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In The News

The Plant Health Toolkit

When it comes to yard care, bugs can be your best friends

HOCKESSIN, Del. (July 6, 2017) – Leading a group of gardening students underneath a sour gum tree (Nyssa sylvantica) along Mt. Cuba Center’s driveway, Jimmy Testa gently pulls down a branch to show students what he sees. “This is a wheel bug nymph,” he points to a red and black insect no bigger than a pencil tip. “This guy will hunt down pests in the garden.”

Testa and students

Jimmy Testa teaches students to identify garden pests and their natural predators

Though this wheel bug is small now, it will grow into a fierce-looking insect with a spine that looks like the blade of a circular saw with an even sharper bite – it attacks with a strike from its proboscis, delivering venom that kills prey within seconds. Humans who attempt to handle this insect can receive the same—but certainly nonlethal—sting. Consider it a friend, though, because this predator insect keeps landscape-devouring pest infestations at bay.

Wheel bug (Arlius cristatus)

The wheel bug (Arlius cristatus) is a predator in the garden, keeping pests at bay.

Testa, a Mt. Cuba Center horticulturist and plant health care specialist, is practicing a process called integrated pest management, or IPM, to encourage beneficial insects, like wheel bugs, to consume the bad ones.

“Ecological plant healthcare is a newer term in the industry. It was just IPM for the longest time, and that’s a great tool in the toolbox, but that mostly focused on insect and disease management,” Testa said. “Nowadays, we know there’s much more to plant health like pruning, plant selection, soil quality and the environment. It’s more than just managing insects. It’s about looking at your entire yard as a whole ecosystem.”


There are two major factors affecting plant health – the bugs and fungi that interact with it (called biotic factors) and the environmental conditions like soil type and where the plant is placed in the landscape (the abiotic factors).

The root flare of this young tree is buried

The root flare of this young tree is completely covered. This will cause problems for the tree as it grows.

“A lot of things that we deal with from a plant health care standpoint are abiotic,” said Mike Leventry, Owner of Verdant Plant Health Care, LLC. “It’s about managing the environment to maintain the plant in a way that you are happy with, and managing your inputs to the environment.”

One of those inputs is plant selection, which is where proper plant health care begins.

“Someone could pay a lot of money to have a tree installed, but from the moment that tree comes off the truck it’s destined for failure,” Leventry said. Trees can be buried too deep in soil even while still wrapped in a protective layer of burlap. Where the trunk meets the roots should flare out at the top of the soil like bell-bottom jeans, instead of like a telephone pole. This part of the tree is called the root flare.

“I like to tell folks to take a couple minutes with a shovel or hand rake to expose the root flare of a new tree,” Leventry said. “Sometimes even on a brand new tree the root flare will be four inches below the soil — that’s just not good for the tree.”

Natural predators can control aphid infestations

Natural predators, like the wheel bug, can keep aphid populations at bay.


The first step to practicing environmentally sound plant healthcare is to get to know your garden. Taking time to figure out what plants are growing—and thriving—as well as the sun, shade, water and soil conditions in different areas of the garden can go a long way when it comes to identifying problems and planning solutions. (When in doubt, consult your local extension office. They answer questions for free, and conduct soil tests.)

“Pay attention to where water flows on your property. That’s the number one thing for root health,” Leventry said. “I commonly see people plant rhododendrons at the corner of a house—they’re a good plant to put against your house—but the corner of the house is where the downspouts are, and that’s a plant that really doesn’t like to have an abundance of water.”

Knowing the garden’s growing conditions makes selecting successful plants from the garden center easier. First and foremost, opt for native plants, Testa says.

Wheel bug (Arlius cristatus)

“They’re the best plants out there, they don’t have as many pest and disease problems,” Testa said. “Most of my budget for dealing with pests and disease goes to the non-native plants in the garden. I’m always fighting issues on the lilacs, the boxwoods, the yews.”

Native trees are especially important members in the landscape, Leventry said. “If someone’s making the decision to plant a tree, that tree is going to be the only tree on that spot from now to 150 years from now, so let’s make sure that’s a native tree that has all the potential habitat for insects and birds.”

While at the nursery, be a discerning shopper. Inspect a plant thoroughly before bringing it home.

“You should be picky about what you put in your yard,” Testa said. “Look at the leaves; see if there are any insect eggs or other signs of pests. Remove it from the pot or burlap and look at the roots, and be suspicious of the discount plant rack – the plant probably hasn’t been sold for a reason.”


When it comes to plants that are long established in the garden, checking the landscape regularly can prevent big headaches later.

“Almost every time someone calls me, I wish they called earlier,” Leventry said. “In some cases, by the time I get there or another plant healthcare person gets there, the damage is already done.”

Looking at the base of trees and shrubs—the roots, root flare, and trunk—can be a good warning for problems on the horizon.

“It all starts down at the base,” Leventry said. “If there’s something wrong with the canopy, or if it’s dying back, there’s a problem in the base of the plant.”

Tree health starts with proper planting

Insects that are present this time of year include aphids and the brown marmorated stink bug. Both can be handled without chemicals. Consider tolerating some presence of aphids in the garden, since they attract the beneficial insects that will keep infestation at bay. However, if it looks like they will cause excessive damage–or are on a plant of sentimental value—a strong stream of water from the garden hose or a spray of organic horticultural oil should take care of them.

Brown marmorated stink bugs can cause severe damage to plant, especially lilac, hibiscus and dahlia. Even more challenging, chemicals are ineffective against them. So, spray them with soapy water, or suck them up with a vacuum and seal them in a garbage bag before throwing them out. Wheel bugs prey upon this insect.

Summer is a time when plant health care issues present themselves. Gardeners who want to learn more about plant health care and integrated pest management can take classes at Mt. Cuba Center, like Integrated Pest Management ($185). Taught by Mike Leventry, this three-session course starting on Thursday, July 13 will teach students how to sustainably manage insect pests in the garden. Plant Disease Management ($125) with Robert Mulrooney takes place on August 4 and 11. For a more basic overview of the topic, students can take Plant Health Care Diagnostics ($90), taught by Mike Leventry, on Wednesday, August 9.

This article originally appeared in the News Journal on July 6, 2017.