Dogwood anthracnose is a significant disease that affects dogwood trees. Understanding this disease is crucial to maintaining the health and longevity of your trees.
Although it is a dreaded and serious infection, there are steps you can take to manage the disease and limit its spread.
To treat dogwood anthracnose, remove and dispose of infected leaves or branches to reduce the spread of the disease. Improve air circulation around the tree by pruning, and regularly monitoring for signs of the disease, especially during wet, cool weather. If necessary, apply a fungicide labeled for control of anthracnose diseases.
In the following sections, you’ll learn all about dogwood anthracnose, exploring its causes, the disease life cycle, its impact on trees, and the conditions that favor its development.
We’ll also discuss the species most susceptible to this disease and provide a detailed guide on the symptoms as well as comprehensive management and control strategies.
- Dogwood anthracnose is a fungal disease that causes leaf spots, stem cankers, and even tree death. It is most prevalent in cool, wet conditions and can spread rapidly.
- Early symptoms include small, purple-bordered leaf spots and stem cankers.
- As the disease progresses, these spots can enlarge and merge, leading to significant leaf blight and premature leaf drop.
- Management involves sanitation, pruning, and, if necessary, fungicide applications.
- Maintaining the overall health of the tree and modifying the environment to make it less favorable for the disease can help prevent dogwood anthracnose.
Knowing the various issues that can plague dogwood trees is critical for ensuring healthy, beautiful trees. Learn all about common dogwood problems in my article Dogwood Diseases and Pests.
Understanding Dogwood Anthracnose
Dogwood anthracnose is a serious disease that can significantly impact the health and appearance of dogwood trees. Understanding this disease is the first step toward effective management and control.
Definition and Causes
Dogwood anthracnose is a fungal disease caused by the fungus Discula destructive.
This pathogen specifically targets dogwood trees, causing leaf spots, stem cankers, and, in severe cases, tree death.
The fungus thrives in cool, wet conditions and can spread rapidly under favorable conditions.
Life Cycle and Mode of Transmission
The fungus that causes dogwood anthracnose overwinters in infected leaves and branches.
In the spring, during wet, cool weather, the fungus produces spores that are spread by wind and rain to healthy parts of the tree or to neighboring trees.
Once the spores land on a suitable host, they germinate and infect the tree, causing the characteristic symptoms of the disease.
Conditions That Favor Dogwood Anthracnose Development
Dogwood anthracnose is most prevalent in cool, wet conditions. The disease is often more severe in shaded areas and in trees that are stressed due to factors such as drought, poor nutrition, or other diseases.
Proper care of dogwood trees, including appropriate watering, fertilization, and pruning, can help reduce the risk of infection.
Impact on Dogwood Trees
Dogwood anthracnose can have a significant impact on the health and appearance of dogwood trees.
Infected trees may display leaf spots, stem cankers, and premature leaf drop. In severe cases, the disease can cause extensive defoliation and dieback and can even lead to the death of the tree.
Dogwood Species Most Susceptible
While dogwood anthracnose can affect all species of dogwood, certain species are more susceptible than others.
These include the flowering dogwood (Cornus florida) and the Pacific dogwood (Cornus nuttallii).
Other species, such as the Kousa dogwood (Cornus kousa) and the Cornelian cherry dogwood (Cornus mas), show more resistance to the disease.
Symptoms and Diagnosis
Recognizing the symptoms of dogwood anthracnose is crucial for early detection and effective management of the disease.
Early symptoms of dogwood anthracnose include small, purple-bordered leaf spots and stem cankers.
These spots may initially appear as small, circular to irregularly shaped areas of tan or purple discoloration.
As the disease progresses, these spots can enlarge and merge, leading to significant leaf blight.
Symptoms as Disease Progresses
As the disease progresses, the leaf spots may become larger and more numerous, leading to extensive leaf blight. The leaves may curl, wilt, and eventually drop prematurely.
Stem cankers, which are sunken areas of dead tissue, may also develop on the twigs and branches. In severe cases, the disease can cause widespread defoliation and dieback.
Diagnosis of dogwood anthracnose is typically based on the characteristic symptoms of the disease.
However, for a definitive diagnosis, a sample may need to be sent to a diagnostic laboratory where the presence of the fungus can be confirmed under a microscope.
Management and Control
Managing dogwood anthracnose involves a combination of cultural practices and, if necessary, fungicide applications.
- Sanitation: Remove and dispose of fallen leaves and pruned material to reduce the source of infection.
- Pruning: Prune to improve air circulation and reduce humidity around the tree. Also, prune out any diseased branches.
- Watering: Water at the base of the tree to avoid wetting the leaves, as moisture on the leaves can promote the disease.
When choosing a fungicide, look for products that are labeled for control of anthracnose diseases. Active ingredients that are effective against dogwood anthracnose include:
- Chlorothalonil: This is a broad-spectrum fungicide that can be effective against a range of fungal diseases, including anthracnose. It’s available under various trade names, including Daconil and Bravo.
- Mancozeb: This is another broad-spectrum fungicide that can be used to control anthracnose. It’s often sold under the trade name Dithane.
- Propiconazole: This is a systemic fungicide that is absorbed by the plant and can provide longer-lasting protection. It’s available under various trade names, including Banner Maxx and Spectator.
- Myclobutanil: This is another systemic fungicide that can be effective against anthracnose. It’s often sold under the trade name Eagle.
Preventing dogwood anthracnose involves maintaining the overall health of the tree and modifying the environment to make it less favorable for the disease.
This includes proper watering and fertilization, avoiding overhead irrigation, and planting in a location with good air circulation and sunlight.
Also, consider planting disease-resistant varieties of dogwood, such as the Kousa dogwood or the Cornelian Cherry dogwood.
Can Overwatering Cause Anthracnose?
Overwatering does not directly cause anthracnose, but it can create conditions that favor the development of the disease.
Overly wet conditions can promote the growth and spread of the fungus that causes anthracnose.
Therefore, it’s important to water appropriately, providing enough moisture for the tree’s needs but avoiding waterlogged conditions.
How Long Does Anthracnose Stay in the Soil?
The fungus that causes anthracnose can survive in the soil for several years, especially in infected plant debris.
This is why sanitation, including the removal and disposal of infected leaves and branches, is an important part of managing anthracnose.
Dogwood anthracnose is a significant disease that can impact the health and appearance of dogwood trees.
However, with knowledge of the disease and its management, you can take steps to protect your trees and maintain their beauty and health.
Remember that the key to managing dogwood anthracnose lies in early detection, appropriate treatment, and preventative measures.
Don’t miss out on learning about other common diseases affecting dogwood trees. Be sure to read these articles: