Methods of Decontamination
A. Physical Methods
a. Soil Solarization
- Cover moist soil with transparent polyethylene sheets for 4–6 weeks during summer.
- Solar heat (50–60°C) kills fungal propagules, nematodes, and weed seeds.
b. Steam Sterilization
- Injecting steam into soil or substrate raises temperature above 80°C.
- Effective against fungi, nematodes, and bacteria.
c. UV Radiation: Periodic UV-C treatment in empty greenhouses to inactivate spores on surfaces.
B. Chemical Methods
a. Fumigants (used cautiously, subject to regulations)
- Formaldehyde solution (2–5%) sprayed or drenched in empty houses, left closed for 2–3 days, then ventilated.
- Methyl bromide (historically used, now banned in many countries).
b. Disinfectants for structures and tools
- Sodium hypochlorite (bleach solution 1–2%) for benches, trays, irrigation lines.
- Hydrogen peroxide or quaternary ammonium compounds for surface sterilization.
c. Soil Drenching: Carbendazim, Captan, or Copper-based fungicides used for soil decontamination before planting.
C. Biological Methods
- Antagonistic fungi: Trichoderma harzianum, Gliocladium virens.
- Beneficial bacteria: Pseudomonas fluorescens, Bacillus subtilis.
- These are incorporated into soil or applied as drenches to suppress fungal pathogens.