You can say a fruit is ripening, rotting, or bletting.

Would you say a fruit is ripe, rotted… bletted? Blet?

Bletted.

> "In Notes on a Cellar-Book, the great English oenophile George Saintsbury called bletted medlars the "ideal fruit to accompany wine."

https://en.wikipedia.org/wiki/Bletting

Not to be confused with blepping.

https://cats.com/why-do-cats-blep