Cooler Winter Weather Sets the Stage for Corn Flea Beetles and Stewart’s Wilt

While the temperatures in January did little to affect average soil temperatures (, the same can not be said for average air temperature. Average winter temperatures in Illinois for 2017-2018 were much colder than 2016-2017 (Figures 1 and 2). Cool temperatures during the months of December, January and February favor increased mortality of the corn flea beetle and the bacterium it vectors.

Figure 1. Average winter temperatures (2016-2017), from Midwestern Regional Climate Network.
Figure 2. Average winter temperatures (2017-2018), from Midwestern Regional Climate Center.


Corn flea beetles are the primary vector of Stewart’s wilt. Erwinia stewartii, the bacterium that caused Stewart’s wilt, survives the winter in the gut of the corn flea beetle and the survival of the corn flea beetle is dependent on winter temperatures. Warmer winters result in greater survivorship of corn flea beetles, thus increasing the potential for Stewart’s wilt. Using the average temperatures of December, January, and February, the potential for Stewart’s wilt can be predicted (Table 1).

Table 1. Projected risk of Stewart’s wilt based on the average temperatures of December, January, and February.

Average temperature of December, January, & February Probability of early season wilt Probability of late season blight
<27° F Absent Trace, at most
27-30° F Light Light to Moderate
30-33° F Moderate Moderate to Severe
>33° F Severe Severe


Corn flea beetles become active in the spring when temperatures rise above 65°F, and they feed on and transmit Stewart’s wilt bacteria to seedling corn plants. The bacterium can spread systemically throughout the plant. Although most commercial field corn hybrids are resistant to Stewart’s wilt, the disease is still a concern for susceptible seed corn inbreds and many sweet corn hybrids.


There are two phases of Stewart’s wilt: the seedling wilt phase and the leaf blight phase. The seedling wilt stage occurs when seedlings become infected at or before the V5 stage. The vascular system becomes plugged with bacteria, causing the seedling to wilt, become stunted, and die. Infections of older corn plants usually result in the development of the leaf blight phase of Stewart’s wilt. This phase is characterized by long, yellow to chlorotic streaks with wavy margins along the leaves. When the late infection phase or “leaf blight phase” of Stewart’s wilt occurs after tasseling, it is generally not a concern in sweet corn because ears are harvested before damage occurs.


Based on the recent winter temperatures from the Midwest Regional Climate Center, early season Stewart’s wilt are estimated to be absent to light in the northern half of the state, while the risk of in the southern portion is much greater. Remember, however, that these are only predictions; numbers of surviving corn flea beetles are not known.


Emerald Ash Borer Webinar series to kick off next week

The Fall 2015 Emerald Ash Borer University webinars
will begin this Thursday, Sept. 17 at 2 p.m.

The presenter is Jill Johnson, Midwest Forestry Coodinator, with the U.S. Forest Service, Northeastern Area.

She will give an overview of the “Great Lakes Restoration Initiative”. The Great Lakes Restoration Initiative was launched in 2010 to accelerate efforts to protect and restore the largest system of fresh surface water in the world — the Great Lakes.

To join the webinar, go to:

The new Zoom webinar platform is now being used, instead of Adobe Connect. You may see a few changes in the look and functionality, but our presenters are still the same high quality!

The webinars will be recorded, and available for viewing after the presentation.

Go to for more information on EAB University.

Brown Marmorated Stink Bug Survey

Got bugs? Are stink bugs causing problems for you at your home or business?

The Brown Marmorated Stink Bug (BMSB) IPM Working Group would like to hear from you to learn more about the problems caused by BMSB and how you are tackling them via this survey.

We encourage you to take the time to fill out this simple survey if you have dealt with or are currently dealing with brown marmorated stink bugs in your area. We continue to monitor the distribution of BMSB in Illinois as well is its progression into a nuisance pest in homes and a pest of crops in Illinois.

We currently have confirmed BMSB in the following Illinois counties. We are still encouraging people to report new infestations and to contact us if you have any questions. 

Please feel free to email Kelly Estes, State Survey Coordinator ( 

Emerald Ash Borer Detected in Louisiana

February 18, 2015

Baton Rouge, La. (February 18, 2015) – The emerald ash borer, a severe insect pest of ash trees, has been confirmed in Webster Parish making Louisiana the 25th state to confirm the presence of this beetle.

Emerald ash borer (EAB) is a federally-regulated plant pest that almost exclusively attacks ash trees. It was first reported in the U.S. in Michigan in 2002.  The beetle, which is native to Asia, most likely entered the country in dunnage or wooden pallets.  Since that time, it has spread down the East Coast as far south as North Carolina and Georgia, and west to Colorado.  Most recently, it was found in southern Arkansas in July 2014.

A U.S. Forest Service and Forest Health Protection employee found evidence of EAB damage in ash trees during a visual survey.  Further investigation revealed larvae (immature beetles) beneath the bark of multiple trees in approximately a two acre area.  Feeding damage creates characteristic S-shaped tunnels, or galleries, in the sapwood causing initial branch dieback. After several years, the infested trees die.  Larvae were collected and sent to the USDA Systematic Entomology Laboratory in Maryland where they were confirmed as EAB.

“Louisiana’s ash trees are primarily located along the Atchafalaya Basin and the Mississippi River Delta. However, ash trees are also planted in many  urban areas for its aesthetic appeal,” said Louisiana Department of Agriculture and Forestry (LDAF) Commissioner Mike Strain, D.V.M. “As mentioned last year when EAB was discovered in our neighboring state of Arkansas, it could be costly for residents or city officials to have them removed once they start dying.”


Emerald Ash Borer Community Preparedness Workshops in Southern Illinois

From the Illinois Invasive Species Awareness Month blog: 

Recent discoveries of Emerald Ash Borer in Perry and Williamson counties underscore the need for communities to be proactive against Emerald Ash Borer (EAB).

The University of Illinois Extension is offering the following programs for local officials, municipalities, park districts, arborists, and others impacted by the recent Emerald Ash Borer findings. The programs will be held at the following locations:

Thursday, November 13
Crab Orchard National Wildlife Refuge Visitor’s Center
8588 Rte 148 Marion, IL 62959
From 8:30 a.m. to 12:00 p.m.

Thursday, November 13
Perry County Government Building Conference Room
3764 State Rte 13/127 Pinckneyville, IL 62274
From: 1:30 p.m. to 4:30 p.m.

Friday, November 14
Shawnee National Forest
50 Highway 145 South Harrisburg, IL 62946
From 8:30 a.m. to 12:00 p.m.

Workshop participants will learn about emerald ash borer, why it is a threat to our natural forests and urban trees, regulatory implications of the recent discoveries, and how to create a community action plan to manage ash trees on city-owned and private property. This workshop will discuss how to take inventory of all ash trees within a community in order to develop budget needs should large-scale ash tree removal become necessary.

The program is FREE, but reservations are required by November 12. To register call University of Illinois Extension, Jackson county at: 618-687-1727 or register online at