Damage thresholds and population dynamics of Meloidogyne chitwoodi on carrot (Daucus carota) at different seed densities

Yield loss of carrot ( Daucus carota ) cv. Nerac caused by Meloidogyne chitwoodi and population dynamics of this nematode were studied using a range of 13 nematode densities at three seed densities (2, 4, 18 seeds pot −1 ) in a climate-controlled glasshouse. Yield and quality data were fitted to Seinhorst’s yield models. Final population densities were fitted to the population dynamic models for sedentary and free-living nematodes. The tolerance limits for yield loss were 0.34, 0.62 and 0.50, while that of quality were 0.012, 0.142 and 0.813 second-stage juveniles (J2) (g dry soil) −1 at increasing seed densities, respectively. The minimum yield (m), increased with seed density: 0.25, 0.30 and 0.50; the minimum quality yield was 0.10, 0.08 and 0.15 J2 (g dry soil) −1 at increasing seed densities, respectively. Both maximum multiplication rates and maximum population densities increased with increasing seed density but were generally low. Carrot cv. Nerac can be considered a bad host for M. chitwoodi .