Well this is more a discussion for the Growing Tomatoes forum than here and you will find much more information there. But as a fellow greenhouse grower I feel for you so I will hit some of the high points. First Late Blight (aka "potato blight"), is cause by the airborne fungus p. infestans and is quite rare (but not impossible) indoors. Further it is characterized by dark black (rather than yellow) areas on the leaves AND the stems and trunk. It is always almost immediately fatal to the plant with total plant failure within a few days. Per Cornell Univ. there have been no verified reports of Late Blight in the northeast so far this year. Early Blight (a. solani) is characterized by yellow leaf damage in a bulls-eye pattern and is not fatal to the plants although it does affect production so replacing the plants would be recommended if early enough in the season. And EB has been VERY active in many parts of the country already this year. Then of course there is Alternaria and several other tomato diseases which many also mistakenly lump under the label "blight". But all except Late Blight will respond to the use of Daconil (chlorathalinil) so I'd sure give it a try. I'd strip off all the affected foliage, spray the healthy foliage well, and transplant a few test subjects deeply and monitor them for new growth before pitching all the plants. As for disinfecting the GH, summer heat if you turn off the vent/fan system and let the temps rise will take care of much of it and then hose down the entire place with a 1:10 diluted chlorine bleach solution. Good luck. Dave

Wow. I haven't heard of Septoria before, but the pictures on Google look spot on. Actually, it looks like the same thing that hit a tomato and brugmansia last year... and a bit similar to what uglified a few mint plants. I'm almost tempted to say that an extra pot of soil, which probably had a sick-ish tomato from last year, was dumped in that part of the raise bed. I'm really hoping that any leftover leaves and whatnot did not introduce the Septoria to the garden. Nothing else around the potatoes are affected yet (peppers and tomatoes). I'll give the baking soda mix a go on the tomatoes (and peppers?). Would vinegar and water work too? I only ask because I was told once to use it for fungal problems with seedlings but I never tried. Is there a particular fungicide you would suggest to combat the Septoria? Thank you so much! I was close to chopping them down and tossing them in the chiminea.

Can't really tell from the pics as they aren't close enough to see the bull's eye pattern. There are 2 very different forms of "blight". Different causes and different symptoms. If there is nothing on the stems, just the leaves, then it could be Early Blight and that is the most likely. But if the stems are also affected and if the leaves develop large dark soft spots then it could be Late Blight. See link below for pictures to compare. In either case a regular spraying program of fungicide is needed. Were these planted in a different site than last year and were they fresh treated seed potatoes or ones you saved from last year? Unfortunately too many folks planted their own saved seed potatoes this year, ones that carried the late blight fungus from last year's epidemic, and we are now seeing a resurgence of last year's late blight problems. Dave Here is a link that might be useful: Potato Diseases

Here are some more pictures including some spots on a nearby pole bean leaf: http://picasaweb.google.com/wsharp/20080714Garden There isn't any halo effect on the underside from what I can tell. The potatoes are growing in a raised bed and I didn't have enough room to pile lots of soil up around them. Any they really have been eaten up by the flea beetles. This bed had sugar snap peas and tomatoes last year that all did well. And this year: sugar snap peas, pole beans, basil, spinach, rosemary, parsley, and some salad mix. Only the potatoes and pole beans have had spots and looked unhappy.