IPM Guidelines For Grains

Maize

Insect pest risk

Fall armyworm (FAW; Spodoptera frugiperda) is a polyphagous pest that reached Australia in early 2020 and has since spread through many northern and eastern cropping regions. It has so far shown a marked preference for maize and sweet corn crops. Australian research is currently looking at how this pest will interact with Australian cropping systems and native vegetation, pest monitoring, natural enemies, developing appropriate thresholds, and management opportunities.  FAW has demonstrated resistance to a range of insecticides overseas, and so resistance management will play an important part of management programs. More information on this pest is available at the Beatsheet.

High risk Moderate risk Low risk
Establishment pests
  • Paddock history of establishment pests.
  • High levels of retained stubble.
  • Dry conditions at crop establishment (increase attractiveness of seedlings to insect pests).
  • Slow crop growth at establishment makes plants more susceptible to damage (soil insects, thrips).
  • Seed dressings provide some protection against low to moderate numbers of establishment pests.
  • Increased sowing rate to compensate for known pest pressure.
  • Use of press wheels to limit soil insect access to seed and seedlings.
  • Weedy fallows (support pests prior to sowing).
 Pre-sowing check of paddocks
Helicoverpa armigera
  • Large population carry-over from winter crops (e.g. chickpea, linseed, canola) or previous summer (northern region).
  • Large egg lay prior to tasselling results in large larvae damaging tassels and impact on crop fertilisation.
 Use of non-selective pesticides for other pests in vegetative stages can flare helicoverpa. Maize varieties with husks extending 50-80 mm beyond the top of the cob and closing tightly around the silks restrict entry of larvae into the cob.

Pest incidence

Pest Crop stage

Emergence

Vegetative

Silking/Tasselling

Grainfill
Black field earwig Damaging
Wireworms Damaging
Cutworms Damaging
Maize leafhoppers Present Damaging
Maize thrips Damaging Damaging
Locusts Damaging Damaging
Whitegrubs (scarabs) Damaging Damaging
Armyworm Damaging Damaging
Swarming leaf beetles Damaging Damaging
Red shouldered leaf beetles Present Damaging Present
Green vegetable bugs Present Damaging Damaging
Corn aphids Damaging
Helicoverpa Present Damaging Damaging
Two spotted mites Present Damaging
Red banded shield bug Present Damaging Damaging
Yellow peach moth Damaging

 

Present Present in crop but gen­er­ally not dam­ag­ing
Dam­ag­ing Crop sus­cep­ti­ble to dam­age and loss

Key IPM considerations for maize

  • Economic damage is most likely to occur during establishment. Use germinating grain baits or direct soil sampling to provide information on risk.
  • Use hybrids with resistance to wallaby ear (a mycoplasma transmitted by maize leafhoppers)
  • Where helicoverpa larvae are present after mid March, the majority will enter diapause when they pupate. Pupae busting to prevent population carryover makes a valuable contribution to the area-wide management of H. armigera in the local area.
  • The use of NPV for helicoverpa control in maize is effective, and can be applied through overhead irrigation (centre pivot/lateral move).

Further information

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