Several phytonematode species have been reported for citrus orchards, but few are considered key pests for this crop. In Brazil, Tylenchulus semipenetrans is the main nematode of citrus orchards widely spread among the country. Different variables are used to determine the level of damage caused by this nematode. Thus, this experiment aimed to correlate the number of females with the number of juveniles of T. semipenetrans in samples of soil and root from 'Pera Rio' orange grafted onto 'Rangpur' lime. The study was conducted in a 14-year-old orchard, located at São Gabriel Farm, Vitoriana District, Botucatu - SP. Sampling was performed in September 2011 at a depth of 0-30 cm, using 10 plants without symptoms, 10 plants with symptoms and plants adjacent to symptomatic ones, totaling 60 plants. For extraction of the nematodes present in the soil, the methodology of centrifugal flotation was adopted, while for the nematodes in the roots the technique using blender and centrifugation was employed. To count the number of females, 1g root of each sample was colored. The data about soil nematode, root nematode, sum of soil and root nematode and females per gram of root were subjected to Pearson's correlation analysis and subsequently to correlation matrix. Considering the analyzed data, there was a strong correlation between the number of juveniles present in the root and the sum of the number of juveniles present in the soil and the root. However, there was no correlation of this variable with the number of females in the root and the number of juveniles in the soil. The number of females in the root was not correlated with any of the other analyzed variables. It is concluded that the best variable to determine the population of T. semipenetrans is the number of juveniles per 10 g of root.
Citrus sinensis; the citrus nematode; damage level
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