An infected elm tree usually exhibits symptoms soon after infection.  Because of the speed with which the disease attacks, detecting symptoms as early as possible is essential for treatment.

The first sign of the disease is the sudden wilting of leaves in the upper reaches of the tree

Next, the leaves change colour from green to yellow to brown. They then shrivel and die.

Timing

If the infection occurs very late in the season, the leaves will appear to fall normally. However, the following spring the new leaves will be smaller than normal. The tree will often die before mid-summer.

In late summer, it may be difficult to distinguish between wilting and natural fall colours.   

Bark Signs