Kitchen Garden Forum

Following the discussion earlier this year on CRF not flying above a few feet, I did a small (and unscientific!) experiment this year. I planted Early Nantes in March in a container on a 3ft high bench, followed by Autumn King in an adjacent container, in May. Also some Autumn King in the ground nearby. None of them had top protection.
Result: the EN (March) were completely free of CRF, the AK in the container (May) had some CRF damage, but nowhere near the ground-sown AK, which were riddled with it.
I suspect the differences are due more to time of sowing than height, though that did have some effect.

Hi John,
Nice to see that you are experimenting. My daughter experimented the same as you and got the exact reverse to you. The only difference was that the bucket was on top of her old coal shed at home and the carrots got eaten alive and the carrots grown in the ground on her allotment half a mile away escaped totally unscathed but were totally unprotected. (You see miracles are possible. )
Here the carrots were covered with anti white fly netting and was 100% successful with no CRF at all.
JB.

Any thoughts JB as to why it is now almost impossible to grow Carrots without net, after all it is a relatively recent product/technique?

Hi Geoff,
My answer is somewhat controversial but I put it down to the rise of Organic growing coupled with a certain association who has continuously lobbied not only our own parliament but the European Parliament to make it that we should all be organic and have nothing in our armoury against such pests.
Organics is fine if practiced by people used to growing but it was the free for all that occurred a few years back following the glossy magazines who's information was far from good advice where growing vegetables is concerned. There were too many people who started off and then found that there was hard work involved and simply abandoned plots generally leaving carpeted covered areas leaving others to clear-up after them.
Such pests have risen an awful lot since those stupid years of ignorance.
I use Anti White Fly netting because it was in stock when I closed my nursery and retired but at £240 a 100m it really has to be bought by somebody who will benefit by making a profit not the normal home gardener. I could still afford to buy it but doubt that I would go to the expense nowadays. The normal netting will give the protection needed and unless you buy a fair quantity that too can cost a bomb.
JB.

Hello John
I think JB is right.
In the good old days you could get some stuff called Bromophos (sp?) and a little sprinkle of it in the soil at sowing time would do the trick. Now of course we cannot be trusted anywhere near chemicals so we have to fight the pest as best we can with netting and barriers.

John

PS Bromophos was a compound containing bromine and phosphorus - the mere mention of these two interesting elements to the anti-chemical brigade would be enough to get hordes of them out onto the fields in protest.

Johnboy wrote: I put it down to the rise of Organic growing coupled with a certain association who has continuously lobbied not only our own parliament but the European Parliament to make it that we should all be organic and have nothing in our armoury against such pests.

I'm not going to get into the contentious aspect, but carrot root fly is one of those things where the commercial control - pyrethroid Lambda cyhalothrin, is still available to amateurs as Westland Plant Rescue Fruit & Vegetable Bug Killer

Otherwise, possible strategies include:

- choosing a windy site (makes it hard for them to fly)
- timing sowing to avoid the worst attacks (Warwick HRI produce predictions of the timing)
- earthing up or mulching to make it harder for the female to lay eggs close to the root (also improves quality by avoiding green sholulders)
- avoiding thinning and taking care hoeing to avoid releasing the carrot aroma which attracts the flies
- use of garlic sprays
- companion planting with onions or French marigolds (though little supporting evidence exists).
- sowing under a barrier, or in an elevated container.

Any others ?

What about the "Grow Your Own" nematodes which seem to be designed for a multitude of pests, including carrot root fly. Do they work?

Hi Tony,
I'm very glad that you bypassed the contentious bit because it was a reply to Geoff and only my personal opinion.
Some of the methods of dealing with CRF that you suggest may work but none of them deals with the basic problem. There has been a massive build-up of pests since the period I mentioned in my previous posting.
Carrot Root Fly, Cabbage Root Fly and White Fly seem to be at an all time high. Strangely I have not seen a White Fly on this plot all year yet the next village to me is inundated with them and they are affecting just about every plant and even shrubs.
Reports from other contributors to this forum seem to have the same predicament.
The normal gardener simply has nothing that is affective to even begin to deal with the problems. Physical barriers only make things worse because
you are shutting them out of your plot only for the pests to move on to the next gardener. This is rather selfish in my opinion although I practice such methods.
This has been my fear for a very long time and I correctly predicted this situation some ten years (or more) ago on this forum.
Things will only get worse without chemical intervention.
JB.

Hi JB
I don't see why preventing pests coming on one's plot is selfish. It's up to your neighbour to protect his/her plot, and if everyone does it then the pests will get the hint and move to China, where the inhabitants can deal with them on a one-to-one basis

Hi John,
Sadly it doesn't work like that. In order to reduce the risk of CRF numbers have got to be reduced. Physical barriers certainly protect the crop but the reason for the barriers is purely because the numbers of the pest are beyond control.
When I first started gardening CRF barrier protection was unheard of and you would maybe lose half a dozen carrots from a 30ft row. Try that today and you would lose the lot. We had a powder that if, put in an old sock and just dab the ground each side of the row of carrots and just the odd few CRF got through. It was also used at the base of cabbage seedlings when you planted them out and virtually no Cabbage RF. It was a general purpose insecticidal dust and it worked and was safe to use.
Sadly I cannot recall the name of it. We now have virtually no other protection other than physical barriers and the CRF find an unsuspecting gardener and he loses his crop. A few carrots we can all bare but the lot is not on.
JB.

JB
Was it Derris powder?

Hi John,
Of course it was. I simply could not for the life of me put a name to it this morning.
Thank you.
JB.

Derris itself is no longer available but formulated as rotenone, the active ingredient, it is still in use and still effective.

Hi Felix,
Thank you for that information. I try very hard not to use chemicals but refuse to lose a crop for somebody else's beliefs so I will use chemicals if they are really necessary to do the job having exhausted all other avenues.
JB.

I have found this which people might find gives good advice against this pest especially the relationship to other affected crops which I did not know.

http://5d.5a.5746.static.theplanet.com/ ... p?artid=99

I now realise I should have binned all infected roots and most of the compost from the pots which was where I had most damage.
The compost is separate from the veg beds and will only be reused in the front garden. Hopefully the turning and shuffling will disrupt the pests cycle.