Landscape Pests: Identification And Control

Many outdoor pests attack gardens and landscapes, which can prove difficult for homeowners to control – not to mention frustrating! Often times, homeowners can’t identify the issue themselves in order to care for it, or it simply goes unnoticed, causing issues for plants and trees down the road.

Emerald ash borer (EAB), white grubs and Japanese beetles are three common pests that we want to feature so that homeowners can know how to identify the pests and know what needs to be done to control them. We’ll walk you through what each pest is and the plants that are susceptible to them, the symptoms you can watch for, the damage that can ensue, and what options you have for treatment.

Our tree and plant care experts are trained to identify and treat pests in your landscape. We can provide a consultation on your property to assess and determine if your lawn, plants or trees are at risk. We have International Society of Arboriculture Certified Arborists and lawn experts on staff who will properly diagnose the problem and can give you an accurate and educated recommendation. If you’d like an expert to visit your property, give us a call at 515.987.0800 or request a quote.

Emerald Ash Borer

Description

Emerald ash borer, commonly referred to by its acronym EAB, causes significant damage to native American ash trees. As you may know, it has become well known throughout Iowa, after it first reached our state in 2010 and quickly made its way into the metro. Many local communities have been hit hard by this pest due to their large number of ash trees. Where there are ash trees, there is concern of an EAB infestation.

Symptoms

If EAB has started infesting the ash tree, the tree might see thinning and yellowing leaves, D-shaped holes in the bark, and canopy and bark loss. The damage is caused by larval feeding in a serpentine pattern underneath the bark. This prevents the ash tree from transporting much needed nutrients throughout the tree to the leaves. In response to the damaged tissue, the tree will sprout new branches. Essentially, the vascular system of the tree becomes damaged leaving the tree unable to hydrate itself. The canopy will begin to decline because the leaves are not receiving adequate water. Eventually, the bark will split where there is dead vascular tissue. Ultimately, the tree will die. The higher the EAB population, the more quickly trees can die. A small tree may die within one to two years of becoming infested whereas a large tree has a window of three to four years.

Timing & Life Cycle

Due to the severity of damage caused by this pest, many people choose to take a proactive approach, before the tree is showing any signs of damage, which includes insecticide treatments. The severity of the infestation and time of year are two factors to consider. In addition, understanding the insect life cycle can help determine treatment options. From August through October, the EAB’s larvae feed on the host tree. The larvae bore through the bark into the cambium layer of the tree. After feeding, the larvae overwinter in the host tree and emerge as adults in late spring.

Treatment & Solutions

You have the option to chemically treat the tree or remove and replace the tree.

Chemical Treatment

Does your tree provide valuable shade, curb appeal or sentimental value? You can choose to protect it. Treatment for EAB is a systematic insecticide to control the pest population. Our process involves a trunk injection. Treatment can actually be a less expensive option than removal and replacement. The preventive treatment is affordable, effective for up to two full growing seasons, and performed from April through October (depending on weather). Due to the aggressiveness of this pest, treatment does not guarantee an ash tree will not become infected.  Unfortunately, if the EAB has severely infested an ash tree, removal of the tree may be the best choice.

Removal & Replacement

Without treatment, EAB damage will cause your ash tree to need removal. You can get a jump start on replacing the value your tree provides by removing it now and planting a replacement. The removal and replacement cost varies and depends on many factors including the tree size and location.

Annual White Grubs

Description

Annual white grubs are one of the most serious and often destructive pests that attack lawns. Not every lawn will become infested with grubs and not every lawn will have the same extent of damage if infested, but when it strikes, this pest will feed on grass roots and cause sections of grass in the lawn to die. These C-shaped creamy white grubs eventually turn into beetles and emerge from the soil to mate and lay eggs, which spawn more grubs, causing the problem to start all over again and spread to neighboring lawns.

Symptoms

Usually, it’s easiest to see the infestation in late summer or early fall. Early symptoms can appear as thinning, yellowing or browning grass, followed by scattered and random dead patches. When found in large numbers, annual white grubs cause serious lawn damage because they chew on grass roots. Grubs are especially prevalent in sunny lawns near pavements. In dry summers, heavily irrigated lawns may suffer more damage because adult beetles will be attracted to those areas to lay their eggs. In wet summers, grub populations usually are more dispersed and damage is less severe.

Lawn damage sometimes is compounded by raccoons and skunks, who dig for grubs. Occasionally, raccoons and skunks will return to a lawn after grubs have been eradicated, causing further damage. Other conditions also cause browning of turf grass, so it is important to identify grubs before deciding on treatment.

Timing & Life Cycle

Annual white grubs have a one-year life cycle. Adult chafer beetles are attracted to vigorously growing turf with damp soil, where they lay their eggs in July. The grubs hatch and feed on decaying organic matter and sod roots until October. When temperatures begin to drop, they tunnel downward in the soil to overwinter. In spring, the grubs move up in the soil and resume feeding. They pupate in May and emerge a few weeks later as adult chafer beetles.

Treatment & Solutions

Lawns can withstand a grub population of up to 12 grubs per square foot before suffering any damage, although lower populations may attract skunks and raccoons. At higher populations, chemical treatments are usually warranted and are generally applied in early July. Only areas of lawn with grubs or grub damage should be treated. It is unnecessary to treat an entire lawn if grubs are located only in certain areas.

Japanese Beetles 

Description

Japanese beetles are a small, metallic green insect. They feed on the leaf tissue, foliage, fruit and flowers of over 300 varieties of plants and trees. Though only a quarter of an inch long, these small insects can do major damage. Just a dozen beetles can devour a plant in a short amount of time. Japanese beetles also pose a risk to your lawn, as their larvae (white grubs) feed on and destroy the roots of plants, especially turf grass.

Symptoms

Devoured and skeletonized leaves are indicative of a Japanese Beetle infestation. Swarms of the insect attack their host, eating as they go. Favorite hosts include rose bushes, linden trees, flowering crabapple and cherry trees, viburnum bushes, elm trees, Japanese maple trees, plus many other trees and shrubs.

While the Japanese beetle won’t typically kill your trees and plants (unless the plant has endured infestations year after year), it will defoliate them, making them appear dead. The Japanese beetles begin by eating the tissue between the veins of leaves and continue until the plant is consumed, leaving only the skeleton. This, in turn, causes the tree or plant to become weak because it is unable to feed itself through photosynthesis.

Timing & Life Cycle

These pests are a seasonal problem: adult beetles typically appear in mid-June through July, feeding during a few weeks of the summer. In late August, the beetles will mate and lay eggs, which will emerge the next summer to attack again.

Treatment & Solutions

Control methods are varied. Although Japanese beetles are difficult to eradicate, insecticides offer a good protective measure. Our team of landscape experts offer an insecticide spray that kills the Japanese beetle on contact. The insect must be present to be effective. In addition, we also offer an option to inject the soil around the host with an insecticide that will kill the Japanese beetles when they begin feeding on the tree or shrub. This option must be done in early spring or late fall for optimal effectiveness. Overall feeding damage can be minimized if control is implemented when the Japanese Beetle first arrives.

If you have plants or trees that are potential candidates for a Japanese beetle infestation, you can check the foliage for a lacy, weakened appearance, looking for holes where the beetles have eaten through the leaf. If you do notice these warning signs or have plants or trees that are potential candidates, give us a call.

Or, if you choose to go the do-it-yourself route, it is important to know the target and surrounding plants, as well as understand that all insecticides can kill bees if used at the wrong time. If you want some guidance, our staff is trained in proper treatment and can perform soil injections to stop these insects before they destroy your lawn, plants and trees. The injection heads straight to the vascular system of the plant or tree and serves as a protectant from the beetles.

Give us a call at 515.987.0800 or request a quote online. Remember – always have your trees examined and worked on by an ISA Certified Arborist, as they are specifically trained in tree care.

Photo credit:

• Japanese beetles feeding on leaf courtesy of Iowa State University Extension & Outreach
• White grubs feeding on grass roots courtesy of L. M. Vasvary