Japanese Beetle

July first marks the beginning of the emergence of the Japanese Beetle in our region. This service alert is designed to give you more information about this pest and a few tips on how to mitigate the damage.


The Japanese beetle is a serious pest of turf, trees and ornamental plants, and a difficult species to attack due to the complex nature of its lifecycle.

The Japanese beetle begins its destruction as a grub or larvae living 2-3 inches below the soil. Grubs feed on grass roots, reducing the ability of the grass plant to take up enough water and nutrients to withstand the stress of hot, dry weather. As a result, large dead patches of grass develop, which can be rolled back like a carpet to expose the destruction. Grub infestation may also be indicated where crows, moles, and skunks are found to be digging up the soil while feeding on grubs.

In early July, the grubs grow into adult Japanese beetles and begin to emerge from the soil to feed, mate and lay eggs. By the Fourth of July, adult beetles will begin to feed on trees, vines and other ornamental plants. This activity typically continues for 6-8 weeks, during which more than 60 eggs will be laid.

Japanese beetles feed in full sun at the top of plants, moving downward as the leaves are consumed. At dusk, the females fly to the turf to lay eggs, burrowing about 2-3 inches below the soil. Grubs hatch a few weeks later, growing quickly and eventually growing to about an inch by late September. Most beetles pass the winter about 2-6 inches below the surface, and then begin feeding in April or May when ground temperatures begin to rise.

Where You’ll Find Them

Around the Fourth of July, Japanese Beetles will begin emerging from the ground and feeding on the leaves of Linden, Birch, Maples and Crabapple trees, as well as rose bushes and other ornamental plants. The beetles will be found feeding between leaf veins, making the foliage look similar to lace. The insects prefer to feed on the outer portions of the foliage where the sun is strongest.

Control Methods

Treating Japanese beetles can be complex due to the nature of the pest’s life cycle and the distances travelled by adult beetles. An effective treatment program may require the application of insecticide to both the trees and turf.

Turf applications can be applied in the spring when the recently overwintered grubs start feeding. However, these grubs can be difficult to kill due to their large size and ground applications are generally more effective when applied in early fall.

If damage is found to trees and ornamental plants, treating adult Japanese beetles is recommended in July and August. The presence of beetles on a plant attracts more beetles. Therefore, by not allowing beetles to accumulate, the plants and trees will be less attractive to other beetles - benefitting the trees and ultimately the turf. In circumstances with advanced infestation, multiple treatments may be required.

Any tree treatment for Japanese beetles should be combined with a fall grub control program so that the life cycle does not repeat itself the following year.


Ascochyta is Back

As temperatures are starting to rise and the summer solstice is upon us, our turf experts are noticing a rise in cases of Ascochyta in the region. Ascochyta is a grass fungus and form of leaf blight that impacts Kentucky bluegrass, ryegrass and tall fescue. Damaged grass appears yellow or bleached, and is particularly noticeable in the mower track. Damage often seems to occur overnight and those unfamiliar with the problem often believe that their lawn has been damaged by a herbicide or similar chemical.

The Ascochyta fungus grows during wet conditions with lots of rain. During wet periods, the fungus spores spread throughout the lawn. Then as temperatures rise, the fungus quickly damages the stressed grass plant.

This year, our turf experts have been seeing damage for the last several weeks. Corporate sites with large, unshaded areas and uncovered athletic fields are particularly vulnerable. Residential sites are also being impacted but only in full sun areas.

The bad news is that there is no current treatment for Ascochyta. The good news is that impacted grasses typically recovers on theirown, with even severely damaged areas making a full recovery in three to four weeks. Raising the mower deck during your next mow may reduce the spread of the fungus while the grass plant works to recover.

For lawns that haven’t yet been impacted, continuing with a comprehensive turf health plan is the best prevention.  A lawn that has been properly watered (with about an inch of moisture per week) and properly fed (with a balanced lawn application program) will be less susceptible to stress and will give your grass plant the best opportunity to continue to thrive during the difficult summer months.

If you have any questions about the health of your residential lawn or commercial site, don’t hesitate to reach out to our turf professionals for a free inspection by clicking HERE.

EAB Update


DES MOINES – Beneficial insects that will help battle the emerald ash borer (EAB), a highly destructive pest of ash trees, will be released in Jefferson County. Over the next few weeks several thousand stingless, parasitic wasps will be released at Whitham Woods near Fairfield, Iowa. This is the first release of the natural enemies of EAB in Iowa.

When EAB was accidentally introduced into North America from Asia, its natural enemies, unfortunately, did not accompany them. This effort is being made to reunite pest and natural enemies to help suppress EAB populations. Following rigorous testing and research one or more parasitic wasp species, native to Asia, have been released in 23 of the 25 states where EAB has been detected. The parasitoids were produced and supplied by the USDA EAB Parasitoid Rearing Facility in Brighton, Michigan.

“Due to the current situation of EAB in and around Fairfield, biocontrol seems justified at this point in time, said Mike Kintner, Iowa Department of Agriculture and Land Stewardship EAB and gypsy moth coordinator. “The use of biocontrol will not be a ‘silver bullet’ for the problems we face with EAB, but the natural enemies will serve as a long-term management strategy to lessen the impact of EAB.”

The two species of parasitic wasps available by USDA Animal Plant Inspection Service target the larval and egg stages of EAB. Tetrastichus planipennisi female wasps, which are about the size of a grain of rice, lay eggs inside EAB larvae, terminating their development into adult beetles. Oobius agrili female wasps, which are the size of a gnat, lay eggs inside EAB eggs, parasitizing them before given the opportunity to hatch. Both species are harmless to people.

According to the USDA Forest Service, Iowa has an estimated 52 million rural ash trees and approximately 3.1 million more ash trees in urban areas. Additional suitable sites will be approved and utilized for biological control releases.

To learn more about how you can prevent Emerald Ash Borer infestation in your trees visit:


More information about USDA’s Emerald Ash Borer Biocontrol Program can be found at:


More information about EAB and other pests that are threatening Iowa’s tree population, go to www.IowaTreePests.com.


Published with thanks to:

Dustin Vande Hoef, Iowa Department of Agriculture and Land Stewardship, 515-281-3375

Kevin Baskins, Iowa Department of Natural Resources, 515-725-8288

Laura Sternweis, Iowa State University Extension and Outreach, 515-294-0775

Emerald Ash Borer is in Iowa

For the last several weeks local media has been reporting that the Emerald Ash Borer has been spotted in central Iowa. The Iowa Department of Natural Resources estimates that there are more than 3 million ash trees in metropolitan areas in Iowa and another 52 million trees in rural woodland areas. The expected loss of these trees could cost more than $2.5 billion over the next two decades.

This Service Alert will provide you with more information about the Emerald Ash Borer and treatment options that will save ash trees from destruction.

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