Agriculture: Small Grains Pest Management Guidelines

Corn Leaf Aphid

  • Rhopalosiphum maidis
  • Description of the Pest

    Key to identifying aphids

    Corn leaf aphids are small aphids that are bluish green to dark olive in color, with a purplish patch around the base of the cornicles. Because of its small size and short antennae, it could be confused with the Russian wheat aphid. Corn leaf aphid, however, has prominent black cornicles and lacks a supracaudal process.

    Damage

    Damage is usually minor. Corn leaf aphid is a vector of BARLEY YELLOW DWARF virus.

    Management

    Biological Control

    Corn leaf aphid is attacked by the usual predators and parasites (see APHIDS – GENERAL CONSIDERATIONS).

    Monitoring

    Check for corn leaf aphid when evaluating the field for other aphid species.

    Management Decisions

    Corn leaf aphid seldom requires treatment.

    Common name Amount per acre REI‡ PHI‡
    (Example trade name) (hours) (days)
    Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.
     
    A. DIMETHOATE
      (Dimethoate 4EC) 0.5–0.75 pt 48 35
      MODE-OF-ACTION GROUP NUMBER1: 1B
      COMMENTS: For use on wheat and triticale only. Do not make more than two applications per year. Do not graze within 14 days. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
     
    B. MALATHION
      (Malathion 8) 1 pt 12 7
      MODE-OF-ACTION GROUP NUMBER1: 1B
      COMMENTS: May be used on wheat, barley, oats, and rye. If alfalfa is in bloom, apply during the night or early in the morning when bees are not foraging in the field. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
    Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI; the longer of these two intervals is the minimum time that must elapse before harvest may take place.
    * Permit required from county agricultural commissioner for purchase or use.
    1 Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).
    Text Updated: 02/09
    Treatment Table Updated: 07/16