1. TREE RISK MANAGEMENT Larry G. Campbell WVU-Harrison County Extension Agent WVU Assistant Professor Photo by L.G. Campbell

2. “When damage, injury or death occurs because of a defective tree, the law usually holds the tree’s owner responsible. Under the law it is your duty to exercise care, good judgment, caution, and foresight by inspecting your trees regularly and recognizing situa- tions that may cause them to break or fall.” Tree City USA Bulletin #15, The National Arbor Day Foundation

3. Hazardous Tree? Bradford Pear Street Planting

4. Hazardous Tree? Photo by L.G. Campbell

5. Hazardous Tree? Photo by L.G. Campbell

6. What is a Hazard Tree? Has a structural defect that may cause the tree or a portion of the tree to fall on someone or something else of value. Key words: -Structural defect -Target: value & intensity of site use.

7. Hazardous? What is the Target? Defective tree in remote woodland setting not frequented by people. Photo by L.G. Campbell

8. Target? Photo by R. Chong & L.G. Campbell Defective Cherry Tree

9. Photo by R. Chong & L.G. Campbell

10. What Do We Look For? Site Structure

11. Site Edge Trees -Trees on edge of natural areas or bordering roads, drives, and parking areas generally are exposed to stress during storms. -May have experienced root damage during land clearing. Lone Trees -Prone to lightning strikes. -If the only remnant of a previously existing wood lot, lone trees may have undersized root systems or low live crown ratios.

12. Site High Traffic Areas -Trees in areas of high vehicular or pedestrian traffic are prone to soil compaction, wounding and subsequent decay. New Development -Native trees that existed on site prior to development have a high incidence of defect and disorder after the site has been developed. -Even if trunk looks healthy, roots may be damaged.

13. Site Wet Sites -Trees on these sites generally have a shallow root system which predisposes it to wind throw from ground or root failure. -Grade changes can result in poor drainage resulting in root mortality. Shallow Soils -Trees in shallow, rocky soils are more prone to wind throw.

14. Susceptibility of Selected Trees to Lightning Damage HighLow Ash Beech Black Locust Birch Elm Horsechestnut Hemlock Maple Oak Pine Poplar Spruce Sycamore Tulip Poplar

15. Structure Top and Crown Trunk or Stem Roots

16. Top & Crown Difference in Species: -Some species are more brittle than others. -Some cities discourage the planting of willows, box elders, silver maple, and Bradford Pear. -Some species like elm have dense branch ends. Bradford Pear Street Planting

17. Top & Crown Tree History: -Trees with a previous history of branch failures are generally more prone to stem and branch failures following the breakage. -Broken branches with stubs unpruned or sprout-like regrowth after storm damage. -Previous topping (internodal pruning) resulting in weakly attached regrowth. Stubs left by this kind of pruning generally decay (see next slides). -Recent unexplained loss of large limbs can be a sign of internal problems.

18. Typical Internodal Pruning of Trees Adjacent to Utility Lines Weak regrowth Photo by L.G. Campbell

19. Internodal Pruning Photo by L. G. Campbell

20. Top & Crown Dead Branches: -Dead limbs are an accident waiting to happen. -”Widow-makers”. -Check any branch over 1” in diameter for dead or missing buds, blunt branch tips, fungal structures, and loose bark.

21. Top & Crown Broken Branches: -Broken limbs (hangers) are detected by the brown, wilted leaves which tend to be retained on the limbs or by the unusual angle of the branch. -Branches break for a variety of reasons such as normal self-pruning, the stress of ice and snow, and by being weakened by storm damage, poor pruning, or rubbing against other limbs.

22. Top & Crown Branch Structure: -Branches that cross or rub lead to weak spots. -Abrupt bends indicate old wounds that are prone to decay & drying of wood tissue. -Narrow crotch angles with included bark. -Long heavy branches exceeding 50% of stem/trunk diameter at point of attachment. -Long arching bends in limbs have a weakness in the arch.

23. Long arching bend may be a point of failure. Photo by L.G. Campbell

24. Top & Crown Unbalanced Crown: -Trees with live crown ratios less than 50% pose at least a moderate risk of stem & root failure due to wind stress. -Unbalanced asymmetrical crowns have weight distributed poorly over stems.

25. Top &Crown Tree Health: -Is the tree vigorous? -Look at leaf cover, leaf size, color, and condition. -Compare to other similar trees. -A healthy tree can still be structurally unsound!

26. Trunk Co-dominant Stems: -Forked trunks are potential points of weakness, especially if one side grows outward. -Narrow angled forks with included bark are susceptible to breakage and infection. Co-dominant stem Photo by L.G. Campbell

27. Co-dominate stem on Cherry with internal decay. Photo by L.G. Campbell

28. Trunk Wounds & Cracks: -Trunk wounds are openings for decay. -Lightning scars and cracks extending to the ground are a cause for concern. -Cracks can indicate that a tree is in the process of failing from decay. -Sheer cracks can appear at co- dominate stem sites along plane of the stem. -Inrolled cracks are a tree’s response to wounds. Decay is always associated with these. -Horizontal cracks indicate high risk. -Vertical cracks on opposite sides of tree are a critical risk. Photo by L.G. Campbell

29. Trunk Decay: -Decay is the most common predisposing factor to stem & branch failure. -California surveys found that decay was present in approximately 80% of reported stem and branch failures. -In any column (trunk), the outer ring is the load bearing area; thus, decay doesn’t necessarily mean an immediate problem.

30. Trunk Signs of Decay: -Loose bark -Cankers -Abnormal swellings especially at base of tree can indicate hollowness. “Adaptive growth” is trees way of dealing with stress caused by hollowness. -Fungus fruiting structures (conks). -Stump sprouts. -Branch stubs. -Burl/knots (abnormal proliferation of wood & bark tissue). -Cavities.

31. Trunk Siebert Decay Detecting Drill used to determine % decay at swelling sites. Photo by L.G. Campbell

32. Trunk Leaning Trees: -Leaning trees are more of a hazard than vertical trees. -If tree has always grown off center, then it is not necessarily a risk. -A sudden lean can indicate root or soil failure. -Look for mound of soil on opposite side of lean and probe for air space.

33. Roots 75% of tree failures are root related. Key tree roots: -Flare or buttress roots which are approximately 3x the diameter of tree long. -Laterals -Sinker roots

34. Roots Soil Failures: -Occurs when soil does not have the strength to keep the root system firmly anchored. -Excessive rainfall leading to saturated soils and winds in excess of 50 mph. -Tulip poplar, poplar, conifers, black locust, and willow are prone to soil failure.

35. Roots Root Failure: -Occur when force on the tree from wind or gravity exceeds the strength of root wood. -In healthy trees this happens when wind exceeds 60 mph. -However, more common where roots have been severely compromised.

36. Root Severance: -Occurs when large support roots are cut during construction activity. -USFS recommends maintaining a distance from tree of 1’ per 11/2” of dbh. -Look for linear depressions in soil near tree to check for old trenches.

37. Roots Root Collar Disorders: -Soil and mulch that cover root collar tissues can lead to decay, disease and death of tissues. -Mature trees with a buried root collar should be considered at risk of failure.

38. Roots The root collar of this tree was covered by backfill from road construction. Notice the “flare roots” which appear as large swellings at the base of tree. Photo by L.G. Campbell

39. Roots Root Disease: -One of the leading causes in root failure. -Occurs most often in old trees. -Common in areas where there is a history of site disturbance and high use. -Trees with root disease generally break at lower stem or root collar.

40. Symptoms of Root Disease: generally evident near the root flare and soil adjacent to flare. -Lack of root flare. -Fungal fruiting structures. -Dead/loose bark. -Cracks or seams in bark. -Bleeding or ooze. -Cracks in soil radiating from the root flares. -Missing roots.

41. Roots Roots usually decay from the tips of the roots and progress toward the root collar. The top of root flares can appear healthy while the lower portion can be decayed. If more than 1/3 of flare roots are significantly decayed, then tree is at critical risk of failure.

42. Roots A check of the flare roots of this tree revealed significant decay resulting in a break at the bottom of the trunk. Crown of fallen tree Photo by L..G. Campbell

43. Hazard Tree?Healthy Tree?

44. This PowerPoint program was assembled by Larry G. Campbell, WVU-Harrison County Extension Agent and WVU Assistant Professor. In addition to this author’s material, some photographs, illustrations, and supporting materials were assembled from various sources publicly available on the Internet. The information was gathered over a period of time and from sources too numerous to list individually. The author would like to acknowledge the assistance of these web sites and publicly express his sincere appreciation for the assistance. This program was assembled solely for educational purposes and primarily for use with statewide WV Master Gardener training programs. The author did not nor will ever receive financial compensation for the preparation of this program. The program may be copied and distributed in parts or in its entirety for educational purposes. If any part of this presentation is distributed, the efforts of Mr. Campbell in assembling the materials must be recognized. The distributor may not receive any financial compensation for this service. Larry G. Campbell WVU-Harrison County Extension Agent and WVU Assistant Professor lgcampbell@mail.wvu.edu WVU-Harrison County Extension Office 301 West Main Street Room 507 Courthouse Clarksburg, WV 26301 (304) 624-8650