The internal wood of infected stems is discolored brown or tan, frequently on only one side of the stem. The necrotic area may extend just a few centimeters or the entire length of the stem. Twig infections may be confused with winter injury or other twig diseases. Younger plants die rapidly within 1 to 2 years of planting. The mortality rate is highest when infection develops at or near the crown.

Disease cycle
The stem blight fungus overwinters in infected stems. Most infections occur during the early part of the growing season - May or June; however inoculum is present almost year-round in the southern states. Wounds caused by pruning, mechanical injury, or other stem diseases are the primary sites of infection. Disease development decreases as wounds heal with time.