Edie, I don't know which specific blight you're talking about b/c its just a general word suggesting a sick tomato plant.

But if you're talking about the two most common fungal foliage diseases, Early Blight and Septoria Leaf spot, all might be well.

Both can be seed borne so what you need to do is to ferment the frut guts, I think you know how to do that, b'c doing that removes not all, but most of any of those two pathogens from the seed coat. And since infection is a quantitative process, there are usually not enough left to cause infection.

If it's the two most common bacterial foliage pathogens,Bacterial Speck and Spot, that's a different story since to date the bacterial pathogens looked at reside not on the seed coat, but within the seed in the endosperm.

Hot water treatment is used for those bacterial ones, but as is oft said, don't try this at home and I won't go into the details.

Hope that helps

Carolyn

Oh, sorry - yes, it is the gruesome twosome of EB and Septoria. So I will do the fermentation and pray that that gets it all. Thanks so much!
Edie

You can also disinfect them even further as many of us seed savers do by using a 1:10 chlorine bleach brief soak or spray on the seeds before drying for storage.

Dave

On the subject of saving tomato seeds, a question or two. Do folks prefer large seeds to smaller; and does lighter or darker color matter?

I usually just take seeds from my one or two best heirloom cherry tomato plants of the season.