I've found at least two berries with adverse effects. Pokeweed berry and flameberry.
Shouldn't baneberries, and any poisonous berries I've missed (like nightshade), also debilitate the player in some way?
Maybe Inflict a few seconds of poison effect?

Yeah, I think they did at one point, but they appear to not currently. I need to go back and check over what needs to.

Alright, here are the changes on this one.
Horsenettle Fruit (Deadly) -> 90% chance of Wither II for 900 ticks
Climbing Nightshade Berries (Unhealthy) -> 90% chance of Nausea III for 200 ticks
Black Nightshade Berries -> Edible when ripe, no change
Baneberries (Very Deadly) -> 100% chance of Wither III for 500 ticks