Thanks for all the comments so far.
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Originally Posted by Carolyn
Pooklette, where are you in zone 5 for it really makes a difference this year in terms of diagnosis,
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I am in southern WI. Usually the leaf spots show up within two weeks of transplant (late May or early June.) This year they held off until mid-July.
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If it's Early Blight ( A. solani) you should see concentric rings within the leaf spots but there's not enough definition for me to see if that's there. Besides, fruits affected by EB have no spots, just infection in a circle around the stem.
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I've never noticed concentric rings. Generally, the leaves have black spots that vary between 1/8" to 1/4" in diameter. Most are round, some are irregular in shape. The black splotches on the stems are similar.
ETA: The leaf spots do not dry up and 'fall out' leaving holey leaves. The spots multiply until the leaf and its entire branch turn yellow and dry up. This usually happens from the bottom of the plant, on up.
I'm starting to think I have been seeing the effects of more than one disease. I have no fruits on the spotty plants yet this year. During the last two 'diseased seasons', here's what I saw:
Some of the green fruits had tiny dark specks like I see in the Bacterial Speck photo here:
http://aggie-horticulture.tamu.edu/p.../bac_spec.html
The black spots that turn my fruits to mush before they've even fully ripened look a lot like the Anthracnose example here:
http://aggie-horticulture.tamu.edu/p...e/anthrac.html
The fruits end up with a bunch of black pencil-eraser size spots that turn soft and start cracking/oozing right around the time they start to blush. By the time the fruits are almost ripe, they're reduced to tomato goo.
ETA: By almost ripe, I'm referring to pink, black, or orange tomatoes that are still green on the stem end. They're definately not tomatoes turned to goo because they're overripe.
Over the last two years I've tried removing the spotty leaves and branches. It still spread like wildfire. I tried dusting the plants with copper powder. Didn't seem to make a difference. I tried mulching around the plants, thinking it would help to prevent the dirt from splashing up on the plants, and it did, but the black spots still showed up.
A few days ago, I broke down and bought Daconil but it's been raining ever since. I have to wait until the rain stops to use it, right? (This year, the spots showed up after the hot dry weather turned perpetually cool and humid. Perhaps that's a clue?)