Host plant status and damage threshold of spinach (Spinacia oleracea) for the temperate root-knot nematode Meloidogyne chitwoodi

Problems with plant-parasitic nematodes remain a major challenge in most field vegetable crops worldwide. In agricultural fields in Belgium, these problems have increased in recent years. A major problem is the quarantine root-knot nematode Meloidogyne chitwoodi. The host plant status of the most commonly grown cultivars of spinach (Spinacia oleracea) and the damage threshold for M. chitwoodi were determined in a climate-controlled glasshouse and in a naturally infested field. The yield data with the final population densities were fitted to Seinhorst's yield and population dynamic models, respectively. The damage threshold values (T) for the relative fresh weight yield were 0.14, 1.08, 11.53 J2 (100 cm(3) soil)(-1), minimum yield (m) of 0.84, 0.64, 0.52 and maximum yield (Y-max) of 12.51, 12.44 and 9.60 for 'Gnu', 'Meerkat' and 'Whale' spinach cultivars, respectively. The maximum multiplication rates (a) were 3.81, 2.38 and 2.72, whilst the maximum population densities (M) were 563, 916, and 922 J2 (100 cm(3) soil)(-1) for 'Gnu', 'Meerkat' and 'Whale', respectively. Meloidogyne chitwoodi had an impact on the spinach yield. The higher the nematode density the lower the yield and vice versa. The tested cultivars were all hosts for M. chitwoodi but differences between cultivars occurred. 'Kolibri' and 'Rhino' were tested as the least sensitive cultivars for M. chitwoodi during the host screening test and bring opportunities for resistance breeding. This is the first report of spinach as a host for M. chitwoodi.