Sclerotium  rolfsii  Sacc .

 Athelia rolfsii  (Curzi) C. C. Tu & Kimbr.

Sclerotium rot

General  

• Soil fungus particularly prevalent in warm tropical and subtropical regions . It is particularly common and feared in many market garden soils in the French overseas departments and territories
• Extremely polyphagous, affecting many cultivated and non-cultivated plants: at least five hundred species belonging to botanical families representing both mono and dicots.
• Known vegetables affected: eggplant, tomato, pepper, various salads, melon, cucumber, watermelon, bean, artichoke, beetroot, carrot, cauliflower, celery, garlic, onion, radish, turnip, sweet potato, etc.
• Observed in the open field as well as under shelters.

• Sensitive botanical family (s)

 Biology

• Conservation : persists for several years rather on the surface of the soil on plant debris, in the form of aggregated mycelium ( figures 1 and 2 ), but especially of sclerotia (figures 3 to 6) free or or associated with plant debris. This fungus is also able to survive on different organic substrates.
• Sources of inoculum :  contamination takes place via the mycelium already present in the soil (figures 4 and 5) or from sclerotia.
• Infection : directly penetrates the tissues and invades them thanks to lytic enzymes.
• Development, sporulation : Rapidly forms mycelium and sclerotia on injured tissue.
• Dissemination : ensured by soil contaminated by sclerotia, tillage, soiled agricultural tools and machinery, water and plants produced in infested nurseries.
• Favorable conditions : appreciates hot climates and proliferates following humid periods and/or irrigation. Favored by acidic, asphyxiating soils and temperatures between 25-35°C.

 Protection

• Carry out crop rotations in virgin land, they are no longer very effective in contaminated soil.
• soil disinfection : fumigant, solarization , biofungicides, etc.
• Lime the soil, provide fertilization calcium-rich
• Avoid planting too deeply , burying the collar of the plants.
• Install mulch to create a mechanical barrier between the soil and the plant organs.
• Eliminate plant debris during and at the end of cultivation, as well as potential host weeds likely to harbor or promote the development and preservation of this fungus in the soil.
• Take care of irrigation : optimal quantity, localized supply, etc.