Bottom leafs dying!

[Huntsmcgee]

So almost overnight well 2 nights the bottom leaves on 3 out of 4 plants curled up and got hard. I'm not sure if it's over/under watering how would I know?. I'm worried it's something that will kill the plants altogether but I pruned off affected stems. Tops of plant seem fine. I also considered if water being on leaves and drying had anything to do or perhaps it's some dreaded wilt virus/fungus