Pesquisa Agropecuária Tropical (Jul 2011)

DIAGRAMMATIC SCALE TO EVALUATE TARGET SPOT SEVERITY IN CUCUMBER PLANT LEAVES ESCALA DIAGRAMÁTICA PARA AVALIAÇÃO DA SEVERIDADE DA MANCHA ALVO EM FOLHAS DE PEPINEIRO

  • Marise Cagnin Martins,
  • Riccely Ávila Garcia,
  • Renata Alves Aguiar,
  • Adriana Teramoto,
  • Marcos Gomes Cunha

DOI
https://doi.org/10.5216/pat.v41i3.12017
Journal volume & issue
Vol. 41, no. 3

Abstract

Read online

<p style="margin-bottom: 0cm; font-style: normal; font-weight: normal; line-height: 120%; text-decoration: none;" lang="pt-BR"><span style="color: #000000;"><span style="font-family: Times New Roman,serif;"><span style="font-size: small;"><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;">The lack of a diagrammatic scale to evaluate the cucumber target spot, caused by </span></span></span></span></span></span><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><em><span style="font-weight: normal;">Corynespora cassiicola</span></em></span></span></span></span><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;">, led to the development of an assessment system for a faster and more reliable way to quantify this disease. So, a diagrammatic scale was elaborated considering the maximum and minimum severity limits of the disease observed in the field. The intermediate values followed logarithmic increments for the target spot symptoms (0.3%, 0.8%, 2%, 5%, 11.5%, 25%, and 46%). For validating the scale, eight raters quantified the disease severity on fifty leaves infected with different levels of the disease. Initially, the severity estimation was carried out without the aid of the scale. Then, the same raters used it to estimate the severity on the same leaves previously assessed. Assessments with the aid of the diagrammatic scale were more precise and accurate, according to most of the raters. The proposed diagrammatic scale was considered adequate to estimate the target spot severity in cucumber leaves, and it can be used in epidemiologic studies and in evaluation strategies for controlling this disease.</span></span></span></span></span></span></span></span></span></p><p style="margin-bottom: 0cm; font-style: normal; font-weight: normal; line-height: 120%; text-decoration: none;" lang="pt-BR"><span style="color: #000000;"><span style="font-family: Times New Roman,serif;"><span style="font-size: small;"><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;">Devido à ausência de escala diagramática para a mancha alvo do pepineiro, causada por </span></span></span></span></span></span><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><em><span style="font-weight: normal;">Corynespora cassiicola</span></em></span></span></span></span><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;">, verificou-se a necessidade de um sistema de quantificação da doença, que proporcionasse maior rapidez e precisão na obtenção dos resultados. Para tanto, uma escala</span></span></span></span></span></span><span style="color: #ff0000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;"> </span></span></span></span></span></span><span style="color: #000000;"><span style="text-decoration: none;"><span style="font-family: Times New Roman,serif;"><span lang="pt-BR"><span style="font-style: normal;"><span style="font-weight: normal;">diagramática foi elaborada, considerando-se o limite máximo e mínimo de severidade da doença observados no campo. Os valores intermediários da escala seguiram incrementos logarítmicos para os sintomas da mancha alvo (0,3%; 0,8%; 2%; 5%; 11,5%; 25%; e 46%). Para a validação da escala, oito avaliadores quantificaram a severidade da doença, em cinquenta folhas com diferentes níveis de doença. Inicialmente, a estimativa da severidade foi feita sem auxílio da escala. A seguir, os mesmos avaliadores, utilizando a escala diagramática proposta, estimaram a severidade nas mesmas folhas avaliadas anteriormente. As avaliações com a escala diagramática foram mais precisas e acuradas, nas estimativas da maioria dos avaliadores. A escala diagramática proposta foi considerada adequada para estimar a severidade da mancha alvo, em folhas de pepineiro, e poderá ser utilizada em estudos epidemiológicos e de avaliação de estratégias de controle desta doença.</span></span></span></span></span></span></span></span></span></p>

Keywords