Newly harvested potatoes in Maine are coming out of the ground with skins looking like they have a case of teenage acne.
Like raised pimples on human skin, white bumps on potatoes grow out of pores — known as lenticels on vegetables — on the tubers’ skin. Depending on the variety, they are more evident on some spuds than others.
The unsightly growths are just the latest sign of how wet this summer has been. Crop experts say these bumps — also known as “water spots” or “water scabs” — are perfectly natural when conditions are as damp as they’ve been.
In the best scenario, the scabs leave you with an unsightly potato that won’t last long in storage. In the worst scenario, they can promote the growth of human disease-causing bacteria and other pathogens.
“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 allow the potatoes to breathe by exchanging gas between inside and outside the tubers, 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.
“I would recommend not storing these tubers for too long,” Ozturk said. “And consume them quickly.”
There will be signs that the potato is unsafe to eat.
“When they are in storage, you may start to see infections and darkened spots on the potatoes,” Porter said. “That is the bacteria damaging the tissue.”
Before eating that potato, you need to trim or cut off any areas of discoloration or decay.
Enlarged lenticels do decrease the overall storage life of your potatoes, but Porter said it can help if you let them dry a few days in the open before storing them.
Correction: A previous version of this story misstated the role lenticels have in potato growth. It has been updated.