The fungus usually enters a tree by way of its roots and spreads from there through the sapwood into the upper branches. When this happens, one or more large limbs or even the entire crown may begin to die back. Infected limbs will sometimes produce sparse, sickly looking leaves which may later wilt suddenly and die usually in July. Sometimes leaves will have marginal browning or scorch symptoms. A diseased tree can die within one season, but usually lingers, dying slowly over several years.
Survival time depends on the size and vigor of the tree, as well as general weather conditions.
Healthy vigorous trees can limit the damage by producing new water conducting vessels free of the fungus. If streaking is found, branch samples 4-8 inches long with stain can be collected and submitted to the county extension office for laboratory confirmation. Once the disease becomes established, it's hard to control. For this reason, it's best to cut down and destroy seriously infected trees. In some cases, though, it may be worth trying to save one, if by pruning out the infected branches, the value of the tree as a landscape plant is not destroyed.