Looks like maybe he decided to get back to his roots.
3 seconds sound clip from Darkwing Duck - Beauty and the Beet (S1E3).
You can hear this line at 00:12:50.587 in the DVD version of the TV Series.
Quote context
[...]
- Good thing I had a light breakfast.
- Sorry, but I'm a slow learner.
- OK, Bushroot, the sprig is up.
- Clever, but you don't get away from Darkwing Duck that easily.
- OK, Bushroot... Huh? He's gone.
- Looks like maybe he decided to get back to his roots.
- Darkwing Duck! Did you find Dr. Bushroot?
- I think that's a safe assumption.
- Oh, poor Dr. Bushroot. I feel so sorry for him.
[...]