Root Maggots in turnips

[BOREAS]

For second year running, problem with root maggots in turnips and swedes. Would sterlising soil with Jeyes (or similar) cure this problem - or is there an alternative?

[BOREAS]

[PAULW]

It is illegal to use JEYES as a soil steriliser its use is a patio cleaner, and why would you want to poison the soil with hydrocarbons.

[Jayb]

Hi BOREAS, Welcome to A4A 
Sounds like they could be cabbage root fly maggots as they can affect most brassicas. Difficult to prevent with swedes and turnips as collars won't work with their swollen roots. PAULW is right JEYES is not licensed for use on soil, I don't think there are any sprays for gardeners use against them. I've found using fleece or debris netting to cover a crop good for keeping them out, but make sure it's clean ground as they can overwinter as pupa from a previous infected crop.

[kt.]

Me personally, I would try the Jeyes fluid.  I used it a few years ago and it worked a treat.  Found this extract from an old JF booklet but not sure if they still recommend it.      The 'booklet' that came with the Jeys Fluid (years ago, before the EU regulations!) It states--"Soil Sterilsation--Application: Fork or rake into the soil 12ml per 5 litres of water,at 10 litres per square metre. Do not plant until at least 6 weeks after sterilsation.* Timing: At any time when no plants are present" Potting Soil: "Application: Saturate 10cm layers of soil with 50ml per 5 litres of water. Leave covered for one week,then uncover and turn soil.Do not plant until 6 weeks after treatment. * Timing; Any convenient time." This booklet also has directions for General Disinfection for Greenhouses/ Frames/Moss/ Fungi and algae etc.and the application strengths. I know we are not supposed to use the 'Old' Jeyes Fluid but can buy the 'EU modified stuff'

Though there are contradicting versions depending which part of the internet you read,  It is still advertised here as being able to be used on the soil .
http://www.gardendirect.co.uk/garden-care/clearing-cleaning/jeyes-fluid

[Melbourne12]

I've been asked to point out that the use of the previous formulation of Jeyes Fluid is against current laws.  I've looked at the safety data sheets for the current formulation of Jeyes Fluid, and it is entirely DEFRA-compliant to use as a garden disinfectant.

We are currently in the rather odd position that ANY use of non-approved substances in the garden as pesticides is illegal.  So if you spray your broad beans against blackfly with washing up liquid solution, you're breaking the law.  I've confirmed this with DEFRA.  Their response is that it "would not be in the public interest" to prosecute such infringements, but that leaves us at the mercy of bureaucratic interpretation.

So personally I'm happy to use the old remedies, but I make sure that I stay friendly with my allotment neighbours in case one of them dobs me in. 

ETA: Looking at the Jeyes website, they rather confusingly sell several products under the "Jeyes Fluid" brand, including a patio cleaner, a decking cleaner, and a drain unblocker.  For the avoidance of doubt, only the general garden disinfectant should be used on soil, although the others are safe for their intended purpose and meet all DEFRA standards.

[ed dibbles]

Grow kohl rabi instead. The variety "supersmeltz" aka "Gigante" grow to a good size without going woody and are easier to grow than turnips or swede. Because the edible part is above ground it doesn't get infested with root fly.

Also the round black skinned winter radishes have a cabbage fly resistant skin in my experience. They are perfect as a winter casserole/stew ingredient (or grated in a winter salad). They are much milder than summer radishes and will stand in the ground all winter.