Control measures

Control measures are difficult because of the very wide host range of these nematodes. Moreover, accurate species identification is critical because of their distinct host ranges.

Different measures and factors have an effect on the control of the root-knot nematodes:

• the use of certified seed tubers is highly advisable as well as avoiding the introduction of soil, rooted plants or seed tubers originating from infected fields or areas;

• because no commercial potato cultivar is fully resistant to root-knot nematodes, nematicide treatment is usually the most effective measure in infested areas but, due to the high toxicity of nematicides, chemical control is now severely restricted by many authorities;

• in the case of low infestation, early planting and early harvest may limit tuber damage, as the disease develops mainly in warm conditions (late autumn);

• black fallow, i.e. sanitary period with no crop at all, reduces soil infestation with root
  knot nematodes more safely than crop rotation which relies on the Meloidogyne species and races present in the field. Rotation with cereal crops is generally recommended in the presence of M. arenaria, M. javanica or M. incognita but not in the case of M. chitwoodi. Other crops like some Brassicaceae have some level of resistance to M. chitwoodi and can be used as green manure crops and may reduce nematode populations;

• for horticultural production, other crops and vegetables are resistant to M. arenaria, M. javanica and M. incognita (i.e. tomato cultivars carrying the Mi resistance gene) and can be successfully used in the rotation;

• alternative methods have been successfully tested under experimental conditions such as biological control using the predator fungus (Arthrobotrys) or the bacterium (Bacillus penetrans) but their application in the field still requires further research.