Sunday, June 22, 2014

European Corn Borer Moth Catches in areas of IL and MO - Time to Scout Conventional (Non-GMO) Corn

We have had some questions and concerns from those in Central and Western Illinois on when to scout for European Corn Borer, because they found out that their conventional (non-GMO) corn had been infested during last growing season, but when it was too late for treatment.

You can keep track of European Corn Borer moth catches for Illinois at 2014 Illinois European Corn Borer Monitoring and Missouri at MU Pest Monitoring Network.

Thus far, there have been ECB moths found in Pike County in Illinois. There were ECB moths trapped on May 22, 31, and June 6, 20, 2014 within the Southwest region of Missouri as well as on May 23, 2014 in East central region of Missouri.

European Corn Borer Moth
The Illinois Water Survey provides a Daily Pest Degree Calculator, where you can enter in the date of "significant" moth catches for a specific location in Illinois and obtain the actual total of accumulated degree days for the European Corn Borer (ECB).

Most recently, there were ECB moth catches in Pike County on June 16th, 18th, and 19th (as of June 22, 2014).  Based on the accumulated degree days provided to us by the Daily Pest Degree Calculator, mating and egg laying should be taking place at this time; therefore, you should be scouting for egg masses.  Scouting for larvae and damage is the secret to first generation scouting.  However, scouting for egg masses becomes critical to managing corn borer thereafter. 

Growers should examine twenty plants in each of five locations for egg masses.  Egg masses will be found on either side of the leaf midrib on the underside of the leaf.  

Larval feeding usually appears as rows of holes that occur in newly emerging tissue.  Thresholds for leaf feeding borers will vary depending upon the value of the crop, product used, expected yield, etc.  Thresholds also vary for subsequent generation egg mass scouting.  Each egg mass probably results in about only four surviving larvae and this is factored into the general threshold. 

If an insecticide application is needed and egg masses are present, the producers may want to wait a couple days until those egg masses hatch to apply the insecticide.  This is noted when the egg masses begin to show black dots on individual eggs.  Those black dots are the head of each corn borer and signify that the borer will soon hatch out. The worksheets used to determine the need for an insecticide can be found at the following U of I fact sheet

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