How to treat a greenhouse after harvest to control spider mites? - briefly
Remove all crop residue, wash and disinfect benches and equipment, then apply a registered miticide or release predatory mite species according to label guidelines. Keep humidity low and use sticky traps for ongoing monitoring to prevent recurrence.
How to treat a greenhouse after harvest to control spider mites? - in detail
After the crop is removed, begin by eliminating all plant debris, fallen fruit, and soil residues that can shelter mites. Sweep floors, vacuum shelves, and discard waste in sealed containers. Wash every surface—benches, trays, and irrigation lines—with a detergent solution, then rinse with clean water.
Adjust the greenhouse climate to discourage mite reproduction. Reduce temperature to 15‑18 °C for several days, and lower relative humidity to 40‑50 %. Increase ventilation to create a gentle airflow, which disrupts mite movement and reduces leaf surface moisture that favors their development.
Introduce natural enemies before re‑planting. Release predatory phytoseiid mites (e.g., Phytoseiulus persimilis or Neoseiulus californicus) at a rate of 1 – 2 million individuals per hectare, distributing them evenly across the growing area. Supplement with predatory insects such as lady beetles or lacewings if mite pressure is high.
Apply a targeted miticide only when monitoring indicates an infestation exceeding 5 % of leaf area. Choose products with low residual activity and minimal impact on beneficials, such as spinosad, neem oil, or abamectin. Follow label‑specified rates, apply in the early morning or late evening, and rotate active ingredients to prevent resistance.
Implement a systematic scouting program. Inspect the undersides of leaves on a random sample of 10 % of plants twice weekly. Record mite counts, predator presence, and environmental parameters in a logbook. Use the data to decide whether biological or chemical measures are required.
Sanitize tools and equipment after each use. Dip pruning shears, harvest knives, and carts in a 70 % ethanol solution or a quaternary ammonium sanitizer for at least 30 seconds. Store tools in a dry, sealed area to avoid re‑contamination.
Finally, establish a crop rotation schedule that includes non‑host species for at least one growth cycle. This breaks the mite life cycle and reduces the initial population for the next planting. Maintaining these practices consistently will keep spider mite levels below economic thresholds throughout the post‑harvest period.