system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does mold grow on overripe fruits and not while fruits are ripening? What stops the mold from forming at an earlier stage?
gpt
Plants defend themselves actively against molds and other pathogens by producing substances thet either kill or doesn't allow to grow the mold, but for this the fruit must be able to communicate with the plant to tell it "send help". Once the fruit falls from the tree or is so ripe that the communication paths do not work,  pathogens win.