Posted: 13/09/2015 at 09:06
Liz, if it's Late Blight, the spores live on in the soil. Or on top of the soil, anyway. That's where the spores finish up after dropping from the foliage. Freezing doesn't kill them. You can turn over the soil, burying the top soil (and the spores) deeply. The spores can't do any further damage from underground. The risk they can pose, lying on the surface, is being splashed up onto foliage next season when watering.
Whether it's Late Blight is another matter. But the above applies to most fungal spores anyway.