Anthracnose Explained: How to Prevent Leaf Spots and Blights

Milosh Potikj | 18 octobre 2023 | 7 MIN READ

Are you having difficulty controlling leaf spots and blight in your garden? If so, the answer may lie in understanding anthracnose. From identifying common symptoms to learning how to prevent these fungal conditions from affecting your plants, this blog post will provide a comprehensive overview of micronutrients, water management solutions, fungicide treatments, and more that can help keep your plants healthy for years.

Read through all the information provided below so you'll be armed with vital knowledge about one of nature's most prevalent plant illnesses--anthracnose!

What is Anthracnose?

Anthracnose, often referred to as leaf spot or blight, is a common fungal disease that affects a wide range of edible and ornamental plants. This disease is caused by various species of fungi in the genus Colletotrichum, which are highly host-specific and often infect only a particular group of plants.

Several common species of Anthracnose fungi exist, including Colletotrichum gloeosporioides, Colletotrichum acutatum, and Colletotrichum lindemuthianum, among others. Each species of anthracnose fungi has its preferred host and environmental conditions for disease development.

For example, Colletotrichum gloeosporioides is often associated with anthracnose in fruits, while Colletotrichum lindemuthianum is commonly found in beans and other legumes.

How Does Anthracnose Spread?

Anthracnose spreads mainly through wind, rain, or irrigation water spores. These spores land on plant surfaces, particularly the leaves, and infect the plant when conditions are favorable--typically when the weather is wet and warm. It's also important to note that the disease can spread from infected to healthy plants through pruning tools, hands, and even clothing. When it comes to fruits, the spores can infiltrate through naturally occurring openings or wounds in the fruit's skin.

Infected leaves or fruit can also spread the disease when they fall to the ground, releasing spores that can infect other parts of the plant or nearby plants. Therefore, good garden hygiene and proper water management are crucial in preventing the spread of this disease.

Symptoms of Anthracnose

Recognizing the symptoms of Anthracnose can be an essential step in protecting your plants. Let's explore some of the key signs to look out for in infected leaves, fruits, and other species:

  • Identifying Leaf Spots and Blights: Anthracnose initially appears as small, irregular yellow or brown spots on the leaf surface. These spots often grow larger, forming circular patches, and may eventually coalesce, causing extensive damage to the leaf. The affected areas may also become sunken, giving the leaf a blighted look.
  • Infected Leaves: Infected leaves often exhibit a water-soaked appearance. As the infection progresses, the spots may darken and lead to leaf drop. The entire leaf may darken and shrivel in severe cases, often mistaken for leaf burn or nutrient deficiency.
  • The Impact on Fruits and Other Species: Anthracnose does not only affect leaves but can also cause significant damage to fruits. Infected fruits often develop dark, sunken spots, which may exude a pinkish ooze in some species. The disease can significantly reduce crop yield and affect the aesthetic appeal of ornamental plants. Moreover, certain species of Anthracnose fungi prefer specific hosts, meaning the disease's impact can vary widely among plant species.

More: How To Recognize and Fix Nutrient Burn.

Causes and Development of the Disease

Causes and Development of the Disease

The development of Anthracnose is driven primarily by pathogenic actions, particularly those belonging to the Colletotrichum genus. The disease's progression and severity largely depend on the specific pathogen, its interaction with the plant host, and environmental factors like air circulation. Let's delve into these aspects:

  • Pathogens and Disease Development: Each anthracnose pathogen has conditions that favor its growth and spread. For instance, Colletotrichum gloeosporioides thrives in wet and warm conditions, causing significant damage to fruits. On the other hand, Colletotrichum lindemuthianum prefers cooler conditions and often targets beans and legumes. The pathogens infect plant tissues, leading to symptoms like leaf spots, blights, and fruit rot.
  • Role of Air Circulation: Proper air circulation plays a crucial role in controlling the spread of Anthracnose. Poor air movement can create damp, stagnant conditions that favor the growth and spread of pathogens. Encouraging good air circulation, such as spacing plants properly and using fans in indoor garden settings, can help reduce humidity levels around plant surfaces, making it harder for the fungal spores to settle and germinate.
  • Pathogen Survival: Anthracnose pathogens are resilient and can survive in plant debris or soil during off-seasons. They become active and start to infect plants when conditions become favorable. Regularly clearing plant debris and practicing crop rotation can help manage the disease by reducing the number of active pathogens.
  • Infection Process: Upon landing on a suitable host, the fungal spores germinate, penetrate the plant tissues, and start to colonize, causing the characteristic symptoms of Anthracnose. Certain practices, such as overhead watering, can facilitate infection by splashing spores onto plant surfaces. Therefore, changing watering practices can help mitigate the disease.

Prevention and Control of Anthracnose

Prevention and Control of Anthracnose

Preventing and controlling anthracnose involves a holistic approach, combining cultural and chemical methods. Let's dive into some measures you can take to protect your plants from this common but troublesome disease.

Effective Water Management

Effective water management is crucial in preventing the spread of Anthracnose. Over-watering or watering at improper times may create conditions conducive to the growth and multiplication of fungal spores. Here are some best practices for water management to help control Anthracnose:

  • Watering Technique: It’s recommended to water plants at the base, avoiding the leaves, as damp leaves can attract fungal spores. A soaker hose or a drip irrigation system can help in ensuring this.
  • Watering Time: Watering your plants early in the morning allows the sun to dry the excess water, reducing the chances of fungal growth. Avoid watering late in the day, as the water may not evaporate before dark, creating a damp environment that encourages fungal growth.
  • Avoid Over-Watering: Over-watering can lead to waterlogged soils and poor root health, making plants more susceptible to disease.
  • Proper Drainage: Ensure your garden or farm has adequate drainage to avoid water accumulation. Puddles of water can become breeding grounds for fungal spores.

Remember, the idea is to keep your plants hydrated but not to create an environment conducive to fungal growth. Striking this balance is key to managing Anthracnose effectively.

More: The Benefits of Silicon For Healthy Plants

Role of Micronutrients in Prevention

Micronutrients are pivotal in enhancing the plant's overall health and disease resistance including Anthracnose. They help to strengthen the plant's defense mechanisms and repair tissues damaged by fungal attacks. Key micronutrients include:

  • Zinc: This micronutrient is essential for producing certain enzymes and proteins that boost plant immunity. Zinc can help plants resist fungal infections by strengthening their cell membranes.
  • Copper: Copper contributes to plant growth and improves the plant's ability to withstand stress, including attacks by fungus. It plays a prominent role in lignin synthesis, a compound that reinforces the cell walls, making them less prone to pathogenic invasion.
  • Manganese: Manganese is vital for photosynthesis and aids in plants' rapid cell development and growth, making them more resilient to fungal diseases.
  • Iron: Iron is instrumental in creating chlorophyll, essential for photosynthesis. Healthy photosynthesis equates to a healthier plant that is more capable of fending off diseases.
  • Boron: Boron helps regulate plant metabolism and the transportation of sugars to areas of the plant battling disease.

Testing your soil regularly is important to ensure it contains adequate micronutrients. If deficiencies are noted, they can be corrected by applying essential nutrients or soil amendments.

Fungicide Treatments: Best Practices

Fungicides are often used as a part of an integrated disease management strategy to control Anthracnose. Here are some best practices for their use:

  • Timing: Apply fungicides early in the disease cycle when infection levels are manageable. This is usually when conditions are conducive for disease development, such as during wet, warm weather.
  • Resistance Management: To limit the potential for the development of fungicide resistance, rotate between fungicides with different modes of action. Following the recommended rate and frequency of application also helps maintain the fungicides' effectiveness.
  • Proper Coverage: For fungicides to work effectively, they must cover the plant surfaces thoroughly. Pay special attention to the undersides of leaves where fungal spores often reside.
  • Safety Measures: Always follow safety guidelines when handling and applying fungicides. Wear protective clothing and avoid spraying on windy days to prevent drift.

Utilizing fungicides as part of a comprehensive prevention and treatment plan can help manage Anthracnose more effectively. Remember, the goal is not to completely eradicate the pathogen but to keep it at levels that do not cause significant damage to your plants.

Learn More: Alternaria Leaf Spot Explained

Frequently Asked Questions

How is anthracnose prevented?

Anthracnose can be prevented through several strategies, including proper watering techniques, effective use of fungicides, maintaining good sanitation practices in the garden or farm, and ensuring plant nutrition. Regular monitoring and early detection also play a crucial role in preventing the spread of this disease. It's always better to prevent the disease's onset than try to control it after the infection.

How do you prevent leaf blight?

Leaf blight can be prevented through consistent monitoring and appropriate fungicides. Implementing crop rotation and practicing good sanitation by removing and disposing of infected plant material can also help manage the disease effectively.

What causes anthracnose leaf blight?

Anthracnose Leaf Blight is caused primarily by the fungus Colletotrichum. The fungus attacks the leaves, causing brown spots, and can eventually lead to widespread damage and defoliation of the plant if left untreated.

How do you control anthracnose naturally?

To improve soil health, anthracnose can be managed naturally by adding organic matter, such as compost or well-rotted manure. This enhances soil fertility and aids in drainage, reducing the likelihood of waterlogging and subsequent fungal growth. Another natural approach is using resistant plant varieties less susceptible to the disease.



In conclusion, effective management of Anthracnose involves a combination of preventative measures and treatment strategies. Keeping plants healthy with adequate watering, balanced nutrition, and proper soil conditions can significantly reduce the risk of fungal diseases. Early detection and intervention are key to minimizing damage when disease occurs. When used appropriately, Fungicides can help control the disease and prevent its spread.

Always remember that a proactive approach is the best defense against this pathogen. Maintaining healthy plants and taking early action at the first signs of disease will go a long way towards keeping your garden or farm Anthracnose-free.


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