Igor Souza Pereira

Análise da dinâmica, estrutura de focos e arranjo espacial da mancha manteigosa em campo

Objetivou-se estudar a dispersao espacial da mancha manteigosa em cafeeiro, por meio de arranjos espaciais e da analise da dinâmica e estruturas de focos da doenca durante tres anos consecutivos. Nesse periodo, nao houve progresso da doenca no campo. Sob plantas doentes, surgiam mudas com sintomas da doenca, um indicio da transmissibilidade via semente. Constatou-se um total de 10 focos, com media de 2,5 plantas/focos e com tendencia desses focos (maior numero de plantas sintomaticas) na direcao das linhas de plantios, tendo disposicao de forma eliptica. Observou-se numero elevado de focos unitarios, correspondendo a 52% das plantas doentes. Pelas analises de sequencias ordinarias runs e doublet verificou-se padrao espacial aleatorio. Tal fato indica que a mancha manteigosa ocorre a partir de plantas isoladas (focos unitarios) e que a principal via de transmissao e a semente (semente/planta/semente).

ESTUDOS HISTOPATOLÓGICOS DA INTERAÇÃO COLLETOTRICHUM GLOEOSPORIOIDES - CAFEEIRO

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.

Estudos histoplásticos da interação Colletotrichum gloeosporioides: cafeeiro

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.

Eventos do processo de infecção de Colletotrichum gloeosporioides inoculados em folhas de Coffea arabica L

The present study was carried out with the objective to provide information on the pre-penetration, penetration and colonization events of isolates of Colletotrichum gloeosporioides from mango and coffee, when inoculated in coffee leaves. The cultivar Catucai Vermelho was used in all experiments. Coffee leaves were selected, standardized and washed in sterile water. After that, circular areas of 0.5 cm in diameter were marked on the undersurface of the leaves. In the center of each circular area, 20 µL of spore suspension was deposited. One isolate from mango and two from coffee presenting blister spot were used in all trials. The time course of the experiments was 3, 6, 8, 12, 24, 36, 48, 72, 96, 144 and 240 hours after inoculation (h.a.i.). All materials were analyzed in scanning electron microscopy. The conidia of all isolates adhered more frequently on the plant tissue depressions and guard-cells forming septum before germination. The most common penetration via was the direct, although some penetration through stomata also occurred. Isolates obtained from blister spot symptoms germinated on coffee leaves after 6 to 8 h.a.i., producing appressoria after 12 h.a.i., and acervuli after 96 to 144 h.a.i. The isolate from mango germinated on the coffee leaves after 6 to 8 h.a.i. and formed appressoria after 8 to 12 h.a.i., but was unable to form acervuli, bearing conidia directly from conidiogenous hypha on the mycelium.

Incidência de Colletotrichum spp. em frutos de Coffea arabica L. em diferentes estádios fisiológicos e tecidos do fruto maduro

Especies de Colletotrichum estao presentes em todos os orgaos do cafeeiro. A importância desses fungos para a cultura do cafeeiro ainda e muito discutida, pois tratam-se de populacoes de especies de Colletotrichum ocasionando diversos sintomas ou colonizando as plantas de forma endofitica. O estudo foi realizado com o objetivo de verificar a presenca de Colletotrichum spp. em diferentes estadios de desenvolvimento do fruto de cafeeiro e nos tecidos do exocarpo+mesocarpo, endocarpo e endosperma de frutos maduros. Este trabalho foi realizado no Laboratorio de Diagnose e Controle de Enfermidades de Plantas da Universidade Federal de Lavras-(UFLA). Os frutos foram coletados na area experimental do Setor de Cafeicultura da UFLA com cafeeiros das cultivares Catuai Vermelho, Catuai Amarelo, Icatu, Topazio, Katipo, Rubi, Acaia Cerrado e Mundo Novo. Nos estadios de formacao do fruto, verificaram-se altos valores de incidencia, com media de 86,6%. Em relacao as cultivares, as maiores incidencias foram em Topazio e Rubi, ambas com 94,4% e as menores incidencias nas cultivares Icatu e Mundo Novo, com 72,8% e 78,4%, respectivamente. A incidencia de Colletotrichum spp. variou tanto entre cultivares como entre os tecidos do fruto. No exocarpo+mesocarpo, as cultivares Topazio, Rubi e Acaia Cerrado tiveram porcentagens de colonizacoes de 84,72%, 79,16% e 77,77%, respectivamente, enquanto a cultivar Icatu teve 48,6%. No endocarpo, a maxima colonizacao foi de 9,72% na cultivar Rubi e a menor colonizacao na cultivar Acaia Cerrado, com 1,39%. No endosperma, a cultivar Rubi teve novamente o maior indice de colonizacao (8,33%) e as cultivares Mundo Novo e Katipo ambas com 1,39% de colonizacao. Verificou-se a presenca de Colletotrichum spp. nas sementes de todas as cultivares estudadas.

Transmissibilidade e efeito do tratamento de sementes de cafeeiros com mancha manteigosa (C. gloeosporioides)

Neste trabalho, os objetivos foram avaliar a transmissibilidade de C. gloeosporioides mancha manteigosa (MM) em sementes e estudar o efeito do tratamento por fungicidas no controle do referido patogeno. Colheram-se frutos cerejas em plantas doentes e sadias, procedeu-se o despolpamento manual secando as sementes a sombra, retirou-se o endocarpo e, em seguida, realizaram-se os devidos tratamentos (fungicida) semeando-as em areia esterilizada. Avaliaram-se os sintomas de necrose e morte das plântulas e a incidencia de C. gloeosporioides, por meio do teste de incubacao em substrato de papel (blotter test), em sementes de cafeeiro tratadas e nao tratadas com mistura comercial de benzimidazol+dimetilditiocarbamato (dose i.a. de 45 g+105 g/100 kg sementes). Com o desenvolvimento das plântulas, observaram-se em sementes de plantas com MM , altos indices de morte de plântulas, tendo apenas 5,2% de sobrevivencia, porem, com a abertura dos primeiros foliolos observaram-se, nestas plântulas, sintomas tipicos da doenca, com posterior morte das mesmas, enquanto que, a partir de sementes sadias, as plântulas apresentam-se vigorosas e em pleno crescimento. Ja, com o uso do tratamento fungicida, observou-se efeito significativo, principalmente em sementes de plantas doentes (MM), nas quais verificou-se uma menor area abaixo da curva de progresso da doenca e, consequentemente, menor incidencia e severidade da doenca. Pelo bloter test, em sementes tratadas, nao houve crescimento de nenhum agente fungico tanto para sementes de plantas com MM como para sementes de plantas sadias. Em sementes nao tratadas, observou-se incidencia de C. gloeosporioides em 29,8% nas sementes de plantas com MM e 1,2% de incidencia em sementes de plantas sadias. Com base nestes resultados, fica evidenciado que neste patossistema, mancha manteigosa - cafeeiro, a principal via de transmissao de C. gloeosporioides e a semente.

Efeito de fungicidas e influência de fatores climáticos sobre a mancha manteigosa no cafeeiro

Neste trabalho, objetivou-se avaliar a eficiencia de alguns fungicidas no controle da mancha manteigosa (Colletotrichum gloeosporioides) do cafeeiro (Coffea arabica L.) em campo, e verificar os efeitos climaticos no progresso da doenca. Foram conduzidos ensaios sobre cafeeiros da cultivar Catucai Vermelho, com aproximadamente 8 anos de idade. Os fungicidas testados foram: tetraconazol, triadimenol, chlorotalonil e mancozeb, nas dosagens de 1,0L/ha, 12Kg/ha, 3Kg/ha e 2Kg/ha, respectivamente. Coletaram-se dados climaticos diariamente, no periodo de outubro de 2004 a maio de 2006. Os fungicidas chlorotalonil e triadimenol foram os que proporcionaram os melhores resultados de eficiencia de controle do progresso de morte de ramos e frutos, destacando a producao de frutos cereja. Entre os meses de outubro a janeiro, verificou-se elevado progresso de mortes de ramos influenciado pelas altas precipitacoes pluviais. Os fungicidas tetraconazol e o mancozeb mostraram-se ineficientes. Plantas com mancha manteigosa, mesmo quando pulverizadas com fungicidas, tiveram significativa queda de frutos, enquanto plantas sadias apresentaram producoes 95% superiores aquelas.

Sensibilidade de Colletotrichum gloeosporioides (mancha manteigosa do cafeeiro) a diferentes concentrações de fungicidas

With the aim of assessing the effect of selected fungicides on Colletotrichum gloeosporioides, the cause of coffee blister spot, in vitro tests were carried out in the Laboratory of Diagnosis and Control/UFLA, Federal University of Lavras, Brazil. In the in vitro experiments the fungicides were incorporated into malt extract medium (MEA 2%) to evaluate the effect on the fungus growth rate, and concavity slides containing water plus fungicide to assess the conidia germination. The fungicides tetraconazol, triadimenol, chlorothalonil and mancozeb were tested on the mycelial growth inhibition (in the concentrations of 1, 5, 10, 25, 50, 100, 500 and 1.000 mg L-1) and on the inhibition conidia germination (in the concentrations of 1, 5, 10, 25, 50 e 100 mg L-1). The fungicides tetraconazol and triadimenol showed high efficiency on the mycelial growth inhibition. Chlorotalonil and mancozeb showed low efficiency and inefficiency, respectively. As to the germination of conidia, chlorothalonil and tetraconazol demonstrated to be more efficient in low concentrations.

Aspectos morfológicos da colonização de Colletotrichum gloeosporioides em órgãos de plantas de cafeeiros e com sintomas da mancha manteigosa

Objetivou-se, no presente trabalho, analisar microscopicamente a colonizacao de C. gloeosporioides, agente da mancha manteigosa (MM), em condicoes naturais da doenca, sobre os diferentes orgaos e tecidos da cultivar Catucai Vermelho: folhas, peciolos, nervuras, ramos, frutos e pedunculos. Todas as amostras foram processadas, obtendo-se imagens em microscopico eletronico de varredura. Os ramos e as nervuras de folhas de cafeeiros com mancha manteigosa apresentando morte descendente e hipocotilos oriundos de sementes tem os vasos do xilema, floema e celulas do cortex colonizados por C. gloeosporioides, ja os frutos com sintoma da mancha manteigosa apresentaram colonizacao nos tecidos do exocarpo, mesocarpo, endocarpo e endosperma.

Histopathological studies of the interaction Colletotrichum gloeosporioides - coffee tree.

In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.In studies involving the interaction Colletotrichum gloeosporioides - coffee trees (Coffea arabica L.) there is little information regarding the pre-penetration, penetration and colonization pathways of this pathogen. The objectives of this work were: 1. to study through scanning electron microscopy (SEM) the pre-penetration and penetration events of C. gloeosporioides in hypocotyls of coffee plantlets; 2. to observe the colonization of Colletotrichum spp. in branches and fruits of coffee trees with blister spot symptoms. The study took place in three trials. In the first trial, it was observed and reported the pre-penetration events of C. gloeosporioides inoculated on hypocotyls of coffee cv. Acaia Cerrado with and without wounds. The second trial was performed to investigate the colonization of diseased coffee branches that presented drastic wilt and local necrosis was observed. Finally the third trial investigated the colonization of this pathogen in diseased coffee fruits. When C. gloeosporioides was inoculated, germination could be observed in wounded hypocotyls 6 hours after inoculation. Better adhesion of conidia was evident at surface depressions of hypocotyls and germination started by emission of one or two terminal germ tubes. Round or sub-round shaped apressoria appeared 12 hours after inoculation. Up to 72 hours, acervula formation was not observed on inoculated tissues. The wilted branches presented colonization in the phloem and cortical tissues. In fruits at different stages of maturation, it was observed colonization in tissues near the epidermis and collapse of the stomata in the affected area.