You'll find 10-20 currently ongoing discussions on late blight over on the Growing Tomatoes forum. If it is early blight you are talking about there are even more discussions on it that a search will pull up for you.

But to advise on what to do you first have to determine exactly what disease you are dealing with as the cause, required treatments, and controls are very different. LB is rare, severe, and dangerous and requires removal of plants, double-bagging, and careful disposal. Early blight is common and can be controlled with anti=fungicide sprays.

Dave

1) Treatable but not aware of any organic treatments. Use either Daconil, Maneb, or Mancozeb. Remove any infected leaves use a shears and wash well between plants to limit spread.

2) Treat the plants and surrounding plants ASAP. When they are killed by frost remove plant, do not compost or burn. Place plants in trash bag and send out with rest of garbage. I wouldn't even send them to a yard waste disposal place.

3) Fruits are okay to eat after washing well (remember you treated them with a fungicide)

4) Noting to do with soil, rotate crops, don't plant tomatoes, peppers, potatoes, or eggplant in the area for 3 seasons (if at all possible).

Blight is a soil borne fungus, if it's bad you'll have problems every year when the conditions are right (lots of rain and high humidity). If your problems are re-occurring treat with fungicide early before your plants are diseased. Poor drainage can be a contributor to problems with blight. Things you can do to help without using a fungicide is mulch heavily with clean wheat straw and use landscaping fabric as a barrier between the soil and straw (helps keep weeds down too). Plant your tomatoes in 5 gal buckets with bottoms cut out that are partially buried in the garden soil, this keeps the leaves further away from the infected soil and allows the soil to warm earlier and expedite growth early in the season. As your tomatoes grow nip the lower leaves for the first foot along the stem, your plants will look funny but soil splashing is less likely to land on leaves and infect them.

I've been working in a garden center all spring/summer and have heard LOTS of blight remedies from people that have been gardening for a long time. These are the things that I've heard most often and/or make the most sense to me. I personally just use the landscape fabric combined with a heavy straw mulch. I haven't had any issues with blight in my garden but I did have an Aunt Ruby German Green with verticillium wilt and is being treated with Mancozeb with much success.

If your plants have Late Blight, here is a FAQ from Cornell that should answer some of your questions: http://www.hort.cornell.edu/department/Facilities/lihrec/vegpath/lbfaq.pdf

The Late Blight that infects tomatoes does not infect cucumbers. Your cukes have something else wrong with them.

Unless Late Blight is in the very early stages on a plant, it's not treatable. If there were just a few leaves with very small spots, plus no spots on the stems and a week of hot dry weather ahead, you'd have a chance. If there are more than a few leaves affected, black blotches on multiple stems, and the weather continues to be rainy, you might as well call it a season.

All of the treatments that are available for the home gardener to use are preventative. They have to be applied before the foliage becomes infected. Organic sprays are very feeble against a virulent disease like Late Blight, they just aren't very effective.

If the plants can't be saved, they should be destroyed immediately to reduce the number of Late Blight spores floating around. Late Blight is an airborne disease -- the spores from your plants can be carried for miles on air currents to infect other peoples' plants and farmers' fields miles away. Double-bag the discarded plants in sealed plastic bags and leave them in the hot sun for a day or two if possible to solarize them, then dispose of them in the trash.

Unblemished fruit is safe to eat.

You don't need to do anything about the soil except make sure you've cleaned up all the infected tomato and potato plants. The corn meal won't make any difference. Late Blight will infect potato tubers if the spores get washed down through the soil onto the tubers, but it does not travel through a potato or tomato plant to infect the roots from within. It does not live in the soil in zone 6. You can plant tomatoes and potatoes there next year, because the spores cannot survive being frozen and when the soil freezes this winter any spores that are on the soil surface will be killed.

Poor drainage may encourage Late Blight by keeping the humidity high around the plants, but rain is a much bigger factor. Late Blight spores germinate and grow on wet foliage and in humid conditions. Keeping the foliage dry will do a lot to keep foliage infections like Late Blight, Early Blight, and Septoria in check.

Several misconceptions:

1. It was said "Blight is a soil borne fungus"
Not so.

2. My cucumbers have blight, too.
Not so. They don't get blight.

Can you post images of your plants?

You need to make certain what the problem is before you do anything that wastes time & money.

Early blight of tomatoes is endemic here, and I am an organic gardener. If your plants are vigorous, you will still get a large set of fruit before the vines die. Also, Gardens Alive sells a couple of products that are organic and hold off blight, though don't completely prevent it in my experience. Fruit is fine to eat. And, in over 40 years of gardening, I have observed that volunteer tomato plants that spring from the compost heap NEVER get early blight, so they go on and on after your carefully tended plants succumb. Another reason for planting open pollinated tomatoes.

West

There are two types of tomato blight.

One is Early Blight, which is very common, and is controlled primarily by preventive spraying and removal of the infected parts. The spores can overwinter in the soil if the plant sheds them and in unremoved or unnoticed plant debris. Early Blight spores are not killed by soil-freeze. Early Blight is a slow-moving fungus so doesn't destroy your plants quickly.

The other is Late Blight, and it's lethal to tomatoes and potatoes within a short period of time, as little as three days. It usually starts at the top of the plant and moves downward in water-rivulets from rain, high humidity, or overhead watering. The symptoms are usually very specific and are relatively easy to identify.

At the bottom is a link to a detailed discussion about LB on the Tomato forum, and it appears that the LB spore-strain occurring in the Northeast does not survive freezing, though that information doesn't get authoritatively into the stew until the end of the discussion.

So, take your time and identify what's causing your plant problems. If it's Early Blight, no need to destroy your plants until they give up the ghost themselves. Again, just remove any affected leaves and continue to preventatively spray them. Bed rotation is recommended to lessen each year's crop of tomato-infection by Early Blight overwintering in the soil, though not everyone can do that.

If it's Late Blight, removing and destroying the plants and all their debris is about the only thing you can do, and hope that next year won't be as bad.

But a positive ID of the problem is required before you do anything. A picture of the plants and fruits here would be a good start. Also you can send pictures to your county agricultural agency and ask for an ID. Or take samples of problem fruits, leaves, and stems in a plastic bag to them and ask for an ID.

Here is a link that might be useful: Late Blight discussion