Diplodia Tip Blight

Now is the time to be taking measures to control Diplodia tip blight.

Diplodia tip blight is a common serious disease on Austrian, ponderosa, and mugo pine in Iowa, and also occurs less destructively on Scots pine. It is caused by the fungus Sphaeropsis sapinea. Symptoms range from tip blight, cankers on branches or trunk, death of cones, and blight of seedlings. Tip blight occurs when the fungus infects buds or shoots. Stunted, brown shoot tips with short needles result. Tissues are often resin-soaked. In the fall, small black fruiting structures of the fungus can be seen on needle bases. The annual death of buds and shoots causes trees to decline gradually from the bottom branches upward. The fungus may also penetrate young stems and cause cankers which eventually girdle and kill branches. Fungal spores are spread during wet weather from early spring until fall. Infected cones serve as a source of spores.

Control:

  1. Avoid planting Austrian pine.
  2. Promote good air circulation by adequate spacing and weed control.
  3. Trees may be pruned to improve their appearance, but this does not control the disease.
  4. Spray chlorothalonil, benomyl, thiophanate-methyl, Bordeaux mixture, or other appropriately labeled copper fungicides at bud swell, then repeat twice at intervals of 10-14 days.



This article originally appeared in the April 29, 1992 issue, pp. , 1992 issue, pp. 67-68.

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Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on April 29, 1992. The information contained within may not be the most current and accurate depending on when it is accessed.