Public Works crews have begun the process of removing 60sycamore and London plane trees in public parkways that were severely damaged by sub-zero temperatures and other physiological factors last week.
On January 7, City Forestry staff responded to a 3-1-1 request regarding a large split in the trunk of a sycamore tree on the 2200 block of Dodge Ave., and discovered several other nearby trees in similar condition. Public Works immediately launched an inspection of all 303 sycamore and closely-related London plane trees on public grounds, and found that 60 retained deep frost cracks, also known as “radial shakes,” that extended to the center of the tree or beyond. In addition, 76 trees had shallow cracks, while 167 trees showed no visible damage.
Because radial shakes compromise the structural integrity of the tree, leaving it susceptible to decay, Public Works crews are removing the 60 trees determined to have severe, irreparable damage. A list of the trees' locations is available at www.cityofevanston.org/assets/TreeDamage.pdf.
Extreme cold alone does not cause radial shakes, but greatly enhances the potential for damage. Because sycamore and London plane trees grow rapidly, seams along the trunk often develop and appear as ridges, which typically heal after each year’s new growth. The extreme cold that began on January 5 followed by intense sunshine caused many trees to split along those seams.
The City will continue to closely monitor the 76 trees with minor cracks, and periodically inspect trees across the city in the case of future sub-zero temperatures.
Residents are encouraged to inspect sycamore and London plane trees located on private property. To schedule an inspection by City Forestry staff, call 3-1-1 or visit www.cityofevanston.org/311.
The City of Evanston thanks the Morton Arboretum and local municipal arborists, who assisted in diagnosing the problem.