Brown spots look like they might be rust. Try 1 teaspoon baking soda in a 1 quart spray bottle. Mix well and mist your leaves. Dahlias are picky about too much water, if new growth is turning brown, or she's wilting but she has plenty of water, cut back. Also, avoid getting the leaves wet. Slugs were eating the heck out of my Dahlias and I put sluggo in the pots around the base of the plant and they look great now. They looked similar to yours. Hope that helps.
Why do these look so bad?? First year I planted them and they are doing terrible!
Brown spots look like fungal, probably from humidity, holes from insects. 🌞
Any way to save it?
Brown spots look like they might be rust. Try 1 teaspoon baking soda in a 1 quart spray bottle. Mix well and mist your leaves. Dahlias are picky about too much water, if new growth is turning brown, or she's wilting but she has plenty of water, cut back. Also, avoid getting the leaves wet. Slugs were eating the heck out of my Dahlias and I put sluggo in the pots around the base of the plant and they look great now. They looked similar to yours. Hope that helps.