Austrian (Pinus nigra), ponderosa and mugo pines are most susceptible to Dothistroma needle blight. The disease, which is also called red band needle blight, can cause permanent loss of needles and, if left untreated for many years, may lead to the death of the tree.

This fungus diseases causes browning of needles along the length of the stem. Unlike Diplodia tip blight which attacks only new growth, this disease affects both the previous and current year's needles. The needles turn brown from the tip and have a reddish brown band part way down the needle that is distinctive of this disease. The ends of the needles may break off leaving a blunt stub. Eventually, the entire needle turns brown and dies.

Cause: This disease is caused by the fungus, Dothistroma (Scirrhia) pini. It usually begins to show up when trees get large and old especially if they are crowded together too closely or are otherwise under stress.

Plant species of pines that are resistant to this disease such as white pine (Pinus strobus).

For new plantings, use native pines such as Eastern white pine and red or Norway pine. There are also a few resistant varieties of Austrian Pine that are available.

For mature trees, two applications of a fixed copper or Bordeaux mixture type of fungicide are recommended to control Dothistroma. If these materials are used, the first application needs to be in mid-May to protect the previous year's needles. The second application should be made in mid-June to provide protection for the new needles.

Maintaining a spray program for several years may help to bring back even severely infected trees. If the disease has progressed too far, however, it may not bounce back even with the recommended applications.

Severity of infection may be minimized by keeping trees in a moderately vigorous state of growth. Proper fertilizing and watering may help minimize stresses. Allowing enough room for root growth and expansion over the life of the tree is also important.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.


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