Are you positive the tree is an American Elm? Your description of the plants involved makes me think of Black Walnut toxicity which affects tomatoes, eggplants, peppers and isn't much of a problem for melons.

that was my line of thinking - nature girl -

I'm not 100% proof positive it's an elm but I know it's not a walnut because they're not hardy here. I do wonder if it could be a tree secreting related chemicals.

do you have pictures?

Elm trees are allelopathic, similar to walnut, but not as bad. This is likely your problem.

Joe

Your peppers, tomatoes and eggplants probably would like more sun. I have a similar problem, but for a different reason. Living near the ocean, we have had a lot of early morning fog, which doesn't clear until almost noon.

Later in the day, a tree cuts out the latter day sun, and my poor solanaceous plants are not happy. Fortunately, we are now going into our "real" summer weather, so these are beginning to perk up.

I'd try to find a bit more sun for your struggling sun-lovers.

Bejay

Congratulations on the large elm specimen. I guess the very cold zones are outside the beetle zone. It's been so long since I've seen a mature Elm tree not sure I would recognize it!

My cousin's DH said he saw a young one, 30 ft tall, under a dead one on our back acreage (they were out picking wildflowers in our back meadow - they live in front of us, or to be more accurate, our land extends behind their 5 acres). He wants to move it - I think anything 30 ft tall, regardless of how big/small the canopy is, is going to have such a large root system that it will die if we try to dig it up (not to mention it will require an excavator, I don't think he can move a 30-ft tall tree in an 8ft pickup as he claims, and we have all ledge so it's probably growing in the cracks). He says it's just going to die for lack of light.

Opinions?

Sorry for the hijack.

Interesting that the U of GA list (link) lists American elm (Ulmus americana) in the top list of offenders, but the literature citation is from Pakistan. Do we know that little about our native trees?

Here is a link that might be useful: U of GA allelopathic trees

Smallish elms like that are common. No point in moving it since it will die from the disease anyway.