[Rosehip]

A neighbour has got carrot fly in her tunnel,carrots sown March/April first time to get it.I wonder if this is from the first batch of carrot fly that laid eggs in May or do you think it might have over wintered in some way?When would you usually see the damage from the May carrot fly?

[Salmo]

Carrot flies usually emerge and lay their eggs in mid-May. If it has followed the season it may have been later this year.

That is in the open. A poly tunnel creates its own climate and carrot flies could have emerged at any time when the tunnel was warm enough.

Carrot flies overwinter as pupae in the ground, or in a compost heap, or in old carrots.

My guess is that they overwintered somewhere within the tunnel.

When carrot fly maggots are attacking carrots the tops take on a reddish tinge. This can be seen from when the carrots are a few inches high. If attacked very early they can kill the plants. Later, when you pull the carrots for Sunday lunch or for the Show, the roots will be spoiled with tunnels where the maggots have been feeding.

The only solution is to cover with a fine mesh tent from when the carrots emerge until mid September.

[Rosehip]

Thanks,thats a great reply lots of good information.The leaves are green no colour change at the moment.Im minding her tunnel for the weekend so will keep an eye out.

[pdblake]

Thanks. Nice to know about the red tinge. You learn something new everyday

[Beetroot queen]

I am sure someone said another sure sign is the greens laying flat but i maybe wrong ? 

[LilacSandy]

Don't forget to practice crop rotation in the tunnel as well, there is no use covering the plants if the fly is already in the ground as it will just emerge under the net.

[DD.]

I am sure someone said another sure sign is the greens laying flat but i maybe wrong ? 

No, you're right!

[seaside]

I am now having an excellent carrot crop sown at the start of April in my greenhouse... no sign of fly whatsoever. The first month or so I covered in fleece, and the door was closed, being rather nervous after last year's fly ruined outside crop.
But the last 7 weeks after the frosts, the door has been wide open 24/7. What I have done though is put a 18" high polycarbonate strip across the door opening, when I am not toing and froing... a good idea in my opinion.

Have now just seeded a second crop outside under a proper little fleece tunnel where carrots have not been for many a few years. But I'm expecting them to get riddled. Poly tunnels/ ghouse should be the way forward provided there are no flies invited to camp over Winter.

[DD.]

They never got though this!

[seaside]

Well, those blue alkathene hoops are exactly what I've used, but my enviromesh is unfortunately otherwise occupied covering my little green friends. But my fleece is good quality and tucked down well so don't expect it to rip, and maybe your comments give me hope for a decent outdoor crop. That would please me no end.
DD, do you ever actually even think of weeding that for half an hour later in the season, or do you keep it totally closed throughout the growing period on pain of death ?. Thinning shouldn't be needed with my sowing technique.

[BobE]

I use a micromesh tunnel bought for £21.  I remove it to do the first thin and weed.  I then do another thin and weed but this time I can use the thinnings as small carrots.  I don't weed again until I start to harvest.  But each time I remove and replace the micromesh tunnel.
I forgot to say that my first thin tries to leave a single finger gap between the plants.

[DD.]

I plan to whip the top off tomorrow very early am and weed. That hopefully will be it as there's not much daylight getting through the foliage now.

I don't thin either, I just let the carrots push each other aside.