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Earworm spikes in southwest PA

Posted: June 29, 2011

Earworm and corn borer captures are low in many areas, but earworm spikes occurred in Indiana and Washington counties, and hover above threshold in about half of the sites.
Corn earworm larva

Corn earworm larva

Corn earworm captures are sporadic.  About half the sites are below threshold, and half are near or slightly above; however strong spikes appeared in two areas.  The spikes were in Indiana and Washington counties.  Other areas at or above threshold are in Blair, Centre, Clinton, and Lancaster counties.  If you have silking corn in Indiana or Washington county, put on at least one spray, and watch for continued flight to see if you need to continue at approximately 4-day intervals.  Otherwise, you may be able to avoid sprays, or go with wide spray intervals, such as a 6-day interval, or approximately 2 or 3 sprays on the crop, starting at very early silk and ending about 5 days before harvest. 

European corn borer captures are low throughout the state.  Only Northumberland County exceeded threshold.  Watch for signs of larva from the earlier generation.  A single spray at row tasel will help clean up populations that established earlier.  The next generation of adults should start to appear in the warmest parts of the state in about a week.

Fall armyworms reports are low to absent. 

In summary, earworm and corn borer captures are low in many areas, but earworm spikes occurred in Indiana and Washington counties, and hover above threshold in about half of the sites.  Be prepared for influxes of earworms if you have silking corn, and a second flight of corn borers starting in about a week in the warm parts of the state.  In many areas avoiding sprays now, or using the widest of spray intervals, can save cost and labor.  Scout for signs of corn borer larval infestation from the earlier flights, and use a single spray at row-tasel to clean up infestations that established earlier.  Monitoring programs should be in place.