Liming and biofungicide for the control of clubroot in cauliflower1

Abstract

ABSTRACT Clubroot, caused by Plasmodiophora brassicae, is a disease that limits the cauliflower cultivation and is difficult to control. This study aimed to evaluate the efficiency of liming combined with the use of Trichoderma harzianum-based biofungicide for the control of clubroot in cauliflower. In a field experiment, the use of the biofungicide in combination with the application of calcined limestone doses (0 Mg ha-1, 1.0 Mg ha-1, 2.0 Mg ha-1 and 4.0 Mg ha-1) was evaluated. Subsequently, in a greenhouse, the biofungicide combined with liming with quicklime (2.54 Mg ha-1) was tested, and cyazofamid and water were tested as controls. The disease severity and attributes related to root and plant development were analyzed. In the field experiment, the healthy root volume and fresh weight, total root dry weight and inflorescence fresh weight and diameter were all significantly increased, while the diseased root volume, in response to the limestone doses, was reduced. The biofungicide reduced the root growth and inflorescence fresh weight. In the greenhouse, liming increased the healthy root volume and fresh weight, as well as total root dry weight, and reduced the disease severity. No significant difference was observed between the biofungicide and the control (water), which were inferior to cyazofamid. The biofungicide was not efficient in controlling the disease and did not favour the growth of cauliflower plants, either alone or combined with liming. Liming reduced the disease severity and increased the cauliflower root growth and yield.RESUMO A hérnia das crucíferas, causada por Plasmodiophora brassicae, é uma doença de difícil controle, sendo limitante ao cultivo de couve-flor. Objetivou-se avaliar a eficiência da calagem, combinada ao uso de biofungicida à base de Trichoderma harzianum, no controle de hérnia das crucíferas em couve-flor. Em ensaio de campo, avaliou-se o biofungicida associado à aplicação de doses (0 Mg ha-1; 1,0 Mg ha-1; 2,0 Mg ha-1 e 4,0 Mg ha-1) de calcário calcinado. Posteriormente, em casa-de-vegetação, avaliou-se o biofungicida combinado à calagem com cal virgem (2,54 Mg ha-1), além das testemunhas ciazofamida e água. Foram analisados a severidade da doença e os atributos relacionados ao desenvolvimento da raiz e da planta. No experimento a campo, houve incrementos significativos no volume e massa fresca de raiz sadia, massa seca total de raiz, massa fresca e diâmetro das inflorescências e redução no volume de raízes doentes, em resposta às doses de calcário. O biofungicida reduziu o crescimento das raízes e a massa fresca das inflorescências. Em casa-de-vegetação, a calagem incrementou o volume e massa fresca de raízes sadias e a massa seca total de raiz, bem como reduziu a severidade da doença. Não foi observada diferença significativa entre o biofungicida e a testemunha (água), que mostraram-se inferiores à ciazofamida. O biofungicida não foi eficiente no controle da doença e não favoreceu o crescimento das plantas de couve-flor, seja isoladamente ou combinado à calagem. A calagem reduziu a severidade da doença e aumentou o crescimento radicular e a produtividade de couve-flor.