BELFAST — It’ll be a good season for foliage, according to experts, even though leaf fungal diseases are turning towering maple trees in certain parts of the state brown instead of bright orange and red.

“I think we’ve actually had a pretty good growing season, for the most part,” Morten Moesswilde, midcoast district forester for the Maine Forest Service said Wednesday. “The colors should be good to excellent.”

He said that this summer he has seen some issues with oaks, maples and birches that he attributes to more rain than usual. The brown spots on some maple leaves are likely a leaf anthracnose, a leaf surface fungus. In some communities, including Belfast and Camden, many of the maple trees have obviously been affected by the fungus and already have started to drop their brown, diseased leaves.

“Will it affect color? It might,” Moesswilde said. “But the leaves should still turn color. They might be a little less bright and will fall a little earlier, but there’s still photosynthesis going on.”

According to the weekly fall foliage report put out by the Maine Department of Agriculture, Conservation and Forestry, last week marked the official start of the season. As of Wednesday, the northernmost tier of the state has moderate color changes with leaf drop of at least 10 percent, and the more southerly portions of the state are experiencing “subtle color changes” and low leaf drop.

According to the report, the state is offering free guided fall foliage tours at several state parks and public reserved lands beginning on Friday, Sept. 27. The first tours of the season will take place at Mount Blue State Park in Weld, Little Moose Public Reserved Lands in Greenville and Aroostook State Park in Presque Isle. For more information on the tours, visit online www.parksandlands.com.

Bill Ostrofsky, forest pathologist for the Maine Forest Service, was optimistic about the annual color show.

“The native maples, particularly the red and sugar maples, which are considered to provide the great backdrop of seasonal color, have vigorous, healthy foliage with no notable problems,” he said last week in a press release. “Given our moderate summer weather, and allowing for this trend into the fall, I expect an outstanding vibrant show, overall.”

Foliage conditions should peak in late October, according to the foliage report.

A few years ago, a wet spring and fall caused widespread fungal infections in Maine’s maple trees. One midcoast forestry expert described this year’s blight as moderate, depending on the area.

Deb Hopkins, the tree warden for Yarmouth, said she hasn’t gotten any calls about the maple fungus in her area.

“Maple trees are pretty sensitive,” she said. “They don’t like wet feet, and considering the amount of rain that we had, I don’t think they’re happy about it. Also, the moisture means it’s a great time for any kind of bacterial thing to grow.”

Ostrofsky told the BDN in 2009 that tar leaf spot and anthracnose are two fungal diseases that cause spots on the leaves of maple trees. The leaves become infected in early May and June when the buds are coming out, and grow on the leaf throughout the summer, causing the leaves to brown up and drop off early. The fungi have a more severe effect on the Norway maple, a non-native species with reddish-purple foliage that has been planted for years as an ornamental tree. Although severely infected trees look terrible, the infection does not generally cause long-term harm to the trees, according to state forestry experts.

Ostrofsky said then that sanitation may be the most cost-effective means of controlling the fungus — raking the leaves from around the tree and disposing them by burning, not composting.

In May, the forest and shade tree health report from the Maine Forest Service stated that fungal diseases in hardwood trees are likely to be much less severe this season than in recent years. The report did caution against emerald ash borer, a small invasive beetle from Asia that has destroyed millions of ash trees since being discovered in the United States in 2002. It has not yet been found in Maine, although earlier this spring it was found just 30 miles from the state’s border in Concord, N.H.

Bruce Watt, a plant disease diagnostician with the University of Maine Cooperative Extension in Orono, said this week that he has had fewer diseased leaf samples sent to him than in past years, which makes him think the fungus is less widespread.

“I don’t think it’s that widespread that you’d notice it and say, ‘Gee, what happened to the leaves?’” he said.