If they are deciduous they may turn yellow before dropping, sometimes frost may cause them to drop while still green. Ash trees are becoming endangered due to the emerald ash bores.
In the Norse eddas, Yggdrasil, the world tree, was an Ash. The spear of Odin was made from the branch of this tree, which is also known by the Celtic name Nion, pronouncedknee-un. This is one of three trees sacred to the Druids (Ash, Oak and Thorn), and this is a good month to do magic that focuses on the inner self. Associated with ocean rituals, magical potency, prophetic dreams and spiritual journeys, the Ash can be used for making magical (and mundane) tools -- these are said to be more productive than tools made from other wood. If you place Ash berries in a cradle, it protects the child from being taken away as a changeling by mischievous Fae.
Elsewhere in Europe, snakes were said to be repelled by ash leaves or a circle drawn by an ash branch. Irish folklore claims that shadows from an ash tree would damage crops. In Cheshire, it was said that ash could be used to cure warts or rickets. In Sussex the ash and elm tree were known as the Widow Maker because the large boughs would often drop without warning.
Ash can be worked with for any number of spells, rituals, and other workings. It's a good time for magical workings related to the inner self.