Dark, black slightly sunken spots on mango

How do mangos get anthracnose?

A spore probably attached itself to this mango back when it was a young fruit. The spore would have then set up a little protective cap over itself, Brecht explained, and patiently waited for the mango to soften and sweeten. Then the fungus would have literally bored into the fruit and gotten busy making this black spot. 

Anthracnose is spread by water, so it’s common to see a string of round black lesions cascading down a fruit in the path of the rain droplets that likely deposited them there. Once in your kitchen and far from the rain, however, one lesion is unlikely to spawn more lesions; rather each black spot will grow in place. Brecht said anthracnose doesn’t spread from fruit to fruit. 

Here’s a honey mango where many more spores settled in.  

Brecht said farmers use fungicides to prevent anthracnose infections in fruit. It can be hard to control, however, he said, because the rain both washes away the fungicide and distributes spores. 

Anthracnose, he said, is particularly frustrating because, unlike most other mango-hungry microorganisms, it doesn’t need a break in the skin to access the fruit. The fungus uses something scientists call a “peg” to bust in. I picture this as a tiny jackhammer. 

“It actually can physically push its way into the skin,” Brecht explained. 

The National Mango Board, which promotes mangos and supports mango producers and retailers, deems anthracnose to be the most prominent disease that growers face. You may also recognize this signature sunken dark spot from other blemished fruits and vegetables in your life. Anthracnose is an umbrella term for a number of fungi that thrive in moist conditions and leave our produce with unsightly dark circles. It is unrelated to anthrax, which is a disease caused by Bacillus anthracis bacteria.