Cabbage maggot on brassicas
Cabbage maggot is the one that kills transplants. The first generation in late spring does the most harm, because a young brassica has too few roots to lose any. Radish, turnip and swede are ruined by any generation, because the root is what you eat. The nematode goes on as a spray or soak on the tray before planting, or as a drench afterwards, and a second treatment is likely needed if the fly arrives more than a week after planting. Keep the soil moist.
At a glance
- Damage
- Seedlings and transplants that wilt and die; tunnelled roots, bulbs and carrots
- Type
- Root
- Settings
- Garden, Field
- Threshold
- An average of 1 egg per stem across 25 plants (UMass)
- Release
- Steinernema feltiae
- Rate
- 100,000–125,000 infective juveniles per transplant, the rate UMass reports trials needed
How to confirm it
Dig up a wilting plant and look at the roots. Root maggots are white or cream, legless and headless, pointed at the front and blunt at the back, up to about 3/8 inch (9–10 mm), with small brown oblong pupae nearby. Carrot rust fly maggots are slimmer and creamy yellow, in rust-brown tunnels on the carrot surface.
Identification, lifecycle, degree days and every control option are on the full Root maggots profile. Not sure it is this pest? Answer four questions about the damage.
Work it out
How many do I need?
Carries Steinernema feltiae and brassicas through so nothing is re-entered. Open the calculator →