I asked Geoff Stebbings about this a few weeks ago at a flower show & he said that it would be O.K. to spread the used compost around the garden or put it in the compost bin/heap after you have removed the blighted plants as the blight spores would be on the plant material in the case of tomatoes. I didn't ask specifically about potatoes but if the blight hasn't washed down into your tubers I would think the compost would be fine & even if it has if you remove all trace of the tubers/roots etc. it should be O.K.Geoff just said don't use the used compost for or near toms/potatoes for now.

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Into every life a little rain must fall.