Death of a Sunflower

Death of a Sunflower

Our sunflowers are dying, one by one, before they've had a chance to bloom. We started out with 15 seedlings, and now there are 5. It seems they have some sort of fungus... the bottom leaves turn speckled yellow and brown, and then the plant just wilts and dies. When I pull the dead ones up, I notice that they don't have a long taproot (like I've heard they're supposed to). I suspect that the roots are rotted by the fungus (or whatever it is). I also suspect that we may have been watering them too much, leading to this sad state of affairs. Sigh. Any suggestions? I'm thinking I'll try not watering the remaining ones for a few days.
Peonies almost  in bloom

Peonies almost in bloom

Tree id please?

Tree id please?

H. Pacific Moon

H. Pacific Moon

Help identifying plant

Help identifying plant

My 2.5 pound Brandywine Tomato from this year…

My 2.5 pound Brandywine Tomato from this year…

bean review

bean review