The fall foliage season has started, at least for some trees.

Some species are turning yellow and shedding their foliage earlier than normal because of the dry summer. But forestry experts do not expect conditions to affect the prime leaf-peeping season.

“We have noticed it especially with paper and yellow birch,” said Bill Ostrofsky, a tree pathologist with the Maine Forest Service.

Touches of red and gold always appear on some trees in the Maine landscape in late August. But the dry conditions have led to more color this year. Until this week, no significant rain had fallen over much of the state since June.

The lack of water caused leaves to droop, then drop, on bushes and trees where the soil was especially dry.

An early warm spring — followed by a frost — affected trees at the time but won’t have an impact on fall foliage. Trees leafed out two or more weeks early, and the subsequent frost killed the foliage on some early blooming trees, such as oaks, Ostrofsky said. In places, those trees put out a second canopy.

Day length, sunlight and temperatures are other important factors for the brilliant leaf coloration.

The fall foliage season is important to Maine’s $10 billion- to $15 billion-a-year tourism industry. A quarter of the 32 million tourists who visit Maine annually come during the foliage season.

Portland city arborist Jeff Tarling said the tree watering truck has been going out daily keeping trees moist. The city has been watering every newly planted tree and others that are under stress.

Tarling recommends that homeowners who are worried about their trees invest in a watering needle hose attachment, which allows the water to penetrate deep into a tree’s root system. He said keeping a hose dripping above the tree’s root system for a few hours will also help.

Tree specialists said it is too early to predict the upcoming foliage season, which usually peaks the first week of October in northern Maine and about the third week of October in southern Maine.

Fritz Appleby, manager at Bradbury Mountain State Park in Pownal, said the foliage at the mountain looks normal for late August. “I have seen some yellow in trees that have stress,” he said.

Gale Ross, spokeswoman for the Department of Conservation’s Maine Foliage Report, said the forests are healthy and she expects a good leaf-peeping season. Ross said weekly reports will begin Sept. 15, just as they have every year.

“Right now, I don’t think we are going to have an early foliage (season),” she said.

Staff Writer Beth Quimby can be contacted at 791-6363 or at: [email protected]