Population dynamics of Belonolaimus longicaudatus in a cotton production system

Belonolaimus longicaudatus is a recognized pathogen of cotton (Gossypium hi rsutum), but insufficient information is available on the population dynami cs and economic thresholds of B. longicaudatus in cotton production. In thi s study, data collected from a field in Florida were used to develop models predicting population increases of B. longicaudatus on cotton and populati on declines under clean fallow. Population densities of B. longicaudatus in creased on cotton, reaching a carrying capacity of 139 nematodes/130 cm(3) of soil, but decreased exponentially during periods of bare fallow. The mod el indicated that population densities should decrease each year of monocro pped cotton, if an alternate host is not present between sequential cotton crops. Economic thresholds derived from published damage functions and curr ent prices for cotton and nematicides varied from 2 to 5 B. longicaudatus/1 30 cm(3) of soil, depending on the nematicide used.