Black cutworms threaten late-planted corn     | Printer-Friendly Format |

BROOKINGS, SD - Destructive black cutworms that cut corn seedlings below the ground have been
detected in late-planted corn.  Corn seedlings that are only in their 2-3 leaf stages are most vulnerable
and must be inspected now.

Kevin Branick, Pioneer Account Manager, reported today that black cutworms have been detected in
the entire southeastern corn growing area of the state from Davison County southward to Union County.
Most of the specimens being found were less than an inch long indicating several more nights of cutworm
activity.

Larvae of black cutworms can be very damaging because they cut the corn growing points from under
the soil.  Entire fields can be lost if not detected and treated early.

Wilted seedlings, scattered pieces of leaves, and small holes on leaves are common signs of black cutworm
infestation.

Cutworms are active at night and hide under loose soil during the day. Scouting during the day involves
scratching the soil surface to expose hidden larvae.

Producers should consider insecticide treatment if 5 percent (one in 20) of the corn seedlings show signs
of cutting or leaf feeding, and if the larvae are still less than an inch long.

Insecticides labeled for use against cutworm larvae on corn as seedling foliar sprays include Asana XL
(5.8-9.6 fluid ounces per acre), Baythroid (0.8-1.6 fluid ounces per acre), Decis (1.0-1.5 fluid ounces per
acre), Lorsban 4E (1-4 pints per acre), Mustang Max (1.28-2.80 fluid ounces), Pounce 3.2EC (4.0-8.0 fluid
ounces per acre), Proaxis (1.92-3.20 fluid ounces per acre), and Warrior (1.92-3.20 fluid ounces per acre).
Always read and follow label directions.

Bt-corn hybrids containing the Herculex I or Herculex XTRA genes are usually able to resist black cutworm
injuries. Bt-corn hybrids containing the YieldGard Corn Borer or YieldGard Plus genes are susceptible to
black cutworm injuries.  High rates of seed treatments such as Poncho 1250 and Cruiser 1250 may provide
adequate protection against black cutworm larvae.


Links to University of Nebraska Entomology:  Biology | Economic Thresholds

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 Web Posted on Monday, June 11, 2007 by Mike Catangui. Last Updated on Monday, June 11, 2007.