Biology, epidemiology

- Conservation, sources d'inoculum

The Meloidogyne spp. persist in the soil for more than two years, in the form of egg masses protected by a mucilaginous matrix. These white to brown masses can be seen on the surface of the galls with a binocular magnifying glass. Meloidogyne hapla survives in freezing soils.

They are very polyphagous and attack very many plants, cultivated or not, on which they ensure their multiplication and their conservation.


- Penetration and invasion

Stage II larvae, attracted by root exudates, enter the roots and migrate through the cortex to the vascular system. During their bites, they secrete enzymes and hormones which will be at the origin of the development of giant cells and galls (figure 2). These will be used for their nutrition. Larval development continues at the same time as the root swells. Ultimately, a gall surrounds a voluminous female piriformis (figure 1). It produces numerous eggs (between 400 and 500 on average, figure 3) which are emitted outside the root, enclosed in a gelatinous matrix (figure 4).


- Dissemination

From diseased plants and many eggs and larvae can be passively transported by runoff, drainage and irrigation water. The larvae actively move short distances in moist soils. Spreads are possible via dust from contaminated soil; these are carried by the wind towards neighboring plots. Contaminated plants, tillage tools and machinery also perform this function.


- Conditions favorable to their development

M. incognita and M. arenaria appreciate the relatively high temperatures (18-27 ° C) found in light, sandy soils. M. javanica tolerates higher temperatures, while cooler conditions M. hapla prefers . In general, their activity is greatly reduced, or even stopped below 5 ° C or above 38 ° C.