How should you treat cucumbers in a greenhouse for spider mites? - briefly
Apply a miticide such as «neem oil» or «sulfur spray» at the first sign of infestation and keep humidity low while washing foliage regularly. Introduce predatory mites like Phytoseiulus persimilis for biological control.
How should you treat cucumbers in a greenhouse for spider mites? - in detail
Cucumber production in greenhouse settings requires systematic measures to suppress spider‑mite infestations and preserve plant health.
Regular scouting is essential. Inspect the undersides of leaves every two to three days for stippled discoloration, fine webbing, and mobile mite clusters. Record population levels to trigger control actions when thresholds (e.g., five mites per leaf) are reached.
Cultural practices that reduce mite development include:
- Maintaining relative humidity above 60 % during the day; low humidity favours mite reproduction.
- Providing adequate air circulation with fans to disrupt mite movement and prevent leaf wetness from dropping excessively.
- Removing heavily infested foliage promptly to limit source populations.
- Rotating cucumber varieties with differing leaf textures to deter mite colonisation.
Biological agents constitute the primary line of defence. Introduce predatory mites such as Phytoseiulus persimilis, Neoseiulus californicus, or Amblyseius swirskii at a rate of 10–20 predators per square metre. Release them when mite numbers exceed the established threshold, and repeat applications every 7–10 days to maintain predator pressure. Ensure that pesticide applications do not harm these beneficial organisms; select products with low toxicity to predatory mites.
When cultural and biological tactics prove insufficient, targeted miticides may be employed. Prefer compounds with short residual activity and specific action modes, such as abamectin, spirodiclofen, or bifenazate. Apply according to label directions, rotating active ingredients to delay resistance development. Avoid broad‑spectrum insecticides that eradicate natural enemies and exacerbate mite resurgence.
Sanitation measures reinforce all other strategies. Clean greenhouse benches, trays, and equipment regularly to remove debris that can shelter mites. Disinfect tools with a mild bleach solution (1 % sodium hypochlorite) before use.
Integrating monitoring, environmental regulation, beneficial‑mite releases, and judicious miticide use creates a robust management program that minimises spider‑mite damage while sustaining cucumber yield and quality.