Dishonorable Mentions There are many other pests to watch for in 2026. Oak wilt ( Bretziella fagacearum ), laurel wilt disease ( Har- ringtonia lauricola ), Phythoptera blight and root rot ( Phytophthora spp. ), spongy moth ( Lymantria dispar dispar ), hem- lock woolly adelgid ( Adelges tsugae ), box tree moth ( Cydalima perspectalis ), and southern pine beetle ( Dendrocto- nus frontalis ) are just a few contenders that urban foresters should keep an eye out for. Kevin Brewer, Northeast regional tech- nical manager at Arborjet | Ecologel warned that climate will play a critical role in shaping the epidemiology of fu- ture pest infestations. “Trees in the Northeast and Midwest are being exposed to new disorders, and climate change is a major influenc- ing factor,” he said. UNDER PRESSURE Climate change is a major driver of the urban forest health crisis. Phytopathol- ogists, entomologists, and plant health care specialists have long forewarned the convergence of climate with other stressors and the deleterious conse-
Beech leaf disease (BLD) is a deadly disorder of beech trees caused by a parasitic nematode. Look for dark- green banding, thickened or leathery texture, and yellowed, curled, or deformed leaves.
mented before, a warning that invasive species recognize no boundaries and can impact communities everywhere. “Beech leaf disease continues to dom- inate concern among tree and na- ture-lovers in much of the Eastern Unit- ed States,” he said. “Just last month, I visited the first site of BLD discovery in North Carolina, with the nematodes having made, rather inexplicably, their way to yet another new state.”
Beech Leaf Disease Beech leaf disease (BLD) is a lethal disorder affecting beech trees ( Fagus spp. ), caused by the parasitic nematode ( Litylenchus crenatae ssp . mccannii .) Ef- fective treatments have been developed for specimen trees and further man- agement research is ongoing. Diseases also pose a significant risk to tree health. Virulent pathogens can quickly multiply and disrupt a tree’s physiological processes, resulting in di- minished canopy cover over time. The rise of one emergent disease has left many industry professionals feeling increasingly uneasy, raising serious concerns for the future of our beech forests. “The threat I am most concerned about is the rapid spread of beech leaf dis- ease,” Tammy Sons, founder & CEO of TN Nursery confided. “Native beech trees are being decimated by this dis- ease, and research is still underway to learn how to manage it.” Dr. Matthew Borden, research scien- tist/plant pathologist at Bartlett Tree Research Laboratories reported how BLD detections are surfacing in areas where the disease had not been docu-
The hemlock woolly adelgid is an invasive insect that attacks hemlock trees by feeding on their sap, leading to tree decline and death. Recognizable by white, cotton-like egg sacs it produces on the underside of branches.
10 | Winter 2026 ArborTIMES ™
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