Leaf diseases seemed to start early this year, IMHO. I've had to prune lots of bottom leaves already, although so far the tops seem healthy enough. (*knock* *knock*)

If you don't get an answer soon, Althea, try posting your note and photo link in the GardenWeb Tomato Pests and Diseases forum. Some VERY knowledgeable people post there, and I'm sure they could tell you by looking at your photo what you've got. Folks there often recommend the TAMU site posted below. To me, your photo looks like some they post as examples of early blight. But it would be good to know. If you're not an organic grower or growing somewhere that allows no chemical sprays of any kind, experts on the Tomato forum highly recommend Daconil, now known as Ortho Disease Control, as a highly effective and very low toxicity preventive measure. (One poster whose opinion I trust indicates that it's lower toxicity than pyrethrins and some of the other natural substances approved for organic growing.)

Good luck! If you find out positively what it is, let the rest of us know too!

Here is a link that might be useful: TAMU tomato problem solver

Thanks for the link Bitterwort. I have already looked at several similar sites and didn't find an exact match. The lack of concentric rings on the spots makes me think it's not EB.

This problem is only affecting my heirloom Soldaki. The others, all heirlooms, are fine (knocking on wood).

I've already asked on Tomato ville, the new site of former and some current gw tomato enthusiasts. No one there has been able to i.d. it yet.

I am an organic gardener so daconil and other such things are out.

I have sprinkled corn meal around the plants. I'll check the Organic forum for other general blight ideas.

If I had to guess at a distance it would be Septoria. It is a fungus, too, and I suppose it could be knocked out by copper or sulfur, both approved for use under organics. However, I grow about 50-75 tomato plants every year and always have many infected plants. They still produce a good yields and I have learn to just live with yucky bottom leaves.

Thanks for you response loodean.

I called the U of M plant pathology lab and found they will test leaf samples for $20. I decided to send a sample to my county extension office. Altheo talked to a tomato grower yesterday who said to just snip off the bad leaves. Sounded like good advice.

Yes, google septoria images, they look quite similar to your photo. From http://www.extension.umn.edu/info-u/plants/BG478.html:

"The two most common tomato diseases are Alternaria (Early blight) and Septoria Leaf Spot. Septoria Leaf Spot is evident around fruit set. Alternaria may be present during all stages. They are similar in appearance. Both cause leaf spots to form on the lowest, oldest leaves and progress upward. Infected leaves yellow, shrivel and die. Septoria leaf spots are small, numerous, dark spots that frequently have white to grey centers. Alternaria leaf spots are larger, less numerous and exhibit a target pattern, formed of rings of dried tissue."

More about septoria at http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p232septoria-tomato.html

Once tomatoes start to flower, it's best to prune off all leaves below the lowest flower set. Lots of mulch and non-splashing watering help delay the onset of many tomato problems.

I was hoping you would offer your opinion Leaveswave, since the Extension protocol says to ask a MG. :~)

I had looked at the Extension pages of common diseases. Of those listed, it looks and acts more like Gray Leaf Spot than Septoria. Gray leaf spot doesn't affect the fruit, so it isn't so bad if you have to have one.

This link doesn't go directly to the description. You have to follow links to tomato leaf diseases and click on the gray-brown spots picture.

Here is a link that might be useful: gray leaf spot