How should cucumbers be sprayed against spider mites in a greenhouse? - briefly
Apply a miticide—e.g., abamectin, spinosad, or neem oil—at the label‑specified rate, thoroughly coating leaves and undersides, and repeat every 5–7 days until mite counts are below the economic threshold. Maintain greenhouse humidity below 80 % to improve spray penetration and control effectiveness.
How should cucumbers be sprayed against spider mites in a greenhouse? - in detail
Effective control of spider mites on greenhouse cucumber plants requires a systematic approach that combines proper product selection, precise application parameters, and ongoing monitoring.
Choose an appropriate miticide. Options include neem oil, horticultural oil, abamectin, spirodiclofen, or a sulfur‑based formulation. Verify that the product is registered for cucumber use and labeled for mite management. Rotate chemicals with different modes of action to delay resistance.
Prepare the spray solution according to label instructions. Typical dilution rates range from 0.5 % to 2 % v/v for oil‑based products and 0.1 % to 0.5 % for synthetic miticides. Use clean, cold water and add a non‑ionic surfact surfactant (0.1 % – 0.2 %) to improve leaf coverage.
Apply the spray when the following conditions are met:
- Temperature: 18 °C – 30 °C (avoid extremes that reduce efficacy or harm foliage).
- Relative humidity: ≥ 60 % for oil‑based products to facilitate leaf penetration; ≥ 70 % for soaps.
- Light intensity: early morning or late afternoon to minimize photodegradation.
- Wind speed: < 5 km/h to prevent drift and ensure uniform deposition.
Use a fine‑mist nozzle that produces droplets of 100 – 200 µm. Adjust pressure to 20 – 30 psi to achieve even coverage on both leaf surfaces and the undersides where mites reside. Calibrate the sprayer to deliver 200 – 300 ml m⁻², ensuring thorough wetting without runoff.
Schedule applications at 5‑ to 7‑day intervals until mite counts fall below economic thresholds (typically < 5 mites per leaf). After each treatment, inspect plants with a hand lens or sticky traps to assess population dynamics.
Maintain a clean greenhouse environment:
- Remove plant debris and fallen leaves that harbor mites.
- Introduce predatory mites (e.g., Phytoseiulus persimilis) as a biological adjunct.
- Keep ventilation adequate to reduce excessive humidity that favors mite reproduction.
Record all spray dates, products used, concentrations, and observed mite levels. This log supports decision‑making and compliance with pesticide regulations.