Black cutworm (BCW) and true armyworm (TAW) moths continued to migrate into Iowa during Week 4 (April 17 to April 23). Last week, our cooperators reported a total of 60 BCW and 13 TAW moths throughout the state.
Week 4 report:
All of the moths were captured in the late part of last week (April 20 to April 22), with 12 TAW and 33 BCW captured on Friday, April 22. Two significant flights of BCW occurred on April 22: one in Buena Vista County (northwest) and one in Mills County (southwest). So far this spring, significant flights have been reported in Buena Vista, Mills, and Taylor (Week 3) counties. Figures 1 and 2 show the Week 4 trap reports for true armyworm and black cutworm, respectively.
Follow the links to see reports from Week 1, Week 2, and Week 3. You can also track moth flights and black cutworm significant flights for Iowa, Illinois, and Wisconsin on https://corn.ipmpipe.org/insects/. In a few weeks, we will begin predicting cutting dates for Iowa, which will be posted on the corn IPMpipe website and ICM News.
Surrounding states also monitor and report BCW and TAW captures. If you live near the state border, it may be beneficial to check these resources periodically. More resources may be available than what is listed here:
- University of Minnesota
- University of Missouri
- University of Illinois
- University of Nebraska-Lincoln
What is a significant flight? A significant flight of BCW occurs when 8 or more moths are captured over a two-night period; this serves as the “biofix” for degree-day accumulation and indicates an increased risk of black cutworm injury in corn. A degree-day model for black cutworm development predicts that larvae are large enough (4th instar or larger) to cut corn plants once 300 degree days (base 50°F) have accumulated since a significant flight occurred. I will predict cutting dates across the state by mid-May and share them on ICM News, so make sure you are subscribed!