Allotments 4 All

If you are leaving the potatoes in the ground you need to be certain there is NO foliage left on the surface to allow spores from that to wash down to the tubers. Bordeux mixture does tend to get washed off whereas dithane with me works better but it is only a preventive not a cure it is like mildew you can prevent but not cure.

I have just looked at the Garden Organic members page on blight and they suggest leaving for 2-3 weeks after -as you say Laurie!
The reasoning is like Goodlife says- it hardens off the skin so less vulnerable to picking up the infection, and the blight spores will have died off as they only survive on living tissue.

I choose not to use sprays, but have no problem with anyone who does! The Italians all use the blue sprays on our sites, you can spot thier plots easily!! I just want a few polytunnels - dream on!!!!