Some maple leaves with the tar spot fungus are covered with spots. (CBC)

For several years the tar spot fungus has been attacking P.E.I. maples, and the problem appears to be growing worse.

Provincial horticultualist Dave Carmichael told CBC News Thursday it's becoming a major problem, especially in urban areas where maples trees are close together. Virtually every maple tree in Charlottetown is covered in black, spotted leaves.

"When the leaves completely, fully expand early in the summer, that's the time when the infection generally occurs," said Carmichael.

"[There's] a lot of leaves laying on the ground. The disease actually starts to break open through these fallen leaves from last year and spread by birds, could be spread by insects or spread by wind to leaves that are vulnerable."

Damp, humid weather the last few years in June has made it easier for the fungus to spread.

An ugly problem

Carmichael said the tar spots aren't necessarily fatal for healthy trees.

The blight will not kill an otherwise healthy tree, says provincial horticulturalist Dave Carmichael. (CBC)

"I don't think it's a major life-threatening thing for a generally healthy tree to a very healthy tree, but certainly weakened trees are more susceptible to decline as time progresses," he said.

While the fungus will not generally kill the trees, it is ugly. That's a concern for Charlottetown, which has hundreds of maple trees along the parks and main streets.

"Basically, it's an esthetic thing," said Charlottetown conservationist Beth Hoar.

"It really makes the tree look quite bad."

There is nothing that can be done to get rid of the tar spots once they've started, but it is possible to reduce the spread the following spring. Rake up all the leaves in the fall, get your neighbours to do the same, and put them out for the provincial recycling program.