What causes brown and black spots on avocados?

Here's what the brown spots, bruises, and stringy black lines on your avocado flesh mean — and whether it's still okay to eat: ... This process actually enables avocados to last longer, as quinones are toxic to the bacteria that cause rot, but it shortens the window of time they can be actually enjoyed. read more

Late in the avocado season, as the fruit matures and contains high amounts of oil, avocados can also develop brown spots in them. This is a result of over-ripening and high oil content. This typically occurs when the avocado is well past the point it should be eaten. read more