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LANDSCAPING | GARDENING | PROBLEM SOLVING

Austrian pines

The Austrian Pine (Pinus nigra) is an extremely tolerant pine of adverse soil conditions and air pollution. This stately tree can be seen in parks, along streets, in residential landscapes, and as farm windbreaks throughout much of the United States. Landscapers use the dark beauty of these trees for backdrops, but it is also an excellent specimen tree because of its leaf pattern.

The Austrian Pine is a native of Austria, northern Italy and Yugoslavia. It was introduced to the United States in 1759. Its forebears were likely worshipped by the Romans over 2000 years ago. Over 217 million were planted during the nation's great dust bowl shelterbelt project. It has thrived for over 200 years in some of the worst soil and climate conditions America has to offer.

  • Can grow up to 60' high with a 20' - 40' spread.

  • Plant in full soil

  • Hardy in Zones 4 - 7

Young trees are pyramidal in shape, but become oval with age and, on some sites, flat topped. Noted for its dark, rich green foliage, Austrian pine provides a pleasant contrast with other plants. Austrian pine needles are stiff, usually straight, 2" - 4" long and are in groups of 2. Needles persist 2 to 3 years. Fruit is a 2 1/2" - 3" long cone. The cone scales do not have prickles. The attractive bark has dark furrows with gray or gray-brown mottled ridges. Winter buds have a distinct silver color.

Planting Tips

Austrian pines are spaced 8' - 12' within a row and 12' - 18' between rows. Large, fast growing deciduous trees should be spaced far enough (20' - 24') between rows to prevent shading pines.

Common Pests

Common insect pests include spider mites and pine needle scale.

Some adelgids will appear as white cottony growths on the bark. All types produce honeydew which may support sooty mold. European Pine shoot moth causes young shoots to fall over. Infested shoots may exude resin. The insects can be found in the shoots during May. Pesticides are only effective when caterpillars are moving from overwintering sites to new shoots. This occurs in mid to late April or when needle growth is about half developed.

Bark beetles bore into trunks making small holes scattered up and down the trunk. Stressed trees are more susceptible to attack. The holes look like shotholes.

Pine needle scale is a white, elongated scale found on the needles. Pine tortoise scale is brown and found on twigs. Depending on the scale, horticultural oil may control overwintering stages.

Common Diseases

Common diseases include Dothistroma needle blight and Sphaeropsis (Diplodia) tip blight.

Diplodia Tip Blight

Diplodia tip blight is a common fungal disease of Austrian pine, although Scots, mugo, and red pine may also be affected. The Diplodia fungus infects the growing buds and shoots, causing the newest needles of a tree to be stunted and brown. These needles appear as short brown tufts at the ends of the branches. Small black reproductive structures of the fungus can be seen at the base of these stunted needles.

The Diplodia fungus (more properly called Sphaeropsis) also produces spores in fruiting structures that develop on the second-year female cones. These spores are carried by rain throughout the tree.

Because it produces most of its spores on the mature cones, Diplodia tip blight often does not show up until trees are 15 to 20 years old and producing the large cones. Once it spreads throughout the tree, though, it can cause the eventual death of all the infected branches. The ornamental value is significantly diminished.

The same fungus also causes a canker disease on Austrian and Scots pines as well as white pine and concolor fir. A Diplodia tip blight infection will often progress and start producing cankers on an infected tree. Individual cankers (areas of dead bark) girdle scattered branches, causing them to die. Often resin oozes from the cankered areas.

Several strategies can be used to minimize damage caused by Diplodia diseases. Trees should be adequately spaced to promote good air circulation. Vigor should be maintained with mulching and watering during dry periods. Branches infected with Diplodia canker should be pruned out during dry weather. Branches with Diplodia tip blight may be pruned to improve tree appearance, but this will not improve the health of the tree. Fungicide sprays may be used for Diplodia tip blight.

Dothistroma Needle Blight

Dothistroma needle blight is a common fungal disease that causes browning of needles of Austrian, ponderosa, and mugo pines. Affected needles have reddish brown spots or bands. The needle tips beyond the bands dry out and turn brown a couple weeks after the bands appear, while the bases remain green. Diseased needles may drop prematurely, several months after they are infected. Typically, the most severely affected branches are towards the bottom of the tree. An entire tree may progressively lose its needles, decline, and die over the course of a few years.

Dothistroma needle blight is caused by the fungus Dothistroma pini (also called Mycosphaerella pini). The fungus is active throughout the growing season and can infect any age of needle during wet weather. However, symptoms typically first appear in early fall, although they may not be noticed immediately.

The best way to avoid Dothistroma needle blight in Iowa is to avoid planting Austrian pine. Austrian pines are very susceptible to both this disease and another disease, Diplodia tip blight, such that they are not a good choice for this area. Where Austrian pines are already planted, Dothistroma needle blight can be prevented by keeping trees in good vigor through watering and mulching, and promoting air circulation through appropriate pruning, adequate spacing, and weeding.

Fungicide sprays may be used if symptoms are found. Sprays should be applied twice in the spring after new growth appears, once in mid-May and again 4 to 6 weeks later. Effective sprays include Bordeaux mixture, copper fungicides, and EBDCs. Spraying may be discontinued when symptoms are no longer found.