Common Landscape Pests and Plant Diseases: How to identify and Control Them

Plant-eating insects are small, but they can do huge damage to your commercial property, and fast. 

A plant disease might not seem dangerous at first. Maybe a
black spot or two, or a couple holes in a leaf. The next thing you know, a whole bed of plants is wiped out. 

We’re talking bugs that can devour an entire evergreen tree. A virus spread by mites can decimate your precious roses. And a massively destructive new pest on the scene is so dangerous to plants and trees, experts want you to kill it on the spot. 

Knowledge is power. What are the most common plant pests and diseases on your commercial property? Aphids. Bag worms. Japanese beetles. Grubs. Cankers. Rose rosette.

And what to do about them? It depends on the bug, but solutions range from picking them off by hand to hosing them off to calling in professionals for skilled disease treatment or Integrated Pest Management. (More on that in a bit.) 

Let’s learn more about common plant pests and diseases, including:

The Dangers of Diseases and Plant-Eating Insects

Spotted Lanternfly

Bagworms

Japanese Beetles

Aphids

Grubs

Cankers

Juniper Twig Blight

Rose Rosette

Turn to Pros for Your Best Defense

First Up: The Dangers of Diseases and Plant-Eating Insects

Insects have a whole host of ways to destroy the plants, shrubs and trees on your commercial property. 

Some use sharp mouth parts to cut a plant’s stem, leaves or roots. Others pierce the plant’s outer layer, then suck the sap from the plant's cells. Still others bore into a plant's stems or a tree’s bark. Your precious plants can wilt, stop growing or die due to insect damage. 

Common plant diseases have their own array of destruction. Diseases can kill plant tissue, cover leaves with ugly black spots, and clog a plant’s vascular system, so beneficial water and nutrients can’t reach all parts of the plant. 

What are the most common plant pests and diseases lurking on your property? 

Let’s start with the most common plant pests and we’ll kick it off with a new guy: 

Spotted Lanternfly

This destructive invasive insect used to be other states’ problem, not a concern here in the Mid-Atlantic. Not anymore. 

Originally from Asia, the spotted lanternfly was first detected in Pennsylvania in fall 2014, when a shipment of stone from Asia arrived there with lanternfly eggs aboard.

But a known hitchhiker, this plant-eating insect is now in every county in Maryland and has also spread to Connecticut, Delaware, Indiana, New Jersey, New York, Ohio, Virginia and West Virginia.

The spotted lanternfly poses a major threat, feeding on over 70 different types of plants and trees.

It devours and destroys plants, from orchards and vineyards full of fruit to valuable hardwood trees.

Its favorite host tree, Tree of Heaven, might be on your property. It’s a very common tree in Maryland, considered a nuisance tree that could be nestled at the back of your property in a wooded area.

The spotted lanternfly is a beautiful insect, with attractive speckled vibrant wings. But don’t let it fool you. 

What to do about it? If you see it, smash it. The U.S. Department of Agriculture strongly encourages people to stomp, squash or swat lanternflies when they see them.

And report your sighting to your Level Green account manager or the Maryland Department of Agriculture’s online survey.

Several agencies and universities are working on different control methods to stop the destructive plant-eating pest, but there isn’t a control procedure available yet. 

Meanwhile, it’s important to monitor for this pest, report it when found and to remove the spotted lantern fly’s favorite food source, Tree of Heaven, from your property. 

Bagworms

Bagworm caterpillars make 1 to 2-inch long bags that hang from the branches of trees and shrubs. Inside: 300 or more eggs. When the eggs hatch in the spring, the tiny larvae crawl out — and they’re really hungry.

These pests can gobble up evergreen trees, stripping them of their needles. They love arborvitae, juniper and pines. 

What to do? Pull the bags off and crush them, if there are just a few of them.
If there are more than you can handle, call the experts. 

Japanese Beetles

These plant-eating insects can make the leaves of roses look like lace — and not in a pretty way. They attack other plants, too, including crape myrtles and birch trees.

Tempted to set out traps specifically designed for Japanese beetles? Don’t bother. Beetles might show up, attracted by the scent, but munch your plants instead of landing in the trap.

Aphids

If you love azaleas, you hate aphids. The beloved flowering shrubs are among their favorite feasts.

Plant pest identification tip: Aphids are small oval bugs and can be brown, yellow, green, red or black and have antennae.
(There are thousands of varieties.) A few aphids won’t do much harm. But if your yard is infested with them, aphids’ appetites will cause wilted leaves and will stunt your plants’ growth.

They also ooze a sweet, sticky fluid that attracts ants and causes a black mold to grow on leaves.

What to do? You can try to hose aphids off of your plants or buy a batch of ladybugs to release on your property. They love gobbling up aphids.

Grubs

These squishy critters are as icky as they sound. Turf pests, they eat your lawn’s root system, causing large sections of grass to die and pull away easily from the soil.

Lawn grubs are actually the immature form of beetles, from Japanese beetles to June bugs.

Plant pest identification tip: White and C-shaped, their bodies are soft and their legs are up near their heads. They eventually turn into adult beetles, emerging from the ground to mate — and create even more grubs.

What to do? Prevention is the best plan of attack. Lawn care pros apply a preventative grub control product in the spring to stop grubs from hatching in the first place. 

Next Up: Damaging Diseases and Plant Disease Identification 

Diseases can be as dangerous to your commercial landscape as insects, settling in and spreading quickly.

Some of the common plant diseases that are the worst offenders:

Cankers

Cankers are dead sections of bark on trees and shrubs, often caused by bacteria or fungus. If enough of a tree or shrub’s bark is affected, all of the plant above the canker can die.

As branches weaken and die, they typically fall off, posing a hazard to people and property below. 

Plant disease treatment? The best defense is to keep trees and shrubs healthy, so they can better resist common plant diseases. Landscaping pros carefully remove the infected parts, sterilizing their equipment between cuts.

Juniper Twig Blight

Juniper twig blight is a fungus that attacks the new shoots and tips of junipers, as well as arborvitae, usually in early spring. The disease will gradually spread into the center of the plant.

What to do about plant disease treatment? Professionals prune out the affected branches, then rake up and dispose of all the debris. 

Rose Rosette

Rose rosette is the latest rose virus confounding experts, as there’s not much that can stop it. It’s slowly taking over even roses that have been bred to be disease resistant, like the Knock Out variety. 

Plant disease identification tip: Infected bushes first show reddened stems and stunted growth. Flowers start to die, and an infected plant can die within a couple years.

What to do for plant disease treatment? Landscaping pros dig up infected plants and dispose of them. Then they keep a close eye on neighboring plants for symptoms.

Level Green Experts: Your Best Defense

These are all good tips, but do you really have time to survey your entire property’s landscaping for insects and common plant diseases, then painstakingly pick off bugs or trim back diseased branches? 

Of course you don’t. And even if you did, it’s often hard to tell what’s attacking your plants — pests in the landscape or disease? That’s where we come in. 

At Level Green, we’re experts in diagnosing the most common pests and landscape plant diseases.

Level Green uses Integrated Pest Management, IPM for short, an effective and environmentally sensitive approach to pest management that uses knowledge about the life cycles of pests and their interaction with the environment to solve pest problems —  while minimizing risks to people and the environment.

We know exactly how to banish common pests and landscape plant diseases so your plants can return to great health — without harming the other, unaffected plants in your landscape.

While you might spray the heck out of your property to try to nab the offender, we’re more targeted in our approach. We know, for instance, that the insects on your roses won’t migrate to the junipers next to them, so we won’t spray the junipers. It’s a safer way to attack.

We can diagnose the difference between grub damage and lack of water. Or maybe your offender is a mole or vole. We’ll act accordingly.

Trust Your Plants’ Health To Level Green

Controlling common plant pests and diseases is a crucial part of commercial landscape maintenance in Washington DC, Maryland and Virginia. 

If you’re not already a Level Green Landscaping client, we’d love to add you to our growing list of happy customers. 

Our focus is on commercial properties like offices, mixed-use sites, HOAs, municipalities and institutions in Maryland, Washington DC and parts of Virginia.

Contact us at 202-544-0968. You can also request a free consultation online to meet with us one-on-one.

We’d love to hear from you.

Image sources: bagworm, japanese beetle, aphids, grub, scale, cankers