The effect of Meloidogyne incognita on the growth of Catalpa bignonioides

A glasshouse experiment was undertaken to ascertain the relationship between population densities of Meloidogyne incognita host race 1 and growth of common catalpa. A range of population densities of 0, 0.0625, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16, 32, 64, 128 and 256 eggs and juveniles/cm3 soil was considered. Tolerance limit of 0.78 for fresh and dry top weight and leaf area and 1.8 eggs and juveniles/cm3 soil for plant height were derived. Minimum relative yields of 0.4 and 0.65 for the same parameters and an equilibrium density of the nematode of 47.5 eggs and juveniles/cm3 soil were estimated. The maximum reproduction rate of the nematode was 123-fold and occurred at the lowest Pi.