Vertical distribution of plant-parasitic nematodes in sandy soil under maize

Distribution of plant-parasitic nematode species at soil depths of 0–15 cm, 15–30 cm, and 30–45 cm was examined in two maize fields in Florida during 1987 and 1988. Soil type in both fields was an Arredondo fine sand, consisting of 94–96% sand at all three depths. On most sampling dates, more than 50% of the Belonolaimus longicaudatus collected occurred at the 0–15 cm depth. Only 20–30% of Criconemella sphaerocephala were present at this depth, and the depth distribution of this nematode differed in the two fields. The greatest densities of Pratylenchus brachyurus often occurred at 15–30 cm. Vertical distributions of Meloidogyne incognita and Paratrichodorus minor were erratic and showed marked seasonal variation. For all species examined except B. longicaudatus, a diagnostic soil sample collected 15 cm deep would recover only a minority of the nematode population present in the soil profile.