The expression "one bad apple spoils the whole bunch" probably has to do with the action of ethylene on fruit ripening.

Question

Quizplus · Accepted Answer

Ethylene is a plant hormone that triggers the ripening process in fruit. When a fruit starts to ripen, it produces more ethylene, which can cause nearby fruits to also ripen and eventually spoil. Therefore, if one fruit in a bunch is already spoiling and producing high levels of ethylene, it can accelerate the ripening and spoilage of the others, hence the expression "one bad apple spoils the whole bunch."

The Expression "One Bad Apple Spoils the Whole Bunch" Probably