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Author Topic: How to avoid carrot fly.  (Read 7998 times)


  • Joined Dec 2010
How to avoid carrot fly.
« on: May 02, 2012, 11:18:41 pm »
Last year was a disaster for me from a carrot growing point of view due to lack of rain and hardly any germinaterd.  I then planted some last autumn and they appeared to do well until I pulled some last month and found that they all had been attacked by something or other which I assume was carrot fly.
This Spring I planted some carrot seed and following the advice of gardening friends I put a tunnel of fleece over them.  This blew away when strong winds attacked the garden so I set up another tunnel but from some bubble wrap I had.
I have two questions.
1.    How to the commercial carrot growers cope with this problem?
2.   How are my carrots meant to receive water with a bubble wrap cover?
3.   Someone may wish to tell me just what I should be doing to successfully grow carrots.

Lesley Silvester

  • Joined Sep 2011
  • Telford
Re: How to avoid carrot fly.
« Reply #1 on: May 02, 2012, 11:27:36 pm »
According to mhy book, growing carrots and onions together (alternate rows) helps because the smell of the onions masks that of the carrots,


  • Joined Dec 2010
Re: How to avoid carrot fly.
« Reply #2 on: May 02, 2012, 11:39:32 pm »
Well, thats worth a try if the rain stops in Oxfordshire tomorrow.  Mnay thanks.


  • Joined May 2010
  • South Lanarkshire
    • ScotHebs
Re: How to avoid carrot fly.
« Reply #3 on: May 03, 2012, 12:25:43 am »
When you sow carrots, if the ground is dry water the drill thoroughly before you sow, then draw dry soil over the seed.  That way the seeds are in moist soil but it doesn't evaporate as the surface is dry.
If you use a polythene cover over your carrots then obviously you have to water them.
A fleece or 'enviromesh' cover is better but it needs to be well held down along the edges and at the ends.
An alternative way to keep out the egg-laying flies is to build a barrier at least 18 inches high around your carrot plot - the easiest way to do this is to make a wooden frame and attach fleece to it.  The female flies can apparently not fly higher than 18" - I have not found this method successful.
If you could grow them higher than that, perhaps on a wall or a shed roof in a fish box or bakers tray, that might work.
There are certain seed varieties which are resistant to carrot root fly.

I grow my carrots inside my polytunnel and still use a mesh mini tunnel over them - great carrots  :yum:

Carrots can be slow to germinate, so a useful trick is to sow a radish seed every 6" along the row, as you do with parsnips, which are even slower - the radishes will germinate first and mark the row, so you can hand weed before the carrots germinate and pull out the radishes too.
Again, because they are slow to germinate, weeds can often swamp them before they emerge.  One way to overcome this is to flame weed the whole area just before the carrots emerge.  To know when they will emerge, place a small piece of glass over part of the row - this will bring on a few seeds early so when they come up, flame weed the rest of the row.  The carrots will emerge a couple of days later into a clean and weedfree seed bed.

Probably the best approach is to do everything, including growing onions or other smelly crops near the carrots in an attempt to confuse the flies.   Home grown carrots are so tasty that it is worth the hassle, but I do know just how disappointing it is to find all those lovely roots are infested with root fly maggots  :carrot: :carrot:
« Last Edit: May 03, 2012, 12:30:27 am by Fleecewife »
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  • Joined Dec 2010
Re: How to avoid carrot fly.
« Reply #4 on: May 03, 2012, 08:55:36 am »
Many thanks for such a full reply.  I'm off to Scotland foe a couple of weeks and hopefully the ground will have dried out a trifle by the time I get back and I can plant some seed.


  • Joined Feb 2010
Re: How to avoid carrot fly.
« Reply #5 on: May 03, 2012, 09:58:37 am »
I plant with onions and never had a problem with carrot root fly, but then some say you dont get them at all up here. Also when you pick carrots fill the holes back in as pulling up releases the carrot smell.


  • Joined Jan 2009
  • Pen Llyn
    • Viable Self
Re: How to avoid carrot fly.
« Reply #6 on: May 03, 2012, 10:47:04 am »
If you delay sowing 'till June you should miss the first generation of flies and only have one lot to deal with. I tend to be rather lazy and our site is very exposed, so barriers and fleece covers don't really work for me. So I grow a resistant variety, usually Resistafly.

I do get some damage from Carrot flies but not so bad that the carrots are unusable. You just have to trim them a bit.

Also sow seed as thin as you can so you don't need to thin the seedlings and try growing the rows very close together - about 6 inches between rows. I find this helps.
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  • Guest
Re: How to avoid carrot fly.
« Reply #7 on: May 07, 2012, 01:22:06 pm »
i used all the above methods, i grew in a deepbed, 1.5m x 1.5m, sowed thinnly enough not to need to thin out, with a plastic barrier about 18inches up from the soil, then sowed spring onion round the outside, and left it till june to sow. i lost only a few to the fly, and harvested a handfull as i needed through the season, that m2 lasted till february.


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