No. 5 Article 3/April 27, 2007

Armyworm and Black Cutworm Moths Are Being Trapped Throughout the State

Captures of both armyworm and black cutworm moths picked up where they left off before the cold weather we experienced in early April. Weather fronts and prevailing winds have directed both species our way, and their captures over time and compared with previous years' captures are worth noting.

For southern Illinois, the most consistent source for this type of information is "The Hines Report," which is updated weekly. Ron Hines, now a seed agronomist for the southern region for Growmark, continues to work with cooperators at six locations to run a "trap line" from the southern tip of Illinois (Pulaski County) to Fayette County in the I-70 corridor. Ron reported two intense captures of black cutworm moths (nine or more moths captured in one or two nights), one at the Pulaski County site (April 19 and 20) and one at the St. Clair County site (April 18 and 19). Dale Baird, University of Illinois Extension crop systems educator in Rockford, reported an intense capture on April 23 in Lee County in northwestern Illinois.

The black cutworm larvae that derive from these and last week's intense captures will threaten corn in vulnerable stages during the first two weeks of May. A lot of corn went into the ground over the past week before widespread rains, so those fields should be targeted for scouting first because the seedlings will be at risk. It's important to note that corn hybrids with Herculex I Insect Protection (with the Cry 1F Bt protein) are labeled for control of black cutworm larvae. These hybrids should effectively control young (first and second) instars before they begin cutting. Cruiser 250 and Poncho 250 also are labeled for control of black cutworms, but past experience and some studies have shown that black cutworms are not controlled very well by either product. We would be interested in receiving any reports of efficacy of these preventive products (Bt corn or seed-applied insecticides), or lack thereof, after cutworm larvae begin their feeding.

Maybe of greater significance are the numbers of armyworm moths being captured at some sites in southern Illinois--Pope, Pulaski, and St. Clair counties. The numbers of moths (270!) captured in the trap in Pope County during the week ending April 24 will make you sit up and take notice. Obviously, wheat and grass pastures will be at risk from the larvae that derive from these flights (refer to related articles in this issue of the Bulletin), so scouting for armyworms and symptoms of their feeding injury by mid-May should be on everyone's to-do list. No-till cornfields with grassy weeds or previous grass crops also should be scouted for armyworm larvae. The armyworm outbreak in 2001 is still fresh enough in most people's minds that vigilance should be much improved this year.--Kevin Steffey

Close this window