(Photo provided by Bob Celaya - Arizona State Forestry)

Aspen leaf rust near Flagstaff.

Some aspen trees in northern Arizona and willows in the east are infected with a fungus called aspen and willow tree rust that makes leaves brown and splotchy, and causes them to drop off earlier than usual.

Arizona Forest Health Specialist Bob Celaya said the fungus grew and spread because of wet weather conditions and could spread more this season.

“If it stays above normal and the leaves don’t turn than it’s possible some additional trees will start to show signs of the rust," Celaya said. "And again it’s largely dependent on what the weather does in the next couple of three weeks."

But some trees are infected while others aren’t, and that may be due to genetic resistance.

He recommends leaf-lovers call ahead before making the trip to find the perfect fall foliage.

“I would suggest they check with a local forest before they go so that when they get up there they do get a chance to see fall color and not be disappointed if it happens to be infected with this rust,” Celaya said. 

Celaya said the disease will only affect the foliage and should not harm the rest of the tree.