How can I combat spider mites in a greenhouse at home? - briefly
Use cultural controls (increase humidity, wash foliage regularly), introduce predatory mites such as Phytoseiulus persimilis, and apply neem oil or insecticidal soap as a targeted miticide when infestations appear.
How can I combat spider mites in a greenhouse at home? - in detail
Spider mites thrive in warm, dry conditions often found in domestic greenhouse setups. Effective management requires a combination of monitoring, cultural adjustments, biological agents, and targeted chemicals.
Regular inspection is essential. Examine the undersides of leaves each morning with a magnifying lens; look for tiny moving specks, webbing, or stippled foliage. Record infestation levels to gauge treatment efficacy.
Cultural tactics reduce mite populations without chemicals:
- Increase ambient humidity to 60‑70 % by misting or using a humidifier; mites prefer low‑moisture environments.
- Space plants to improve air circulation, preventing microclimates where mites multiply.
- Remove heavily infested leaves and dispose of them away from the greenhouse.
- Rotate crops annually; avoid planting the same species in the same location for more than two seasons.
Biological controls provide long‑term suppression:
- Release predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus according to supplier instructions; these predators consume several spider mites per day.
- Introduce beneficial insects like lady beetles or lacewings that also feed on mite eggs.
- Maintain a refuge of non‑crop vegetation to sustain predator populations.
When cultural and biological measures are insufficient, apply selective acaricides:
- Use neem oil or insecticidal soap, spraying until runoff covers both leaf surfaces; repeat every 5‑7 days until mites disappear.
- Apply horticultural oil at the lowest effective concentration; avoid application during extreme heat to prevent phytotoxicity.
- Reserve synthetic miticides (e.g., abamectin) for severe outbreaks, rotating active ingredients to delay resistance development.
Preventive steps keep infestations low:
- Quarantine new plants for at least two weeks, inspecting them before introduction.
- Clean greenhouse benches and tools with a mild bleach solution to eliminate residual eggs.
- Seal cracks and install fine mesh screens to block external mite entry.
An integrated approach—constant scouting, environmental optimization, predator release, and judicious use of acaricides—provides reliable control of spider mites in a home greenhouse. Monitoring results after each intervention ensures timely adjustments and long‑term plant health.