BP-34
Have you ever had a white pine that died for no apparent reason? If so, the tree may have suffered white pine decline. This disorder has been a problem for many landscapes in Indiana. Affected white pines show various symptoms of decline or dieback. Sometimes trees appear healthy for a decade or more before decline symptoms are noticed. Other pine species don't appear affected by the disorder.
Declining trees usually look a paler green, or even yellowish, compared to healthy trees. Needles often are shorter than normal; sometimes the tips of needles turn brown. Needles from the previous season often drop prematurely, giving the tree a tufted appearance.
With loss of needles, the tree has reduced ability to produce the energy it needs to survive. Reduced shoot growth (shortened internodes) is common on trees experiencing decline.
With severe or compounding stress factors, the tree may gradually decline and eventually die. Decline may be gradual or rapid, depending on the number and severity of stress factors.
Trees less severely affected but under additional stresses may gradually decline and eventually die. Decline may be gradual or rapid, depending on the number and severity of stress factors.
Do not mistake annual needle drop for white pine decline. It is normal for conifers to drop their oldest needles in the fall. This annual shedding occurs on all trees at about the same time, and always occurs in the fall. An abnormal needle drop would occur in the spring or summer, affecting only one or a few trees, rather than all or most of them.
Injury from de-icing salt also causes the death of white pine needles and branches. Symptoms from salt show up on the side of the tree closest to the salted road. Trees closest to the road are most severely injured.
Pine species differ in their adaptation to various locations. Eastern white pines grow best on deep, light, well-drained, and slightly acidic soils and are intolerant of both drought and water retentive soils ("wet feet"). Most of the soils in Indiana fall outside this optimum. This means these pines are subjected from the moment they are planted to low levels of site-related stress. White pine tends to be chlorotic (yellowed) on alkaline or compacted soils, or when planted where root growth is restricted.
Many other factors besides soil type can contribute to overall stress experienced by a tree, such as genetic differences in ability to withstand stress; weather conditions including excess rainfall, early fall or late spring freezes, and drought; injury from de-icing salt; planting pines in shade or too close together so self-shading occurs; mechanical injury from construction, lawn mowers, motorized string weeders, or animal feeding; raising or lowering of soil levels due to grading; and insects and disease.
Trees under stress from environmental factors are more susceptible to attack from insects and diseases. These agents are not the principal cause for decline but occur on the scene only after stress has occurred.
White pine root decline, caused by the fungus Leptographium procerum (Verticicladiella procera) attacks pines under stress from wounds or site factors. Dieback can result from chocolate-colored cankers that form at the base of affected trees. This disease cannot be diagnosed based on symptoms alone; laboratory tests are needed for confirmation. Contact the Purdue Plant and Pest Diagnostic Laboratory for information on sampling for this disease.
Remove and destroy dead white pines since dead trees are attractive to bark-inhabiting insects that may affect surrounding trees. Try to determine the cause of decline or death and correct the problem before planting another white pine in the same spot.
When planting white pines avoid low spots so that trees are not standing in water after heavy rains, or plant in an area that has good drainage. Don't plant on sites that have a high pH (greater than 7.0) or where the pines are exposed to splash from de-icing salt. Make sure the trees have plenty of space for root expansion, and plant where they are not in deep shade. Use proper planting methods (see Purdue University bulletin HO-100, Planting Landscape Trees and Shrubs) and provide adequate water, especially during the first few years. Use mulch around the tree base to conserve moisture and keep weeds down.
If your site is unsuitable for a white pine, consider another species. The tree you choose should be adapted to the sites and soil types in which they are planted. Colorado blue spruce (Picea pungens), white spruce, (P. glauca), and Norway spruce (P. abies) do well in Indiana. If a deciduous alternative would be acceptable, bald cypress (Taxodium distichum) has very few disease or insect problems and has a nice pyramidal shape. Larch (Larix decidua) also could be planted.
RR 5/94
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture Cooperating. H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to our programs and facilities.