Cooperative
Extension
Service


University of Illinois
at
Urbana-Champaign


No. 20/August 8, 1997

Information Not Included Last Week: My Apology

In the European corn borer article in last week's issue of this Bulletin(no. 19, August 1, 1997), I referred to a figure and a table that were not included in the print version; the Web version included the figure but not the table. I apologize for the oversight. The figure referred to was the "Management Worksheet for Second-Generation Corn Borer," which is included in this issue (Figure 1).

Figure 1. Management worksheet for second-generation corn borer.

_____ number of egg masses/plant (cumulative count, taken a few days apart)x4 borers/egg mass*=_____ borers /plant
_____ borers /plantx_____ 3% yield loss /borer** (do not use a decimal)=_____ % yield loss
_____ % yield loss (use a decimal)x_____ expected yield loss (bu/A)=_____ bu/A loss
_____ bu/A lossx$ ____ price/bu=$ ____ loss/A
$ _____ loss/A x_____ % control (use a decimal; 0.75)=$ ____ preventable loss/A
$ _____ preventable loss/A-$ ____ cost of control/A=$ _____ gain (+) or loss (-) per acre if treatment is applied

*Assumes survival rate of 20% (4 borers/egg mass).
**5% for corn in the early whorl stage; 4% for late whorl; 6% for pretassel; 4% for pollen shedding; 3% for kernels initiated. Use 3% per borer per plant if infestation occurs after silks are brown. The potential economic benefits of treatment decline rapidly if infestations occur after corn reaches the blister stage.

The table I referred to listed the insecticides we suggest for control of second-generation corn borers. That table also is provided in this issue (Table 2). I apologize for any inconvenience this may have caused.

Table 2. Insecticides suggested for control of second-generation European corn borers in field corn.

InsecticidesAmount of product broadcast per acre
*Ambush 2Ea6.4 to 12.8 oz
Dyfonate II 15G6.75 lb
Lorsban 4E1.5 to 2 pt
Lorsban 15G6.5 lb
*Penncap-M2 to 4 pt
*Pounce 1.5G6.7 to 13.3 lb
*Pounce 3.2ECa4 to 8 oz
*Warrior 1EC2.56 to 3.84 oz

aApply Ambush 2E prior to the brown-silk stage.
*Use restricted to certified applicators.


Kevin Steffey, Extension Entomology, (217)333-6652