The Carrot Rust Fly Never Forgets

heirloomgal

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Carrot planting season isn't far away, and it's been several years now that this pest has been afflicting my carrots. For the past two years I've interplanted my carrots with podding radishes and this has worked pretty well, though not perfectly. Once these things showed up, they just kept coming back. I'd rather not do the fleece covering, if I can help it. I have found very little info online or even at gardening centres/greenhouses about this pest and how to make him either go away, forever, or manage them better than what radishes can do...I've heard about the coffee grounds method and I just have a hard time imaging that would work given the tenacity of this pest. Any ideas gardeners?
 

Dirtmechanic

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So its the in ground stage that is the problem? I found this on the utah state website:

Chemical​

Granular insecticides are usually best when incorporated into the furrow at planting to prevent larval attack on the roots.

Biological​

Natural enemies of carrot rust flies include the parasitoids Chorebus gracilis, Eutrias tritoma, and Aleochara sparsa which target the early larval and pupa stages of the carrot rust fly.
 

flowerbug

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i haven't grown many carrot crops here so i don't have a lot of direct experience but i did see when reading up on them a mention that some kind of wind break can block their path.

they also suggested making sure to plant away from previous plantings as much as you can.

my other suggestion would be to try to plant them in rotation where the previous crop was onions or garlic.

finding out the bugs and other controls that like to eat them and making sure to encourage those is always an interesting way to learn about ecology and diversity.

this is all i can think of at the moment, but i hope it helps.
 

digitS'

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I've had some experience with the critters but not with controls. Oregon State University says that the adult isn't a strong flier which must be why they haven't arrived in my distant garden from the ground here at home ;).

OSU also says that the adults are attracted to the smell of the carrots and lay eggs in the soil around them. I can understand why coffee grounds would make sense for a try. Maybe even at the time of sowing seed since ... OSU also says that that late sowing have less problems because it's the first hatch of adults that cause the most problems.

The bug experts also tell us that all carrot relative roots are eaten by the rust fly larva however, they sure take more interest in carrots than the parsnips growing right beside them here at home. I learned in recent years that cilantro plants can be used roots and all and I have never noticed any damage to their roots. Catch crop ideas might still be worth a try. Fennel is so very much loved by bees ... I wonder ...

Steve
 

heirloomgal

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Thank you @digitS' @flowerbug @Dirtmechanic! These little worms are such a pain, and I can see that after all these years they have not forgotten that they, once, had a good meal here. I stopped planting for 3 years just to try and break their cycle, with no luck. They've passed on to their offspring the address to a good meal, and now I'm permanently in their phone book. Argh!
 

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Thank you @digitS' @flowerbug @Dirtmechanic! These little worms are such a pain, and I can see that after all these years they have not forgotten that they, once, had a good meal here. I stopped planting for 3 years just to try and break their cycle, with no luck. They've passed on to their offspring the address to a good meal, and now I'm permanently in their phone book. Argh!
Every time I try to keep doing the same thing in the same place I attract pests. I even attract the property tax people. No spray works on everything, but do what you can.
 

heirloomgal

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OK, tell me what you are doing so I don't do that!
Hahahahah, actually that is a GREAT question though because if someone had told me NOT to do what I did, I wouldn't have suffered this problem for the last 8 years!!! Now, I'll have them FOREVER. Seriously.

Okay, this is what I did. Planted in a block instead of a single row, so set myself up for some major thinning. This took me probably three days, it was a large block and was growing like grass. The strong smell from those thinnings sitting there next to my bed (for 3 days) brought them. That's it. I left the smelly thinnings next to the bed, and now I've got them for good. So, never thin carrots and dispose of those things anywhere NEAR your garden!

I've tried planters over 3ft high (apparently a height they can't fly up to - yeah right), rotations to other areas garden plots, not planting for years, 'Resistafly' carrots, garlic, adding totally new & fresh soil to 'the carrot area'. You name it. It's that they remember. Smell gets them there, but memory keeps them glued on. My next door neighbour directly (and close) beside me grows carrots and gets no rust fly. So it's a memory thing, or they'd go to his too. Gosh, I made that one mistake and how my carrots and me have paid!

The icing on the cake is, aside from probably commercial carrot growers, no one else on earth seems to have this problem but me...:eek:
 
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Dirtmechanic

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Hahahahah, actually that is a GREAT question though because if someone had told me NOT to do what I did, I wouldn't have suffered this problem for the last 8 years!!! Now, I'll have them FOREVER. Seriously.

Okay, this is what I did. Planted in a block instead of a single row, so set myself up for some major thinning. This took me probably three days, it was a large block and was growing like grass. The strong smell from those thinnings sitting there next to my bed (for 3 days) brought them. That's it. I left the smelly thinnings next to the bed, and now I've got them for good. So, never thin carrots and dispose of those things anywhere NEAR your garden!

I've tried planters over 3ft high (apparently a height they can't fly up to - yeah right), rotations to other areas garden plots, not planting for years, 'Resistafly' carrots, garlic, adding totally new & fresh soil to 'the carrot area'. You name it. It's that they remember. Smell gets them there, but memory keeps them glued on. My next door neighbour directly (and close) beside me grows carrots and gets no rust fly. So it's a memory thing, or they'd go to his too. Gosh, I made that one mistake and how my carrots and me have paid!

The icing on the cake is, aside from probably commercial carrot growers, no one else on earth seems to have this problem but me...:eek:
I am thinking that they have laid eggs in the soil and the fly itself is the minor issue. I have a similar relationship with nematodes. I find we get along best when I kill everything in the soil as deep as I can. This does not stop them from coming back, but it does give me a window of time to grow plants to maturity without attack. When they are fully grown, the various pathogens have a lesser effect and that effect is often displayed after the major production has ceased for the season.
 

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it looks like to me that you would be able to stop their local life cycle by rotation planting in a new location (where you haven't grown carrots before) along with using row covers so that the remaining bugs can't lay new eggs on your plants.

somewhere locally there may be a wild source which supports their population (to get them through the three years you didn't grow them), so you may need to use row covers in the future.

that's what i would do if it were important for me to grow them.

i do know that there are people who grow carrots organically for commercial quantities. i wonder how they are managing this pest... perhaps it hasn't made it to where they are located (i'm pretty sure these would be southern California and perhaps even down into Arizona for their winter crop), but i don't know for sure.
 

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