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Carrot Fly FAQ (fwd)
Carrot Fly FAQ V. 1.0 by Ronald Lowe
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<H2><A HREF="nph-dnquery?search=thread+threaded=1+RECNUM=%3c421981591wnr@we118can.demon.co.uk%3e">Carrot Fly FAQ v1.0</A></H2>
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From: <A HREF="dnauthor-profile.tcl?author=Ronald%20Lowe%20%3carlo@we118can.demon.co.uk%3e">Ronald Lowe <arlo@we118can.demon.co.uk></A>
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Date: 1996/02/06</H3>
MessageID: 421981591wnr@we118can.demon.co.uk<BR>
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reply-to: arlo@we118can.demon.co.uk
newsgroups: uk.rec.gardening
Given below is version 1.0 of the Carrot Fly FAQ.
The author would like to offer sincere thanks to all those who took time
and trouble to read the Draft. Their comments, criticisms, suggestions,
(and indeed praise), were just what was needed to spur him on to finish
this FAQ.
It is the intention of the author not to update this FAQ until the autumn.
He hopes that at that time he will receive shoals of mail from anybody
and everybody telling him how good / bad their Carrot crop was, and how
effective / ineffective were the preventive measures they took.
In the meantime comments on v1.0 will always be welcome.
--
Ron Lowe (arlo@we118can.demon.co.uk)
Wisdom comes in 10 parts, 9 of which are silence.
The tenth is brevity of language.
(Old Scottish proverb).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CARROT FLY FAQ. VERSION 1.O (6TH FEBRUARY 1996)
This FAQ will be maintained by Ron Lowe,
(arlo@we118can.demon.co.uk), to whom all correspondence should be
sent.
-------------------------------------------------------------------------
Before you start remember the old military maxim
"Know your Enemy"
GOOD READING
(1). Organic Gardening. 1988 version. Author Roy Lacey.
Approved by the Soil Association.
ISBN.0-7153-9175-5
(2). Which? Guide to Pests and Diseases. 1991 version.
ISBN. 0-340-55000-7
(3). Know and Grow Vegetables. 2 paperbacks.
ISBN. 0-19-857547-5 (book 1)
0-19-286017-8 (book 2)
( My copies now quite old, 1979 & 1982. May be out of print).
(4). Garden Pests and Diseases. R.H.S. 1992 version. Soft back.
ISBN. 1-85732-906-6
(5). Which? Guide to Gardening without Chemicals. 1990 version.
ISBN. 0-340-52796-X
Excluding (3) all may be available in your local library.
------------------------------------------------------------------------------
CARROT FLY
(Psila rosea)
1. WHAT IS A CARROT FLY ?
An adult carrot fly is a very small black fly which has been described as
"a low flying miniature cruise missile". The fly is reputed to be attracted
to the Carrots by smell. It lays it's eggs in the soil adjacent to the
Carrot(s). The grub of the fly over-winters in the ground gorging itself on
your Carrots, pupates and lays eggs in early spring. Eggs will ideally be
laid near to Carrots but Parsley, (and Cow Parsley), Celery, (and
possibly Parsnips), are also liked. After the spring generation have
hatched they lay eggs in June and July and this generation hatches and
matures in enough time to have another frenzy of egg laying August /
September time.
2. HOW DO I KNOW MY CARROTS HAVE GOT THE FLY ?
Basically you will not know until you lift the crop. In severe infestations
the first sign is that the Carrot leaves look an orange / reddish / rusty
colour. They then turn yellow. On lifting an affected Carrot it will be seen
that the root end will be black or dark. Close examination of what appear
to be good Carrots may reveal small holes in the Carrot. If Carrots are
put in a bucket of water badly affected ones will come to the surface.
This however does not mean that those which do not float are totally
unaffected.
3. I THINK MY CROP IS AFFECTED. WHAT DO I DO ?
Lift the crop. There is no point in leaving them in the ground as all you
are doing is giving the carrot fly maggot ideal board and lodgings. Give
the Carrots the bucket of water test and discard any which come to the
surface. Of the others you may, with a bit of judicious cutting and
scraping, be able to salvage something. Any you consider eatable open
freeze for 24 hours, or blanch and freeze, then bag and store.
4. CAN I PREVENT CARROT FLY ATTACKS ?
There are 5 options you may wish to try...
1. <STRONG>Companion</STRONG> <STRONG>planting</STRONG>.
2. Prevent the fly getting to the carrots.
3. Apply an insecticide to the soil to prevent eggs hatching.
4. Use a fly resistant variety.
5. Careful timing.
Lets look at the options...
4.1. It is thought that if a screen of strong smelling vegetables is
planted around the row(s) of carrots it will deter the fly. Onions or Garlic
are usually used. However Carrots are an all the year crop whereas
Onion and Garlic are usually of sufficient height for a couple of months of
the year only. Most gardeners will have lifted their Onions and Garlic well
before the fly is at it's most numerous in the early Autumn. You could try
the newish spring onions of the Ishikuro type that can be picked at
almost any stage from small to leek size.
(gareth@swansea.demon.co.uk).
4.2. This is a fairly satisfactory method. The author grows his early
Carrots in a cold frame which is about 28" tall at the rear and 12"
tall at the front. A percentage of the crop is usually affected, (very
roughly 10 - 15%).
Good Reading (1) suggests building a screen approx 18" high
around the Carrot rows using stakes and polythene sheeting.
Other suggestions are...
1. This year I used fleece on a number of crops - very impressed.
If you can bear to have your garden looking like a snowscape, this
will give much earlier crops and will protect from most flying insects
such as carrot fly and cabbage white butterflies.
(gareth@swansea.demon.co.uk).
2. I grew carrots under loose agryl fleece with the carrots pushing it
up as they grow and I got pretty clean carrots This was in the vale
of York where carrot fly is terrible. The only problem was taking it
off to weed properly which was a hassle. (uhba023@rhbnc.ac.uk).
3. Have you tried growing them under that gauze matting type of
thing, it has a name, but I can't remember it. It lets enough light
and rain through, but keeps the pesky carrot flies out. It is also
used to bring on early crops etc. (R.C.Dobson@ncl.ac.uk).
4. Marshalls are selling a new product "Enviromesh" for crop
protection. It can be laid over hoops. It's more expensive than
fleece (?15.75 for 15ft x 7ft) but is supposed to last at least 5
years. (mjl@jet.uk).
Suggested Suppliers of Fleeces.
Netlon Ltd
Kelly Street
Blackburn
Lancs
BB2 4PJ
(01254) 262431
----
Nortene Ltd
Linenhall House
Stanley Street
Chester
CH1 2LR
(01244) 346193
----
Pan Products Ltd
Faraday Road
Aylesbury
Bucks
HP19 3RY
The first two I believe do both screens and fleece, the last only
ground cover materials. (rob@mgctech.demon.co.uk).
-----
Agriframes - (01342)319111 7.95 UKP for 40*5 ft roll. A local
nursery sells it by the metre off a huge roll. I can't remember the
price, but it was the cheapest by far and you can get it cut to the
length of your beds - overlapping smaller bits is a pain.
(gareth@swansea.demon.co.uk).
4.3.1. There are a great many brands of insecticide on sale in garden
centres and ironmongers. The author spent quite a bit of time in 3
local centres reading labels and not once did he find the words
"carrot fly". It would appear that using chemicals may be a bit hit
or miss. However Good Reading (4) suggests the following...
When sowing treat the seed drill with diazinon and chlorpyrifos,
phoxim, (however see para 4.3.2. below).
This will protect the plants for about 6 - 8 weeks. Carrots not to be
lifted until the autumn should also be watered thoroughly in late
August with spray strength pirimiphos-methylin
2. There are few insecticides available to amateur gardeners for the
following reasons. Firstly to do the job strong products are needed
which are generally too toxic for amateurs to use. Secondly
Carrots have a habit of accumulating pesticide in the root and
therefore only chemicals which are poorly systemic are generally
used. Normally the soil is treated and not the Carrot. Thirdly
amateur usage often requires different residue trials to be carried
out and under EU rules for North Europe only this can cost over
100,000 per product per crop. Minor uses such as carrot fly is
unlikely to be supported in the future.
At present only a few products have carrot fly as an approved use.
Chlorophos (PBI) containing diazinon & chlorpyrifos
Soil Pest Killer (Miracle) containing pirimiphos-methyl
Both are dusts used at sowing or transplanting. Pirimiphos-methyl
(Sybol) drench can be used afterwards but is bound onto organic
matter and will not penetrate far into the soil.
Caution...There are no other actives approved for amateur use that I
am aware of. Phoxim approvals (Murphy Soil Pest Killer) were
revocated in 1994 with a sell out period to the end of 1996 (I
believe). (rob@mgctech.demon.co.uk).
4.4.1 Marshalls sell a variety called Sytan that is claimed to be less
attacked by carrot fly than other varieties. In the past 2 years, my
experience is that their claim is fully justified. It doesn't taste quite
as good as a true Nantes, but is close.
I recommend it. Sytan is 1.16 for a medium packet, 1.75 for a
large one, but there is also postage - see the catalogue for details.
(nmm1@cam.ac.uk).
2. The resistant varieties like T&M 'Flyaway' (I think!) are getting
quite good press. (gareth@swansea.demon.co.uk).
3. Good Reading (5) suggests the quick maturing variety Nandor.
5.1 If using fleece or other barrier method the seeds can be sown in
Feb / March and lifted in July leaving clear soil before the major
problem of second generation larvae develops.
Secondly delay sowing until early June and sow thinly. The carrots
are then quite young at the second generation egg laying time and
are less attractive. If sown thinly they will not need to be thinned
and therefore not produce the odour of damaged carrot which will
really attract the fly. If the carrots are then lifted in October /
November (they will be small but relatively uninfested) any
remaining larvae are left without a source of food and die over
winter.
5. ANYTHING ELSE I CAN DO ?
As the fly is reputed to be attracted to Carrots by smell it would suggest
that care should be taken when harvesting to prevent as far as possible
any bruising of the foliage. Good spacing may help in this respect. As
Carrot seed is notoriously difficult to sow perhaps trying pelleted seeds
may help.
Do >
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