Diplodia Pine Shoot Blight

Diplodia is caused by the fungus Diplodia pinea and survives in new growth, branches, and if left untreated can infect the main truck itself. . This pathogen commonly affects mature trees that have been stressed as a result drought, pollution, soil compaction, water competition, and other planting site related issues. Repeated infections can stunt growth, deform, and eventually lead to total tree decline

Affected trees: red, Austrian, scots, mugo, white, and ponderosa pine; spruce and douglas fir can also be affected.

Noticeable Signs

Common signs of Diplodia tend to show:

  • as new needles emerge they tend to turn yellow, then brown, and eventually die back towards the branch.
  • black fruiting bodies can be seen on cones or at the base of the needles.
  • if left untreated the disease can infect the branches or the main stem; thus turning into a canker phase that create wounds and can ooze sap.

Treatment/Management  

It is very important to maintain a treatment plan for Diplodia, as there is no cure for this disease. We recommend an annual fungicidal spray program that consists of two sprays in late spring; the first being right when the new growth emerges and the second approximately 21 days after.