disease affecting onions, garlic and shallots

[Jasper ShawParticipant]

Hi Charles,

This morning I saw a suspicious moist, fluffy yellow substance on the soil surface, strangely located around specifically only one of the onions growing at my allotment. I have no idea what it was but it was almost like a whipped cream/shaving foam texture (I should have taken a picture but forgot to!) There was nothing behind this substance apart from a slightly macerated, brown layer of skin on the onion. This prompted me to look closer at all my other plants on this particular bed. Despite the foliage looking deceptively healthy on most of the plants unfortunately it looks like many, if not most of them have have a disease of some sort.

The onions in particular just pull out of the ground so easily with no root-like resistance (some are growing at an angle close to the ground, rather in an upright position which I think would suggest weakness in the root structure of the plants). Is it possible I could have planted the sets to shallow?

The bulbs of the shallots are really under-developed and the layers of skin on them are pretty damp.

Many of the garlic bulbs are rotten and seem to have come off the worst out of this (in so much as there is nothing edible left of them that is below the soil surface!).

This is my first season of growing onions, shallots and garlic so am very inexperienced in all of this – I’m thinking it could be white rot and perhaps some other fungal disease like neck rot too.

I sowed all these as sets (bought from Suttons) at the end of September last year. It is of course disappointing and I will probably grow all alliums from seed from now on (and avoid over-wintering shallots and onions!)

What I would like to ask you is what do think the problem might be (based on the description and attached pictures) and what would you suggest doing to minimize the damage and to prevent it from happening again – eg. pull up all the plants now to avoid further damage and avoid growing alliums on this bed for many years to come. I suppose on the positive side if I did pull up all the plants now it would free up some space for planting out vegetables of other families.

If this is a fungal disease I’m not sure how it got there – I did successfully grow a few spring onions on this same bed last year, but it really was only a few.

Any advice you might suggest would be kindly appreciated.

Best wishes,
Jasper

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[Jasper ShawParticipant]

have to list the photos one per post because of image size, sorry.

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[Jasper ShawParticipant]

last one.

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[charlesModerator]

Jasper it looks bad, sorry to say.
Your description is of white rot, a fungal disease often found on allotments from gardeners not knowing the plot history, (like you), and over-cultivation of soil.
The photos however show quite healthy roots which would be covered in white fungus if its white rot. I still think you have that, perhaps also some disease brought in with sets or even the garlic seed.
No remedy I know once plants are affected.
Can you make a bed in your back garden, on clean soil?

[Jasper ShawParticipant]

Thanks Charles – yes it is tricky not knowing the history of the plot. I have some young leek plants which not long ago I planted out on a bed on the other side of the plot so here’s hoping the fungus is isolated to the solitary bed.

Unfortunately I don’t have access to a private garden at present – but I’m sure at some point in the future I will, which on the backdrop of this experience I will then be able to make wholehearted use of for growing healthy alliums!

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