The Carrot Root Fly & A Rock Cake Tray Bake

When I studied ‘horticulture’ at college, we looked at various pests and diseases and one thing I learnt was if you ‘know your enemy’, then it is easier to avoid it altogether or make sure it doesn’t do too much damage.

Last year I looked at the life cycle and ways to avoid the allium leaf miner, slugs and codling moths.  Once you know the life cycle of a pest, it is easier to understand how you can avoid it.

Today I thought it would be fun to look at a problem that we all encounter when we grow carrots, the dreaded Carrot Root Fly.

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The symptoms:

Unfortunately I haven’t got a photograph to show you, but there is a really good photograph here.

When you are growing carrots, the first symptom of carrot root fly that you may see, is the foliage on older plants turning a red colour and having a stunted growth– but not always.  The first sign, unfortunately, can be when you lift the carrot out of the ground and you see brown, rusty tunnels just below the skin.  If you cut into the carrots, you may find the creamy, yellow maggot inside that causes the damage.  It is approximately 9mm long.

Carrots that are left in the ground a long time are susceptible to more damage, as the maggot will continue feeding over winter and move from carrot to carrot.  The carrots can also start to rot where the damage has occurred.

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The Life Cycle Of A Carrot Root Fly:

Usually there are two generations of carrot fly each year, but in some areas there may be three.  In April and May the first generation of adult females will lay their eggs in cracks in the soil near to members of the  ‘Umbelliferae’ family, which includes carrot, celery, dill, fennel, parsley, parsnip and celeriac.

The eggs will hatch after approximately one week and the larvae will start to feed on the carrot roots.  It takes approximately three months for the larvae to develop into mature adults.

So in July or August, the adult will mate and then lay their eggs and the life cycle will begin again.  Some of the larvae will emerge as adults in autumn, but some will overwinter in the carrot roots.

Parsley

Parsley

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How to avoid the Carrot Root Fly:

The carrot fly, flies low to the ground.  I have read many times that if you erect a barrier surrounding your carrots, approximately 60cm high and no more than one meter wide, the female won’t be able to fly in.  Unfortunately, I have learnt the hard way and I had still had a problem with carrot fly when I did this.  I can only assume that the wind blows the female fly over the barrier.

Below are some easy ways to avoid the pest:

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  • The easiest way I have found to avoid carrot root fly is to completely cover your crop with environmesh to stop the female fly from laying her eggs.

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  • Before the female carrot fly lays its eggs, it feeds on pollen and nectar.  Her favourite plant to feed from is cow parsley.  So when cow parsley starts to flower, you can safely assume that the first generation of the carrot root fly is around.  With this in mind, make sure you cover your carrots before the cow parsley starts to flower.

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  • The Carrot root fly is attracted by the smell of bruised roots.  Sow your carrot seed very thinly, so  you will not need to thin them.

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  • Make sure you don’t grow carrots in the same ground as the year before, as the larvae may still be in the soil when you sow your new carrots.

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  • Companion planting can help to stop the female smelling the host plants.  Growing plants with strong smells around your carrots can help e.g. onions, garlic, basil and marigolds etc.   From experience, I have found this is only partially effective and needs to be used with other methods of controls.
Calendula

Calendula

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  • You can use ‘nematodes’ to help with the problem, but personally I find them expensive to use.

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  • When sowing, use cultivars that are less susceptible to carrot root fly e.g. Fly Away’, or ‘Resistafly etc.  These varieties aren’t completely resistant, but they can be used with other methods to avoid the pest.

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  • Finally, choose the best time to sow your carrots to avoid the main egg laying period (see the life cycle).  Late sown carrots (after mid-May) avoid the first generation of this pest, similarly carrots harvested before late August avoid the second generation, but again this is best used with other methods of controls, as weather conditions dictate when the flies will be active.
Celeriac

Celeriac

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I hope you have found the information useful.  I will put it all together with other subjects I have written about, in the link at the top of the top of my blog titled ‘Pests , Diseases, Weeds & Interesting Information’ .

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A Rock Cake Tray Bake

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If you have been reading my blog for a while, you will know that I usually ‘batch bake’ at the weekend, ready for the week ahead.

Most weeks I bake bread and cakes and freeze them.  This way, they stay fresh for the week ahead, ready for packed lunches etc.

I made my daughters favourite this weekend, which is a chocolate brownie tray bake, which is easy to make and freezes really well.  You can find the recipe here.  I also made a tray bake that I haven’t made for a while, a ‘Rock Cake Tray bake’, which is also really nice:

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Rock Cake Tray Bake Recipe:

450g self-raising flour

200g soft margarine

100g granulated sugar

200g sultanas

2 eggs

2 tablespoons milk

50g Demerara sugar

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Preheat your oven Gas mark 6 / 400F / 200C

Rub the flour and margarine together until it resembles bread crumbs.

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Stir in the granulated sugar and sultanas.

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Stir in the eggs and milk until it is all combined.

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Press the mixture into a tin (approximately 23cm x 33cm) lined with greaseproof paper, using the back of a metal spoon.

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Sprinkle the demerara sugar over the top and lightly press it into the cake mixture.

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Bake for 30 minutes.

Cut into slices while it is still warm.

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Enjoy!

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Thank you for reading my blog today.

I will back on Friday at approximately 4pm.

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15 thoughts on “The Carrot Root Fly & A Rock Cake Tray Bake

  1. Thank you for the info on the carrot root fly, many a time i have pulled carrots that have black lines running through them, i havent bothered with carrots this year but may have a try next year.
    Sue

  2. Carrot root fly. You know, so often when I am feling garden grumbly and I read your blog I am reminded of how thankful I should be. I mean, I only have slugs and snails. You have a whole RANGE of creeping meanies to watch out for, and many of them have to be treated differently. What have I got to complain about?? Two slimey mingrels that can be controlled with a little bit of time and vigilence! Thankyou for repeatedly putting things into prospective for me, Mrs Thrift 🙂

  3. Good day. What I found a bit puzzling about your information is when do you consider a carrot to be viable for attack? When the plants are small and have small white roots they are hardly worthy of a fly’s attention are they? Surely it’s only when the carrot is a carrot (if you get what I mean) is it then a viable meal for a maggot.

    • Hi Ken, thanks for commenting. That really is a good question which I have been unable to find an answer to, though I have read that the larvea do eat the root hairs of the carrot first before burrowing into the carrot. I don’t take any chances and cover my carrots from the day I sow them to make sure they don’t succumb to the dreaded carrot fly.

  4. My understanding is, the most likely time they appear is when you thin the carrots. I plant mine in a blue 45 gallon tub as the carrot fly does not fly very high and this has worked well for me. And its a nice deep depth for long carrots, It was a tip given by me by a very elderly gent many years a go.

  5. Must admit that I don’t hold sway to the idea the carrot fly are low fliers and are deterred by barriers. Like you I use enviromesh and if I need to weed just lift up the covering and stick my head under.

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