Corn earworm - Helicoverpa armigera, Native budworm - Helicoverpa punctigera
Pest status: Major. Helicoverpa is less damaging in peanuts than other legume crops but high populations can inflict significant damage. Helicoverpa are more prevalent in many newer production regions (e.g. Central Queensland) than in peanut´s traditional South Burnett heartland.
- Native budworm tends to attack leaves and growing points.
- Corn earworm usually damages flower and pegs.
- Peanuts have a high tolerance of defoliation with high populations of 12/m2 having little impact on yield in well grown crops.
- The consumption of flowers and pegs during podding can reduce crop potential.
Monitoring and control
- Sample weekly during vegetative, flowering and pegging stages with a beat sheet.
- Sample five 1-metre lengths of row at six locations across the field.
- Control larvae if threshold of 12 larvae/m2 is reached in the vegetative stage.
- Threshold for flowering and pegging stages is 3-5 larvae/m2, the higher value applying to well-watered crops.
- Small helicoverpa can be effectively controlled with biopesticides such as NPV.
- For current chemical control options see Pest Genie or APVMA.
Where possible, avoid successive plantings of summer legumes. Good agronomy and soil moisture are crucial as large, vigorously-growing plants suffer less defoliation for a given helicoverpa population and have less risk of damage. In water-stressed crops, terminals are more attractive to larvae than wilted leaves. Vigorously growing plants with adequate available moisture are better able to replace damaged leaves and compensate for flower and pod damage.
The number of beneficial insects varies with crop age, from crop to crop, region to region, and from season to season. The combined action of a number of beneficial species is often required to have a significant impact on potentially damaging helicoverpa populations. It is therefore desirable to conserve as many beneficials as possible.
Natural enemies of helicoverpa include predators of eggs, larvae and pupae; parasites of eggs and larvae; and caterpillar diseases.