What should I do? Treat with fungicide? Remove leaves? Pull plants? I have 7 other tomato plants, planted at least 3 feet apart. These are two of the biggest. Other veggies are nearby, including peppers, but they aren't susceptible, are they?

And how would tomato plants get this?

You'll find much more info about this over on the Tomato Forum here linked at the top of this forums front page so I hope you don't mind if I just hit the highlights.

Early Blight or, in this case, Septoria Leaf Spot are the 2 most common tomato diseases and both are caused by fungus found in the soil and in the air. They are both so common that the real issue is how to be one of the lucky few who avoid getting them, not how you got them. :) The only way to avoid getting them is to use a regular program of fungicide spraying from the day you plant them outside.

As to what to do now, first you immediately strip off any and all affected leaves and dispose of them outside the garden and you continue to do this as the affected leaves develop but no you don't need to pull the plants. They will still produce. Then you begin a regular weekly fungicide spraying program to slow it. Fungicides won't cure it but they can prevent new leaves from becoming infected.

Follow the label instructions on which ever fungicide you choose for mixing and application rates.

Dave

I hate to ask, but did you turn the leaves over and examine the undersides for any tiny insects, mainly spidermites? It's just that it looks a lot like my plants did when I had a spidermite problem and I thought that the fungus problems usually start at the bottom of the plant, not the top. But I haven't yet had the joy of meeting early blight, so I may be out in left field...

Cheers!

No........digdirt is right. I had a bounty harvest last year, when everyone else got little or no tomato crop. I did remove daily any lower leaves with any sign of symptoms. Heavy mulch (I used straw) under the plants when you set them in will prevent water from splashing up off the soil to infect the lower leaves with early blight. It's not accidental that you see symptoms on lower leaves first because it's splashed up from irrigation or rains.

I do not use fungicides on my food crops and I still kept it under control, though not entirely free of early blight. Lotsa work on my part but I canned a couple hundred quarts of tomatoes. I felt sorry for some local producers, however, who lost whole fields of them. He definately should have done exactly what digdirt said, including the fungicides.

I think you have what he said you had....not early blight.

Thanks so much. I'd been looking at photos and can't tell the difference between early blight and septoria leaf spot. I'll order some fungicide, remove the affected leaves and read some more.

Oh, and I haven't seen anything on the underside of the leaves.

My toms had that when I first put them in the ground. I applied Bonide's Sulfur/Copper/Pyrethrin dust once and it cured it. After that they started growing really well and have quite a few large toms waiting to ripen.

Since the Pyrethrin had nothing to due with killing the fungi (I needed it because I had Colorado Potato Beetles at the same time) you could probably find some straight copper/sulfur dust to use.