Early blight is characterized by dead brown spots that usually start on the lower leaves and spread up the plant. Upon close inspection, you can see concentric rings within the spots. Although early blight is most severe on the leaves, it sometimes occurs on the stems and can cause severe defoliation. Certain varieties (Roma and Supersonic) are more tolerant of early blight than others.
Septoria leafspot is characterized by numerous small black spots on the leaves. The centers of these spots later turn white and tiny black dots appear in the white centers. The disease starts on the bottom leaves and may become severe in wet weather.
After taking an informal survey of some lady friends the other day, there were reports of "my plants are perfect" to "I've lost them all." A surprising number had no tomatoes survive this year.
Tomato plants need to be inspected daily because disease and pests can get the best of them fast. There is a point with tomatoes that no amount of spray or dusting can bring them back to life. Plus, you will notice many of the problems are weather related and this year's excessive rain is a big culprit.
If you think you have one of the above "wilts", try a commercial aid first - reading directions carefully and hope for the best. Some caution about washing the tomatoes - heed that advice closely before eating.
If you totally loose the plants, pick all tomatoes (green and ripe). Either lay out in the sun to ripen or eat/freeze/can process. There are many great recipes for salsa that incorporate green tomatoes - not to mention fried green tomatoes.
Thought I'd include the following nutritional information: