PPDL Picture of the Week for
September 10, 2012

Drought Stress: The First To Go

Tom Creswell, Plant & Pest Diagnostic Lab Director, Purdue University

The prolonged drought this summer has affected a broad range of trees and shrubs. Several trees have died during the heat and on closer examination we usually find an additional underlying problem. The following pictures provide examples of the types of contributing problems that can make a tree or shrub “the first to go” when placed under drought stress.

Click images to enlarge

Figure 1 (Sweetgum). This sweet-gum tree showed severe dieback very quickly.

Figure 2 (Sweetgum). The underlying problems: Bark splits early in the growth of the tree followed by a fungal infection causing canker and wood rot.

Figure 3 (Gingko). One Gingko in a row of 3 died in early summer.

Figure 4 (Gingko). The underlying problems: Damage at planting or during mowing operations at the base of the tree. Also note the weed/grass competition and lack of mulch.

Figure 5. Norway Maple.  The underlying problem is recent transplant. Although both were watered periodically only one of these two survived. Uniformity of watering and root ball to top growth ratio are important in determining how well a tree survives transplant. 

Figure 6. These dwarf lilac are severely wilted. Most will recover but blooming and growth next year may be affected by the stress. The underlying problems are tree root competition and reflected heat from the parking lot and sidewalk.

Figure 7 (Weeping Alaskan cedar). A group of 3 weeping Alaskan cedar were showing extreme stress and browning in July.

Figure 8 (Weeping Alaskan cedar). The underlying problem: Nice tree planted in the wrong location. This tree is adapted to fertile well-drained soils in the cool humid climate of the Pacific northwest. Planted here in clay soil in an open, exposed area with no irrigation they will have little chance to survive long term.

Figure 9. These arborvitae appear to be well established with plenty of room for root growth, however Arborvitae require even moisture to thrive and are often early casualties of drought when not irrigated.

Figure 10. This row of maple showing severe leaf scorch is a reminder that young trees need to be watered regularly during dry periods for several years after transplant until well established.




Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service