Aphids
Aphids suck sap from shoot tips and leaf undersides, curling leaves and slowing growth. They breed fast in spring and early summer, but ladybirds, lacewings, hoverflies and birds usually catch up within a few weeks.
Pests
What it looks like
Look under leaves and at the soft tips first.
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Colonies on shoot tips Green, black, pink or grey insects packed along soft stems. -
Curled leaves Young leaves pucker and curl over the colony. -
Sticky honeydew Shiny, sticky leaves below, often turning black with sooty mould. -
White cast skins Pale moulted skins scattered on the leaves.
How to confirm it
Aphids are easy to see with a hand lens.
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Turn leaves over
Colonies sit under leaves and along tips.
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Look for ants
Ants running up the stems farm aphids for honeydew.
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Check for predators
Ladybird larvae, hoverfly maggots and mummified aphids mean control is arriving.
What to do
Start gentle; most outbreaks need nothing stronger.
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Squash or wash off
Rub colonies off by hand or knock them off with a jet of water, early in the day.
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Pinch out tips
On broad beans and heavily infested shoots, pinch out the tips.
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Let predators work
Leave ladybirds, lacewings and hoverflies to build up.
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Spray only if needed
Use a soft soap or plant oil spray, direct on the aphids, if seedlings are at risk.
Prevent it next time
- Avoid heavy nitrogen feeding, which makes soft growth aphids love.
- Grow flowers for hoverflies and lacewings near crops.
- Cover young brassicas and carrots with fine mesh.
- Check new plants before bringing them home.
What not to do
Do not use broad-spectrum insecticides; they kill the predators that keep aphids down, and aphids return first.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Aphids, Royal Horticultural Society