MINNEAPOLIS (AP) — Many maple trees across the Minneapolis area are sick and have been turning color and dropping leaves before the official start of autumn.

Alan Branhagen is the director of operations at the Minnesota Landscape Arboretum. He says the arboretum has been flooded with questions about the early leaf drop.

Branhagen says rot may be causing the maples to decline. Irrigation systems and thick mulch can result in conditions that are too soggy for the trees.

Certified arborist Travis McDonald says many of the trees are suffering from root girdling, which is when roots grow around each other and prevent nutrients from going to the tree.

Branhagen says many distressed maples lack stability and therefore should be removed because they're more prone to windfall.