovered from one apricots orchard near almonds orchards: : Pm. minimum and Pm. venezuelense. Based on the DNA sequence analyses and morphological features, C. hispanica and Pm. amygdalinum proved distinct from all known species, and have been described. The most common species recovered from almond samples were P. richardsiae and D. seriata, followed by other species belonging to the family Botryosphaeriaceae and C. hispanica. The most frequently species isolated were also widely distributed and present in more regions. Subsequently, two pathogenicity tests were carried on almond trees by using representative isolates of some of the most frequent species. The first one was held for two consecutive years (2013 and 2014) with five species of Botryosphaeriaceae (D. olivarum, D. seriata, N. luteum, N. mediterraneum and N. parvum) and two species of Diatrypaceae (E. lata and E. leptoplaca). Fungi were inoculated on 1-2 years old almond trees of four different cultivars ('Jordi', 'Ferragnes', 'Pons' and 'Vivot') under field conditions. Nine months after inoculation, the total length of internal necrosis was evaluated. All species were pathogenic on almond. Neofusicoccum luteum caused the longest average lesion during the first year, and N. mediterraneum and N. parvum caused the longest lesion during the second year. Eutypa leptoplaca caused the shortest lesion length in both years of study. In addition, fungal lesion length varied depending on the variety of almond evaluated. In the first year of study, the more tolerant variety was 'Jordi', while in the second year, 'Ferragnes' and 'Vivot' varieties showed the highest degree of tolerance to fungal infection. In the second trial, almond seedlings variety 'Ferragnes' were inoculated with C. hispanica, Pm. amygdalinum, Pm. iranianum and P. richardsiae. Six months after inoculation the lesion length was evaluated. All species inoculated were pathogenic on almond, being P. richardsiae the most virulent species. Finally, the ability of some commercial fungicides to protect pruning wounds from infection by four species of Botryosphaeriaceae (D. seriata, N. luteum, N. mediterraneum and N. parvum) was evaluated. This study was conducted in two phases, an initial in vitro evaluation (mycelial growth assay) with 10 fungicides, followed by an evaluation of five fungicides, which proved to be effective in the in vitro trial, applied on pruning wounds at 1 and 7 days after inoculation. Internal lesion length and the percentage of re-isolation of the pathogen were calculated. tebuconazole and pyraclostrobin were the most effective fungicides in the in vitro evaluation, followed by cyproconazole and thiophanate-methyl. Thiophanate-methyl was the most effective fungicide to protect pruning wounds from infections caused by species of Botryosphaeriaceae. / [ES] Desde el año 2008, en parcelas de diferentes zonas de la isla se ha constatado la presencia síntomas de decaimiento de ramas y muerte de almendros, que recuerdan a los descritos por diferentes autores en otras zonas del mundo causados por hongos patógenos de la madera en diversos cultivos. Para estudiar su etiología se realizaron prospecciones en parcelas de almendros de la isla durante seis años (2009-2014). Se caracterizaron los síntomas y se tomaron muestras que se analizaron en laboratorio. En los análisis se obtuvieron 14 especies fúngicas de muestras de almendro: Collophora hispanica, Diplodia olivarum, D. seriata, Eutypa lata, E. leptoplaca, Fomitiporia mediterranea, Neofusicoccum luteum, N. mediterraneum, N. parvum, Omphalotus olearius, Phaeoacremonium amygdalinum, Pm. iranianum, Phellinus pomaceus, Pleurostomophora richardsiae y dos especies encontradas sólo en muestras de una parcela de albaricoqueros junto a parcelas de almendros: Pm. minimum y Pm. venezuelense. Collophora hispanica y Pm. amygdalinum son dos nuevas especies fúngicas. Las especies más frecuentes en las parcelas de almendro estudiadas fueron P. richardsiae y D. seriata, seguidas por las otras especies pertenecientes a la familia Botryosphaeriaceae y por C. hispanica. Las especies que se aislaron con mayor frecuencia, fueron a su vez las que tuvieron una distribución más amplia; presentes en más comarcas. Posteriormente, se estudió la patogenicidad a almendro de algunas de las especies detectadas. Se realizaron dos ensayos de patogenicidad, el primero se realizó dos años (2013 y 2014) con las cinco especies de Botryosphaeriaceae (D. olivarum, D. seriata, N. luteum, N. mediterraneum y N. parvum) y las dos de Diatrypaceae (E. lata y E. leptoplaca) aisladas, que se inocularon en árboles de 1 a 2 años de cuatro variedades de almendro ('Jordi', 'Ferragnes', 'Pons' y 'Vivot') en una parcela experimental. El ensayo se evaluó a los nueve meses de la inoculación, midiendo la longitud de las necrosis internas producidas. En este ensayo se demostró la patogenicidad a almendro de las siete especies que se ensayaron. Las especies que causaron las lesiones de mayor longitud fueron N. luteum el primer año de ensayo, y N. parvum y N. mediterraneum el segundo año. Ambos años, la especie que causó las lesiones de menor longitud fue E. leptoplaca. La dimensión de la lesión producida por el hongo inoculado dependía de la variedad de almendro evaluada. La variedad 'Jordi' fue la menos sensible el primer año de estudio, y 'Vivot' y 'Ferragnes' lo fueron el segundo año. En el segundo ensayo se estudió la patogenicidad de las especies C. hispanica, Pm. amygdalinum, Pm. iranianum y P. richardsiae en plantones de almendro de la variedad 'Ferragnes' en invernadero. Nuevamente, la evaluación se realizó a los seis meses de la inoculación, midiendo la longitud de las lesiones internas. Todas las especies inoculadas resultaron patógenas a almendro, siendo P. richardsiae la especie que causó la mayor longitud de lesión. Finalmente, se evaluaron fungicidas para la protección de heridas de poda frente a la infección por cuatro especies de Botryosphaeriaceae (D. seriata, N. luteum, N. mediterraneum y N. parvum). Este estudio se llevó a cabo en dos fases; en primer lugar, una evaluación in vitro (reducción del crecimiento miceliar) con diez fungicidas y, posteriormente, una evaluación de cinco de estos fungicidas, elegidos entre los más efectivos in vitro, aplicándolos en heridas de poda uno o siete días tras el corte y la inoculación. Como en los casos anteriores, para evaluar este estudio se midió la longitud de la lesión, pero además también se calculó el porcentaje de reaislamiento del patógeno inoculado en cada caso. Los fungicidas tebuconazol y piraclostrobin, seguidos de ciproconazol y metil tiofanato, se mostraron como los más efectivos en la evaluación in vitro, mientras que el fungicida más efectivo para la protección de / [CAT] Des de l'any 2008, en parcel¿les de diferents zones de Mallorca s'han observat símptomes de decaïment de branques i mort d'ametllers, que recorden als que diferents autors han descrit en altres zones del món causats per fongs de fusta en diversos cultius. Per estudiar la seua etiologia es van realitzar prospeccions en parcel¿les d'ametllers de l'illa durant sis anys consecutius (2009-2014). En aquestes prospeccions es van caracteritzar símptomes i es van prendre mostres que es van analitzar al laboratori. En les anàlisis de laboratori es van obtenir 14 espècies fúngiques de mostres d'ametller: Collophora hispanica, Diplodia olivarum, D. seriata, Eutypa lata, E. leptoplaca, Fomitiporia mediterranea, Neofusicoccum luteum, N. mediterraneum, N. parvum, Omphalotus olearius, Phaeoacremonium amygdalinum, Pm. iranianum, Phellinus pomaceus i Pleurostomophora richardsiae i dues espècies trobades només a una parcel¿la d'albercoquers situada a prop de parcel¿les d'ametllers: Pm. minimum i Pm. venezuelense. Collophora hispanica i Pm. amygdalinum són dues espècies noves. Les espècies més freqüents en les parcel¿les d'ametller estudiades van ser P. richardsiae i D. seriata, seguides per les altres espècies pertanyents a la família Botryosphaeriaceae i per C. hispanica. Les espècies que es van aïllar amb més freqüència, van ser també les que van tenir una distribució més àmplia; presents en més comarques. Posteriorment, es va estudiar la patogenicitat d'algunes de les espècies detectades. Concretament, es van realitzar dos assajos de patogenicitat. El primer es va dur a terme dos anys (2013 i 2014), amb les cinc espècies de Botryosphaeriaceae (D. olivarum, D. seriata, N. luteum, N. mediterraneum i N. parvum) i les dues de Diatrypaceae (E. lata i E. leptoplaca) aïllades, que es van inocular en arbres d'1 a 2 anys de quatre varietats d'ametller ('Jordi', 'Ferragnes', 'Pons' i 'Vivot') en una parcel¿la experimental. L'assaig es va avaluar als nou mesos des de la inoculació, mesurant la longitud de les necrosis internes produïdes. En aquest assaig es va demostrar la patogenicitat respecte l'ametller de les set espècies que es van assajar. Les espècies que van causar les lesions de major longitud van ser N. luteum el primer any d'assaig, i N. parvum i N. mediterraneum el segon any. En els dos anys dels assajos l'espècie que va causar lesions de menor longitud va ser E. leptoplaca. Es va observar que la dimensió de la lesió causada pel fong inoculat depenia de la varietat d'ametller avaluada. La varietat 'Jordi' va ser la menys sensible el primer any d'estudi, i 'Vivot' i 'Ferragnes' ho van ser el segon any. En el segon assaig es va estudiar la patogenicitat de les espècies C. hispanica, Pm. amygdalinum, Pm. iranianum i P. richardsiae en plançons d'ametller de la varietat 'Ferragnes' en hivernacle. L'avaluació es va realitzar als 6 mesos de la inoculació, mesurant la longitud de les lesions necròtiques internes. Totes les espècies van resultar patògenes d'ametller, sent P. richardsiae l'espècie que va causar les lesions més extenses. Finalment, es va realitzar un estudi d'avaluació de fungicides per a la protecció de ferides de poda enfront de la infecció per quatre espècies de Botryosphaeriaceae (D. seriata, N. luteum, N. mediterraneum i N. parvum). Aquest estudi es va dur a terme en dues fases, una avaluació in vitro (reducció del creixement micelià) amb 10 fungicides i, posteriorment, una avaluació de cinc d'aquests fungicides, elegits entre els més efectius in vitro, aplicant-los en ferides de poda a 1 o 7 dies després del tall i la inoculació. Novament per avaluar aquest estudi es va mesurar la longitud de la lesió, però a més també es va calcular el percentatge de reaïllament del patogen inoculat en cada cas. Els fungicides tebuconazol i piraclostrobin, seguits de ciproconazol i metil tiofanat, es van mostrar com els més efectius in vitro, mentre que el fungicida més efect / Olmo García, D. (2016). Etiología y control de las enfermedades fúngicas de la madera del almendro en la isla de Mallorca [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/60158 / TESIS
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Approches multidisciplinaires sur le mode d’action, l’efficacité et l’élaboration de stratégies d’utilisation d’actifs biologiques contre divers bioagresseurs de Vitis vinifera / Developing a multidisciplinary approach testing the mode of action, the effectiveness and the deployment of ecofriendly strategies using biological antifungal products against a broad range of pest of Vitis viniferaBellee, Anthony 30 November 2016 (has links)
La vigne est une culture pérenne sensible à de nombreux bioagresseurs et sur laquelle il est nécessaire de réaliser de nombreux traitements pesticides, susceptibles de causer des problèmes environnementaux, de santé humaine et d’apparition de résistance au sein des populations de bioagresseurs. Aujourd’hui, il est indispensable de développer des stratégies nouvelles de lutte contre les bioagresseurs, plus raisonnées mais permettant de conserver une viticulture compétitive. L’utilisation de produits de biocontrôle semble, en ce sens, être une approche prometteuse permettant d’allier agriculture durable et intensive.Deux écoproduits généralistes à fort potentiel ont été identifiés, comme possédant des actions intéressantes sur les principales maladies cryptogamiques de la vigne. Le premier est un extrait naturel de plante, sans action fongicide directe mais capable de stimuler efficacement et de façon systémique les défenses de la plante. Le second, quant à lui, est un microorganisme qui possède une forte action antagoniste fongicide, mais aussi la capacité à stimuler les défenses de plante. Dans un premier temps, des études en conditions contrôlées ont mis en évidence l’efficacité des deux actifs pour inhiber le développement de diverses souches d’Erysiphe necator, Plasmopara viticola, Botrytis cinerea et Botryosphaeriaceae. En parallèle, des expérimentations au vignoble, ont confirmé le fort potentiel de ces produits de biocontrôle, avec des bonnes efficacités, particulièrement stable avec l’extrait naturel. Ces différentes études nous ont permis d’identifier et d’élaborer des stratégies d’utilisation pour ces deux produits de biocontrôle. / Grapevine is a perennial crop sensitive to many fungal pathogens that require numerous pesticide treatments. However, its uses lead to environmental, human health and fungicide resistance problems. Developing sustainable pest management strategies while keeping a good wine quality is of major importance. In this sense, the use of bio-pesticides products seems to be a promising approach to combine sustainable and intensive agriculture.Two generalist bio-pesticides of great potential have been preliminary identified, forits actions on major fungal diseases of grapevine. The first one is a natural plant extract, with no direct fungicide action but able to systemically stimulate plant defenses. The second one is a microorganism showing strong antagonist fungicide actions, and important ability to stimulate plant defenses. First, the studies conducted in controlled conditions have demonstrated the effectiveness of both products in the suppression of various isolates of Erysiphe necator, Plasmopara viticola, Botrytis cinerea and Botryosphaeriaceae. In parallel,the good efficiencies of these products have been confirmed during vineyard assays. This was especially well demonstrated for the natural extract. As a whole, these studies confirm thepotential of these two products as promising bio-pesticides, of which the strategy of application have been further defined.
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Biological control of the grapevine trunk disease pathogens : pruning wound protectionKotze, Charl 12 1900 (has links)
Thesis (MScAgric (Plant Pathology))--Stellenbosch University, 2008. / In recent years, several studies have conclusively shown that numerous pathogens,
including several species in the Botryosphaeriaceae, Phomopsis, Phaeoacremonium, as well
as Phaeomoniella chlamydospora and Eutypa lata, contribute to premature decline and
dieback of grapevines. These pathogens have the ability to infect grapevines through pruning
wounds, which leads to a wide range of symptoms developing that includes stunted growth,
cankers and several types of wood necrosis. Pruning wounds stay susceptible for 2 to 16
weeks after pruning and sustained levels of pruning wound protection is therefore required.
The aims of this study were to (i) evaluate the ability of several biological agents to protect
pruning wounds, (ii) characterise unknown Trichoderma strains and identify their modes of
action and (iii) determine the optimal time of season for biological agent application.
Several biological agents were initially evaluated in a laboratory for their antagonism
against trunk disease pathogens. The best performing control agents were tested in a field
trial conducted on Merlot and Chenin blanc vines in the Stellenbosch region. Spurs were
pruned to three buds and the fresh pruning wounds were treated with benomyl as a control
treatment, Trichoderma-based commercial products, Vinevax® and Eco77®, Bacillus
subtilis, and Trichoderma isolates, USPP-T1 and -T2. Seven days after treatment the pruning
wounds were spray inoculated with spore suspensions of four Botryosphaeriaceae spp.
(Neofusicoccum australe, N. parvum, Diplodia seriata and Lasiodiplodia theobromae),
Eutypa lata, Phaeomoniella chlamydospora and Phomopsis viticola. After a period of 8
months the treatments were evaluated by isolations onto potato dextrose agar. Trichodermabased
products and isolates in most cases showed equal or better efficacy than benomyl,
especially USPP-T1 and -T2. Moreover, these isolates demonstrated a very good ability to
colonise the wound tissue.
The two uncharacterised Trichoderma isolates (USPP-T1 and USPP-T2), which were
shown to be highly antagonistic toward the grapevine trunk disease pathogens, were
identified by means of DNA comparison, and their ability to inhibit the mycelium growth of
the trunk disease pathogens by means of volatile and non-volatile metabolite production
studied. The two gene areas that were used include the internal transcribed spacers (ITS 1
and 2) and the 5.8S ribosomal RNA gene and the translation elongation factor 1 (EF). The ITS and EF sequences were aligned to published Trichoderma sequences and the percentage
similarity determined and the two Trichoderma isolates were identified as Trichoderma
atroviride. The volatile production of T. atroviride isolates was determined by placing an
inverted Petri dish with Trichoderma on top of a dish with a pathogen isolate and then sealed
with parafilm. Trichoderma isolates were grown for 2 days on PDA where after they were
inverted over PDA plates containing mycelial plugs. The inhibition ranged from 23.6% for
L. theobromae to 72.4% for P. viticola. Inhibition by non-volatile products was less than for
the volatile inhibition. Inhibition ranged from 7.5% for N. parvum to 20.6% for L.
theobromae. In the non-volatile inhibition USPP-T1 caused significantly more mycelial
inhibition than USPP-T2.
The timing of pruning wound treatment and subsequent penetration and colonisation
of the wound site was also determined. One-year-old canes of the Shiraz and Chenin blanc
cultivars were grown in a hydroponic system, pruned and spray treated with a spore
suspension of Trichoderma atroviride (USPP-T1) as well as a fluorescent pigment. On
intervals 1, 3, 5 and 7 days after treatment, the distal nodes were removed and dissected
longitudinally. From the one half, isolations were made at various distances from the pruning
surface, while the other half was observed under ultra-violet light to determine the depth of
fluorescent pigment penetration. Shortly after spray-inoculation of a fresh pruning wound,
Trichoderma was isolated only from the wound surface and shallow depths into the wound (2
to 5 mm). One week after inoculation, Trichoderma was isolated at 10 mm depths, and after 2
weeks, at 15 mm depths. Fluorescent pigment particles were observed to a mean depth of 6
mm, which suggests that initial isolation of Trichoderma at these depths was resultant of the
physical deposition of conidia deeper into the pruning wound tissue, whereas the isolation of
Trichoderma from deeper depths might be attributed to colonisation of grapevine tissue. In a
vineyard trial, fluorescent pigment was spray-applied to pruning wounds of Shiraz and
Chenin blanc grapevines during July and September at intervals 0, 1, 3, 7 and 14 days after
pruning. One week after treatment, the distal nodes were removed and dissected
longitudinally. Each half was observed under UV light and the pigment penetration
measured. For Chenin blanc and Shiraz, July pruning wounds showed significant deeper
penetration of the pigment than pruning wounds treated in September. Moreover, pruning
wounds made in September showed pigment particles in longitudinal sections up to 1 day
after pruning, whereas wounds made in July showed pigment particles up to 3 days in the
xylem vessels. These findings suggest that the best time for application of a biological
control agent should be within the first 24 hours after pruning.
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