Crops
Nacobbus spp.
Nacobbus spp. are sedentary or migratory endoparasitic nematodes (figure 1) which cause various alterations on salad roots:
- necrosis linked to the destruction of cells and the formation of cavities in the cortex;
- galls morphologically very comparable to those caused by Meloidogyne spp. and in particular by Meloidogyne hapla . This is the reason why we talk about the disease of false root-knot nematodes. First, females establish a feeding site in the root, close to the vascular system. They feed to the detriment of the cells, grow strongly and induce the formation of small round galls. Their eggs are expelled and grouped together in a gelatinous matrix. They are the most efficient form of survival of these nematodes in decaying plant debris. Several species have been reported on lettuce (consult the table indicating these Main nematodes reported on lettuce, chicory and endive ): Nacobbus aberrans , Nacobbus batatiformis , Nacobbus serendipiticus .
These nematodes, which are very polyphagous, affect both cultivated plants and weeds. Their attacks seem infrequent on salad. To our knowledge, they are not rife in France.
Confusions of diagnosis are possible with Meloidogyne spp., Mainly in production areas where these two genera of nematodes are found in mixture. These confusions are not normally detrimental because the control methods to be implemented to combat them are identical.