INFLUENCE OF THE SOIL ON THE TRANSPORT OF THE SPORES OF PASTEURIA-PENETRANS, PARASITE OF NEMATODES OF THE GENUS MELOIDOGYNE

Transport of spores of Pasteuria penetrans and of juveniles of Meloido gyne javanica was assayed under a water drip supply in four soils: a s andy soil, a clay soil and two sandy-clay soils. For the sandy soil, 6 7.7% of spores of P. penetrans and 78% of juveniles of M. javanica per colated with water in spite of high reproduction of M. javanica in tha t soil. For the clay soil, only 0.12% of juveniles and 10.6% of spores moved down. But 50% of spores still remained in that soil after extra ction and so could not be available for attachment. Transport of juven iles of M. javanica and of spores of P. penetrans was easier in the sa ndy-clay soil which was originally free of P. penetrans and contained 6% less clay than the other which was naturally infested by P. penetra ns. A survey conducted on vegetable crops in Senegal confirmed that ju veniles of Meloidogyne spp. infected by P. penetrans were abundant in sandy soils with about 10% of clays. So, the availability of spores of P. penetrans to attach juveniles of M. javanica would depend on a bal ance of soil texture and porosity, and on the capacity of colloids to release spores adsorbed to the soil matrix.