Posted 18 August 2008. PMN Crop News.
European Corn Borers
University of Illinois at Urbana-Champaign. aces.illinois.edu
Urbana-Champaign, Illinois (August 9, 2008)--Mike Roegge, Crops Educator for Adams/Brown Extension, writes that based upon degree day accumulations since the first moth flight captures of European Corn Borer (ECB), producers of non GMO corn should be on the lookout for second generation ECB. The second generation is beginning to hatch and will do so for a couple more weeks. Scouting is done by examining the leaves for ECB egg masses and determining infestation levels.
The majority of leaves will be laid near the ear, so concentrate scouting efforts on those leaves. The female also prefers to lay eggs on latest planted corn (pollinating with fresh silks is ideal). Egg masses will range in size from a nickel to quarter. They will initially be a whitish color, but as the larvae are just ready to hatch, you'll note the black heads inside the eggs.
Once the larvae hatch, you'll have 10-14 days in which to make a decision on treatment. Once larvae reach the 3rd instar, they begin tunneling into the midrib and then the stalk, which makes treatment impossible.
Scout by examining the undersides of leaves (near the ear) of at least 50 random plants throughout the field. Make note of the number of egg masses found, stage of corn, and any hatched larvae. Treatment should be timed as most of the larvae are hatching or just about to hatch.
Generally speaking, it will take quite a few egg masses found for treatment to be economical. However, the calculator found on the web site below will help you generate economic data to aid in your determination. www.ipm.uiuc.edu.
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