How to combat spider mites on orchids? - briefly
Prune heavily infested foliage, isolate the orchid, and treat all plant surfaces with a horticultural oil or neem‑oil spray (2–3 ml per litre of water) every 5–7 days. Keep humidity above 60 %, minimize leaf dust, and inspect regularly to prevent re‑infestation.
How to combat spider mites on orchids? - in detail
Spider mites are tiny arachnids that feed on orchid foliage, causing stippling, yellowing, and webbing. Early detection relies on inspecting the undersides of leaves with a magnifying lens; look for tiny moving specks and fine silk. Once an infestation is confirmed, a multi‑step strategy maximizes control.
Physical removal
- Gently rinse plants with lukewarm water, directing the flow over both leaf surfaces to dislodge mites and webs.
- Use a soft brush or cotton swab dipped in soapy water (1 % mild detergent) to scrub heavily infested areas.
Cultural measures
- Increase ambient humidity to 60–70 %; spider mites thrive in dry conditions. A humidifier or a pebble tray filled with water can raise leaf moisture.
- Maintain temperatures between 65–75 °F (18–24 °C); extreme heat accelerates mite reproduction.
- Avoid excessive fertilization with high nitrogen, which promotes tender growth favored by the pest.
Chemical options
- Apply horticultural oil (e.g., neem or mineral oil) at a rate of 2 ml per liter of water, covering all leaf surfaces, especially the undersides. Repeat every 5–7 days until no mites are observed.
- If oil treatments prove insufficient, use a miticide containing abamectin or spinosad, following label instructions for concentration and interval.
Biological controls
- Introduce predatory insects such as Phytoseiulus persimilis or Amblyseius swirskii; release 10–15 predators per plant, ensuring they have a food source by maintaining a small population of non‑target mites.
- Apply Bacillus thuringiensis var. israelensis as a spray; it targets mite larvae without harming the orchid.
Preventive practices
- Quarantine new orchids for at least two weeks, inspecting them daily for signs of infestation.
- Clean tools, pots, and work surfaces with 70 % isopropyl alcohol before handling plants.
- Rotate crops in greenhouse settings; avoid planting orchids adjacent to known mite hosts such as citrus or indoor foliage plants.
Monitoring continues after treatment. Inspect plants weekly for at least six weeks, documenting mite counts. If numbers rise, repeat the most effective method from the list above or combine oil treatment with predator release. Consistent application of these integrated tactics eliminates spider mites and preserves orchid health.