system
Given the following post, respond as if you're commenting on Reddit:
human
Why does fallen fruit begin to grow mold while fruit still attached to the tree does not?

My guess is that the tree as some form of defense against fungi but I am at a loss to what mechanisms make up that defense.
gpt
When the fruit falls, it gets squashed, bugs and ants start biting into it creating a nice entry for mold.

Sometimes fruit also gets moldy while still on the tree, typically when birds peck on it or wasps start biting it.