skip to main content
What Are The Most Damaging Tree Diseases In The Foothills and High Country?

What Are The Most Damaging Tree Diseases In The Foothills and High Country?

Wednesday, October 02, 2024

The foothills and high country of North Carolina are home to lush forests and rich biodiversity, but these areas face increasing threats from tree diseases. Trees are essential for the environment—they help stabilize the soil, provide habitats for wildlife, and regulate water systems—and also for the local economy, supporting industries such as timber and tourism.

Visitors flock to the region for hiking, camping, birdwatching, and other nature-based activities, drawn by the opportunity to explore the diverse ecosystems and wildlife habitats that the forests provide. 

The tranquil beauty of the forests, combined with the abundance of outdoor recreational opportunities, makes the region a popular destination for nature enthusiasts and adventure seekers alike.

Our region, known for its extensive forests of oaks, pines, hemlocks, and dogwoods, is under constant threat from pathogens that weaken or kill trees, leading to massive environmental and economic consequences. 

Understanding the most damaging tree diseases in the foothills and high country is key to effective forest management and ensuring the sustainability of these valuable ecosystems.

In this comprehensive blog, we will explore the most destructive tree diseases in the region, their symptoms, how they spread, and strategies for prevention and management.

Why Tree Diseases Matter to People in the Foothills and High Country

Tree diseases are a major concern because they can have devastating ripple effects on the ecosystem and economy. In addition to reducing forest cover, which is essential for carbon storage and regulating water cycles, diseased trees can lead to increased soil erosion, loss of wildlife habitat, and higher risks of wildfires. 

Economically, diseased trees mean less timber production, increased management costs, and a decline in forest-based tourism.

Healthy forests provide a variety of ecosystem services:

  • Carbon sequestration: Trees absorb carbon dioxide and store carbon, helping to mitigate climate change.
  • Water regulation: Forests filter water and maintain watersheds, reducing the risks of floods and improving water quality.
  • Wildlife habitat: Trees provide shelter, food, and breeding grounds for a wide range of animal species.
  • Timber production: Many rural economies depend on the sustainable harvest of timber for wood products.
  • Tourism: Forests draw visitors for hiking, camping, birdwatching, and other outdoor activities.

When tree diseases strike, these benefits are diminished or lost entirely, which makes it critical to manage and prevent the spread of harmful pathogens.

Common Tree Diseases in the Foothills and High Country

The most dangerous tree diseases affecting the foothills and high country can be classified based on the pathogens involved, including fungi, bacteria, and viruses. Below, we discuss some of the most destructive tree diseases, focusing on their symptoms, modes of transmission, and management practices.

1. Oak Wilt

Causal Agent: Bretziella fagacearum (fungus)
Susceptible Trees: Primarily red oaks but can also affect white oaks

Oak wilt is one of the most destructive diseases affecting oak trees in North America. The fungus responsible for the disease infects the vascular system of the tree, preventing water and nutrients from circulating. Red oaks are particularly susceptible and can die within a single growing season if infected.

Symptoms of Oak Wilt: 

  • Leaves wilt, often starting at the edges and moving inward, turning brown and eventually dropping off.
  • Foliage loss usually begins at the top of the tree and moves downward.
  • Infected trees may develop dark streaks in the wood, visible when the bark is peeled away.
  • Red oaks can die quickly, while white oaks may show a slower decline.

How Oak Wilt Spreads:

Oak wilt spreads in two main ways: through root grafts between neighboring trees and via sap-feeding beetles that carry fungal spores. Human activity, such as pruning trees during the growing season, can also spread the disease by exposing fresh wounds to beetles carrying the fungus.

Oak Wilt Management:

  • Avoid pruning oak trees in the spring and summer when sap-feeding beetles are active.
  • Remove and destroy infected trees to prevent the disease from spreading.
  • Trenching between infected and healthy trees can help prevent the disease from traveling through root grafts.
  • Fungicide treatments may help in high-value trees but are not a guarantee of survival.

2. Hemlock Woolly Adelgid (HWA)

Causal Agent: Adelges tsugae (an invasive insect)
Susceptible Trees: Eastern hemlock, Carolina hemlock

The hemlock woolly adelgid (HWA) is a small, aphid-like insect that feeds on the sap of hemlock trees. It causes the tree to weaken, lose its needles, and eventually die. Without intervention, HWA can kill large stands of hemlocks, devastating both the trees and the ecosystems they support.

Symptoms of Hemlock Woolly Adelgid:

  • The presence of white, woolly egg sacs on the underside of hemlock branches.
  • Premature needle drop and thinning of the tree canopy.
  • A general decline in tree vigor, with branches dying back over time.
  • Complete tree death can occur in as little as four to 10 years, depending on environmental conditions and infestation severity.

How Hemlock Woolly Adelgid Spreads:

HWA spreads primarily by wind and through birds or human activity. Infested nursery stock or other infected plant material can introduce the pest to new areas, and from there, it can quickly spread to nearby hemlocks.

Hemlock Woolly Adelgid Management:

  • Systemic insecticides, such as imidacloprid, can protect trees from HWA infestations for several years.
  • Introducing predatory beetles that feed on HWA has shown promise as a biological control method.
  • Regular monitoring and early treatment are essential to preventing widespread tree loss.

3. Dutch Elm Disease (DED)

Causal Agent: Ophiostoma species of fungi
Susceptible Trees: American elm and other elm species

Dutch elm disease (DED) is caused by a fungal pathogen spread by bark beetles. The disease blocks the flow of water through the tree, leading to wilting, defoliation, and death. It has been responsible for the massive decline of American elm trees across North America, especially in urban and rural settings.

Symptoms of Dutch Elm Disease:

  • Leaves wilt and turn yellow, beginning at the top of the tree.
  • Dark streaks in the sapwood beneath the bark.
  • Progressive dieback of branches and death within one or two seasons after infection.
  • Wilting often starts in isolated branches but spreads throughout the tree.

How Dutch Elm Disease Spreads:

Dutch elm disease is primarily spread by elm bark beetles, which carry fungal spores from infected trees to healthy ones. The fungus can also spread through root grafts between closely spaced trees.

Hemlock Dutch Elm Disease Management:

  • Fungicide injections can be used as a preventive measure in healthy elms.
  • Severing root grafts between infected and healthy trees can help stop the disease's spread.
  • Infested trees should be promptly removed and destroyed to eliminate the beetle population and limit the spread of the fungus.

4. Chestnut Blight

Causal Agent: Cryphonectria parasitica (fungus)
Susceptible Trees: American chestnut and some hybrid chestnut species

Chestnut blight is one of the most notorious tree diseases in U.S. history, having nearly wiped out the American chestnut tree, which was once a dominant species in eastern forests. The blight infects the bark and creates cankers that girdle the tree, preventing it from transporting water and nutrients.

Symptoms of Chestnut Blight:

  • Sunken, orange cankers on the bark.
  • Orange-colored fungal spore masses on the surface of the canker.
  • Tree death occurs when cankers girdle the trunk or branches, cutting off nutrient flow.
  • Although the root system often survives, new shoots typically succumb to the blight before they can mature.

How Chestnut Blight Spreads:

Chestnut blight spreads through spores carried by the wind, rain, animals, and human activity. It enters the tree through wounds in the bark, where it quickly establishes and causes cankers that can girdle the tree.

Chestnut Blight Management:

  • There is no cure for chestnut blight, but breeding programs are working to develop resistant hybrid varieties.
  • Fungicide treatments can slow the disease in some cases but are not a permanent solution.
  • Quarantines and restrictions on the movement of infected plant material can help reduce the spread.

5. Pine Wilt

pine wilt

Causal Agent: Pinewood nematode (Bursaphelenchus xylophilus)
Susceptible Trees: Primarily non-native species like Scots pine, though some native pines can be affected.

Pine wilt is caused by the pinewood nematode, which infects the vascular system of pine trees, blocking water transport and causing rapid tree death. The disease progresses quickly, often killing trees within a few months of infection.

Symptoms of Pine Wilt:

  • Needles turn brown and wilt, often starting at the top of the tree.
  • Rapid decline in tree health, with death occurring within weeks to months.
  • The resin flow may be reduced or absent in affected trees.

How Pine Wilt Spreads:

The nematodes are spread by sawyer beetles, which lay eggs in stressed or dead trees. When the adult beetles emerge, they carry the nematodes with them to healthy trees, where the cycle begins again.

Pine Wilt Management:

  • Infected trees should be removed and destroyed to prevent the nematodes from spreading.
  • Insecticides may reduce beetle populations and limit the spread of nematodes.
  • Replacing susceptible pines with resistant species can help reduce the impact of pine wilt.

6. Dogwood Anthracnose

Causal Agent: Discula destructiva (fungus)
Susceptible Trees: Flowering dogwood, Pacific dogwood

Dogwood anthracnose is a fungal disease that has severely impacted native dogwoods, particularly in cool, moist climates. It causes leaf blight, branch dieback, and cankers, which can eventually lead to tree death.

Symptoms of Dogwood Anthracnose:

  • Brown or tan leaf spots with purple borders.
  • Cankers form on branches and the trunk, leading to dieback.
  • Premature leaf drop and thinning of the tree canopy.
  • Tree decline may occur over several years, with eventual death.

How Dogwood Anthracnose Spreads:

The disease spreads via wind and rain and can be transferred on contaminated pruning tools or equipment. It thrives in shady, moist environments, making forested areas particularly susceptible.

Dogwood Anthracnose Management:

  • Pruning out infected branches and removing fallen leaves can help reduce the spread of the fungus.
  • Fungicide applications may be effective if started early in the infection process.
  • Increasing airflow and sunlight exposure by thinning surrounding vegetation can help reduce moisture and prevent the spread of spores.

7. Emerald Ash Borer (EAB)

In addition to fungal and bacterial diseases, many tree diseases are spread or exacerbated by insects that damage trees and introduce pathogens. Managing insect populations is an essential part of controlling these diseases.

Causal Agent: Agrilus planipennis (an invasive beetle)
Susceptible Trees: All species of ash

The emerald ash borer (EAB) is a highly destructive invasive insect responsible for the rapid decline of ash trees across North America. The larvae of the beetle burrow into the tree's bark and feed on its inner tissues, disrupting the tree’s ability to transport water and nutrients.

Symptoms of Emerald Ash Borer:

  • D-shaped exit holes in the bark left by emerging adult beetles.
  • Thinning and dieback of the tree canopy, starting from the top.
  • Increased woodpecker activity, as they feed on the larvae.
  • Complete tree death usually occurs within two to five years of infestation.

How the Emerald Ash Borer Spreads:

EAB spreads through the movement of infested firewood, logs, and nursery stock. Adult beetles can fly short distances to find new host trees.

Emerald Ash Borer Management:

  • Systemic insecticide treatments can protect healthy trees from infestation.
  • Infested trees should be removed and destroyed to prevent the beetles from spreading.
  • Quarantines and firewood restrictions help limit the movement of infested material to new areas.

8. Laurel Wilt

In addition to the established tree diseases discussed above, new and emerging threats continue to affect the foothills and high country. These diseases and pests are often introduced through global trade and human activity, making it essential for forest managers and landowners to stay informed and vigilant.

Laurel wilt is a devastating disease caused by a fungus carried by the redbay ambrosia beetle, an invasive species. It primarily affects trees in the laurel family, including redbay, sassafras, and avocado. The fungus clogs the tree's vascular system, causing rapid wilting and death.

Symptoms of Laurel Wilt:

  • Leaves wilt and turn brown, often hanging on the tree even after they die.
  • Dark streaking in the wood.
  • Death occurs within weeks to months of infection.

9. Beech Leaf Disease

Beech leaf disease is a relatively new threat to American beech trees, causing severe leaf distortion and premature leaf drop. While the exact cause of the disease is not fully understood, it is spreading rapidly and leading to a decline in tree health.

Symptoms of Beech Leaf Disease:

  • Dark bands on the leaves, often accompanied by curling and distortion.
  • Premature leaf drop, leading to thinning canopies.
  • Overall decline in tree health over time.

10. Long-Term Strategies for Managing Tree Diseases

Effectively managing tree diseases in the foothills and high country requires both short-term and long-term strategies. Immediate actions may include removing infected trees, applying fungicides or insecticides, and quarantining affected areas. However, long-term solutions focus on building the resilience of forest ecosystems through diversity and sustainable practices.

Increasing Forest Diversity

One of the best defenses against widespread tree disease is forest diversity. Monocultures, or the planting of a single tree species, are more vulnerable to disease outbreaks. If a pathogen or pest targets a specific species, it can easily spread through an entire stand of trees.

Encouraging biodiversity by planting a mix of tree species reduces the chances of a single disease wiping out large areas of forest. Mixed-species forests are also more resilient to other stressors, such as climate change and extreme weather events.

Monitoring and Early Detection

Regular monitoring of tree health is essential for detecting diseases early before they can spread. Landowners, forest managers, and local authorities should be vigilant for the symptoms of known diseases and report any unusual signs of tree decline to the appropriate agencies.

By staying informed and proactive, it is possible to manage tree diseases more effectively and reduce their long-term impact on forests in the foothills and high country.

11. Preventive Measures for Tree Health

Preventing the spread of tree diseases is often easier than managing them once they have become established. Here are some key preventive measures to keep in mind:

  • Regular Monitoring: Conduct regular inspections of trees for signs of disease, such as leaf discoloration, wilting, or fungal growths. Early detection is crucial for managing tree diseases before they become widespread.
  • Proper Pruning Techniques: Prune trees during their dormant season to reduce the risk of infection. Disinfect pruning tools between trees to avoid spreading pathogens.
  • Watering and Drainage: Ensure that trees have proper water drainage to prevent waterlogged soil, which can lead to root rot and other water-related diseases.
  • Insect Control: Use insecticides where necessary to control pests like bark beetles and aphids, which can spread diseases or weaken trees.
  • Fungicide Application: In areas known to have fungal threats, preventive fungicide treatments can help protect vulnerable trees.
  • Sanitation and Removal of Diseased Trees: Promptly remove and destroy infected trees and branches to prevent the disease from spreading to healthy trees.
  • Avoid the Spread of Infected Firewood: Don’t transport firewood from infested areas, as this can introduce invasive species like the emerald ash borer to new locations.

12. Economic Impact of Tree Diseases

economic impact of tree diseases

Tree diseases don’t only affect the environment—they also have substantial economic repercussions. In the foothills and high country, industries like forestry, tourism, and real estate are all heavily dependent on healthy trees and forests. The increasing prevalence of tree diseases threatens the stability of these industries.

Timber Industry

The timber industry is one of the largest economic sectors in the foothills and high country. Tree diseases like oak wilt, pine wilt, and Dutch elm disease reduce the volume and quality of available timber, leading to economic losses. 

When trees are harvested before reaching maturity due to disease, the value of the wood is significantly reduced. Moreover, the costs of managing diseased forests—through tree removal, pest control, and disease monitoring—drive up the overall expense for timber companies.

Tourism

The scenic beauty of the forests in the foothills and high country is a major draw for tourists, who come to hike, camp, birdwatch, and enjoy the natural surroundings. Tree diseases that cause large-scale die-offs can significantly alter these landscapes, making them less attractive to visitors. 

For example, entire stands of hemlocks have been lost to HWA, leaving behind dead trees that no longer provide the shade and beauty that once attracted tourists.

Furthermore, dead and dying trees present safety hazards, as they are more likely to fall during storms or other extreme weather events, posing risks to visitors in recreational areas. This can lead to a decline in park attendance and a loss of tourism revenue.

Property Value

Healthy trees are an important asset for property owners, providing shade, improving air quality, and enhancing the overall aesthetic value of a landscape. However, tree diseases can significantly diminish property values by killing off valuable shade trees or leaving behind barren and unattractive landscapes. 

Additionally, homeowners may face significant costs for tree removal and replacement, as well as potential damage to homes or infrastructure caused by falling diseased trees.

Trust Church & Church Lumber Company for Expert Forestry Management

Tree diseases are a growing threat to the forests of the foothills and high country, but with the right management strategies, their impact can be minimized. At Church & Church Lumber Company, we are dedicated to helping landowners manage and protect their forests from the devastating effects of tree diseases.

Our experienced team offers comprehensive forestry management services, including disease prevention, tree removal, and long-term planning to ensure the health and vitality of your forested lands. We specialize in sustainable practices that promote forest diversity and resilience, helping you maintain a healthy and thriving forest.

Whether you need help managing a current tree disease outbreak or want to implement preventive measures to protect your trees for the future, Church & Church Lumber Company is here to assist you. With our expertise, you can trust that your forest will remain a valuable resource for generations to come.

Contact Us Today for Help With Managing Your Forests

If you're concerned about the health of your trees or need expert guidance on managing tree diseases, reach out to Church & Church Lumber Company. Our team is ready to help you protect your forested lands and ensure their long-term sustainability. 

Contact us today to learn more about our services and how we can assist you in managing tree health in the foothills and high country.