Cabbage root fly
Young brassicas lag behind, turn bluish or yellow and wilt on warm days. White maggots of about 8 mm feed on the roots and stem base; radishes and turnips show tunnels.
From April, the cabbage root fly lays its eggs in the soil against the stems of brassicas, radishes and turnips.
What can you do?
- Fit a brassica collar (a disc of card or felt) around the stem straight after planting so the fly can’t lay eggs there.
- Cover the plants with fine insect mesh, well secured at the edges.
- Pull up badly affected plants with their roots and put them in the general waste, not on the compost heap.
Prevention
Rotate brassicas every year and keep them under insect mesh from planting. Sturdy, well-rooted plants survive an attack better.
When to watch out: April–August