What remedy should be used against spider mites on eggplants in a greenhouse? - briefly
Use a horticultural oil (e.g., neem or mineral oil) applied to all leaf surfaces to smother the mites. For heavy outbreaks, a registered miticide such as abamectin may be added following label instructions.
What remedy should be used against spider mites on eggplants in a greenhouse? - in detail
Spider mites rapidly colonize eggplant foliage in greenhouse environments, causing stippling, yellowing, and reduced fruit set. Effective control requires an integrated approach that combines chemical, biological, and cultural tactics.
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Chemical options
Abamectin: Apply 0.5 ml L⁻¹ as a foliar spray at the first sign of infestation; repeat after 7 days if mite counts remain high.
Spinosad: Use 1 ml L⁻¹ spray; reapply in 10 days. Both products must be registered for use on Solanaceae and observed for resistance development.
Sulfur: Dust or spray at 1 kg ha⁻¹; avoid use when temperature exceeds 30 °C to prevent phytotoxicity. -
Biological agents
Phytoseiulus persimilis: Release 5–10 predatory mites per plant; maintain humidity above 60 % to support predator activity.
Neoseiulus californicus: Apply at 2 g m⁻² weekly; effective under lower humidity conditions.
Entomopathogenic fungi (Beauveria bassiana): Spray spore suspension at 1 × 10¹² conidia L⁻¹; repeat every 5 days during peak mite activity. -
Cultural measures
Temperature regulation: Keep greenhouse temperature between 20–25 °C; lower temperatures slow mite reproduction.
Relative humidity: Maintain 65–70 % RH; high humidity reduces mite colonization and enhances predator survival.
Sanitation: Remove heavily infested leaves, dispose of plant debris, and clean benches to eliminate mite reservoirs.
Reflective mulches: Install aluminum‑foil mulch to deter mite settlement on lower leaves. -
Monitoring and thresholds
Inspect the underside of leaves with a hand lens twice weekly. Initiate treatment when mite density exceeds 5 mites per leaf fragment (≈0.5 cm²). Record counts to assess control efficacy and adjust spray intervals accordingly. -
Resistance management
Rotate chemical classes every 3–4 applications; combine with predatory mites to reduce selection pressure. Avoid consecutive use of the same mode of action.
Implementing these measures in concert limits spider mite populations, protects foliage health, and sustains fruit yield throughout the greenhouse production cycle.