White onion root rot

**bluemoon** · 30-03-2008, 11:23 AM

From what I understand, having never suffered from this problem myself, once you have this disease it's pretty much goodbye to growing onions. For this reason I've often wondered if it is a good idea to put onion peelings in the compost bin. As far as I'm aware there's no real 'cure' for the problem. I suppose you could build a raised bed and try growing onions in that. If you look at the seed catalogue from 'Robinson's' - they of the mammoth onion - they say that they have grown onions on the same bed, every year, for over 100 years, so crop rotation obviously isn't necessary, and I know that many people who grow onions for horticultural shows stick with the same bed year after year, claiming this builds-up fertility. If you import some sterile topsoil for a raised onion bed, then use the techniques used by these onion experts, you might get a worthwhile crop. You'd have to ensure that no tools, boots or gloves which had been used in the general beds though were used for the onions or you'd just spread it back. I'm also not certain how the disease reproduces, if it's windblown spores for example, then there's probably little you can do to protect them. It may mean that you have to give onions a complete rest for several years, and sadly this applies to leeks, garlic and any other members of the family.

**Terryr** · 30-03-2008, 02:10 PM

Hi Bluemoon. Yes, what you are saying is correct. There is lots on this disease on the net. It is a big commercial problem in the USA. I understand it is possible to spray with a garlic concentrate that prompts the fungus spores to kick into life. However, as there is no plants there the fungus dies and then the growers plant. I am not able to do that. It is extremely persistent.
I was just wondering if anybody had tried onions in grow bags.
Cheers

**Snadger** · 30-03-2008, 02:26 PM

I know its no help to you, but I wonder why concerted efforts haven't been made by breeders to develop an onion that is white rot resistant?
They've done it with brassica's and there are now clubroot resistant cabbages and cauli's! The swedes I grew last year were also clubroot and mildew resistant!
You could check out which fungicides are available to use on food crops and water them with it as recommended?

Soil sterilisation is the answer, but there are no legal products to achieve this!

**Terryr** · 30-03-2008, 02:36 PM

Hi snadger. I am trying a clubroot resistant cabbage myself this year. I had not come across the cauli as yet. i must look out for it.
Thanks for your interest.

**Two_Sheds** · 05-07-2008, 09:40 AM

I've just pulled up some of my (Wilko) onions, and one of them had White Rot. Only one ~ so it came in the set, not in my soil.

Would it have spread itself into my soil now? I'm going to grow onions in another place next year anyway, but this is worrying.

**zazen999** · 05-07-2008, 11:07 AM

Only my shallot sets had onion rot... I grow many many onions and nothing else had it - my shallots were from T&M as well...very disappointed.

**debjay** · 05-07-2008, 11:36 AM

Hi

***** fluid is supposed to help by sterilizing the ground but we are not supposed to use it for that purpose (EEC rules

)
Or there is Armillatox
Armillatox - The environmentally friendly herbicide, fungicide and insecticide
Debbie

**TinyT** · 05-07-2008, 04:15 PM

I had quite a lot of rot on my galic and onions. I think I inherited quite a bit of ground with it in. I've heard red onions don't pick up the rot so easily. Looking at my current red onions they don't appear to have any (for now!). I guess if somebody was looking into trying to create a hybrid onion seed that was rot free - red onion seeds may be a starting ingredient?? It would be good if there was 'rot-free' garlic too.

**Tam** · 05-07-2008, 04:37 PM

The note about not composting onion waste is correct, because onion plants without any signs of the disease can carry the fungal spores. I have also heard that potato peelings should not be composted as they could carry the dreaded blight. Until I was told this, I always bunged potato waste into the compost bins without blight appearing, but, safety first, I don't now and blight is apparently much more widespread now.

**mjryder** · 10-07-2008, 03:41 PM

Mike

Hi, I have read with interest the thread relating to White Rot in Onions. My garden suffered from this dreadful disease some years ago after hireing someone to rotivate my garden for me. Worse mistake of my life!! have suffered ever since. I did in fact contact an expert at "Gardening Which" for advice and was told that this spore can remain in the ground for close to 20 years with no "cure". I do try onions and garlic ever few years to see what happens but its the same every time - disaster. I have now given up growing any of the onion family except salad onions in fresh compost in a large flower pot!. Sorry to hear that you have it as well.
Mike

**Two_Sheds** · 10-07-2008, 05:46 PM

Onion white rot is a serious disease of the onion family ~ it is nearly impossible to eradicate from the soil.
It is caused by a fungus ... and is capable of surviving in the soil for up to 15 years, during which time it can infect any onion or onion relative planted in its presence.

Prevention: Practise a three or four year crop rotation. If the infection is diagnosed do not grow onions in that area of the garden again.

Removing infected plants and increasing the space between host plants will help to reduce the severity of the disease. Destroy infected plants by burning or putting them in sealed bags in the dustbin. Do not compost infected material.

No chemical control is available. If necessary, contractors can be employed to sterilise the ground. Royal Horticultural Society - Gardening Advice: Onion White Rot

**Two_Sheds** · 10-07-2008, 05:46 PM

I've checked my Shallots - about a third have White Rot. Bummer

**Two_Sheds** · 19-07-2008, 08:09 AM

I've now found White Rot in just one of my onions on my Suffolk plot. So, looks like def. came in the sets (Wilko) and not in the soil. I feel a letter coming on ...

**baggyman** · 19-07-2008, 08:44 PM

Originally posted by Two_Sheds View Post

Onion white rot is a serious disease of the onion family ~ it is nearly impossible to eradicate from the soil.
It is caused by a fungus ... and is capable of surviving in the soil for up to 15 years, during which time it can infect any onion or onion relative planted in its presence.

Prevention: Practise a three or four year crop rotation. If the infection is diagnosed do not grow onions in that area of the garden again.

Removing infected plants and increasing the space between host plants will help to reduce the severity of the disease. Destroy infected plants by burning or putting them in sealed bags in the dustbin. Do not compost infected material.

No chemical control is available. If necessary, contractors can be employed to sterilise the ground. Royal Horticultural Society - Gardening Advice: Onion White Rot

How do the contractors sterilise the ground?

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