The black cutworm trapping program is in full operation and catching moths during their annual spring migration into Iowa. This year we have an intensive trapping program with 87 traps in 67 counties.
Black cutworm adult moth.
The trapping program is an important first step in black cutworm management because it provides an indication as to when the moths arrive. We then use degree days to calculate when larvae will reach a size that they can start cutting corn. This cutting prediction is an important second step in cutworm management that tells us when to scout corn fields.
Significant captures (eight or more moths in two consecutive nights in a sticky trap) have been reported mostly from southern Iowa. There were two early flights in late April that produced a high number of moth captures in both southwestern and southeastern Iowa. This was followed by another large flight May 4-7 that also moved moths into north central and western Iowa. The only significant capture in northern Iowa was Hancock County, but there was a scattering of moths collected in Clay and Crawford counties. No moths had been captured in east central or northeastern Iowa as of May 10. The University of Nebraska reports a significant capture in the extreme southeastern corner of the state, Richardson County, which coincides with our late April captures.
Cutworm scouting date projections, as of May 12, 1997.
First cutting is anticipated based upon when and where moths were captured and the predicted dates when larvae could reach the cutting stage. The map is our best estimate for black cutworm cutting. Remember that moth captures do not predict a cutworm problem, but the information can help us determine when to scout corn fields. In next week's Integrated Crop Management, we will discuss scouting and management options for the black cutworm.
This article originally appeared on pages 63-64 of the IC-478 (9) -- May 19, 1997 issue.