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)||x||4 borers/egg mass*||=||_____ borers /plant |
|_____ borers /plant||x||_____ 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 loss||x||$ ____ 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.
|Insecticides||Amount of product broadcast per acre|
|*Ambush 2Ea||6.4 to 12.8 oz|
|Dyfonate II 15G||6.75 lb|
|Lorsban 4E||1.5 to 2 pt|
|Lorsban 15G||6.5 lb|
|*Penncap-M||2 to 4 pt|
|*Pounce 1.5G||6.7 to 13.3 lb|
|*Pounce 3.2ECa||4 to 8 oz|
|*Warrior 1EC||2.56 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