How to treat soil in a greenhouse for spider mites? - briefly
Apply a horticultural oil or neem‑oil soil drench, covering the root zone and re‑treating every 7–10 days until mites are eliminated. Use sterile growing media, maintain proper moisture, and monitor with sticky traps to prevent reinfestation.
How to treat soil in a greenhouse for spider mites? - in detail
Treating greenhouse substrate infested with spider mites requires an integrated approach that targets the pest while preserving plant health.
First, remove visible infestations. Discard heavily damaged plants or heavily colonized pots. Clean pots, trays, and benches with a 10 % bleach solution, then rinse thoroughly and allow to dry.
Second, modify the growing medium. Replace the top 2–3 cm of soil with fresh, sterile substrate. If the entire medium is compromised, repot plants in a sterile mix composed of peat, perlite, and vermiculite in a 2:1:1 ratio. Sterilize the new mix by steaming at 100 °C for 30 minutes or by treating with a hydrogen peroxide solution (3 % w/v) followed by thorough drainage.
Third, introduce biological antagonists. Apply predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus directly onto the soil surface. These agents consume spider mite eggs and juveniles and can establish in the substrate, reducing future outbreaks.
Fourth, employ chemical controls judiciously. Use soil‑active acaricides that are registered for greenhouse use, such as abamectin or spirodiclofen, according to label rates. Apply as a drench, ensuring uniform coverage of the root zone. Rotate products with different modes of action to prevent resistance.
Fifth, adjust environmental conditions. Maintain relative humidity at 70 % or higher, as spider mites thrive in dry air. Increase ventilation and misting to raise humidity without encouraging fungal diseases. Keep temperature within the optimal range for the crop, typically 20–25 °C, to support plant vigor.
Sixth, monitor regularly. Inspect soil and foliage weekly using a hand lens. Record mite counts and treatment actions in a log. Early detection allows rapid response and limits spread.
Finally, implement sanitation protocols. Train staff to wear disposable gloves and shoe covers when handling plants. Clean tools with 70 % alcohol between uses. Store all substrate in sealed containers to prevent re‑infestation.
By combining removal, substrate renewal, biological agents, targeted acaricides, environmental management, vigilant monitoring, and strict hygiene, greenhouse growers can effectively suppress spider mite populations in the soil and protect crop productivity.