Diplodia kills trees by killing the new foliage year after year or by initiating girdling stem cankers on stressed trees. Nursery seedlings are usually killed in the first year of infection. Peak spore production and infection usually coincide with host bud break and shoot and needle elongation. The fungus invades and kills succulent shoot tissue, and forms pycnidia on dead tissues. Spores from current-year infections may be disseminated in the same or following year.
Infection can also occur through wounds caused by various agents.
The fungus invades woody tissue under such conditions. Identification Shoot blight and branch and stem cankers are the most common symptoms of Diplodia . Shoot blight is common on trees of all ages, but cankers are more prevalent in saplings and pole-sized trees. Collar rot is frequently observed in nursery seedlings. All symptoms are generally characterized by conspicuous amounts of resin.