Corn earworm alert

Every year in August, we are on the lookout for the arrival of large numbers of corn earworm moths that migrate into Ohio from the southern USA. Over the past three days, we have seen a surge in the catch of corn earworm moths in our pheromone trap in Columbus; the catch from Monday (8/14) to Wednesday (8/16) was 11 moths, but the catch from Wednesday (8/16) to Friday (8/18) was 41 moths, with a total of 60 for the full week. We have corn earworm pheromone traps at eight other locations in Ohio; last week these were reporting a catch of only 0 to 3 moths in one week, but it is likely that the catch at these other locations will show an increase during the coming week. Now that most of Ohio’s grain corn is starting to dry out, any patches of sweet corn will be more likely to be attacked by this pest. Once corn earworm is detected, silking sweet corn should be sprayed with insecticide every 2-6 days to prevent injury to kernels. The choice of an appropriate spray interval is as important as the choice of product to use. Details about the most appropriate spray interval based on pheromone traps are shown in the chart below.

Although the corn earworm is the key pest of sweet corn, European corn borer and fall armyworm are two other pests that sweet corn growers should be aware of  at this time of year.  The second generation of European corn borer (ECB) is now underway but it has been slow to start and is present at low density at all nine Ohio sites where we have traps. This pest will be infesting sweet corn as well as peppers. On sweet corn, ECB can be controlled by the spray schedule used to control corn earworm. On peppers, ECB can be controlled by insecticide sprays every 7 days. Fall armyworm (FAW) activity in recent weeks has been variable, with only a trace of FAW moths detected in traps in Columbus, Celeryville, and Wadsworth but FAW moths have been more abundant at South Charleston. Damage by fall armyworm is often most noticeable in whorl-stage corn but it can also be severe in silking corn.

Weekly catch of these three moth pests is shown on our online trap report page: , where there is a tab for each pest along the bottom of the sheet.

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