Here some suggestions from West Coast Seeds
http://www.westcoastseeds.com/topicdetail/topic/11/
Late Blight has been around these parts for years, but our amazing sun drenched spring/summer has certainly helped delay its onset this year ....
I was saving some of the old West Coast catalogues that showed how to set up poly tunnels to keep plants dry - but did a 'clear the clutter' thing and out they went