How to fight spider mites in a greenhouse on cucumbers? - briefly
Monitor cucumber foliage daily, prune and discard heavily infested leaves, and maintain low humidity to discourage mite proliferation. Apply a targeted miticide—such as neem oil, sulfur, or a licensed acaricide—and, when possible, introduce predatory mites (e.g., Phytoseiulus persimilis) for biological control.
How to fight spider mites in a greenhouse on cucumbers? - in detail
Spider mites thrive in warm, humid greenhouse environments, especially on cucumber foliage. Effective control requires a combination of cultural, biological, and chemical measures applied systematically.
Maintain optimal greenhouse conditions. Keep temperature below 25 °C during the hottest part of the day and ensure good air circulation with fans or vent openings. Reduce leaf wetness periods by watering at the base of the plants rather than overhead, which discourages mite reproduction.
Sanitize all equipment, pots, and benches before introduction of new seedlings. Remove heavily infested leaves and dispose of them away from the production area. Quarantine any new stock for at least two weeks, inspecting thoroughly for signs of infestation.
Introduce natural enemies. Predatory mites such as Phytoseiulus persimilis and Neoseiulus californicus consume all life stages of the pest. Release rates of 10–20 predatory mites per square meter provide rapid suppression. Maintain a refuge crop (e.g., bean leaves) to sustain predator populations.
Apply miticides only when monitoring indicates populations exceed economic thresholds (approximately 5 mites per leaf underside). Use products with low toxicity to beneficial insects, such as neem oil, horticultural oil, or abamectin, following label rates and rotating active ingredients to prevent resistance. Apply sprays early in the morning or late afternoon to minimize photodegradation and leaf burn.
Monitor regularly. Inspect the undersides of leaves with a hand lens at least twice weekly. Record mite counts and predator presence to adjust treatment timing. Sticky traps placed near ventilation openings help detect adult dispersal.
If severe outbreaks occur, combine treatments: first apply a miticide with rapid knock‑down effect, then introduce predatory mites once residue levels fall below the toxicity threshold indicated on the product label. Repeat applications according to the recommended interval, typically every 7–10 days, until populations drop below the threshold.
Document all interventions, environmental parameters, and observations. This record supports decision‑making, facilitates compliance with integrated pest management protocols, and provides a basis for future improvements.