[chimaera]

I have lost almost all the onions I have grown over the last 2 years to white rot, so this year planted onions, shallots and garlic in a bed that had not been used before. They all, and the garlic in particular, had looked poorly  with yellow outer leaves from the start, and today I pulled one of the worst garlic and it was just a fuzzy mass of rot. Shall i just dig up the whole lot and burn them, or can i try something to save at least some of them?

Charlie

[Yorkie]

I suspect that the soil is  now well and truly contaminated, and there's no cure so my view would be to bin and burn the lot.

However, as I'm not a regular onion grower I'd wait for others to comment rather than act immediately on my answer.

[Ivor Backache]

I had white rot last year and my diary tells me that I first had it on the 14th June.
My understanding is that it requires a minimum temperature and with all the cold weather lately I am very surprised you have so early.
My remedy this year was to remove all the soil from a bed and restock it with clean soil. Onions and shallots are growing very well and no symptoms of rot.
With the season about three weeks behind you should have some success with seeds sown in big pots of clean soil/compost. My second spring sowing are still small and will be planted out next week.
Meanwhile burn everything that is deseased. If you have a plant that appears OK then wash all the soil off it and transplant in a pot of compost and see what happens.

[SG6]

If the onions are in a bed then I guess that there is little that you can do. It sounds as if onions and related crops are off limits to you. The infection will have spread either naturally or from your footware and the garden tools.

If in a raised bed then replacing the soil will help but I suspect that the infection will eventually return.

Look for resistant onion varieties and give them (one I think) a try. But they are resistant not immune.

[Trillium]

Many states in the USA that commercially grow onions and use only certified seed stock have all crops wiped out due to onion rot, so it's not the lack of certified seed. The fungus spreads and nothing will prevent it, nor is the fungus picky about non certified seed.

Here's a lot more info:

http://www.ipm.ucdavis.edu/PMG/r584100511.html

[Jakell]

I had white rot last year and my diary tells me that I first had it on the 14th June.
My understanding is that it requires a minimum temperature and with all the cold weather lately I am very surprised you have so early.
My remedy this year was to remove all the soil from a bed and restock it with clean soil. Onions and shallots are growing very well and no symptoms of rot.
With the season about three weeks behind you should have some success with seeds sown in big pots of clean soil/compost. My second spring sowing are still small and will be planted out next week.
Meanwhile burn everything that is deseased. If you have a plant that appears OK then wash all the soil off it and transplant in a pot of compost and see what happens.

 I too think that it is too cold for white rot to have started up yet. I had a lot of white rot last year and this did not start up until mid-June. Also my onions grew well for a while and did not succumb rapidly, when they did succumb, this was not apparent above ground ie they looked healthy for a while, they just stopped growing well, if at all.
 Maybe this is not white rot, but just looks similar.

[chimaera]

The sets were all bought and pre packaged, so should be clean. The outer leaves have gone brown, an din the worst this is the majority of the leaves. The bulb was covered in white mould and the outer layers peeling. I'll leave them a bit longer to check what the rot is.

Charlie

[Trillium]

If there was some mold on the bulbs still in the package, then the store didn't keep them well ventilated and the bulbs started going moldy from within. This is totally different from onion rot disease.

And if you got this same moldy stuff on garlic, then the bulbs were old and didn't keep well over winter in the shop so you bought dud stock. If I must buy packaged bulbs, then I always feel them up  to make sure I'm getting what I pay for and not a pile of empty casings.

[Jakell]

The sets were all bought and pre packaged, so should be clean. The outer leaves have gone brown, an din the worst this is the majority of the leaves. The bulb was covered in white mould and the outer layers peeling. I'll leave them a bit longer to check what the rot is.

Charlie

 Whether it is white rot or not, my commiserations. My bet is that it is not.

 My onion sets had a thin powdery coating on arrival (from Thompson and Morgan), but as the bulbs seems solid, I was not worried, any softish ones get thrown away.

 I had quite a lot of white rot last year, mainly due to previous tenants not rotating at all. I'm going to be using the 'Onion soup' method described under 'management decisions' here:

http://www.ipm.ucdavis.edu/PMG/r584100511.html

 on my non-allium beds for a few years, last year's bed is going to be going out of action until it is clear of white rot.

 edit to add: you can get cheap garlic powder from equestrian suppliers, if you use culinary stuff it will be ruinously expensive.

[granjan]

I tried a garlic spray last year, as suggested in Trillium's link.  I'm giving alliums a miss at the allotment this year but will spray again when the weather is a bit warmer.  Perhaps, the garlic powder would be more convenient as you can dig this in as you go.  It doesn't seem too dear if you find the right supplier.

Sadly, it's a case of trial and error.  The good thing about garlic is that it can put off some predators as well

[granjan]

Sorry I meant Realfood's link

[Jakell]

I tried a garlic spray last year, as suggested in Trillium's link.  I'm giving alliums a miss at the allotment this year but will spray again when the weather is a bit warmer.  Perhaps, the garlic powder would be more convenient as you can dig this in as you go.  It doesn't seem too dear if you find the right supplier.

Sadly, it's a case of trial and error.  The good thing about garlic is that it can put off some predators as well

 I hadn't actually thought of applying it in its powder form, but I may consider this. I am going to make a solution from the powder to water in (not for spraying), this way I can make sure it is spread evenly, and make it go further, I am treating every other bed other than my allium bed be so it has to cover a lot of ground, also I'm thinking of doing two applications, on in mid June and the other mid-late July in case the conditions for the first application were not ideal.

[chimaera]

The sets were good when I got them, and started to grow away OK in the autumn, but in spring the outer leaves went brown. The fungus on the bulb is identical to white rot (I know; I've had it the last 2 years), but that is why I thought it unusual to get it this early.

Charlie