How should spider mites on cucumbers be treated in a greenhouse? - briefly
Use a miticide (e.g., abamectin, neem oil) or release predatory mites while regularly scouting and removing heavily infested foliage. Maintain low humidity, provide adequate ventilation, and avoid excessive nitrogen fertilization to suppress mite reproduction.
How should spider mites on cucumbers be treated in a greenhouse? - in detail
Effective management of spider mites on cucumber plants grown in greenhouse conditions requires an integrated approach that combines cultural, biological, and chemical tactics.
First, preventive cultural measures reduce the likelihood of infestations. Maintain optimal temperature (22‑28 °C) and relative humidity (60‑70 %) to discourage mite reproduction. Implement strict sanitation by removing plant debris, disinfecting benches, and limiting movement of personnel and equipment between aisles. Rotate crops annually and avoid planting cucumbers in the same location for more than two consecutive seasons. Use reflective mulches or aluminum foil strips to repel mites from leaf surfaces.
Second, biological controls provide rapid population suppression while preserving beneficial insects. Release predatory mites such as Phytoseiulus persimilis, Neoseiulus californicus, or Amblyseius swirskii at a rate of 10‑20 predators per leaf when mite densities reach 2–5 mites per leaf. Ensure compatible environmental conditions: temperatures above 20 °C and low pesticide residues. Augment with entomopathogenic fungi (e.g., Beauveria bassiana) applied as a foliar spray at 1 × 10¹² conidia L⁻¹, repeating every 7‑10 days until mite counts fall below economic thresholds.
Third, chemical interventions serve as a last resort when mite populations exceed economic injury levels (typically >5 mites per leaf). Select miticides with low residual activity and minimal impact on predatory mites, such as abamectin (0.5‑1 mg L⁻¹), spirodiclofen (0.2‑0.3 mg L⁻¹), or bifenazate (0.5 mg L⁻¹). Apply according to label rates, rotating active ingredients to prevent resistance development. Observe a pre‑harvest interval of at least 5 days and a re‑entry interval consistent with safety guidelines.
Monitoring is essential throughout the production cycle. Inspect the underside of leaves twice weekly using a 10× hand lens. Record mite counts per leaf and adjust control measures based on a decision matrix:
- 0–1 mites/leaf: continue cultural practices only.
- 2–5 mites/leaf: introduce or augment predatory mites.
-
5 mites/leaf: combine biological agents with targeted miticide applications, ensuring rotation of chemistries.
Document all interventions, environmental parameters, and pest observations to refine the management program over successive crops. This systematic strategy minimizes crop loss, preserves greenhouse ecology, and complies with integrated pest management principles.