Control of root-knot nematodes in organic farming systems by organic amendments and soil solarization

The efficacy of organic amendments, with or without soil solarization, for the control of the root-knot nematodes Meloidogyne incognita and M. javanica in organic farming systems was tested in pot, container and greenhouse experiments. Broiler litter, cottonseed meal, feather meal or soybean oilcake, which had been effective in reduction of galling caused by M. javanica on tomato plants in pot experiments, were applied to a field at 0.75–2.0 kg m−2. In three experiments, soil solarization alone reduced nematode populations in the soil and galling indices on tomato and pepper plants, whereas the amendments alone were not effective. Combinations of the amendments with soil solarization were more effective than the amendments or soil solarization alone in reducing nematode populations and galling indices in most cases. High soil temperatures and accumulation of ammonium/ammonia in these treatments seemed to be involved in controlling root-knot nematodes. Nematode control efficacy on the edges of solarized beds, with or without amendments, was lower than that in the middle of beds. Soil solarization in combination with organic amendments could be used for root-knot nematode control in organic farms.