White onion rot

[Alison and Keith WoollacottParticipant]

All the growers on our allotment site have experienced the same problem – the onion growth has turned yellow, died at the edges, they have slightly white blotchs and are falling out of the ground. Growth has stopped resulting in very small onions. Is it likely to be white onion rot and can the onions be eaten?

[charlesModerator]

It is not white rot or you would see dramatic white fungus at the base of all onions, and they go yellow very fast. Sounds like mildew, or possibly onion fly. Are there any maggots to be found in the bulbs/ Or more likely, are any green leaves looking mouldy? In either case the onions are fine to eat.

I cover it in This Month. If everyone is affected I suggest you all agree not to grow the overwintering Japanese onions which harbour mildew. White Lisbon are ok.

[bluebellParticipant]

In part of the plot that I didnt think was effected by white rot I planted out some leeks which were doing well until last week when they started to look very tatty and sorry for themselves. On investigation it is definately white rot.

Have to say Im very surprised having read the infor on RHS site which indicated that it only occours when it is cool and damp – our soil has been very dry and whilst it is now cool at night it is not a low temperature that I would ahve thought would impact leeks.

[charlesModerator]

Sorry to hear this Bluebell.
I have found white rot common in warmer weather, such as in June on onions, so that advice seems odd.

I wonder where it came from, are they your plants? Were you aware of it in that spot before? Best send the affected plants for recycling and be careful not to spread the affected soil around, it will gradually diminish, but that does not help for now.

[bluebellParticipant]

I have only had the plot a couple of years and was told that onions had been fine on it with previous grower so have tried several places and sadly all appear to be infected. I can salvage and eat some of the leeks as not badly infected and it does appear to be odd clumps not the whole crop.

https://www.rhs.org.uk/advice/profile?pid=226 this made me think it was less likley at this time of year. SO looks like I will not be growing alliums for the next 15 years

[charlesModerator]

Well I reckon four years is a viable time for white rot to die out, or almost all, having found that at Lower Farm. I think that no dig helps by not spreading the fungus around. Life is too short to wait 15 years..!

[bluebellParticipant]

Hope not to be on this plot in 15 years – possibly not even 5! but that depends on the semi retirement plan.

Thanks for your advice and hope Charles.

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