- Conservation, sources d'inoculum
Spongospora subterranea is a chromiste able to keep several years in the soil in the absence of susceptible hosts, thanks to its spores rest ( resting spores ). It can multiply, and therefore be sustainable, by colonizing the roots of other plants, cultivated or not (corn, sorghum, tobacco, peas, cauliflower, radish, turnip, many Solanum spp., as Such S. nigrum ? ?). It is sometimes introduced into the plots through manure, sludge, etc.
- Penetration and invasion
Its resting spores are subsequently the source of either cause myxamoeba or biflagellate zoospores which root contamination. Once in the tissues, many cells hypertrophy, which gradually leads to the formation of tumors.
- Sporulation and dissemination
At the same time, polynucleated plasmodia form within the tissues, which subsequently give rise either to zoosporangia (figure 1) producing new zoospores responsible for secondary contamination, or to cystosores which cause resting spores.
- Conditions favorable to its development
The disease mainly occurs in poorly drained soils, high humidity , at temperatures between 16 and 18 ° C . It can also occur in drier soils and at high temperatures.