Drought conditions are creating a calcium deficiency in tomato plants in Maine. Lack of calcium leads to blossom end rot that also affects peppers and eggplants. Credit: Sarah Walker Caron / BDN

Those red, juicy tomatoes gardeners dream about all summer are the latest victims of Maine’s ongoing drought conditions.

Growers around the state are finding ripening tomatoes on their vines that look perfect, until they see the base of the fruit is brown, black and soft. The same is also happening to eggplants and peppers.

The culprit is a disorder called blossom end rot, according to an agriculture expert, and the problem started before the fruit even appeared. And while the vegetables may look unappealing, they are not inedible, and there is still an opportunity for Maine gardeners to take action to prevent it in future plants.

Blossom end rot is a result of calcium deficiency in the plant and when conditions are dry, it makes it very hard for the tomatoes to draw in enough calcium through its roots, according to Frank Wertheim, agriculture and horticulture educator with the University of Maine Cooperative Extension.

“It happens in the development of the fruit in the flowering stage,” Wertheim said. “It’s a problem when the soil is going through an extreme wet-dry cycle, which we all know it has been this summer.”

Maine is currently experiencing its third year of dry conditions with most of the state experiencing moderate drought or abnormally dry conditions, according to the National Oceanic and Atmospheric Administration.

“There is often adequate calcium in the soil,” Wertheim said. “But in a dry cycle the flower is not getting that soluble calcium because the water is cut off just when the plant needs it the most because the calcium is there, but it can’t get to the plant.”

Drought conditions are creating a calcium deficiency in tomato plants in Maine. Lack of calcium leads to blossom end rot that also affects peppers and eggplants. Credit: Sarah Walker Caron / BDN

That means blossom end rot is more of a water relations problem than a soil issue. It also means that for tomatoes already affected there is not anything you can do about it.

“Once they have experienced the drought conditions, it’s pretty much too late,” Wertheim said. “So now it’s more preventative care, and we are in one of the worst droughts I can remember in Maine.”

But there is some hope for future tomatoes this season.

“When I get phone calls about blossom end rot the first thing I ask is, ‘Is the soil mulched?’” Wertheim said. “The answer is almost always no.”

Mulching around the plants helps keep the soil more uniformly moist, he said. It also allows the soil to hold the moisture longer.

Any plants that are getting ready to flower now would benefit from being mulched, according to Wertheim. He also said applying calcium directly to the soil could help. You can use epsom salts, crushed oyster shells, egg shells, wood ash, gypsum or a commercial product to get that calcium boost for your tomatoes.

But before adding anything, Wertheim does recommend having your soil tested to see if it even needs that extra boost.

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Tomatoes affected by blossom end rot are still edible, just cut away and discard the discolored base.

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Julia Bayly

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.