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Mite
Two-spotted spider mite
Tetranychus urticae
The pest most likely to cost you a season here, and the one most often brought in on your own planting material.
What you see
- 01Bleached, stippled or otherwise discoloured foliage
- 02Loss of plant vigour; leaves curling, browning and dropping early
- 03Fine webbing on leaf undersides in heavier infestations
What brings it on
Hot, dry conditions and dusty field edges. Populations build explosively — by the time damage is obvious on the upper leaf surface, the colony underneath is already large.
Why it costs money
Feeding removes cell contents, cutting vigour and yield. Damage is cumulative and cannot be reversed within the season.
What to do
- Check ten plants on delivery, leaf undersides, with a hand lens — importing mite with planting material is the most expensive avoidable mistake in the crop
- Scout leaf undersides through the season, not the tops
- Sample properly and count: published guidance works to thresholds of fewer than five mites per mid-tier leaflet early in the crop, rising to 15–20 later as plants tolerate more
- Predatory mites, particularly Phytoseiulus persimilis, are among the most effective natural enemies and feed only on spider mites
Spray strategy. Treat on counts, not on appearance. Rotate acaricide modes of action — this species develops resistance faster than almost anything else you will spray — and protect predator populations rather than flattening them with broad-spectrum products.
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