What to do with spider mites on cucumbers in a greenhouse? - briefly
Inspect plants regularly, prune heavily infested foliage, and treat remaining vines with horticultural oil or neem spray while keeping greenhouse humidity above 60 % to deter mite proliferation. Introduce predatory mites (e.g., Phytoseiulus persimilis) and rotate cucumber crops to sustain long‑term control.
What to do with spider mites on cucumbers in a greenhouse? - in detail
Spider mites quickly colonize cucumber vines when humidity is low and temperatures exceed 25 °C. Early detection prevents severe leaf loss and fruit deformation.
Inspect plants twice weekly. Look for stippled leaves, fine webbing on leaf undersides, and moving specks. Use a white sheet or hand lens to confirm presence.
Control measures follow a hierarchy:
- Environmental adjustment – raise relative humidity to 60–70 % with misting or foggers; reduce daytime temperature by 2–3 °C if possible. Cooler, moist conditions hinder mite reproduction.
- Cultural practices – prune heavily infested vines, discard removed material, and clean benches and trays with a 10 % bleach solution. Rotate cucumbers with non‑host crops each season.
- Physical barriers – install fine mesh screens on ventilation openings to exclude wind‑borne mites. Use sticky traps of yellow or blue color to monitor population trends.
- Biological agents – release predatory mites (e.g., Phytoseiulus persimilis, Neoseiulus californicus) at a rate of 10–15 predators per m² when mite density reaches 5–10 per leaf. Maintain a refuge crop such as basil to sustain predator populations.
- Botanical extracts – apply neem oil or rosemary‑based sprays at 2 % concentration every 5–7 days, ensuring thorough coverage of leaf undersides. Rotate with different modes of action to avoid resistance.
- Chemical interventions – if mite numbers exceed economic threshold (approximately 10 mites per leaf), use acaricides with short residual activity, such as abamectin or spiromesifen, following label rates and a minimum 7‑day pre‑harvest interval. Alternate products from different chemical classes to preserve efficacy.
After any treatment, re‑inspect after 48 hours. Repeat actions until counts fall below two mites per leaf. Record dates, products, and observed effects to refine future integrated pest‑management plans. Maintaining optimal humidity, regular scouting, and timely release of predatory mites provides the most sustainable control of spider mite infestations on greenhouse cucumbers.