Knowing how much of our city is shaded by ash trees, I have been dreading the inevitable season when the voracious emerald ash borer strikes in earnest. It always helpsl to feel as if you're doing something, so the Park Board and the University of Minnesota are offering such an opportunity on Saturday in Powderhorn Park, home to 160 ash trees, the park board announced Thursday.

Starting at 10:30 a.m., volunteers will tag Powderhorn's ash trees with information on how to identify them and the telltale signs of emerald ash borers, an invasive insect that has already devastated millions of ash trees throughout the Midwest and elsewhere in North America.

The University of Minnesota Tree Care Advisors, a program that creates a squad of citizen tree experts, is one of the event organizers. The park board says a potluck will follow the ash tagging event. Sign up at www.mntca.org.