How to fight spider mite on cucumbers in a greenhouse? - briefly
Inspect cucumber vines frequently, prune and discard heavily infested leaves, and treat remaining plants with a suitable miticide (e.g., neem oil or a horticultural oil) or introduce predatory mites; keep greenhouse humidity above 60 % and limit nitrogen fertilization to suppress mite development. Rotate crops and thoroughly clean benches between productions to reduce future outbreaks.
How to fight spider mite on cucumbers in a greenhouse? - in detail
Spider mites rapidly colonize cucumber plants in protected environments, causing stippling, yellowing, and reduced yield. Their life cycle completes in 5‑7 days at 25 °C, allowing populations to explode if unchecked.
Regular scouting is essential. Inspect the undersides of leaves every 2‑3 days, using a 10× hand lens. Count mites per leaf; thresholds of 5–10 adults per leaf indicate the need for intervention. Record observations to track trends.
Cultural measures reduce habitat suitability. Maintain humidity above 60 % by misting or fogging, because low humidity favors mite reproduction. Space plants 30–45 cm apart to improve air circulation and leaf drying. Remove heavily infested vines promptly to limit sources of reinfestation. Rotate cucumber varieties each season to disrupt mite life cycles.
Physical tactics provide immediate suppression. Apply a strong jet of water to foliage for 30 seconds, dislodging mites and eggs. Install fine mesh (≤ 30 µm) on ventilation openings to prevent entry of airborne individuals. Use sticky traps coated with oil to monitor adult movement.
Biological agents offer sustainable control. Release predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus at a rate of 10–20 predators per square meter when populations exceed the scouting threshold. Ensure compatible temperature (20–30 °C) and avoid broad‑spectrum insecticides that would harm the released agents. Supplement with entomopathogenic fungi (e.g., Beauveria bassiana) applied as a foliar spray at 1 × 10⁸ conidia L⁻¹, repeating every 7 days until mite numbers decline.
Chemical options remain a last resort. Select acaricides registered for cucumber greenhouse use, such as abamectin (0.5–1 mg L⁻¹) or spiromesifen (100–200 g ha⁻¹). Rotate active ingredients with a minimum 7‑day interval to prevent resistance. Observe pre‑harvest intervals and adhere to label restrictions.
Integrating all tactics yields an effective management program. Begin with environmental adjustments and vigilant scouting, introduce biological control agents when thresholds are met, employ water sprays or traps for rapid reduction, and reserve targeted chemicals for severe outbreaks. Document each action, monitor outcomes, and adjust the schedule to maintain mite populations below economic injury levels throughout the production cycle.