Carrot fly
The low-flying carrot fly is drawn by the smell of carrot leaves and lays eggs at the base of the plants. The larvae tunnel through the roots, which then rot. Complete cover with fine mesh is by far the best protection.
Pests
What it looks like
The damage is underground.
-
Rusty tunnels Brown channels just under the root skin. -
Maggots Creamy larvae in the tunnels. -
Discoloured leaves Foliage turns reddish or bronze and wilts in sun. -
Rotting roots Tunnels let in rot, especially in stored roots.
How to confirm it
Lift a carrot.
-
Look at the tunnels
Narrow rusty channels under the skin.
-
Check the leaves
Reddish leaves in patches of the row.
-
Timing
Damage in late summer and autumn, and in stored roots.
What to do
Keep the fly off.
-
Cover the crop
Cover completely with insect-proof mesh from sowing.
-
Build a barrier
A 60 cm (2 ft) barrier around the bed helps where mesh is impractical.
-
Sow late
Sowings after early summer miss the first generation.
-
Lift promptly
Harvest the whole crop in autumn rather than leaving it in the ground.
Prevent it next time
- Sow thinly so you do not need to thin; thinning releases scent.
- Rotate carrots each year.
- Grow resistant varieties.
What not to do
Do not thin carrots in the evening or leave thinnings lying; the smell draws the fly.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Carrot fly, Royal Horticultural Society