DETROIT, Mich. (WXYZ) — Homeowners across Metro Detroit are being warned to keep a close eye on their boxwood shrubs as the popular plants face a growing number of threats — including diseases, pests, harsh weather, and a newer invasive pest that can cause rapid, widespread damage.
Boxwoods are among the most common plants found in yards throughout the region.
"When you go through most neighborhoods around the area, just all throughout Michigan, they are abundant, on everyone's property," Chris Ellison, a garden pharmacist with English Gardens, said.
But more homeowners have recently noticed their once-green boxwoods turning brown.
"I'm looking at my boxwoods, I had three that were just totally brown in one area that I took out and then I had a hedge that was half dead," Tricia LaSota, a boxwood owner, said.
Staff with Michigan State University Extension say the health of boxwoods can be impacted by several factors, including harsh winters and droughts. Diseases like boxwood blight, and a range of pests, also pose ongoing risks.
"Things like boxwood psyllids, spider mites, the boxwood leafminer — (these are) all common pests they can get," Caitlin Splawski of MSU Extension said.
Now, a newer threat is proving especially damaging to the plant.
"It's called the box tree moth and they exclusively feed on boxwoods," Splawski said.
Experts say the box tree moth is native to East Asia and arrived in Michigan in 2022. The pest does its most damage in its caterpillar stage and is currently under quarantine in 13 counties in the southeastern portion of the state.
"You could go away for the better part of a week up north on vacation, not knowing those caterpillars have been there, and then you get back home and half of your shrub is brown and defoliated," Ellison said.
Experts say early detection is critical to protecting boxwoods from the moth.
"When the caterpillars are younger, they actually fold or sew the leaves flat shut together and they will hide in there before we start feeding," Ellison said.
Ellison recommends spraying an organic insecticide known as BT to help kill the pest. Using the right fertilizer can also promote new growth in affected shrubs.
"We are finding that this Boxwood Turbo Grow is superior to anything else we've used in the past," Ellison said.
Homeowners with questions about their boxwoods can consult professionals at English Gardens. Plant samples can also be sent to the MSU Extension lab for analysis.
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