How should cucumbers be treated for spider mites in a greenhouse? - briefly
Apply an approved greenhouse miticide—such as sulfur, neem oil, or a spirotetramat formulation—directly to foliage, especially the undersides, and repeat every 5–7 days until mite numbers fall below the economic threshold. Support chemical action with sanitation, humidity control, and releases of predatory mites (e.g., Phytoseiulus persimilis).
How should cucumbers be treated for spider mites in a greenhouse? - in detail
Effective spider‑mite management on greenhouse cucumber production requires an integrated approach that combines monitoring, cultural adjustments, biological agents, and, when necessary, chemical interventions.
Regular scouting should be performed at least twice weekly. Examine the undersides of leaves with a magnifying lens; count the number of mites per leaf and look for characteristic webbing. Record data to detect population thresholds (generally 5–10 mites per leaf) that trigger action.
Cultural measures reduce mite establishment:
- Maintain relative humidity above 60 % during the day; low humidity favors mite reproduction.
- Keep temperature between 20 °C and 25 °C; extreme heat accelerates life cycles.
- Provide adequate air circulation with fans to disrupt microclimates where mites thrive.
- Remove plant debris and prune heavily infested leaves promptly to eliminate breeding sites.
- Rotate crops with non‑host species or use clean seedling trays to prevent introduction.
Biological control agents are the cornerstone of sustainable control:
- Release predatory phytoseiid mites (e.g., Phytoseiulus persimilis, Neoseiulus californicus) at a rate of 10–15 predators per square meter when mite numbers exceed the threshold.
- Apply entomopathogenic fungi such as Beauveria bassiana as a foliar spray; follow label rates and repeat applications every 7–10 days until populations decline.
- Encourage natural enemies by providing refuge plants (e.g., sweet alyssum) and avoiding broad‑spectrum insecticides that harm beneficials.
If mite pressure persists despite the above tactics, selective miticides may be employed:
- Use acaricides with a short residual activity (e.g., abamectin, spirodiclofen) at the lowest effective concentration.
- Rotate chemistries with different modes of action to prevent resistance; follow a recommended rotation schedule (e.g., MOA 1 → MOA 2 → MOA 3).
- Observe pre‑harvest intervals and residue limits to ensure market compliance.
Post‑treatment sanitation includes washing equipment, disinfecting trays, and replacing any contaminated growing media. Document all interventions in a pest‑management log to refine future decisions.
By adhering to this systematic protocol, growers can keep spider‑mite infestations below damaging levels while preserving plant health and product quality.