The suitability of onion (Allium cepa cv. Sweet Vidalia) as a host for Meloidogyne incognita, M. arenaria, and M. javanica was evaluated. The effect of M. incognita on yield and economic return of directseeded and transplanted onions also was evaluated. Nematode reproduction was evaluated in two greenhouse trials with six replications each. All three nematode species increased with final egg counts of 19,300 for M. incognita, 32,100 for M. arenaria, and 40,350 for M. javanica in the first trial and 167,200 for M. incognita, 71,600 for M. arenaria, and 101,950 for M. javanica in the second trial. Final egg counts were similar (P =0.05) among the three species in the first trial, but M. incognita produced more eggs (P =0.05) than M. arenaria in the second trial. The application of 1,3-D in directseeded onions increased the weight (kg/ha) of large and colossal sizes in both seasons and the weight of small and medium sizes in 2002-2003. In transplanted onions, the weight of colossal onions was increased in 2001-2002, but weights were unaffected in 2002-2003. Onion is a good host for all three Meloidogyne species tested, and M. incognita can reduce yields and economic return when onions are direct-seeded. Transplanted onions in this study did not suffer economic loss.
