Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1998.tde-20220208-055916
Document
Author
Full name
André Luis Paradela
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1998
Supervisor
Title in Portuguese
Comunidade fúngica associada a brotações de Eucalyptus em jardim clonal e seu envolvimento na etiologia da podridão de estacas utilizadas para a produção de mudas
Keywords in Portuguese
BROTAÇÃO
EUCALIPTO
FUNGOS FITOPATOGÊNICOS
MUDAS
PODRIDÃO DE ESTACAS
PRODUÇÃO
Abstract in Portuguese
A podridão de estacas se constitui num sério problema para a produção de mudas de eucalipto através de estaquia. Brotos provenientes do jardim clonai infectados por fungos endofiticos podem ser responsáveis pela introdução do inóculo primário nas casas de vegetação. A doença é comprovadamente causada por espécies do gênero Cylindrocladium e Rhizoctonia, porém outros fungos são suspeitos de estarem associados à podridão. Com o objetivo de se conhecer a comunidade fúngica endofitica possivelmente associada à podridão e de se estudar a etiologia da doença, foi feito um levantamento em um jardim clonai de um hÃbrido de Eucalyptus grandis x Eucalyptus urophylla, localizado em Santa Rita do Passa Quatro, SP, através de isolamentos em meio de cultura, durante o perÃodo de outubro de 1996 a novembro de 1997. Foram realizados testes de patogenicidade em casa de vegetação com os fungos que predominaram neste levantamento. Visando avaliar o controle quÃmico da doença, foram efetuadas aplicações foliares semanais de benomyl (0,5 kg/ha) e oxicloreto de cobre (1,1 kg/ha) iniciadas, duas semanas após o corte comercial, durante a etapa de levantamento. Posteriormente, foi também testada a imersão de estacas comerciais em suspensões de captan (1,5 g i.a./l) e de benomyl (0,75 g i.a./l). Diversos gêneros foram detectados como ocorrendo endofiticamente nos brotos, aparecendo com maior freqüência Botryosphaeria, Colletotrichum e Guignardia. Foi demonstrado que Colletotrichum e Botryosphaeria estão envolvidos na etiologia da doença e que Cylindrocladium candelabrum é o principal patógeno responsável pela redução do enraizamento das estacas. Quanto ao tratamento quÃmico, a pulverização das touças no jardim clonai não se mostrou eficiente, o mesmo ocorrendo com o tratamento de imersão das estacas.
Title in English
Fungal community of eucalyptus sprouts in a clonal garden and its role on the etiology of cutting rot
Abstract in English
Cutting rot is a serious problem in the vegetative propagation of Eucalyptus. Cylindrocladium and Rhizoctonia are known to be the major genera of pathogens involved in the etiology of the problem. Other fungi, however, are also commonly associated endophytically with symptomless sprouts originated from the clonai Garden which could also contribute to the causality of the disease after their introduction in the greenhouse with the cuttings. A survey was carried out in order to evaluate the fungal community possibly associated with the cutting rot in the greenhouse in a commercial clonai garden located in Santa Rita do Passa Quatro, SP, during the period of october 1996 to november 1997. Two sprout samplings were made for each of the 6 commercial harvest cuts that were performed during the survey period and fungal community evaluated by plating sprout stem pieces on potato-dextrose-agar. Fungi which predominated in the survey had their pathogenicity tested trough cutting inoculation in a commercial greenhouse. During the survey of the fungi, foliar applications of benomyl (0.5 kg/ha) alternated with copper oxichloride (1.1 kg/ha) were done weekly in part of the clonal garden, in order to test an altemative for the control of the disease. In addition, a trial was carried out to test the fungicidal treatment of the cuttings before planting, by immersion in a suspension of captan (1.5 gil) or benomyl (0.75 gil). Several genera of fungi were detected in association with the sprouts, Colletotrichum, Guignardia and Botryosphaeria being the most common ones among those that were identified. It was also demonstrated that Colletotrichum and Botryosphaeria may be involved in the etiology of the cutting rot, but were less aggressive than Cylindrocladium candelabrum, a common species found in the study area, which reduced the rooting of the cuttings. The fungicidal sprays in disease incidence and severity as well the fungicidal cutting treatment gave no differences in relation to the non treated controls.
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Publishing Date
2022-02-08