What do we have? It's called "late blight", and it kills tomato and potato plants. It's the same disease that was responsible for the Irish Potato Famine in 1840.
Why do we have late blight?
The ladies explained that we always have late blight, but it usually lies dormant. This summer, being unusually cold, wet, and darker than most, has been a perfect opportunity for late blight (being something like a fungus) to rear its ugly head. And it has; of the farmers she knows across Massachusetts, all have crops affected by late blight.
What didn't help, they explained, was that the big box retailers all purchased infected plants this year from one mega-distributor in Alabama (Bonnie Plants), so if you bought your tomato plants from a Lowes, Home Depot, etc. you probably bought an infected plant.
They also said late blight can obliterate a fully healthy crop - not just a backyard garden, but an actual farmer's crop - in 3 days.
Since we were growing mainly potatoes for our local farmers market, its likely our whole garden will be destroyed. What was the one extra, special crop we were growing for ourselves? Tomatoes.
From our friend who runs the community exchange we're part of-
What you should do as a gardener:
Visit the following websites to get an idea of what to look for. The first is the Cornell plant disease website. It has good background information and photographs.
The second is the UMASS Vegetable site. It also has basic information and photographs, but it is updated regularly to reflect what's going on in Massachusetts. It also explains how to dispose of your diseased plants.
More news on the subject:
Boston Globe - There's a Tomato Fungus Among Us
WickedLocal - Across the Pond and Beyond: A blight on our tomatoes
NYTimes - Outbreak of Fungus Threatens Tomato Crop