Spatial distribution of Huanglongbing em citros utilizando a geoestatistica

The aim of this study was to use geostatistics to verify the spatial distribution of Huanglongbing (greening) in oranges orchards on agricultural property located in the city of Araraquara, Sao Paulo. To determine the number of plants with greening, periodic inspections every three months were made from March 2005 until July 2007, counting the number of plants in each stand with the characteristic symptoms of the disease. A descriptive analysis of the data was undertaken, and geostatistics were used to verify the spatial distribution of greening through the adjustment of semivariograms and interpolation of data by kriging. The spatial dependence of plants with greening formed a beam of aggregation of 300 to 560 m, indicated an aggregated distribution of the disease. Diagrams of kriging showed that initial focus of plants with greening started at the border in the farm and there was an expansion of the disease through the entire area. The interval of inspections every three months was not appropriate to reduce the greening in the farm. Index terms: Semivariogram, kriging, Diaphorina citri. Os objetivos do trabalho foram avaliar a distribuicao espacial e a expansao da Huanglongbing (greening) em talhoes de citros de uma propriedade agricola localizada no municipio de Araraquara-SP, utilizando a geoestatistica. Para determinar o numero de plantas com greening, foram realizadas inspecoes periodicas em intervalos de tres meses, no periodo de marco de 2005 a julho de 2007, contando-se, em cada talhao, o numero de plantas com os sintomas caracteristicos da doenca. Realizou-se a analise descritiva dos dados e, para verificar a distribuicao espacial do greening, utilizou-se a geoestatistica atraves do ajuste de semivariogramas e da interpolacao dos dados por krigagem. A dependencia espacial de plantas com greening apresentou raio de agregacao de 300 a 560 m, indicando distribuicao agregada da doenca. Por meio dos mapas de krigagem, observou-se que o foco inicial de plantas doentes ocorreu nos limites da fazenda, com expansao do greening por toda a area. O intervalo de inspecao de tres meses nao foi adequado para a reducao do greening na fazenda. Termos para indexacao: Semivariograma, krigagem, Diaphorina citri.