How to eliminate spider mite in a greenhouse? - briefly
Apply cultural measures—prune affected foliage, keep humidity below 60 % and ensure good air circulation—then treat with a miticide such as neem oil or insecticidal soap, and release predatory mites (e.g., Phytoseiulus persimilis) for biological control. This integrated approach suppresses populations quickly and prevents recurrence.
How to eliminate spider mite in a greenhouse? - in detail
Spider mites thrive in warm, dry greenhouse conditions; effective control requires an integrated approach that combines sanitation, environmental adjustments, biological agents, and, when necessary, chemical interventions.
Begin with rigorous scouting. Inspect the undersides of leaves twice weekly, looking for stippled foliage, fine webbing, and moving motile stages. Record infestation levels to gauge treatment thresholds.
Implement cultural measures:
- Reduce relative humidity to 60 % or higher by increasing ventilation, using foggers, or installing misting systems with larger droplet sizes.
- Maintain temperatures below 80 °F (27 °C) during peak mite activity periods.
- Remove heavily infested plants promptly; discard them in sealed containers to prevent spread.
- Clean benches, trays, and support structures with a mild detergent solution, then rinse and dry before reuse.
Apply mechanical controls:
- Spray affected foliage with a strong jet of water (≈10 psi) to dislodge motile stages. Repeat every 2–3 days until populations decline.
- Use sticky cards placed near plant canopies to monitor adult movement and capture dispersing individuals.
Introduce biological agents:
- Release predatory mite species such as Phytoseiulus persimilis or Neoseiulus californicus at a rate of 1–2 predators per square foot. Ensure release occurs early in the infestation cycle for maximum suppression.
- Maintain a habitat that supports predator longevity by providing pollen or yeast supplements.
When cultural and biological tactics fail to keep populations below economic injury levels, employ selective acaricides:
- Choose products based on mode of action (e.g., neem oil, spinosad, abamectin) and rotate classes to avoid resistance buildup.
- Apply at the lowest effective concentration, covering both leaf surfaces thoroughly. Observe pre‑harvest intervals and re‑entry times specified on the label.
- Follow a spray schedule of 5–7 days between applications, monitoring mite counts to adjust timing.
Finalize with preventive practices:
- Quarantine new stock for at least two weeks, inspecting for signs of mite presence before introduction.
- Use reflective mulches or aluminum foil strips to deter mite colonization by disrupting visual cues.
- Keep greenhouse aisles clear to facilitate movement of personnel and equipment, reducing hidden microclimates where mites can proliferate.
By consistently integrating these tactics, greenhouse operators can suppress spider mite outbreaks, protect plant health, and minimize reliance on chemical controls.