Anthracnose: How To Identify, Prevent, And Treat The Fungal Disease

Anthracnose: Identification, Prevention & Treatment

Anthracnose refers to a group of related fungal diseases that affect plants, including vegetables and trees, in the garden.

Anthracnose disease can cause foliar blight in dry heat or stem rot in wet months. It’s important to learn how to identify this disease as well as the types of anthracnose treatments that are most effective.

What Is Anthracnose?

Anthracnose disease is caused by one of several types of anthracnose fungus. These are fruiting bodies that look like small dark spots on plant leaves or stems. They produce spores and release them in slimy masses.

Fungi (e.g. Colletotrichum cereale) live on dead and rotting organic matter. They cause different types of blight that appear as dark spots on foliage, leaves turning yellow and brown, and/or lesions on leaves. The lesions look sunken and can quickly meld into each other to form irregular lesions.

Plants Affected by Anthracnose

Anthracnose disease can attack a large variety of plants. The vulnerable plants include deciduous and evergreen trees and shrubs It can also affect perennial and annual flowers, as well as vegetables and turfgrass.

Note that each species of fungi targets one host species, or sometimes several closely related species Trees are one of the primary targets of anthracnose disease. These tree fungus issues are sometimes called leaf, shoot, or twig blight.

Symptoms of Anthracnose

One difficult aspect of identifying anthracnose disease is that the symptoms vary widely from plant to plant. Weather conditions can also alter the types of symptoms that appear.

Perhaps the most common symptom is spots. They are small spots, often dark brown or black, and can appear on twigs or leaves of some hosts, including oak. On other anthracnose hosts, like maple and willow, you will see irregular dead areas or lesions along leaf veins.

Mature leaves resist the infection, but symptoms include spotty lesions followed by defoliation. Very young, tender leaves curl and distort when they are infected. Only part of each young leaf will die. You can sometimes see sunken, infected areas on twigs, branches, and stems or trunks. Some trees with compact canopies, like Chinese elm, are particularly vulnerable to permanent damage.

How to Prevent Anthracnose

Most fungal diseases result from wet leaves and stems. Anthracnose is no exception. Infections happen when the foliage is wet for extended periods of time.

To prevent this disease from finding a foothold in your garden, irrigate your backyard plants in the morning, as early as possible. This gives the plants the entire day to dry before nightfall. If you do see infected plants, clip off the plant parts that are infected and toss them in the garbage, not in the compost.

Cleaning up the garden in the fall is always a good idea. And it can reduce the fungal infection the following spring.

Anthracnose Treatment

There is no cure for anthracnose disease. However, sometimes fungicides, applied at the appropriate times, can prevent the fungal disease from spreading to other parts of the affected plant.

During hot, rainy periods, consider using contact fungicides that inhibit spore germination. Again, this will not kill the fungus but can limit the extent and severity of outbreaks. You’ll need to cover the plant with fungicide spray according to the schedule set out on the label. In most cases, you’ll need to thoroughly spray as buds begin to open in spring. It may be difficult or impossible to get appropriate spray coverage on mature trees.

FREQUENTLY ASKED QUESTIONS

• Will anthracnose go away on its own?Anthracnose diseases are fungal in nature, and take off in cool, wet weather. They will diminish and can even disappear in warm, dry weather.
• Can a tree recover from anthracnose?Anthracnose disease can present a threat to trees when severe infections – resulting in defoliation, branch dieback or cankering - occur year after year. However, in less serious cases, the disease does not cause permanent damage to trees.