These pimple-ish things are a sign that it's been pretty damp this summer, and they're mostly not a big deal. But, now and then, they might help bad bacteria and other microorganisms to spread and cause problems.
From WGME 13:
“The tubers have adapted to grow below the ground where there is less air available,” Gregory Porter, professor of crop ecology and management at the University of Maine, said. “When the soil gets saturated there is less [oxygen] and more water, and the common response from the potatoes is that the lenticels will enlarge.”
The lenticels are what allows the potatoes to breathe by converting some chemical gasses into oxygen, said Ibrahim Kutay Ozturk, potato plant pathologist with the University of Maine Cooperative Extension.
“During wet seasons, sometimes tubers have to work extra hard,” Ozturk said. “Therefore the lenticels are swollen up to ease gas exchange.”
It’s usually safe to eat a potato that has enlarged lenticels, Porter said. But you should examine it carefully first.
Enlarged lenticels can let in pathogens or bacterias that rot the potatoes flesh. Once a potato begins to rot or spoil, it can harbor bacteria that cause salmonella, listeria or botulism, if eaten.
The longer the potato is out of the ground and in storage, the greater the risk for these pathogens taking hold.
Wow, potatoes are turning out to be riskier than you'd expect.
Remember that story where a whole family got taken down by fumes from spoiled spuds? And now, with these germ-covered "acne" bumps, you seriously start wondering what other innocent-looking stuff in the produce aisle might pack this much danger.
