Residents may want to keep an eye on their Oak trees for signs of premature decline. Oak Wilt disease has been more prevalent in the Palos area this year than in years past. All species of oaks are susceptible to Oak Wilt; however trees in the red oak family (e.g., black, red, pin, and scarlet oaks) typically die within 1 year of the fungal invasion. Red Oaks often die in less than one month after symptoms appear.

Evidence of Oak Wilt will appear at or near the top of the tree. Leaves turn dull green, bronze or tan, beginning along the tips and leaf edges. Leaves at branch ends will begin to fall soon after symptoms appear Discoloration and defoliation will progress throughout the crown within weeks as twigs and branches die. Total defoliation and death will transpire over a short period of time sometimes leaving tan leaves clinging throughout the winter to killed oak trees that normally drop all of their leaves during winter months.

Oak Wilt is caused by a fungus (Ceratocystis fagacearum) which clogs the vascular system of oak trees preventing the flow of water and nutrients. Red Oaks are more susceptible than members of the White Oak family because they do not have the ability to produce tyloses or vascular plugs which White Oaks create to contain damage from disease. Although White Oaks have a natural defense system against this disease, the process is only slowed and not stopped. White Oaks may live for years fighting off the fungal invasion, however they act as a carrier for the spread of the disease.

Oak Wilt is spread mainly two ways—through insect transmission and root transmission. The main culprit in the spread of the disease is the Nitidulid beetle. The beetles transfer fungal spores attached to their bodies as they move from tree to tree. Severely infected trees and stumps should be removed immediately to stop transmission through the connecting root systems of the oak trees.

If caught early, Oak Wilt can sometimes be controlled with certain fungicide injections. Trenching or chemically killing roots between diseased and healthy trees can prevent transmission through root grafts. Although no treatment is a guarantee for success against Oak Wilt, anything done to save an oak helps contain the disease and keep it from spreading to healthy oaks.