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Sweet Corn Got Worms?

Posted: August 17, 2010

Managing sweet corn worms is the major pest management challenge for sweet corn growers in mid to late summer. European corn borer (ECB), corn ear worm (CEW), and fall army worm (FAW) all are potential threats to this valuable crop. First generation ECB is the early season threat but CEW requires the most attention from late July until the end of the season. Fall army worm is an occasional pest.

Growers have a very valuable tool, http://www.pestwatch.psu.edu/ that tracks the emergence of sweet corn pests throughout the season. Extension educators, in cooperation with farms throughout Pennsylvania and surrounding states, have deployed traps to monitor the presence of these key pests. Shelby Fleisher, Penn State entomologist, interprets the data weekly and supplies a timely tip at the website to help growers make decisions. Growers can monitor the trap catches in PA and neighboring states themselves, anytime, by visiting the website.

Historically, July and August are the months when monitoring for these pests pays off. There is usually a “lull” between first generation ECB and the arrival of large corn earworm populations from the south in July. This often affords growers the opportunity to stretch intervals between insecticide sprays to the maximum, as long as they have cleaned-up first generation ECB with timely row tassel sprays. By early August, corn ear worm populations begin to increase, sometimes dramatically. At this time, close attention to the trapping data is important so that growers can tighten the spray intervals to protect the crop.

So, Pestwatch works in two ways. First, it saves growers time and money by preventing unnecessary sprays. Later, it helps growers protect the crop when CEW pressure can increase unexpectedly. Of course, growers still need to check fields themselves occasionally for other pests such as Japanese beetles, sap beetles and aphids which may require treatment.

In addition to trap data and interactive maps, the Pestwatch site provides links to a wide range of Extensions information on vegetable culture and pest management from Penn State and our sister Land Grant Universities including Cornell, Rutgers and Maryland.