Department Resources

Beech Leaf Disease

American Beech Tree

American beech (Fagus grandifolia) native to eastern North America, is a beautiful hardwood forest tree known for its smooth gray bark. Beech trees are critical to the native forest ecosystem. They provide food to a wide variety of wildlife including deer, small mammals, turkeys, and many other native birds. A hard mast tree, their fruit is a nutrient-dense nut, rich in essential fatty acids, vitamins, minerals, and proteins. These seeds last through the winter and serve as a food source when other plants have long stopped producing fruit.

Not only are American beech very beautiful trees, but they are also tied with red maple for the County’s most common tree species. According to an analysis conducted by the UFMD, there are approximately 4.3 million beech trees in the County, approximately 9% of all trees. Beeches are also a familiar ornamental tree in urban landscapes.

American Beech Leaves, photo credit Rob Routledge, Sault College, Bugwood.org — American beech leaves, photo credit Rob Routledge, Sault College, Bugwood.org

American beech fruit (nut), Bill Cook, Michigan State University, Bugwood.org

Beech Leaf Disease observed in Burke Lake Park

European beech leaves, Robert Vidéki, Doronicum Kft., Bugwood.org

Beech Leaf Disease (BLD) is a new disease of native American beech (Fagus grandifolia) as well as the commonly planted European beech (Fagus sylvatica), and some other Fagus species including ornamental cultivars such as copper, purple, golden, weeping and fern-leaf beech.

The disease is caused by a foliar-feeding nematode (a microscopic roundworm), Litylenchus crenatae subsp. Mccannii which is species-specific to beech trees. The nematodes enter the tree’s leaf buds in the fall where they overwinter, multiply, and feed on newly forming leaf tissues. The nematodes and the damage they have done are already present in the leaves when they expand in the spring. The nematodes multiply and spread throughout the tree from year to year until leaf buds no longer produce leaves. As healthy foliage decreases, the tree’s energy, nutrient, and water uptake decreases, and the tree eventually dies. BLD is nearly one hundred percent fatal. Seedlings and saplings die in one to three years; more mature trees in four to ten years. A small percentage of beech has shown resistance, but BLD has the potential to drastically alter the composition of forests in the eastern US. Research is ongoing to fully understand this disease.

BLD Nematode, photo by Paulo Vieira, USDA, ARS — *BLD Nematode, Photo Credit: Paulo Vieira, USDA-ARS*

Scientists are comparing these nematodes’ DNA with that of similar nematodes native to Japan to determine if that is its origin.

Life stages of the Beech Leaf Disease Nematode, Photo Credit: Paulo Vieira, USDA-ARS

Recent research shows that the nematodes that cause BLD are likely spread by birds, insects, rain and wind, and that other microscopic organisms may be involved. They move on water films on the tree and have been found in the leaf litter under infected trees. People can unknowingly introduce them to new areas by moving infected beech tree seedlings, saplings, tree parts, and leaf litter.

BLD was first identified around Cleveland, Ohio in 2012, and has subsequently spread into Michigan, Ontario, New England, New York, Pennsylvania, West Virginia, Northern Virginia, and Maryland.

In Fairfax, it has been found in several locations including Burke Lake Park, Pohick Stream Valley Park, Lake Mercer, NOVA Parks near Bull Run creek and the Occoquan River.

The symptoms of the disease first appear on leaves as dark green, interveinal stripes. It is usually identified first on saplings and the lower foliage of larger trees. Infected leaves may also become puckered, cupped, leathery or distorted. Some leaves on a single branch may be infected while others are not. It spreads throughout the tree and from tree to tree progressively from year to year.

Other diseases of beech leaves can sometimes look something like BLD, but if you look for the dark green interveinal stripes of BLD in May-June before beech leaves are typically affected by other diseases, the diagnosis is easier. The other diseases are native and are not serious on their own because if they are present at all in any given year, it would be later in the season. They can contribute to decline when BLD has already infected the tree.

Woolly beech aphid, photo credit Petr Kapitola, Central Institute for Supervising and Testing in Agriculture, Bugwood.org< — Woolly beech aphid, photo credit Petr Kapitola, Central Institute for Supervising and Testing in Agriculture, Bugwood.org

Eriophyid mites, photo credit Linda Haugen, USDA Forest Service, Bugwood.org

Erineum mites, photo credit Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org

Anthracnose, photo credit Nancy Gregory, University of Delaware, Bugwood.org

If you see beech leaf disease, you can report it to pestmail@fairfaxcounty.gov. Provide photos and a location with your report. You can also provide a report by phone 703-324-1770 TTY 711.

Additionally, you can report your sighting on iNaturalist. It is an easy-to-use app that shares information with other community scientists. Find directions on their website.

Research to find safe treatments is ongoing. Currently, there are no treatments proven to be effective for BLD in beech forests. UFMD is tracking the spread of the disease while safe treatments are sought. The County is not treating beech trees for BLD.

For yard trees we recommend good tree care such as proper mulching and watering during droughts. Beech trees are shallow rooted so protecting roots from mower damage and soil compaction is essential.

We recommend caution when considering soil treatments and treatments being offered by some tree care or landscaping services. PolyPhosphite 30 and other phosphate (0-0-27) fertilizers are known for stimulating plant defenses when applied to the soil around young trees 2” - 4”. However, potassium phosphate is a salt, so care should be taken not to apply too much, especially when attempting to apply it around a large tree or under dry conditions. Too much can harm or even kill the tree. It is against the law to apply at rates above what the label specifies. When applying chemicals the label is the law.

Broadform, a fungicide/nematicide, is a broad-spectrum treatment which can kill nematodes when sprayed on beech leaves; however, it should be applied by a professional arborist only under certain conditions. Foliar spray should only be considered for isolated beech trees. The spray does not enter the beech leaf buds where nematodes reproduce. Moreover, nematodes multiplying in nearby trees can migrate to re-infect the tree. The chemicals are highly toxic to aquatic organisms, so should not be used near bodies of water, or hardscape (pavement) leading to storm drains. If the tree is tall or overhangs a neighbor’s property it may not be possible to spray the foliage. The County does not recommend treating beech trees.

Trees under 4” diameter may do well with only phosphite soil treatments regardless of their proximity to other beech trees. Always follow the label directions.

UFMD is monitoring the spread of BLD, tracking the latest scientific research about the disease, and participating in research projects to help find safe Integrated Pest Management (IPM) tools to manage it.

If you see beech leaf disease, you can report it to pestmail@fairfaxcounty.gov. Provide photos and a location with your report. You can also provide a report by phone 703-324-1770 TTY 711.

Additionally, you can report your sighting on iNaturalist. It is an easy-to-use app that shares information with other community scientists. Find directions on their website.

Seedlings and saplings can die within 3 years, more mature trees in 4 to 10 years.

Pest Alert—Beech Leaf Disease

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Beech Leaf Disease