It’s Important to Check for Beech Leaf Disease

Quick Facts About Beech Leaf Disease

• Beech Leaf Disease (BLD) is a new disease to the United States.
• This disease poses no threat to humans.
• BLD causes rapid decline and mortality of American beech and European beech; mortality can occur between 2 to 10 years depending on the size of the tree. BLD has also been reported to impact Oriental beech and Chinese beech.
• BLD is caused by an invasive nematode, which is a microscopic roundworm that cannot be seen with the naked eye.
• BLD is recognized best by opaque banding of diseased leaf tissue (see photo below).
• Infection starts in the leaf buds.
• Highly infected and damaged leaves become thickened, distorted, prematurely shed, and branch dieback ensues. Decline and mortality follow.
• Thiabendazole, the active ingredient in Arbotect 20-S, is currently the most effective treatment option. Proper application is key to high efficacy and beech health.

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Disease Distribution - In the United States, Beech Leaf Disease (BLD) was first discovered in 2012, in Cleveland Ohio. Since that time, the disease has spread from Michigan to Canada, Maine and south to Virginia to include New Jersey.

Infection and Life Cycle - The contagious nematode only infects beech species and is limited to the leaf and leaf bud tissue and overwinters in infected buds. In late-winter or early-spring, eggs are laid in the infested tissues and are moved within the leaves as they expand in the spring. Juvenile nematodes are found in symptomatic tissues by mid-summer and adult populations build into the fall. As the season progresses, adult nematodes exit the leaf tissue and migrate to next year's leaf buds.

The infected banding can become thickened, hardened, and sometimes discolored or yellowed. The progression of leaf symptoms can be rapid from one year to the next. Highly infected leaves become malformed, thickened, shriveled, and shed. Defoliation generally occurs from the lower canopy and moves upwards.

Impacts - American beech help maintain forest health, ecosystem functioning, habitat provision, and wildlife resources. The loss of these trees throughout its range will lead to a decline of forest quality, ecological function, populations of flora and fauna, and overall biodiversity.

American beech provides abundant resources for wildlife such as larval hosting for hundreds of species of beneficial insects that are essential parts of the forest food web. Beech nuts, a wildlife superfood, are sought after by numerous forest mammals and birds. Beeches provide vital nesting sites and shelter. Without American beech as a resource, several wildlife and plant populations will be stressed, decline, or will be eliminated completely.

American beech is a long-lived growing for 300–400 years. It grows in the shade of other trees, provides deep shade at maturity, and inhibits growth of earlier succession flora as well as invasive plants.

Management/Treatment - To date, cultural control options have not yet been shown to prevent disease. Pruning of initially infected leaves and small branches may slightly slow infection progression, but pruned trees can re-infect the tree.

Thiabendazole, the active ingredient in Arbotect 20-S, is currently the most effective treatment option. Proper application is key to high efficacy and beech health.