SPATIAL DISTRIBUITION OF HUANGLONGBING (GREENING) ON CITRUS USING GEOSTATISTIC

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 lcriging. 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.