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Issue No. 24, Article 3/November 11, 2005

Annual European Corn Borer Survey Results

The results are in from our annual fall survey of second-generation European corn borer populations. Continuing with the method we used in 2004 to present these results, we will not print a table of averages of numbers of European corn borer larvae per 100 plants and percentage infestation in counties and crop reporting districts. Rather, the results are available in a PowerPoint slide set on the IPM Web site (http://www.ipm.uiuc.edu/fieldcrops/insects/european_corn_borer/index.html). This link directs you to the European corn borer page. Look for Fall Survey 2005 under "Related Links" and click. More discussion on the background and how the fall survey is conducted can be found in the fact sheet labeled "Fall Survey."

The PowerPoint slides present the following information for each Illinois crop-reporting district:

  • Average number of European corn borer (ECB) larvae per 100 plants for the counties surveyed in each district
  • Average percentage infestation of ECB for the counties surveyed in each district
  • Percentage infestation of ECB in 10 fields within one of the counties surveyed in each district (prepared as an example of variability of infestation within a county)

Most slides include the averages for the district (orange) and the state (red). The slide set concludes with four slides that depict the average number of ECB per 100 plants for all crop-reporting districts and the state, the average percentage infestation of ECB for all districts and the state, a state map depicting the average number of ECB per 100 plants in each county surveyed, and a state map depicting the average percentage infestation of ECB in each county surveyed.

We invite you to use the information we have provided in the PowerPoint slide set. We ask only that you acknowledge the University of Illinois Department of Crop Sciences if you use the information in any educational meetings.

After low populations in 2004, ECB populations rebounded and were higher in 2005. The average number of second-generation ECB per 100 plants in Illinois in 2005 was 34.4, more than double the number in 2004 (15.6). Average percentage infestation of corn plants was 24.2, also higher than the 17.1 percent infested in 2004. Remember, this does not necessarily equate to economic infestations of ECB in 2006. Many factors affect survival (and mortality) of ECB, not the least of which are time of planting and weather conditions during moth flights. The number of corn borers that will overwinter throughout the state is higher than in 2004 but is still low, especially compared to historic numbers (Figure 1).

Figure 1. Historic summary of European corn borer per plant in Illinois during annual fall survey, 1943?2005 (graph courtesy of Robert Bellm, University of Illinois Extension).

This survey would not be possible without the help of University of Illinois Extension IPM and Crop Systems educators, graduate students, and faculty and staff in the Department of Crop Sciences. We would like to thank these individuals for helping us to keep our record of European corn borer populations intact from 1943 through 2005 (with the exception of 2 years when the survey was not conducted). Without their willingness to help, such a time-consuming and labor-intensive task could not be completed.

If you have any questions about our results or use of the slides we have provided, please don't hesitate to contact us.--Kelly Cook, Mike Gray, and Kevin Steffey

Kevin Steffey
Mike Gray
Kelly Estes

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