How to disinfect soil in a greenhouse after spider mites? - briefly
Remove plant debris, then apply a soil drench of neem oil or horticultural oil at the recommended rate and flush the medium with water. Allow the substrate to dry completely before re‑planting to ensure the mites are eradicated.
How to disinfect soil in a greenhouse after spider mites? - in detail
After a spider‑mite infestation, the first step is to eliminate all plant material that shows visible damage. Dispose of affected foliage in sealed bags and remove any debris that could shelter surviving mites.
Next, extract the growing medium from the beds. If the soil will be reused, treat it before returning to the greenhouse:
- Solarization – spread the soil in a thin layer (2–3 cm) on a black plastic sheet, cover with clear polyethylene, and expose to direct sunlight for 5–7 days at temperatures above 45 °C. This heat kills mites, eggs, and most associated pathogens.
- Steam sterilization – pass saturated steam through the soil at 80–100 °C for 30 minutes. Use a commercial steamer or a portable unit designed for horticultural applications.
- Chemical disinfection – apply a registered soil fumigant (e.g., methyl bromide alternatives) according to label directions. Ensure proper ventilation and personal protective equipment.
- Biological amendment – incorporate a high‑dose preparation of entomopathogenic nematodes or the fungus Beauveria bassiana into the soil. These agents attack mite stages that survive physical treatments.
After treatment, allow the medium to cool and dry to a moisture content of 40–50 % before reseeding or transplanting. Verify the absence of mites by examining a sample under a magnifier.
Finally, implement preventive measures: maintain humidity above 60 % where possible, avoid excessive nitrogen fertilization, and introduce predatory insects such as Phytoseiulus persimilis to the greenhouse environment. Regular monitoring and sanitation reduce the risk of recurrence.