Sweet Corn – Ear Worm (Heliothis)

Crop:         Sweet Corn
Insect(s): Ear Worm (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 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
  7. DO NOT use mixtures of insecticides for controlling
  8. Cultivation after harvest to destroy pupae will greatly assist in managing
  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
  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.

Mode of Action Group as specified on product labelActive ingredient
1AMethomyl, Thiodicarb
3ASynthetic pyrethroids (several)
6Emamectin benzoate

CODE:H=high pressure period
M=medium pressure period
L=low pressure period

URL: https://croplife.org.au/resources/programs/resistance-management/sweet-corn-heliothis-ear-worm-2/
Content last updated: July 1, 2019

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 27 June 2019. All previous versions of this strategy are now invalid.