it looks more like septoria than early blight at this stage.

if individual lesions get larger and form "target-like" concentric rings it will be early blight. If the stay small but possibly become more numerous its septoria

I see this affliction occasionally. I have never heard of "septoria" before, so I appreciate the suggestion.

I suspect that many things can cause this damage, though. Nothing happens in a vacuum, and this does seem to have a causal agent... though it has never swamped a plant on my watch, in over ten years... around here where it remains either cool and damp or hot and dry.

I snip off any leaves like this, with ample clear margins, and that seems to solve the problem. Mostly, afflicted leaves are near the bottom of an afflicted plant.

Leaves that lie on the ground inevitably rot. So it is important to trim excess foliage at the bottom of the plant accordingly. I also thin the interior on a large, densely-foliated plant... to facilitate air movement.

Here is a link that might be useful: Ohio State University notes on septoria

Thanks.

I'm new to all this so bear with me. I noticed several of the young tomatoes on this vine have the light brown marking you see in the pic. Would that be a symptom conjunct with that of the foliage, BER, sunscald, or completely typical and nothing to worry about?

Since you've been spraying Daconil regularly, I think Septoria is less likely (as long as you've gotten good coverage). If it's been fairly cool, in the 65-70 range during the day (at least until just recently), you're probably looking at bacterial speck (Pseudomonas syringae pv. tomato). Since it's bacterial, Daconil won't stop the infection, and it likes cool humidity... it survives on weeds, seed coats of unfermented seeds, old tomato plant debris, and so on.

The good thing about speck is that it doesn't threaten the plant's health at all when the plant is this size; it's a threat to seedlings, and not always then. It tends to go away as the weather warms up (though then you're more likely to see bacterial spot, caused by Xanthomonas). Bacterial diseases are slow-moving and combatted by taking off affected leaves, increasing airflow in the plant and, in bad cases, copper sprays. Most of the time a little isn't harmful.

Pick off the spotted leaves, make sure you have good airflow in the plant, and don't worry about it too much unless it really starts multiplying a lot.

--Alison

Torquill's credentials are most impressive. Thank you, T, for posting.

Hey, johnpeter, just because I have credentials that doesn't mean I can't be wrong. If I started thinking that way, I'd have a VERY big letdown the next time somebody puts a big hole in my confidently-asserted diagnosis. Which happens often enough right now that I know better, but it's too easy to slip into the mode of "the person with a degree knows everything". From both sides. :)

That said, I saw a *lot* of speck this spring, and I'm pretty familiar with it by now. My diagnosis stands as I review it now; I don't think I missed anything.

--Alison

Thanks for the help.

It has been pretty warm around here lately. The average high in June was a little over 80. I think we have to go back to the first week of May for a weekly high of under 70. I'll pick off leaves and make sure I get good coverage as advised.

Thanks again.