Beech Bark Disease
American beech is an important climax species and is the only forest associate of every major deciduous forest type in the eastern United States. Beech is threatened throughout its range by beech bark disease (BBD). This disease complex is caused by the introduced beech scale insect (Cryptococcus fagisuga) working in conjunction with native fungi (Neonectria ditissima and N. faginata). The result of BBD is mortality of large trees and eventual formation of dense stands of deformed sprouts of root sucker-origin that perpetuate a disease generated condition termed the “aftermath forest.” Where the disease is established, BBD is resulting in significant impacts on wildlife and reductions in forest productivity.
- In North America BBD has occurred for over 100 years and its range continues to expand.
- In the Southern Region BBD occurs in high-elevation forests in North Carolina, Tennessee and Virginia.
- Silviculture alone is not sufficient to reduce impacts when beech comprises greater than 25% of the basal area of a stand.
- Natural resistance to BBD exists in 1-2% of the beech population and no sophisticated molecular techniques are needed to identify this resistance if the scale is present.
- Mapping disease spread and identifying high risk areas
- Conducted by R8-FHP in partnership with R9, research & state cooperators
- GIS will continue to play a critical role in mapping spread and predicting risk to uninfected stands
- FHP staff is currently funded and organized to conduct this work effectively
- "What needs
- Effective IPM strategies need to be developed that account for the large variations across the range of beech
- Increased partnerships with research are needed
- Little funding will be available
- Technology needs to be developed
- The greatest impacts of BBD are likely to be on wildlife populations but the potential for impacts of the disease are relatively unknown
- Increased partnerships with NGO and GO wildlife groups are needed
- Little funding will be available
- Technology exists
- Current FHP staff and structure unlikely to meet the need should impacts to wildlife needs become significant
- Naturally occurring host resistance is not being exploited
- Increased partnerships with research, state and NGO land managers are needed with Forest Service research being the lead
- Funding may be available
- Technology needs to be developed for rapid detection of resistance over wide areas and silvicultural strategies are needed to enhance te survival and propagation of resistant trees once detected
- FHP staff and structure currently organized to be an effective cooperator with research
Beech bark disease represents a novel but under-utilized model for forestry and forest health research in that:
- It follows such a consistent, predictable and orderly succession of species/events
- It has been present for a long time period, but still has un-colonized portions of host range into which to expand
- It results in a consistent and identifiable modified post-disease stand structure
Beech bark disease has not been causing the same effects in the South as those historically seen in the Northeast. The apparent center for diversity for beech appears to be in the southern United States where three distinct clines of American beech exist. Potential for greater disease resistance coupled with different climate and newly emerging introduced insects and diseases indicates that the future status of large, co-dominant beech in forest stands in the South remains unclear. As the beech scale continues to spread south and west there are valid concerns that information regarding disease management is still needed and that much additional work remains to be done.
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Updated: February 2010