Article taken from https://agcrops.osu.edu/newsletter/corn-newsletter/2024-25/lep-monitoring-network-%E2%80%93-news-wbc-and-cew-update-15 by Stephanie Pflaum, Amy Raudenbush, Maddie Brillhart, Nic Baumer, Lee Beers, CCA, Trevor Corboy, Allen Gahler, Don Hammersmith, Mary Jo Hassen, Alan Leininger, Ed Lentz, CCA, Sarah Noggle, Les Ober, CCA, Jordan Penrose, Mike Sunderman, Frank Thayer, Kyle Verhoff, Brooks Warner, Jacob Winters, Curtis Young, CCA, Andy Michel, Kelley Tilmon
We have just finished out our 15th week of monitoring for Ohio pests at the Lep Network. This past week, we have seen a continuation of WBC numbers trending down and a slight increase in the CEW average. As was mentioned last week, WBC populations across Ohio have most likely hit their peak numbers of the season and a decline should be expected. While we are most likely beginning to round out of the peak for this pest, any counties with averages that are still above 7 should continue scouting until their county numbers have significantly declined.
Western Bean Cutworm numbers are peaking in many counties across the state
This past week was our 6th week monitoring for WBC in Ohio. The statewide average for WBC decreased again from 1.9 during the week ending on July 21st to 1.0 for the week ending July 28th. The counties with the highest averages are Sandusky (19.0), Huron (7.0) and Henry (4.8) (Figure 1). While we are relatively certain that we have surpassed the peak in WBC moths for this year and are starting the decline, it is still important to be scouting for WBC egg masses (Figure 2). As mentioned above, if this week’s average topped 7 moths in your county, see below for tips on how to scout for this damaging pest. Counties that should continue scouting this week are: Huron and Sandusky.
How to scout for WBC egg masses:
- Identify fields with corn that is pre-tassel or just starting to tassel as these pests need tassels to feed on until the full ear forms.
- Examine the upper 3 – 4 leaves of 20 plants in 5 different field locations (100 plants for field), for egg masses (Figure 2).
- Record the number of egg masses found. Newly laid egg masses are a white/cream color that darken as they mature to a dark purplish color.
- If 5% of plants have egg masses, a treatment may be necessary. Be sure to time the treatment when the majority of the egg masses are mature (purple).
To view a more detailed video on scouting – click here: https://youtu.be/qGjpwtfkObM?si=CFPzX1rlqt6jzyJw
Western bean cutworm moth map
Week 6
July 22nd to July 28th, 2024
Figure 1. Average western bean cutworm (WBC) moths captured from July 22nd to July 28th. The bold number on the left indicates the average moth count for the week, followed by the standard number on the right which indicates the total number of active traps set up in that county.
Figure 2. Western bean cutworm egg mass under microscope Photo credit: Stephanie Pflaum, The Ohio State Department of Entomology, Wooster Campus
Corn Earworm
This is our 8th week monitoring for CEW pests in Ohio. The statewide average for CEW this past week has increased from only 0.02 during the week ending on July 21st to 0.18 for the week ending July 28th. The counties with the highest averages are Morgan (2.0), Clinton (1.0) and Auglaize (0.3) (Figure 3). To learn more about the corn earworm, check out one of our previous newsletters: https://agcrops.osu.edu/newsletter/corn-newsletter/2019-27/corn-earworm-field-corn-watch-molds
Corn earworm moth map
Week 8
July 22nd to July 28th, 2024
Figure 3. Average corn earworm (CEW) moths captured from July 22nd to July 28th. The bold number on the left indicates the average moth count for the week, followed by the standard number on the right which indicates the total number of active traps set up in that county.