Powdery mould on onion leaves?

[StringfellowParticipant]

Some of my February sown Bedfordshire Champ onions have developed a blacky/ grey dusty mould on their leaves. What is this? It’s my first time growing onions on this spot of my allotment so I’m wondering if it is anything to do with white rot or if it’s the onset of downy mildew. Other growers down there are having similar cases.

Many thanks.

[charlesModerator]

Bad news for your onions, its a horrid disease, unrelated to white rot but usually turns leaves yellow within 7-10 days and the bulbs can’t swell any more. Have you had some damp weather as that is usually a cause? For instance here has been dry and dry air too for 16 days, resulting in healthy onion leaves, unlike the wet summer of 2012 for example.

[StringfellowParticipant]

Thanks. This is such a shame as they have been growing so well with some already bulbing up a bit. The weather has been dry and warm for at least ten days so this is a mystery. Am I best pulling the lot and eating what can be salvaged, or is it better to destroy them? This would also free up space for more second crops……but I’d rather of had a lovely onion harvest

I’ll try again next year tho!

 

[charlesModerator]

I wonder if Bedfordshire Champion is a little prone to the disease. Hard to say from here how badly your leaves are infected but they will grow more for a while, maybe give them another week, then pull and find somewhere to dry them, being careful not to cut or damage the necks so that infection cannot enter bulbs, some should store for a while at least, once dry.

[StringfellowParticipant]

I sowed and planted Red Baron in addition to the Bedfordshire Champion onions and, whilst there is some sign of trouble on the Red Baron, it is far less so than on the Bedfordshire Champ. I’ve attached a photo of the BC; is this downy mildew/ neck rot disease? If so, I’ll try Santero next year instead.

Thanks for your advice, we shall eat what can be saved. I hope yours grow well and through to maturity!

[charlesModerator]

Santero and Hylander are two varieties with resistance to mildew, worth trying, but some years are just difficult. Interesting that Red Baron is resisting a bit, hope you get a fair harvest and thanks for the pic which shows it clearly.

[StringfellowParticipant]

Thanks again. Tuckers do a biggish pack of Hylander seed so I may well go with that and try again next year. Plenty of folk growing OW onions nearby on site, so this may not have helped the situation. 

The new photo attachment facility is a great addition to your site.

[BarbMember]

All the onions on our allotment site in Doncaster have been affected by downy mildew this year.  It started with the over wintered onions which I pulled up,saving what I could by slicing up and freezing the bulbs.  I am now faced with the problem of how to deal with the three hundred main crop (3 different varieties) which have gone the same way and not likely to store in the usual way.

[devonstewParticipant]

It is one of the downsides of over wintered onions that they can pass on the mildew to maincrop and other alliums. Shame because they fill quite a long gap in onion production

[BarbMember]

I will definitely be giving over wintering onions a miss from now on.

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