What is the most difficult pest you deal with in your garden?

We have had too much rain so we have that powdery mildew on melons and squash. Bugs on tomatoes that look like stink bugs and sting the tomatoes and ruin them. That Bayer fruit and veggie spray got rid of them in one application. Ants are everywhere. And recently started losing pepper plants with a white fungus around the base of stem. Maybe more info than you asked for. I am in zone 8, southeast part of Texas.