Morton Arboretum's Plant Clinic fields questions about tree health

  • The emerald ash borer has killed thousands of trees across the suburbs. Questions about protecting and replacing ash trees are among the most common queries posed to the staff and volunteers at the Morton Arboretum Plant Clinic.

    The emerald ash borer has killed thousands of trees across the suburbs. Questions about protecting and replacing ash trees are among the most common queries posed to the staff and volunteers at the Morton Arboretum Plant Clinic. Daily Herald File Photo

Updated 8/25/2015 9:28 AM

A row of large sprawling trees that once formed a lush canopy over suburban streets lay stacked in manageable lengths along the curb waiting to be hauled away. It is a sad sight. The destruction a half-inch metallic green beetle can cause ash trees is hard to comprehend.

The emerald ash borer first was confirmed in Illinois in 2006. In Lisle alone, 1,042 trees will be or have been removed due to the insect, according to the Arboretum Village's website. The problem is compounded in larger communities. Morton Arboretum experts estimate 10 percent to 40 percent of a community's trees may be ash.


Whom can homeowners turn to for information? What can we learn from this hardship?

The Morton Arboretum in Lisle is our collaborator in finding answers. Its Plant Clinic has the knowledge and experience to help, backed-up by a team of scientists, professionals and dedicated volunteers.

In June alone, 1,183 people contacted the clinic, according to Sharon Yiesla, plant clinic assistant. Roughly 15,000 inquires come to the free clinic in a typical year. Situated in its own offices directly across the courtyard from the arboretum's Visitors Center, the volunteers and arboretum staff are a wealth of information that could help homeowners and communities.

Besides the emerald ash borer, the most-asked question this year has been about the beautiful magnolia that has large fragrant blossoms in early spring before it leafs out.

"The season's big question has been about magnolia scale, which is very prevalent this year," Yiesla said. "With all the rain this season, we are getting numerous calls on a widespread range of fungal problems."

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The Plant Clinic has a convenient three-page handout all on the scale insects. The magnolia's symptoms include a sticky, dripping material called honeydew and a dark fungus called black sooty mold that drops onto plants, sidewalks and whatever is below the magnolia. In late July and August, the young crawlers emerge from white weblike dots.

The Plant Clinic can inform you about steps to take if this is a problem in your landscaping. Be prepared to use good sanitation in the fall by getting infected leaves out of the garden.

The arboretum began its Plant Clinic in 1929 with one staffperson answering questions. In 1968, the Plant Clinic established regular office hours and a rotation of staff. By 1992, volunteers were recruited and trained for the clinic. This year, the clinic has two full-time staff members and 52 trained volunteers, Yiesla said. They do not need any additional volunteers at this time.

Both nonmembers and members of the arboretum can contact the Plant Clinic in person, by phone or by email.

"The clinic, in conjunction with other staff and volunteers, also publishes Plant Health Care Reports to alert readers to current pest problems," Yiesla said. "When we see things coming into the Plant Clinic or our scout reports on our grounds, these are reported on our website."


The web address is

While you might expect the Plant Clinic to answer all your tree-related questions, it also answers questions on garden flowers, plant and weed identification, and many more garden and landscaping questions.

Helpful tools at the website allow you to list your preferences and select a tree that will meet your criteria. Another useful feature identifies all the plants you may see in container gardens on the arboretum grounds to make it easy to implement at home. The website has all containers numbered and located on a map.

"We want people to use the services of the Plant Clinic at the Morton Arboretum," Yiesla said. "Our advice is science-based and unbiased."

In the summer, the clinic is open 10 a.m. to 4 p.m. Mondays to Saturdays. Winter hours are 11 a.m. to 3 p.m. weekdays. Admission to the arboretum applies for in-person visits.

What can we learn from the emerald ash borer invasion?

"We preach to diversify our tree selection so this doesn't happen again," Yiesla said. "We encourage people to look around and if your neighbor has a certain tree, plant something completely different. Sometimes a certain tree gets repeated a lot in one neighborhood, so we try to encourage people to plant different trees."

Yiesla encourages people to consider oak trees; some like the swamp white oak can make a good street tree. The ginkgo is a tree that does not have a lot of problems.

Yiesla said that entomologists, scientists who study insects, warned about this because in 2012 there was a drought that stressed trees. We were alerted that we would see an increase in wood boring insects and an increase in scale, and we are seeing both now.

Trees add beauty, shade and wind-breaking attributes, which are valued components in all landscapes. It is important that we learn more about these valued statesmen in our environment, and there is no better place to experience trees than at the Morton Arboretum in Lisle where trees are essential to its mission.

• Joan Broz writes about Lisle. Her column appears monthly in Neighbor.

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