The Veg Plot

The curse of the carrot root fly

carrot leaves with carrot root fly

We’ve had a few early harvests of sweet, young carrots but yesterday’s trip to the allotment showed a reddening of some leaves. This is a sight to make grown growers weep. For where there are red leaves on top there’s usually trouble below. And, sure enough, the orange root was riddled with tiny tunnels indicative of the carrot root fly. So we pulled up the lot with only a few carrots at one end of the row being salvageable for supper.

The damage is caused by the fly’s larvae after the eggs are laid at the base of the carrots. They hatch, burrow, and destroy.

Below are methods used to combat this gardeners curse, but unless your neighbours are similarly thorough it could take military style planning, and luck, to guarantee root fly avoidance.

Night picking
The flies are most active during the day and are attracted to the plants by their carroty odour, which is stronger when pulling and thinning out plants. We pulled and thinned in the evening hours. Next year we’ll pull at night.

Smell distraction
You could try masking the eau de carrot with pongier plants. Ours were sown next to onions and garlic, which obviously didn’t work. Next year we’ll pull at night after a beer and curry session.

Sow thinly
Avoid the need for thinning by sowing thinly. Although this is counterproductive to the theory of sowing thickly so that the slugs don’t devour everything and actually help out on the thinning process. Come to think of it… how can we make sure the slugs only eat at night after a beer and curry session…?

Create a barrier
These insects fly low, so try erecting barriers around your crops. Serious carrot munchers encase their entire crops in fleece, burying the edges in soil so they can’t crawl underneath.

A bad altitude
The height theory can be also work by growing carrots in tall tubs and under filling the pots by a few inches. I had a root fly free harvest last year using this method.

Succession for success
Apparently the flies are only busy laying eggs through mid spring and late summer, having a rest from their mayhem from now until the end of August. By sowing throughout the sowing season, and keeping your rows well away from each other, some crops might just survive.

Sow a different variety
There are root resistant seeds available, but we haven’t tried any yet. If anyone can recommend a variety then do let us know.

1 Comment

  • You could also try growing them in tall containers, as the flies like to travel close to the ground…. a container like a bin perhaps? 😉

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