If while walking through the city's parks or neighborhoods you thought you were seeing an unusually high number of distressed or dying pine trees, you're right. An infection called Diplodia tip blight is killing many of the area's mature pine trees.

Diplodia tip blight is increasing and it is almost impossible to eradicate. As many of the area's pines die, the appearance of parks and residential landscapes will undergo a dramatic change.

Pines belong to the conifer family: trees that are mostly evergreen, cone-bearing, and have needles for leaves. Americans have enjoyed a long love affair with conifers, and pines in particular. With their scented needles and cones, pines have come to represent the continent's great wilderness. Their lush-green canopies add depth to landscapes. And pines are frequently used as wind breaks and privacy screens.

Diplodia tip blight is caused by Sphaeropsis sapinea, a winter-hardy fungus found throughout Eastern and Central US and Canada. It spreads from tree to tree. Spores of the fungus grow at the base of infected needles from spring to fall, and spread easily during warm summer rains. The most obvious symptoms of tip blight are stunted and deformed new shoots that become tan or brown. The shoots die quickly, and the infection slowly works its way down the branch. Severely infected trees have large sections that look dried, blanched, or burnt. Tip blight weakens infected trees and they eventually die from a combination of stress, fungal disease, and pests.

City forester Ian Nadar has been following the Diplodia tip blight problem for 25 years.

"It is a naturally occurring thing," he says. "It has always been here, but there is some question of why we're seeing more of it."

One reason could be decreased rainfall in the Northeast, which stresses the trees and makes them more vulnerable to the infection, Nadar says.

Tip blight can attack any pine, but certain pines are more vulnerable than others. Reports of infection on Red pines, Scots, Ponderosa, and Mugo are common, but Austrian pines, which are not indigenous to the US, are the most vulnerable. Probably 85 to 90 percent of Austrian pines in Rochester are infected, Nadar says.

"They are quite noticeable because starting in the early 1900's, they became a favorite tree for landscapers and homeowners," says Nadar. "You see them in parks and residential spaces alike."

Young trees, hardier in their growth stages, seem to be able to withstand tip blight. But once the tree's growth starts to slow down, somewhere around 20 years, tip blight becomes an issue. Just as the tree is reaching maturity at 25 or 30 feet tall, its beauty in the landscape is lost.

No one knows how many of the city's pines are being destroyed by tip blight. The only record the city keeps is of trees planted through its streetscape urban foresting programs.

"We don't know exactly how many trees are infected in the parks and we don't know how many residents are having the problem," Nadar says. "I hate to guess, but it's probably about 15 percent of the pines. What we do know is Austrian pines, sooner or later, are going to get it, if they don't already have it."

Some prime examples of tip blight, Nadar says, are at the Culver Road and Highland Avenue entrances to Cobbs Hill Park. Both entrances have pine groves where tip blight can be seen up close. And it's easy to imagine what the areas will look like as the trees die.

"I've been studying this so long that I can spot it immediately," Nadar says. "I see it everywhere. I noticed the other day that even the trees outside the county offices on Reservoir Road in Highland Park have it."

There are fungicides available to treat tip blight, but Nadar says they are difficult to apply and spraying usually does nothing more than slow the progression of the infection.

"I would tell people who have an infected tree in their yard to save their money for the tree's removal costs and replanting," he says.

Cutting away the damaged branches may slow the tree's deterioration, Nadar says. Raking up needles and cones will help, too. But the city, Nadar says, will be approaching the tip-blight problem in its parks through tree removal and replanting.

"We are going to begin next year removing a few trees at a time and replanting a few at a time over the next five years," he says. "We won't be taking them out all at once because it will be too drastic a change. This way we can address the problem without it being quite so obvious. The problem is deciding what to plant in their place."

White pines are somewhat resistant to tip blight, but are highly sensitive to salt, which means they can't be planted near major roads. Fir trees may be a worthy substitute.

"The spruce is a possible substitute," Nadar says. "There's the Colorado Blue and there is just the regular green spruce, which is a very dark green. They are a little more salt tolerant. A lot depends on where the trees will go."

Rochester is an older city and many of its trees are reaching the end of their lifecycles, says Walter Nelson, horticulturist with Cornell University's Cooperative Extension.

"With Diplodia tip blight, you get these trees that are just so ugly that they are what I call aesthetically dead," says Nelson. "A home owner may feel that trimming a few branches will give it another 10 years. It's something they can live with. But aesthetically, these trees begin to take away from the beauty of public spaces. So we have to realize that trees have to come down."