[mjg000]

What is the best thing to do with it?  Presumable ok to go into beds to be used for anything except tomatoes or potatoes next year?

[JayG]

The usual advice is that blight can only over-winter on living plant material (usually 'volunteer' spuds left behind after harvesting) but last time I looked about a year ago, there is still some 'official' uncertainty as to exactly how blight survives in different conditions.

Having said that, I think most people, including me, use spent compost as a general soil improver without appearing to cause problems, although as you suggest I don't use it near, or on, spuds or toms.

[Aunt Sally]

The blight spores don't live in the soil, only in living material - the plants themselves and the tubers - the soil will be safe to use for anything.

SNAP, JG

[mumofstig]

That's what we've been told - but there's much research being done on oospores.

The pathogen can also produce resting spores (oospores) in the plant tissues that can contaminate the soil. Little is known about their survival and their potential as a source of the disease. The investigations into oospores are continuing and more information may be available in a few years.

https://www.rhs.org.uk/advice/profile?pid=217

A research pdf here
http://potatoes.ahdb.org.uk/sites/default/files/publication_upload/DavidCooke_Blight_Population_Update.pdf
seems to show that oospores do survive in the soil between crops. So rotation is important.

[Aunt Sally]

Thanks, Mum.  That is information I didn't know!

[cadalot]

I was considering freshening up the tomato compost and growing some over wintered onions, what would you suggest would be the best way of putting some nourishment back into the compost?

[JayG]

I'd use dried chicken manure pellets - slow release nitrogen + PK + trace elements - won't need much to keep them ticking over until spring.

[Salmo]

There are probably enough nutrients left in the compost for the onions. They want to grow hard to withstand the Winter and any additional nitrogencould make soft growth. You could add a little general fertiliser, growmore, chicken pellets or liquid feed, but I would not.

This idea of oospores remaining in soil for several years has been around for some time. In theory it is a threat but I do not think any oospores have ever been found in the UK " in the wild". I may be wrong but I do not think it is anything us mere mortals need worry about in our gardens and plots.

[mumofstig]

If it happens in fields in Wales.....

On-going experiments at Henfaes, funded by Potato Council, have shown that new crops planted on the same site as crops infected with both mating types of blight become infected from the soil and that new strains of blight are generated.

http://www.sarvari-trust.org/late-blight.html

[Salmo]

If it happens in fields in Wales.....

On-going experiments at Henfaes, funded by Potato Council, have shown that new crops planted on the same site as crops infected with both mating types of blight become infected from the soil and that new strains of blight are generated.

http://www.sarvari-trust.org/late-blight.html

These are experimentally infected plants. I stick by my guns. Never been found "in the wild" in the UK.

[mumofstig]

I keep an open mind 

[JayG]

My take on this is that whenever I see a safe/safer option I'll take it - why take unnecessary risks if you're not sure?

[snowdrops]

So where do we get blight from every year. If the infected material is disposed of?

[mumofstig]

It usually appears first on the Eastern side of the country first, so we assume that it blows over from the continent. Often it seems that farmers(?) are not so good at destroying last years crop remnants - as blight is often shown by Blightwatch  as found in old outgrade heaps. It makes me very  when I see it

Also, from new research, link shown above, scientists think that maybe some of the new types may be able to make spores that overwinter in the soil.