Bay sucker
A sap-feeding psyllid whose nymphs shelter under the rolled edge of a bay leaf, thickening the margin and curling it downward until it yellows and finally goes brown and brittle. It is the commonest complaint about a potted bay in Britain and is routinely diagnosed as drought, cold or scorch — all of which brown a leaf edge and none of which roll and thicken it first, or leave white waxy fluff inside the curl.
Caused by: Trioza alacris · also called bay psyllid, curled bay leaves, bay leaf blister
What brings it on
Sheltered positions and clipped potted plants, where the dense growth gives the nymphs cover and the plant cannot outgrow the damage. Two generations a year, with the second doing most of the visible harm in late summer.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Bay sucker
- Royal Horticultural Society: Bay — problems
Checked 2026-08-13
Usually seen: May, June, July, August, September
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Clip in early summer and open the crown so air moves through it, and check the new flush as it hardens — the nymphs settle on young leaves and the damage is done before the leaf has finished expanding.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Bay — pruning
Checked 2026-08-13
Dealing with it once it is there
- Pick off and bin the curled leaves as they appear, which removes the nymphs with them and is enough on a clipped plant. A bay recovers its appearance over one or two flushes; the damaged leaves never uncurl, so the plant is judged on what comes next rather than on what is already marked.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Bay sucker — control
Checked 2026-08-13
Widely repeated, and not supported
Recorded so GrowingHQ can address them. These are not alternative approaches — they are things the evidence does not back.
“Brown edges on a potted bay mean it needs more water.”
Drought browns a bay leaf flat, from the tip and margin inward. Bay sucker rolls and thickens the margin first and leaves waxy white fluff and nymphs inside the roll, and watering a plant with curled leaves changes nothing.
Horticultural consensusCommonly said, not supportedmoderate confidence
- Royal Horticultural Society: Bay sucker
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.