It’s too early to panic. Was lettuce the only seed that was effected when directly sown?
The lettuce was the only plant (seeds) I tried. I was trying to see if I could get it going when it was till pretty cool outside: Ie., marginal risk of frost, but I could cover if necessary.
I might try a small patch where I scrape off the top couple inches of soil, add new (purchased from Menards?) topsoil, and plant in that.
You’d think some sort of fungicide applied to the soil would work, but I’m not finding much except those intended for lawns. Might not be safe for veggies? Daconil, maybe?