Sweet Corn – Corn Earworm (Helicoverpa armigera) aka Heliothis

Crop:         Sweet Corn
Insect(s): Corn Earworm (Helicoverpa armigera) aka Heliothis


  1. The critical stage of infestation is during Even low levels of heliothis infestation are unacceptable at the silking stage. Because sweet corn is less attractive to heliothis before flowering and it is picked soon after silking is completed, there is a relatively short period of protection required.
  2. Control of heliothis at the tasselling stage (occurs prior to silking stage) can be important in some regions as the tassel can act as a nursery for heliothis, which can then move onto the young developing cobs. Control of heliothis at this stage is not as difficult as at the silking stage.
  3. Use of biological insecticides, Bt and Nuclear Polyhedrosis Virus (NPV), in the early stages of crop development is
  4. Monitor crops regularly, at least weekly during silking and do not spray unless pest thresholds are
  5. Labels of new products place a limit on the number of If further control is required on one planting, chemicals from different mode of action groups within the same window should be used.
  6. DO NOT retreat a spray failure with a product from the same chemical group.
  7. DO NOT use mixtures of insecticides for controlling heliothis.
  8. Cultivation after harvest to destroy pupae will greatly assist in managing heliothis.
  9. Seek local advice on pest incidence and on the risk of resistance developing from insecticide programs used to control heliothis in crops other than sweet corn
  10. To help prevent the development of resistance to any one specific active ingredient (see table below), observe the following instructions:
      a. Use in accordance with the current IRMS for your region;

      • b.  Apply a specific active ingredient using a “window” approach to avoid exposure of consecutive insect pest generations to the same mode of action. Multiple successive applications of a specific active ingredient are acceptable if they are used to treat a single insect generation;

        • c. Following a “window” of a specific mode of action product, rotate to a “window” of applications of effective insecticides with a different mode of action;

          • d. The total exposure period of any one mode of action “active window” applied throughout the crop cycle (from seedling to harvest) should not exceed 50% of the crop cycle;

            • e. Incorporate IPM techniques into the overall pest management program; and

              • f. Monitor insect populations for loss of field efficacy.


Group* Active ingredient
1A Methomyl, thiodicarb
3A Synthetic pyrethroids (several)
5 Spinetoram
6 Emamectin benzoate
28 Chlorantraniliprole

*Refer: CropLife Australi Expert Committee on Insecticide Resistance Mode of Action Classification for Insecticides

Notes regarding the application of insecticides:

  1. To ensure the most effective control of the pest:
  • Product labels should at all times be carefully read and adhered to;
  • Full recommended rates of registered insecticides should always be used; and
  • Ensure good coverage of the target area to maximise contact.

URL: https://croplife.org.au/resources/programs/resistance-management/sweet-corn-heliothis-ear-worm-2-draft/
Content last updated: June 30, 2022

CropLife Australia’s Resistance Management Strategies provide a guide for crop protection product rotation through product groups. The strategies are a useful tool that supports farmers’ adoption of resistance management. All crop protection products must be handled and applied strictly as specified on the product label or APVMA permits.

These Resistance Management Strategies do not replace product labels. They are a guide only and do not endorse particular products, groups of products or cultural methods in terms of their performance. It is important to check with the Australian regulator’s (APVMA) product database for contemporary information on products and active constituents. The database can be sourced through www.apvma.gov.au

The information given in this strategy is provided in good faith and without any liability for loss or damage suffered as a result of its application and use. Advice given in this strategy is valid as at 30 June 2022. All previous versions of this strategy are now invalid.