Broad & cyclamen mites
Polyphagotarsonemus latus & Phytonemus pallidus
Invisible mites that twist and bronze the growing tip so convincingly that the plant is usually thrown away as a virus. Hot water and heat treatment are the answers.
How to know it
You will not see them; they are under 0.2 mm and need a 20× lens at least. Identify by the damage, which is unmistakable once known: the newest leaves are small, thickened, brittle, curled downward at the edges and often bronzed or silvered, while everything older on the plant is perfect. Flower buds are deformed or fail to open.
What you'll see
- The growing tip stunted and twisted, with tiny hardened leaves crowded together.
- A bronze, coppery or silvery sheen on the undersides of the newest leaves.
- Leaf margins rolled down and the tissue brittle rather than soft.
- Flower buds blasted, or flowers opening streaked and distorted.
- Perfect older growth below the damage — the detail that separates it from a virus or herbicide drift.
Where it comes from
A generation takes under a week in warm conditions, so numbers explode. They live in the folded newest leaves and in the buds, which is why sprays so rarely reach them, and they travel between plants on your hands, on tools and by riding whitefly. Cyclamen mite prefers cool and humid; broad mite prefers warm.
Greenhouses, propagation benches, houseplants and pepper crops. High humidity and crowded plants favor both. Almost every garden case arrives on a bought plant.
Dealing with it
- Cut the damaged growing tips off and bin them; the mites are in that tissue and nowhere else.
- Dip a small infested plant in water at 43–45 °C for 15 minutes, which kills the mites and most plants tolerate well.
- Spray sulfur or horticultural oil into the growing tip specifically, repeating every five days for three rounds.
- Release predatory mites — Amblyseius swirskii or Neoseiulus cucumeris — which is the most effective control under glass.
- Wash your hands and tools between plants; you are the main way they travel.
Keeping it out
- Quarantine new plants for a month and watch the growing tip.
- Do not take cuttings from an affected plant.
- Keep the greenhouse from becoming crowded and humid, and space plants so leaves do not touch.
- Discard badly affected bedding and houseplants rather than nursing them; they are a reservoir.
- Check strawberry runners and cyclamen especially, which are the two classic carriers.
What it goes for
Peppers and chillies, cyclamen, African violet, begonia, impatiens, gerbera, strawberry and many greenhouse plants.
Who hunts it for you
- Minute pirate bugOrius spp. A pinhead-sized true bug that is the best natural check on thrips, and happily spears aphids, mites, and insect eggs too. It needs pollen when prey is scarce, so keep something flowering nearby. Grow to recruit it: Cosmos,Fennel,French marigold,Sweet alyssum
- Predatory mitesPhytoseiulus & Amblyseius Fast orange mites that hunt spider mites egg-by-egg, and cousins that clear thrips and fungus-gnat larvae. Sold as a biological control for greenhouses; outdoors they follow humidity — mist and mulch, don’t dust with sulfur.
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com