Address any questions or comments regarding this newsletter to the individual authors listed after each article or to its editors, Nathan Johanning, 618-687-1727, or Bronwyn Aly 618-382-2662, The Illinois Fruit and Vegetable News is available on the web at: To receive email notification of new postings of this newsletter, contact Nathan Johanning at the phone number or email address above.

In This Issue:

Upcoming Programs (listings for beginning and established growers)

Regional Reports (southern Illinois, Dixon Springs)

Fruit and Vegetable Production and Pest Management (Modified Growing Degree Days for Insect Development, Cooler Winter Weather Sets the Stage for Corn Flea Beetles and Stewart's Wilt, Early Spring Reminders on Insect Management)

University of Illinois Extension educators and specialists in fruit and vegetable production and pest management

Upcoming Programs

Check the Illinois SARE calendar for a full list of programs and links for registration. and
Also see the University of Illinois Extension Local Food Systems and Small Farms Team's website at: and the calendar of events at

Regional Reports

From southern Illinois... We have stayed fairly wet in the last few weeks.  Mainly from the storm system that was over us around the time the last issue came out.  In total for the week of 2/19 (through Saturday), we ended up with about 5.5" of rain in Carbondale and 7.4" of rain at Dixon Springs.  I did hear one report of totals as much as 11" in some locations.  Needless to say that has at least mostly replenished our dry soils and things are wet.  We have had about 2 to 2.5" of rain across the area since then with about 0.5 to 1" of that coming this past Monday.  We have mainly been in the 50s and 60s for highs, but a front has come through in late Tuesday dropping highs to around 40° and lows in the mid to upper 20s.  The forecast is for highs to stay in the 40s and 50s and some more rain chances by the weekend.

Given the weather, there isn't a whole bunch of activity out in the field quite yet. Pruning on tree fruit, grapes, brambles and blueberries is ongoing and now is the time to be thinking about applying dormant sprays for disease suppression and scale control.  Over the weekend, I was at home at the farm in Monroe County and did my apple and peach pruning.  So far everything looks good and no bud activity yet.  We do have an old (probably Kiefer or similar) pear tree and when pruning it, I did notice a little bit of swelling and green starting to show on flower buds.

Now is the time to be considering your burndown and preemergence herbicide applications in asparagus.  Down here we have seen asparagus emergence as early as mid-March in previous years and many of the herbicides need to be down a week or two before any fear of having emerged spear tissue.  If you are using any form of glyphosate (ie Roundup), you want to make sure that no spears are emerged as it will kill emerged spears and can translocated to injury to the crown.  Our best timings for herbicide applications in asparagus is now before emergence and then at the end of harvest.  There are many burndown and residual herbicide options for asparagus and refer to the 2018 Midwest Vegetable Production Guide for more details.

Nathan Johanning (618-687-1727;

From Dixon Springs Agricultural Center... Even with the heavy rains of last week and area flooding making things seem dreary, spring is in the air at DSAC.  Seed orders and supplies have all arrived, generating excitement for the 2018 growing season! 

The first round of seeding began this week with various varieties of tomato, pepper, cucumber, and flowers.  It is important to reach and maintain optimum soil temperatures when starting seeds as this helps seeds to germinate in a timely manner and hopefully avoid damping off issues.  By using 20 slot seeding trays, we are able to keep our varieties separated easily, labeling each individual row.  We plan to have transplants ready for planting into the high tunnels by mid-April.

When putting the new plastic on the high tunnel last week, we were reminded of a small detail that could save someone a lot of unnecessary heartache.  Remember to tape or cover any sharp edges that plastic might snag on and rip, potentially costing a few hundred dollars to buy a new roll of plastic, as well as losing valuable growing days waiting for replacement plastic to arrive.  Granted small holes can easily be patched or repaired but it is always nice to start out hole free, if possible, with brand new plastic.

By burying the thermocouple under the soil inside the tray, the heat mat will maintain the selected soil temperature. Photo by B. Aly.
Note the sharp edges at the end of the wiggle wire channel and on the corner of the hip board. Both of these spots have the potential to cause tears or rips in plastic as it is being pulled across the frame. Duct taping any edges or corners takes just a few minutes but could end up saving both time and money.

Each pepper variety is seeded into an individual row with a corresponding tag, keeping varieties identified and separate during the seed germination and grown on process. Photo by B. Aly.

"An ounce of prevention is worth a pound of cure." -- Benjamin Franklin
Photo by B. Aly.

Bronwyn Aly (618-382-2662;

Fruit and Vegetable Production and Pest Management

Modified Growing Degree Days for Insect Development (Base 50°F, January 1 through March 4)

Station Location

Actual Total

Historical Average (11 year)

One- Week Projection

Two-Week Projection






St. Charles













































Rend Lake










Dixon Springs





Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Degree day accumulations calculated using the Illinois IPM Degree-Day Calculator (a project by the Department of Crop Sciences at the University of Illinois and the Illinois Water Survey).

Kelly Estes, State Survey Coordinator, Illinois Cooperative Agricultural Pest Survey (217-333-1005;

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 cannot 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.

Figures 1 and 2. Average winter temperatures of 2016-2017 and 2017-2018.

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



Trace, at most



Light to Moderate



Moderate to 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 is 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.

Kelly Estes, State Survey Coordinator, Illinois Cooperative Agricultural Pest Survey (217-333-1005;

Early Spring Reminders on Insect Management

At the Illinois Specialty Crops, Agritourism, and Organic Conference at Springfield in January, the Illinois Specialty Growers Association requested that I resume contributing articles for the Illinois Fruit and Vegetable News.  They offered me a small contract for this work, so ... here I am, back again, providing updates on insect management topics for the 2018 season.  Efforts are ongoing to refill my previous position in some form at the University of Illinois, and I don't intend that my newsletter contributions take the place of a full-time entomologist serving the research and extension needs of fruit and vegetable industry in Illinois.  I do hope to meet a small portion of those needs by providing some reminders and updates as the growing season progresses.  A few topics for this time of the season and a few reminders for the upcoming months include:

Contributions from Weinzierl Fruit and Consulting, LLC are provided through support by the Illinois Specialty Growers Association.  Visit for more information or to join the association.

Rick Weinzierl, Weinzierl Fruit and Consulting, LLC (217-621-4957;

Less Seriously...

Or maybe "more seriously" this issue....

University of Illinois Extension Specialists in Fruit and Vegetable Production & Pest Management

Extension Educators – Local Food Systems and Small Farms

Bronwyn Aly, Gallatin, Hamilton, Hardin, Pope, Saline, and White counties


Bill Davison, Livingston, McLean, and Woodford counties


Laurie George, Bond, Clinton, Jefferson, Marion, & Washington counties


Zachary Grant, Cook County


Doug Gucker, DeWitt, Macon, and Piatt counties


Nathan Johanning, Franklin, Jackson, Perry, Randolph, & Williamson counties


Grant McCarty, Jo Daviess, Stephenson, and Winnebago counties


David Shiley, Coles, Cumberland, Douglas, Moultrie and Shelby counties


James Theuri, Grundy, Kankakee, and Will counties


Extension Educators – Horticulture

Chris Enroth, Henderson, Knox, McDonough, and Warren counties


Richard Hentschel, DuPage, Kane, and Kendall counties


Andrew Holsinger, Christian, Jersey, Macoupin, & Montgomery counties


Extension Educators - Commercial Agriculture

Elizabeth Wahle, Fruit & Vegetable Production


Campus-based  Extension Specialists

Mohammad Babadoost, Plant Pathology


Mosbah Kushad, Fruit & Vegetable Production