This episode is part of the early "Funimation" dub, featuring the original English voice cast for the Straw Hats. The episode is found in Season 3 (Drum Island Arc).
Kureha informs a shocked Chopper that the mushroom is deadly poison, not a cure, causing him to weep in heartbreak over his unintentional mistake. One Piece (Dub) Episode 86
The scene emphasizes the theme of inheritance, where Hiriluk passes on his dream and spirit to Chopper and Dalton. This episode is part of the early "Funimation"