Dogwood Antracnose

What Is Dogwood Anthracnose?

Dogwood Anthracnose is a serious fungal disease caused by Discula destructiva that affects flowering dogwood trees (Cornus florida) and Pacific dogwoods (Cornus nuttallii). First identified in the U.S. in the late 1970s, the disease has since spread across the eastern and central parts of the country, including the St. Louis region.

This disease thrives in cool, damp spring and early summer conditions—making dogwoods growing in shaded, moist, or densely wooded environments especially vulnerable. Once established, the fungus can infect leaves, twigs, branches, and eventually the main trunk, causing progressive dieback and, if untreated, tree death.

Dogwood Anthracnose is particularly aggressive toward native dogwood species that are under environmental stress, such as drought, poor soil drainage, or previous mechanical damage. It has become one of the most devastating diseases for dogwoods in landscapes, parks, and natural forests.

Signs Your Tree Might Have Dogwood Anthracnose

Early detection is key when it comes to managing Dogwood Anthracnose. The disease typically starts in the lower leaves and branches, then progresses upward through the canopy. Keep an eye out for the following warning signs:

• Tan to brown leaf spots with purple or dark brown borders, often starting at the tips or edges of the leaves
  
  
• Large blotches where spots merge, sometimes covering most of the leaf surface
  
  
• Premature leaf drop during spring or early summer, well before the normal fall shedding
  
  
• Wilted, curled, or scorched-looking leaves even when the tree is adequately watered
  
  
• Dieback of twigs and branches, particularly starting in the lower canopy and moving upward
  
  
• Cankers on stems or branches, which appear as sunken, darkened, or cracked areas
  
  
• Thin canopy or sparse foliage, often with dead branches visible throughout the tree
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• Fungal fruiting bodies (tiny dark specks) on dead leaves, twigs, or cankered areas, especially in humid conditions
  
  

How Dogwood Anthracnose Spreads to Other Dogwood Trees

Dogwood Anthracnose spreads primarily through airborne spores produced by the fungus Discula destructiva. These spores are released during wet, cool conditions in spring and early summer, which are common in the St. Louis region. Once released, the spores can travel short distances through the air, landing on nearby dogwood leaves, twigs, or bark.

Here’s how the disease typically spreads:

• Rain splash and wind carry fungal spores from infected leaves and twigs to healthy dogwoods nearby.
  
  
• Overhead watering can contribute to spread by mimicking natural rain conditions and increasing humidity around the tree canopy.
  
  
• Contaminated pruning tools used on infected trees can transfer spores to healthy ones if not properly disinfected.
  
  
• Fallen infected leaves and twigs left on the ground act as a reservoir for the fungus, allowing it to overwinter and re-infect nearby trees in the next season.
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• Close proximity planting in shady, damp environments allows the disease to move easily from one tree to another.
  
  

Are Other Trees in Missouri at Risk of Dogwood Anthracnose?

Dogwood Anthracnose, caused by the fungus Discula destructiva, is highly specific to certain dogwood species in the Cornus genus. It does not affect trees outside this group. Here's how it breaks down:

• Highly Susceptible Species
  Native flowering dogwood (Cornus florida) and Pacific dogwood (Cornus nuttallii) are most at risk when conditions are cool, wet, and shaded. These species lack natural resistance to the pathogen.
  
  
• More Resistant or Tolerant Dogwood Species
  
  
  
  • Kousa dogwood (Cornus kousa) and cultivars—especially certain hybrid varieties—tend to be much more resistant to the disease and often experience only mild symptoms if infected.
    
    
  • Other dogwood relatives—such as Tatarian dogwood (Cornus alba) and red-osier dogwood (Cornus sericea)—also show resistance to Discula destructiva, making them safer alternatives in areas where anthracnose is a concern.
    
    
• No Risk to Unrelated Trees
  Trees outside the Cornus genus—like oaks, maples, sycamores, ash, elm, or walnut—are not hosts for Dogwood Anthracnose. Those trees may be affected by other anthracnose diseases, but not this one.
  
  

Treatment and Prevention for Dogwood Anthracnose

Dogwood Anthracnose can be managed effectively with a combination of cultural practices, preventative care, and—if needed—targeted fungicide treatments. Early detection and proactive maintenance are key to protecting your dogwood trees and limiting the spread of infection.

Cultural and Preventative Steps:

• Prune infected branches during dry weather to prevent the spread of fungal spores and improve air circulation within the canopy. Always disinfect pruning tools between cuts.
  
  
• Rake and remove fallen leaves and debris around the tree’s base in fall and spring to reduce overwintering fungal material.
  
  
• Improve airflow and sunlight exposure by thinning nearby vegetation or choosing a planting site with better drainage and sun access.
  
  
• Water during drought conditions, especially in the summer and fall, to reduce stress and improve the tree’s natural resistance.
  
  
• Mulch properly, keeping mulch away from the trunk while maintaining even soil moisture.
  
  

Fungicide Applications:

• Apply preventative fungicides in early spring—at bud break and again after flower bract drop. Repeat treatments may be needed every 10–14 days during wet periods.
  
  
• Commonly used fungicides include:
  
  
  
  • Chlorothalonil
    
    
  • Mancozeb
    
    
  • Propiconazole
    
    
  • Copper-based fungicides
    
    
• Fungicides are most effective as a preventative measure or in early stages of infection. Severely diseased trees may require more extensive intervention.
  
  

Plant Resistant Dogwood Varieties:

• Consider planting Kousa dogwood (Cornus kousa) or disease-resistant hybrids like the Stellar series (‘Aurora’, ‘Ruth Ellen’, ‘Constellation’) in high-risk areas.
  
  
• These varieties offer similar visual appeal with significantly stronger resistance to anthracnose.