Anthracnose Disease: Identification, Impact, and Control

Due to the heavy rains we’ve been seeing this year Anthracnose has been running rampant. Anthracnose is a group of fungal diseases that affect a wide range of plants, including trees, shrubs, and crops. This disease is characterized by dark, sunken lesions on leaves, stems, flowers, and fruits. It can cause significant damage, leading to reduced yields and aesthetic issues in ornamental plants. 

We’ve put together some information on Anthracnose below so you know how to identify Anthracnose and help prevent it.

What Causes Anthracnose?

• Fungi: The primary culprits behind anthracnose are fungi from the genera Colletotrichum and Gloeosporium.
• Environmental Factors: Warm, wet conditions favor the development and spread of these fungi.
• Host Plants: Commonly affected plants include:
  • Trees: Oak, Maple, Sycamore
  • Crops: Tomatoes, Beans, Cucumbers
  • Ornamentals: Dogwood, Hydrangea

Signs and Symptoms

Identifying anthracnose early is crucial for effective control. Look out for the following:

1. Leaf Spots: Brown or black spots, often with a yellow halo, on leaves.
2. Blighted Leaves: Leaves may curl, dry out, and fall prematurely.
3. Stem Cankers: Sunken lesions on stems and branches, which may girdle and kill them.
4. Fruit Rot: Discolored, sunken areas on fruits, often leading to decay.

Life Cycle of Anthracnose

Understanding the life cycle of anthracnose can help in timing control measures:

• Overwintering: The fungi survive in fallen leaves, twigs, and infected plant debris.
• Spore Release: In spring, spores are released and spread by wind, rain, or irrigation.
• Infection: Spores land on susceptible plant tissues, germinate, and begin infection.
• Spread: The disease spreads rapidly in warm, humid conditions, affecting more plants.

Anthracnose life cycle diagram created by Jay Ram Lamichhane

Impact on Plants

The impact of anthracnose varies depending on the plant and the severity of the infection:

• Reduced Photosynthesis: Large lesions reduce the leaf area available for photosynthesis.
• Premature Leaf Drop: Trees may lose leaves early, weakening them over time.
• Crop Loss: Infected fruits and vegetables may become unmarketable, leading to economic losses.

Prevention and Control

Managing anthracnose requires a combination of cultural practices, chemical treatments, and resistant varieties:

1. Cultural Practices:
   • Sanitation: Remove and destroy infected leaves, twigs, and plant debris.
   • Proper Spacing: Ensure good air circulation around plants to reduce humidity.
   • Watering Practices: Avoid overhead watering to minimize leaf wetness.
2. Chemical Control:
   • Fungicides: Apply fungicides labeled for anthracnose, especially during wet weather.
   • Timing: Early application during bud break or at the first sign of symptoms is most effective.
3. Resistant Varieties:
   • Select Resistant Plants: Choose plant varieties that are less susceptible to anthracnose.

Conclusion

Anthracnose is a challenging plant disease that requires vigilant monitoring and proactive management. By understanding its causes, symptoms, and life cycle, you can take effective steps to protect your plants. Regular cultural practices combined with timely chemical treatments can help minimize the impact of this disease.

‍