How to treat a greenhouse in spring before planting for spider mites? - briefly
Thoroughly clean the greenhouse, discard all plant residues, and apply a preventive miticide or horticultural oil at the recommended rate before sowing; then maintain lower humidity and moderate temperatures while regularly inspecting foliage for early signs of infestation.
How to treat a greenhouse in spring before planting for spider mites? - in detail
Begin the season with a thorough inspection of the structure. Remove all plant debris, fallen leaves, and spent growing media. Clean benches, shelving, and walls with a mild detergent solution, then rinse and dry. Seal cracks and gaps that could allow entry of wild insects.
Adjust the microclimate to discourage spider mite development. Set daytime temperatures between 18 °C and 22 °C and keep relative humidity above 60 % during the first weeks after sowing. Use ventilation fans and misting systems to maintain airflow and moisture levels. Avoid excessive fertilization with high nitrogen, which can accelerate mite reproduction.
Implement cultural barriers before seedlings are placed. Install fine mesh screens on vents and doors. Apply a thin coat of horticultural oil or neem‑based product to all surfaces, including pots and trays, following label directions. This creates a residual barrier that reduces initial colonization.
Introduce biological agents early. Release predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus at a rate of 10–20 predators per m². Distribute them evenly across benches and ensure a continuous food source by maintaining a low‑density spider mite population or providing supplemental pollen.
If monitoring indicates rising mite numbers, apply selective acaricides. Choose products with low toxicity to beneficial insects, such as spinosad or abamectin, and rotate modes of action to prevent resistance. Apply according to the manufacturer’s schedule, typically every 7–10 days, and cease treatment once populations fall below economic thresholds.
Maintain a regular scouting program. Examine the undersides of leaves at least twice weekly, looking for stippling, webbing, or moving mites. Record observations in a log to track trends and adjust control measures promptly.
Conclude the pre‑planting phase by establishing a sanitation routine: weekly removal of plant waste, periodic cleaning of irrigation lines, and periodic replacement of filter media. This ongoing maintenance sustains a low‑mite environment throughout the growing season.