A problemática do cancro bacteriano da actinídea na região de Entre Douro e Minho
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2017-12-19
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O cancro bacteriano da actinídea, causado por Pseudomonas syringae pv. actinidiae (Psa) é uma doença que está incluída na Lista A2 da OEPP devido à sua gravidade crescente na região do Mediterrâneo. As condições meteorológicas determinam a multiplicação e o padrão de dispersão de Psa, bem como a relação entre a bactéria e as operações culturais no pomar, pouco estudadas, e que podem influenciar o controlo biológico a efetuar.
Os objetivos deste estudo são relacionar as condições meteorológicas com a eficácia da aplicação de Bacillus subtilis (Serenade Max ®) no controlo da doença, determinar se a severidade da doença aumentou ao longo do ciclo cultural, monitorizar a passagem da doença de um ciclo vegetativo da actinídea para o seguinte, e ainda avaliar o efeito da aplicação de Bacillus subtilis na produtividade e qualidade dos kiwis. Dois pomares de A. deliciosa cv. Hayward, com sintomas típicos de Psa e com diferentes idades, localizados em Valença, foram selecionados para ensaios de controlo biológico, produtividade e qualidade. Trinta plantas foram selecionadas de um pomar novo (6 anos) e outras trinta de um pomar velho (30 anos). Psa foi identificada e caracterizada por testes morfológicos, bioquímicos e moleculares. A eficácia de Bacillus subtilis foi avaliada através da incidência da doença, e correlacionada com as condições meteorológicas. Foi utilizada uma escala standard para a infecção na folha (escala de sintomas de 0 a 4) para determinação da severidade da doença. A monitorização dos sintomas da Psa foi executada a cada 30 dias, de junho de 2016 a setembro de 2017. Foram avaliados parâmetros produtivos e qualitativos da fruta como o número de frutos por planta, número de frutos por ramo lateral, peso por planta em kg, teor de sólidos solúveis totais, pH, firmeza da polpa, acidez e matéria seca. A severidade da doença diminui no verão, caraterizado por condições pouco favoráveis para a Psa, como as elevadas temperaturas e escassa precipitação. Bacillus subtilis foi parcialmente eficaz no controlo da Psa no pomar novo (6 anos), e mostrou não ser eficaz na protecção das folhas no pomar velho (30 anos). A passagem da doença de um ciclo cultural para outro ocorreu, e a aplicação de Bacillus subtilis na floração considerou-se uma solução viável para o controlo de Psa biovar 3 apenas no pomar novo (6 anos). O acompanhamento das prospecções oficiais em Portugal, permitiu concluir que o número de freguesias com Psa continua a aumentar, evidenciando uma dispersão mais lenta do que nos anos anteriores.
Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv actinidiae (Psa) is a disease included in the EPPO A2 List because currently increased in the Mediterranean region. The climatic conditions determine the multiplication and dispersion behavior of Psa and the relationship between the bacteria and cultural practices, although poorly understood, may influence its biological control (BC). However, the literature regarding the growth of the bacteria with the climatic conditions in Portugal is scarce. The aims of this study were to correlate the climatic conditions with the efficacy of Bacillus subtilis (Serenade Max ®) in disease control, to determine if disease incidence increased over the growing season, and to monitor carry-over of disease from one season to the next and also, to evaluate the effect of Bacillus subtilis (Serenade Max ®) on yield and kiwifruit quality in infected orchards with different ages. Two “Hayward” orchards of Actinidea deliciosa with typical symptoms of Psa and with different ages, located in Valença, North of Portugal, were selected for BC, yield and quality assays. Thirty plants were randomly selected from a young orchard (6 years old) and other thirty plants from an old one (30 years old). Psa was identified and characterized by morphological, biochemical and molecular tests. The efficacy of Bacillus subtilis was evaluated by the disease incidence, and correlated to climatic conditions. A standardized leaf infection index (0 to 4 scale of symptoms) was used to determine the disease severity. The number of fruits per plant, number of fruits per lateral branch, kg per plant, ºBrix, pH, pulp hardness, titratable acidity and dry matter obtained in plants of both orchards are discussed. Monitoring of Psa symptoms was performed every 30 days, from June 2016 to April 2017. The severity of the disease decreased in the summer season, characterized by unfavorable conditions for Psa such as high temperatures and scarce precipitation. Bacillus subtilis was partially effective in controlling Psa in the six-year-old orchard, and showed no efficacy in the protection of leaves in the thirty-year-old orchard. The disease carry-on from one season to the next, and the Bacillus subtilis applied at flowering could be considered as a suitable solution for the control of Psa biovar 3 only for the new kiwifruit orchard (6 years old). The follow-up of the official surveys in Portugal allowed us to conclude that the number of orchards with Psa continues to increase, showing a slower dispersion than in previous years
Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv actinidiae (Psa) is a disease included in the EPPO A2 List because currently increased in the Mediterranean region. The climatic conditions determine the multiplication and dispersion behavior of Psa and the relationship between the bacteria and cultural practices, although poorly understood, may influence its biological control (BC). However, the literature regarding the growth of the bacteria with the climatic conditions in Portugal is scarce. The aims of this study were to correlate the climatic conditions with the efficacy of Bacillus subtilis (Serenade Max ®) in disease control, to determine if disease incidence increased over the growing season, and to monitor carry-over of disease from one season to the next and also, to evaluate the effect of Bacillus subtilis (Serenade Max ®) on yield and kiwifruit quality in infected orchards with different ages. Two “Hayward” orchards of Actinidea deliciosa with typical symptoms of Psa and with different ages, located in Valença, North of Portugal, were selected for BC, yield and quality assays. Thirty plants were randomly selected from a young orchard (6 years old) and other thirty plants from an old one (30 years old). Psa was identified and characterized by morphological, biochemical and molecular tests. The efficacy of Bacillus subtilis was evaluated by the disease incidence, and correlated to climatic conditions. A standardized leaf infection index (0 to 4 scale of symptoms) was used to determine the disease severity. The number of fruits per plant, number of fruits per lateral branch, kg per plant, ºBrix, pH, pulp hardness, titratable acidity and dry matter obtained in plants of both orchards are discussed. Monitoring of Psa symptoms was performed every 30 days, from June 2016 to April 2017. The severity of the disease decreased in the summer season, characterized by unfavorable conditions for Psa such as high temperatures and scarce precipitation. Bacillus subtilis was partially effective in controlling Psa in the six-year-old orchard, and showed no efficacy in the protection of leaves in the thirty-year-old orchard. The disease carry-on from one season to the next, and the Bacillus subtilis applied at flowering could be considered as a suitable solution for the control of Psa biovar 3 only for the new kiwifruit orchard (6 years old). The follow-up of the official surveys in Portugal allowed us to conclude that the number of orchards with Psa continues to increase, showing a slower dispersion than in previous years
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Actinidea deliciosa , cancro bacteriano , produtividade , qualidade condições meteorológicas , Bacillus subtilis