Distribution of Nematodes, Soil Factors and Within-field Variation in Sugarcane Growth

A common feature of plant-parasitic nematodes on annual crops is that they have an uneven distribution within a field and the symptoms of damage, normally associated with high population densities, occur in patches (McSorley,1998). Where a susceptible annual crop is replanted year after year the nematodes spread and the patches increase in size and eventually coalesce (Brown, 1987; Swarup and Sosa-Moss, 1990). Monocropping for decades, as is common in sugarcane agriculture, will enhance the horizontal spread of the common nematodes and lead to their more uniform distribution (Delaville et al., 1996). One factor likely to interfere with the uniform spread of the nematodes is soil texture as this can influence their abundance and distribution (Cadet et al., 1994; Norton, 1989; Upadhyay et al., 1972). For example, species of Meloidogyne are frequently more numerous and more pathogenic in light textured soils, giving rise to greater symptom expression in the sandier areas within the field (Kincaid, 1946; Prot and van Gundy, 1981).