Diplodia Tip Blight and Canker

Plants Affected:

Images of This Plant Disease:

Image of black dots caused by the Sphaeropsis on a pine cone

Black dots (spore-producing structures of the Sphaeropsi fungus) are visible on cones from trees affected by Diplodia tip blight

Image of stunted, brown needles on a pine with a case of Sphaeropsis

Stunted, brown needles on the tips of branches are a hallmark of Diplodia tip blight

Image of Sphaeropsis on a fir tree

Sphaeropsis on a Fir tree

Diplodia tip blight is caused by the fungus Sphaeropsis sapinea. The most conspicuous symptom of Diplodia blight is brown, stunted new shoots with short, brown needles. Needles on infected new shoots often become discolored while still encased in fascicle sheaths. Entire new shoots may be killed rapidly by the fungus. New shoots throughout the crown may be infected, although damage is generally first evident in the lower crown. In addition to tip blight, the fungus may cause resinous cankers on main stems and branches (seen often in fir trees), misshapen tops, death of cones, blight of seedlings, basal cankers, and sometimes death of entire trees.

Infection of new shoots can be reduced significantly by fungicide (such as chlorothalonil, benomyl, or Bordeaux mixture) applied at bud swell, one week later, then 2-3 weeks later. Trees may be pruned to improve their appearance, but this practice does not decrease the likelihood of new infections because a great number of fungal spores are released from diseased cones. (Pruning or shearing should be avoided in the spring.) Young pines in plantings may become infected if they are located near old, cone-bearing trees. Either the old infected pines should be removed, or pine seedling beds or plantings should not be located near them.

See this article for more information about canker diseases.