P&PDL Picture of the Week for
April 27, 2009

Diplodia Tip Blight of Pine

Tom Creswell, P&PDL Director, Plant Disease Diagnostician

Austrian pine is frequently attacked by Diplodia (Spaeropsis) tip blight, although the disease can also be found on Scots, mugo and red pine. Diplodia tip blight on Austrian pines in the landscape typically produces symptoms on trees after cone-bearing age.  Stressful site and environmental growing conditions such as drought predispose 2-needled pines to infection by Diplodia.

The first symptoms on Austrian pine arise in late April through early May. Needles and shoots are stunted and killed very quickly and shoot tips are often quite resinous.
Infections year after year can lead to the death of older needles as well as branch dieback and ultimately tree death.  Branch cankers are often coated with exuded resin, which dries and leaves white patches and droplets on the bark.

Avoid using Austrian Pine in drought prone situations and make sure existing trees get adequate water during dry summer periods. Prune out and destroy dead and dying branches promptly. The best prevention for this disease is to keep the trees growing as vigorously as possible. Invigorate the root system, as recommended in the publication (HO-140) available for download at http://www.hort.purdue.edu/ext/HO-140.pdf

The lack of effective control measures on large Austrian pines infected with Diplodia and other fungal needle blights have caused many to forgo using Austrian pine in the landscape in favor of other trees.

For more information on ID and control of Diplodia tip blight go to:
http://www.ces.purdue.edu/extmedia/BP/BP_24_W.pdf

 

 

Figures 3, 4 courtesy of Christine Engelbrecht, Department of Plant Pathology, Iowa State University

Click image to enlarge

Dieback

Figure 1. Mature Austrian pine trees
with dead lower branches
due to Sphaeropsis tip blight.

Dieback

Figure 2. An elongating shoot which
was killed by Sphaeropsis tip blight
(Note stunted dead needles).

Tip blight

Figure 3. Diplodia tip blight on an Austrian pine branch.

On cone

Figure 4. Black reproductive structures of the Diplodia fungus on a pinecone.

 

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service