What Is the Threat
Anthracnose leaf blight is a fungal disease that can develop in the leaves and twigs of certain shade trees inÂ southern Maryland.Â The fungusÂ winters in dead twig and bud tissue over the winter and spreads to new plant growth in the spring.Â
When this occurs, it can cause dark, unsightly spots to developÂ along the veins of theÂ tree’s new leaves. Those spots can range from light tan to dark red or brown in color and tend to worsen in damp, cool conditions. In severe cases, the infection can lead to widespreadÂ defoliation or total leaf loss.Â
Where Is the Threat
There are two different types of fungi that can lead toÂ Anthracnose leaf blight:Â ApiognomoniaÂ andÂ Discula. Each type affects different tree species, so it’s important to understand the difference between the two.
In southern Maryland,Â ApiognomoniaÂ tends to affectÂ American and California Sycamore trees above any other species, although newer cultivars such as theÂ London Plane Sycamore have been shown to be more resistant. TheÂ DisculaÂ fungi are more prone to affectÂ Flowering Dogwood trees.
However, these aren’t the only trees that can fall victim to this disease. Other susceptible species include:
Symptoms ofÂ Anthracnose Leaf BlightÂ
Anthracnose leafÂ blightÂ will first appear as dark, irregular lesions on the surface of the tree’s leaves. Often, those lesions are encircled by red edges that join close to one another.Â
In time, the spots will spread along the edges of the leaf and within its veins.Â If left untreated, the fungi will completely kill the affected leaf. Then, they will spread down through the leafstalk, or petiole, and attack the adjacent twigs.
This can result in major spring leaf drop, as well as limb dieback. Infected Flowering Dogwood trees can also developÂ epicormic sproutingÂ in affected areas along their trunk.Â
The severity of these symptoms hinges on the amount of rainfall in the climate, as well as the temperatures that occurÂ when the buds break and leaves emerge in the spring.Â Note that leaf drop tends to occur primarily in the spring, when the weather is cool and wet. Specifically, temperatures below 55 degrees Fahrenheit are most likely to increase the severity of this condition.Â
Infected treesÂ tend to retain their leaves in the fall. In any season, the infection can also make the tree more susceptible to future pests.
What to Do About the Problem
If you suspect that your tree has developedÂ Anthracnose leaf blight, then prompt treatment is key.
If possible, treat your tree in the late summer or early fall, before the infection has time to take hold.Â If you choose to treat in the spring, then it’s best to do so as early as possible, before new twigs are affected by the traveling fungal spores.Â
If you live in our around Charles, Calvert St. Mary’s, orÂ Anne Arundel County, our team is here to help. We can recommend a trunk injection treatment that will inhibit fungal cell development while strengthening the tree from the inside out.Â