Most Common American Elm Tree Pests:
Identification and Treatment Guide

American elm trees are beloved for their graceful arching branches and vibrant fall foliage. However, these majestic trees are susceptible to various pests that can threaten their health and longevity. In this guide, we will explore some of the most common pests that can afflict American elm trees, how to identify them, and the best treatment strategies to protect your trees.

Dutch Elm Disease

One of the most devastating threats to American elm trees is Dutch elm disease (DED). This fungal infection is spread by elm bark beetles and can quickly kill a tree if left untreated. Symptoms of DED include wilting leaves, yellowing foliage, and visible streaking in the wood under the bark. If you suspect your American elm tree has Dutch elm disease, it is crucial to act quickly to prevent further spread.

Treatment: The most effective treatment for Dutch elm disease is prompt removal and destruction of infected trees. Additionally, fungicide injections can help protect healthy trees from becoming infected. Proper sanitation practices, such as removing and destroying infected branches, can also help prevent the spread of this devastating disease.

Elm Leaf Beetle

Elm leaf beetles are another common pest that can wreak havoc on American elm trees. These small, yellowish-green beetles feed on elm leaves, causing defoliation and weakening the tree over time. Signs of an elm leaf beetle infestation include skeletonized leaves and droppings on the ground beneath the tree.

Identification: Elm leaf beetles are small beetles with distinctive yellow and black stripes on their bodies. They often congregate in large numbers on the undersides of leaves.

Treatment: To control elm leaf beetle infestations, consider using insecticidal sprays or introducing natural predators like ladybugs or lacewings to your garden. Regularly inspecting your trees for signs of infestation and promptly addressing any issues can help prevent widespread damage.

Elm Scale Insects

Elm scale insects are another common pest that can affect American elm trees. These small, oval-shaped insects feed on the sap of the tree, causing yellowing leaves, stunted growth, and branch dieback. Heavy infestations can weaken the tree and make it more susceptible to other pests and diseases.

Identification: Elm scale insects are small, flat insects that attach themselves to the bark or leaves of the tree. They secrete a sticky substance called honeydew, which can attract ants and promote the growth of sooty mold.

Treatment: To control elm scale insects, consider using horticultural oils or insecticidal soaps to suffocate the insects. Pruning heavily infested branches and improving tree health through proper watering and fertilization can also help reduce scale populations.

Elm Phloem Necrosis

Elm phloem necrosis is a condition caused by a phytoplasma infection that affects American elm trees. This disease is spread by leafhoppers and can lead to wilting leaves, branch dieback, and overall decline in tree health.

Identification: Symptoms of elm phloem necrosis include yellowing or browning of leaves, twig dieback, and abnormal growth patterns such as witches’ brooms.

Treatment: Unfortunately, there is no cure for elm phloem necrosis once a tree is infected. Preventative measures such as controlling leafhopper populations and maintaining tree health through proper watering and fertilization can help reduce the risk of infection.

Conclusion

Protecting your American elm trees from common pests requires vigilance, early detection, and prompt action. By familiarizing yourself with the signs of infestation and implementing appropriate treatment strategies, you can help ensure the health and longevity of these iconic trees in your landscape. If you suspect your trees are being affected by pests or diseases beyond your control, consider consulting with a professional arborist for expert advice and assistance in preserving your valuable green assets.