The Silent Invasion: How a Microscopic Nematode is Harming Beech Trees

On Tuesday, June 3, Tenafly Nature Center hosted a professional development workshop focused on the treatment of Beech Leaf Disease (BLD), a growing ecological concern across the Northeast. The event, held in partnership with Rainbow Eco-Science, brought together over a dozen arborists, foresters, and conservation professionals for hands-on training in the latest treatment methods.

BLD, first discovered in Ohio in 2012 and reported in New Jersey by 2020, primarily affects the American beech (Fagus grandifolia). For years, the cause of the disease was unknown, but researchers have since identified a microscopic nematode, Litylenchus crenatae mccannii, as the culprit. This roundworm infests and feeds on the tree’s buds before leaf emergence.

Symptoms of BLD include:

• Dark striping between leaf veins, curling, or leathery texture

• Diminished bud and leaf production

• Premature leaf loss, especially during summer months

These symptoms interfere with the tree’s ability to photosynthesize and store essential carbon reserves, placing mature trees at risk of fatal decline within 2 to 6 years if left untreated. Given the American beech’s role as a dominant, late-successional species in Northeastern forests, the spread of BLD poses a serious ecological threat.

Fortunately, a treatment developed in part by Rutgers University offers new hope. A systemic injectable fungicide/nematicide — also used in managing Dutch elm disease — has shown promising results. Although the treatment process is labor-intensive and expensive, it provides a viable option for protecting high-value or ecologically significant beech trees.

During the July 3 workshop, participating professionals received detailed instruction on the proper application of this treatment, ensuring it is administered effectively and safely. Events like this are part of Tenafly Nature Center’s ongoing commitment to environmental education and forest health.