Plant Diagnostic Clinic Ready for the 2013 Season

2013 Season at the University of Illinois Plant Clinic

After the extra early season last year, now we are in the midst of an extra late one. Samples have been slowly appearing this spring here at the Clinic in our 38th year of operation.  The unusually cool wet weather has kept many out of the field and landscapes.  The University of Illinois Plant Clinic began year-round operation in the fall of 2011, when we moved from our facility on St. Mary’s Road to our new location in Jonathan Baldwin Turner Hall on the south end of the Urbana campus.    With the new phone system at the U of I we actually have voice mail too.  During the winter our hours are reduced, but, we resumed regular business hours, 8am-12pm and 1pm-4:30pm on Monday April 29th, 2013.


One of the Diagnostic labs at the University of Illinois Plant Clinic

Plant Clinic services include plant and insect identification, diagnosis of disease, insect, weed and chemical injury (chemical injury on field crops only), nematode assays, and help with nutrient related problems, as well as recommendations involving these diagnoses. Microscopic examinations, laboratory culturing, virus assays, and nematode assays are some of the techniques used in the clinic. Many samples can be diagnosed within a day or two. Should culturing be necessary, isolates may not be ready to make a final reading for as much as two weeks. Nematode processing also requires about 1-2 weeks depending on the procedure. We send your final diagnoses and invoices to you through both the US mail and email.  If you provide your email address on the sample form you will get your information earlier.

Please refer to our website for additional details on sampling, sample forms, fees and services offered. If you have questions about what, where, or how to sample call us at 217-333-0519 during operational hours.  Whenever submitting a sample, provide as much information as possible on the pattern of injury in the planting, the pattern on individual affected plants, and details describing how symptoms have changed over time to cause you concern.

Our fees vary depending on the procedure necessary.  General diagnosis including culturing is $15, ELISA and immunostrip testing is $25, Nematode analysis for SCN or PWN is $20, Specialty Nematode testing (such as corn) is $40.  Please include payment with the sample for diagnosis to be initiated. Checks should be made payable to the University of Illinois or to the Plant Clinic. Companies can setup an account, call and we will accommodate you. Call if uncertain of which test is needed or how to send a sample.

Preparing media for diagnostic culturing



Sending a sample thru US mail or Overnight delivery service address packages to:

University of Illinois Plant Clinic
1102 S. Goodwin, S-417 Turner Hall
Urbana, IL 61801




Map to the University of Illinois Plant Clinic S-417 Turner Hall, 1102 S. Goodwin, Urbana IL 61801

Drop off a sample:

You can also drop off a sample at S-417 Turner Hall. Park in the metered lot F 28 on the east side of Turner or at the ACES library metered lot on the west side of Turner. Come in the South door. Take the elevator located in the SE corner of the building.  Turn left when exiting the elevator; we are located along the SE corridor of the 4th floor.  Please use the green drop box located just outside S-417 if we are temporarily out of the office.

Social Media:

We have a lot of ways to keep you up to date on what is happening at the Plant Clinic and about other plant and pest issues.  Follow the U of I Plant Clinic on Facebook, or, follow U of I Plant Clinic’s Stephanie Porter on Twitter: or,  check out our Illini Plant and Pest podcasts or,  follow the U of I Plant Clinic on Blogger

Regards, Suzanne Bissonnette

The Trapping Line: April 23

Black cutworm trap

Black cutworm pheromone sticky trap

UPDATE(4/25): Additional volunteers needed. Kelly Estes, Coordinator of the Illinois Cooperative Agricultural Pest Survey suggests anyone interested in monitoring traps contact her at: or 217-333-1005.

Currently, black cutworm moth pheromone traps are active in the University of Illinois insect monitoring program.  Traps for other species will be brought online as the season progresses. Extension Educators and volunteers monitor the traps and report the results through the North Central IPM PIPE system, hosted by Iowa State University. We will keep you updated about the trapping network here in the Bulletin.

Here is the current list of black cutworm moth captures:

County 11 12 15* 16 17 18 19 22* 23
Lee 1 0 0 1 0 0
Grundy 0 2 5 6
Champaign 1 1
Logan 1 2 4
Menard 0
Macon 3 1 0
Macoupin 1 0 0 1
Fayette 0 0 1 0 0 0 2
Madison 0 0 0 0 0 2
Edwards 0


The full website and current map can be found here.

The first date to expect damage is calculated based on growing degree day accumulations after the first intense flight, nine or more moths in a 2-day period.

Pyramided Bt Cotton and Factors Leading to Potential Compromised Longevity: Cautionary Findings for Bt Corn and Western Corn Rootworm?

In late March 2013, an article was published in the Proceedings of the National Academy of Sciences (PNAS) titled “Potential shortfall of pyramided transgenic cotton for insect resistance management.” The authors of the paper were as follows: Thierry Brévault, Shannon Heuberger, Min Zhang, Christa Ellers-Kirk, Xinzhi Ni, Luke Masson, Xianchiun Li, Bruce E. Tabashnik, and Yves Carrière. The scientists pointed out in their introduction that the first generation of Bt cotton plants, those expressing the Cry1Ac protein, were first used by US producers beginning in 1996. During that same year, corn producers began to grow Bt corn hybrids for European corn protection across many Corn Belt states. From 2003 to 2011, the authors of the PNAS paper indicated that the use of cotton plants expressing a single Cry protein were gradually phased out as producers began to use more pyramided products (either Cry1Ac + Cry2Ab or Cry1Ac + Cry1F). The scientists who wrote this PNAS article outlined several assumptions that explained the justification and increased use of pyramided cotton plants: 1) assumed – evolution of field resistance could be delayed by using more pyramided Bt cotton products, 2) assumed – insects that were resistant to one Cry protein would be killed by the other Cry protein expressed in plant tissue (redundant killing), 3) assumed – recessive resistance and only insects that had two resistant genes (homozygous for resistance) for each Cry protein (toxin) would survive on pyramided cotton plants, and 4) assumed – insects that are resistant to both Cry proteins are very rare within the overall population (assumed that target insect population has not been exposed to either Cry protein). Central to the effectiveness and long term durability of pyramided Bt plants is the concept of redundant killing. Redundant killing can be potentially compromised according to the authors of the PNAS article by the following factors: 1) some susceptible insects survive even though exposed to the Cry proteins, 2) as plants mature, Cry protein concentrations may decline, potentially increasing the number of survivors, 3) if an insect population has an inherently reduced susceptibility to a given Cry protein, exposure to reduced Cry protein levels as plants age may increase overall survivorship of the target insect pest, and 4) if cross resistance exists between Cry proteins being expressed in Bt plants.

The investigators reported that a Helicoverpa zea (cotton bollworm) strain that had been selected for resistance to the Cry1Ac protein had increased survivorship on pyramided cotton plants. They also concluded that cross resistance occurred between the Cry1A and Cry2A proteins. By using these data, they ran some simulation models and determined that the use of pyramided Bt plants – designed to substantially delay resistance development – could be compromised for Helicoverpa zea. They further pointed out that in order to prolong the usefulness of pyramided Bt plants to control Helicoverpa zea, large refuges may be needed as part of an IPM program that integrates several management strategies.

As we move forward into the 2013 growing season, it is increasingly clear that more corn producers will rely upon pyramided Bt hybrids for corn rootworm control. Have some of the assumptions regarding redundant killing already been violated with respect to the western corn rootworm and the use of pyramided Bt hybrids? Unlike the use of high dose events for many lepidopteran pests, Bt hybrids for corn rootworms are generally recognized as low dose – there are survivors and occasionally severe pruning in some high pressure fields. The following passage in the PNAS paper is worthy of reflection: “Previous experimental evidence on the pyramid strategy comes primarily from a model system with diamondback moth and noncommercial Bt broccoli plants producing Cry1Ac and Cry1C. Although most of the optimal conditions for pyramids apply to this model system, they may not apply for some other pest-Bt crop combinations, particularly when pests have inherently low susceptibility to one or more of the toxins in the pyramid.” We also know that root protection generally declines with some corn rootworm Bt hybrids as the season progresses. Consequently, a late-hatch and prolonged feed period can result in more severe root damage. Thus far, there has been no confirmation of western corn rootworm cross resistance between Cry3Bb1 and Cry34/35Ab1. That’s good news. However, as new rootworm Bt proteins (e.g., eCry3.1Ab) enter the market place and are expressed in pyramid combinations, potential cross resistance will need to be continuously evaluated.

Soil Insecticide Use on Bt Corn Expected to Increase this Spring Across Much of Illinois

What a difference a year can make. Many of us will recall the record-breaking warm temperatures of last March across the Corn Belt of the United States. Those temperatures fueled a rush towards planting in April and the earliest emergence of western corn rootworm adults that I have witnessed. On June 7, 2012, I reported that severe rootworm injury had already occurred in a cornfield located in Cass County along with plentiful adults that were causing considerable injury to the corn leaves. I don’t anticipate a similar early emergence this season with snow still commonly found in many fields across the northern one-half of Illinois.

As I have done for many years, I used hand-held clickers (Turning Technologies) to poll producers at the 2013 Corn and Soybean Classics held in several Illinois locations in January.  Growers were asked if they intended to plant a Bt hybrid for corn rootworm protection in 2013? On average, for the five locations, nearly 92% (n = 568 responses) of the producers indicated that Bt hybrids would be targeted at corn rootworms for the upcoming growing season (Figure 1). The range in “yes” responses was 87.6% (Moline, n = 97 responses) to 95% (Champaign, n = 121 responses and Malta, n = 88 responses). Not surprisingly, and similar to previous growing seasons, the use of Bt hybrids will remain a key tactic used by producers in 2013 for corn rootworm protection.

As more pyramided Bt hybrids enter the market place, the type of refuge used will continue to change in a very significant manner. In 2012, the traditional 20% structured refuge was still the dominant refuge approach used by producers in the Corn Belt. Based upon responses received at the 2013 Corn and Soybean Classics, this refuge strategy will no longer remain dominant for Illinois producers. Overall, the most common refuge (Figure 2) that will be used by producers who took part in these regional meetings will be the 5% seed-blend (refuge-in-a-bag) with 43% (n = 572 responses) indicating they will be moving in this new direction. The second most common refuge tactic will be the 10% seed blend (refuge-in-a-bag) with 31% relying upon this approach. Together, these data indicate that nearly 3 out of 4 producers who responded to this question will use a seed-blend as their refuge management strategy for corn rootworms. The advantages of a refuge-in-a-bag (RIB) are straightforward – convenience, ensured compliance, and favorable from a resistant management vantage point for western corn rootworms (based upon emergence patterns and inter-field dispersal dynamics of adults).In 2013, I anticipate a sharp increase in the use of planting-time soil insecticides with corn rootworm Bt hybrids. On average, nearly 47% (n = 571 responses) of producers indicated they intend to use both a soil applied (at-planting) insecticide and a corn rootworm Bt hybrid this spring (Figure 3). For the Moline meeting, nearly 56% (n = 93 responses) of the producers are likely to follow this strategy for 2013. From my perspective, the escalation of soil insecticide use along with corn rootworm Bt hybrids has been fueled primarily over concerns of Bt resistance and high commodity prices. Producers who intend to use a soil insecticide with their corn rootworm Bt hybrid this spring offered several reasons for this approach (Figure 4). On average, concerns over secondary insect infestations and Bt resistance were the top issues cited for this practice. However, nearly 27% of the producers acknowledged that they view the use of a soil insecticide with a corn rootworm Bt hybrid as “cheap insurance.” Regarding the potential insect resistance management (IRM) benefits of a soil insecticide used in combination with a Bt hybrid, more research is warranted on this topic. In addition, I think it is worth mentioning that one of the key benefits touted concerning the use of Bt hybrids for corn rootworm management was the reduction of soil insecticide use. It is a bit surprising that 10 years after the first Bt hybrids entered the market place for corn rootworms (2003), that a heightened interest in the use of soil insecticides has surfaced in such a significant fashion.

Mike Gray