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Black Cutworm Migration Update

April 20, 2001
Captures of black cutworm moths continue in many areas of the state. Ron Hines, senior research specialist, Dixon Springs Agricultural Center, Pope County, continues to find a steady "flow" of moths into his pheromone traps through mid-April. So far, most of the captures in Ron's traps have not been intense (nine or more moths caught over a 1- to 2-day period). Sporadic reports of intense captures have occurred elsewhere in the state. For instance, Kevin Schumacher, Effingham Equity, indicated that he caught 15 black cutworm moths in his trap on April 9. Dale Baird, crop systems Extension educator, Rockford Extension Center, reported that he caught six moths in his trap on April 13 and two additional moths on April 14 in Lee County. As we indicated in last week's Bulletin (no. 3, April 13, 2001), black cutworm moths have spread throughout the state. Based on the intense captures reported by Ron Hines on April 3, Bob Scott, Illinois State Water Survey, projects that cutting of seedling corn plants is possible in fields near Pope County as early as April 20. Southern Illinois producers should not delay their scouting efforts in those fields with emerging corn plants. Be on the alert for pinholes in the leaves as soon as the seedlings emerge. For central Illinois counties, cutting of corn plants could begin as early as May 8. This projected cutting date is based on an intense flight that occurred in Piatt County on April 7 and was reported by Doug Gucker, Piatt County Extension Unit.

What fields are most at risk in developing economic infestations of black cutworms?

Black cutworm moths are attracted to weedy areas in fields. The availability of actively growing (green) weeds creates very attractive ovipositional (egg-laying) sites for female moths. Soybean debris is more attractive than corn residue, and bare soil is unattractive for black cutworm oviposition. Growers report more instances of black cutworm injury in corn following soybeans than continuous corn, and the fine texture of soybean residue may be the key contributing factor. Corn grown in rotation with wheat also is at greater risk from cutworms, especially if weeds were present during the egg-laying period.

Are certain weeds more attractive to black cutworm moths?

Yes. Fields that contain winter annual and perennial weeds prior to final tillage and planting are most at risk to an infestation of black cutworms. Those fields infested with common chickweed, mouse-eared chickweed, bitter cress, shepherd's purse, yellow rocket, and pepper grass are likely candidates for the development of a black cutworm infestation.

How do delays in planting and tillage affect the potential for cutworm damage?

Research suggests that when tillage or herbicide applications were applied 1 to 2 weeks prior to planting, minimal cutting of corn seedlings occurred, presumably because cutworm larvae starved. If tillage operations and herbicide applications were delayed until 2 days prior to planting or made the same day of planting, more corn plants were cut. The researchers who conducted this study believed that corn plants emerged before significant numbers of black cutworms starved. Their assumption was that cutworm larvae survived on plant debris (at least 10 days) until corn emergence occurred.

We will continue to provide updates on black cutworm moth captures and projected cutting dates. Don't let cutworms surprise you this springinvest some time in scouting fields of emerging corn plants.--Mike Gray

Field infested with winter annual weeds--prime target for black cutworm females.

Seedling corn plant cut by black cutworm larva.

Scouting for black cutworms and taking stand counts.

Author: Mike Gray

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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