Many dead brown leaves hanging on the twigs often indicate foliage died suddenly. Foliage that dies over a longer period of time (months) often drops from the tree as the tree forms abscission layers at the base of the petioles. Sudden death could be caused by factors above ground or below ground.

Below ground factors to look for include
· lack of water
· severe root damage
· soil flooding
· over-fertilization
· root disease

Above ground factors could include
· twig girdlers
· cold damage
· salt injury from the air or soil
· stripped bark from squirrels
· branch breakage
· herbicide injury
· heat from truck/bus exhaust pipe
· sustained hurricane force winds
· mechanical injury from insect ovipositing

Except for fire blight and some other diseases, insects and diseases usually do not cause this type of symptom.

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