Soil samples were collected from April 2013 to June 2014 in an experimental orchard planted with 14 rootstocks, aged 17 years and associated with the variety “Valencia late”. The density of Phytophthora spp. propagules was determined by spreading soil on a selective medium. The lowest densities were found in the vicinity of Citrus aurantium, Citrus macrophylla, Poncirus trifoliata, Cleopatra mandarin, citrumelo 4475 and Goutou. By contrast, the highest densities were found in the vicinity of Citrus volkameriana, sunki mandarin and Carrizo citrange. In general, the values recorded ranged for 100 propagule/g of soil (in the rootzone of sour orange) to more than 1200 propagule/g of soil (in the rootzone of Citrus vokameriana). Furthermore, our results provided a classification of the rootstocks studied according to the season when their inoculum density peaks: Winter for Poncirus trifoliata, Cleopatra mandarin and sunki mandarin, and summer for Gou-Tou, Citrus volkameriana, Citrus aurantium and citrumelo 4475.
