Novice

I'd post this question on the tomato forum, and include a picture. There are several experts who could probably help you out, and you may be in the area that's being so badly affected this year.

But. Not all yellowing leaves are a result of blight at all. You'll need to provide more information if you ask on that forum. Where you are, how often you water, your fertilizer, your weather, if they're the oldest leaves that are just giving up the ghost, etc.

Far too many people have been innoculated with the belief that any plant problem is going to be a disease or pest problem that needs a spray to control that they cannot believe what anne stated above. All plant problems start with the soil they are growing in, so start there.

"All plant problems start with the soil they are growing in, so start there."?

C'mon. That's a very broad brush to be painting with again. Mechanical injury, poor watering habits, herbicide drift, rusts, wilts, ..... I can think of a dozen w/o breaking a sweat that are totally unrelated to the soil. There are many pests AND diseases that don't give a whit (that's whit) about how robustly the plant is growing. Again, it sure would be nice to see a picture or get more precise information so we can maybe put the diagnosis in front of the cure.

It does SOUND like blight or a mold disease, but a picture might be more helpful. The problem with molds & things fungal is that they're best treated prophylactically because they are very hard to fix once they have a hold, and those fungicides apt to be effective as a fixitive don't fit well with an organic ideology.

Al

Mechanical injury most likely would not be soil related, although most mechanical damage happens when the gardener is cultivating the soil. Poor watering, herbicide drift, rusts, wilts, are most all soil borne problems, but as I have said many times plants growing in a good, healthy soil will be less likely to have problems.

thanks. tapla, you are right. Can't upload pics yet, since I don't even have my own computer, and need discs to save pics from digital camera/video recorder got for Christmas.
I know that it helps to have pics.
However, I strongly feel it's fungal- as we've had lots of rain, the garden doesn't get as much sun as it did (neighbor's trimmed tree has REALLY come back) , and besides there hasn't been much sun!
There is actually some weird fungus growing in my garden in the north beds, and spreading rapidly. It's not mushrooms, it's a fungus. I've never seen it before and can't get rid of it.
Sigh. Now where do I plant my late summer greens?
Um, kimmser, your soil answer is sounding like a broken record. Perhaps one day I will achieve perfect soil, but until then my main problem is mother nature thinking it's spring and not summer.

Just because you see the fruiting bodies of fungi in your soil is no reason to think they necessarily represent something harmful to your plants. It's much more likely that if it was an unfavorable cultural condition that made the spread of the fungus possible, the unfavorable cultural condition would be more of a concern than the fungus itself.

Of course though, botrytis (gray mold), powdery mildew, early/late blight, and the wilt diseases are more serious issues.

Are your tomatoes in the same place they were last year? Are you careful not to wet the foliage when you water? Are the infected leaves too many to remove & destroy, & still have a plant you consider viable & potentially productive?

Al

My sungold has been very prolific so far, just yesterday I noticed alot of the upper leaves turning yellow. I guess I'll go home and take a pic and probably prune off the yellow leaves.