IPM Guidelines For Grains

• Check weekly as high numbers can defoliate seedlings.
• Larvae that have developed on weeds can move onto seedlings.

• Larvae feed on the fruiting parts of plants and on the terminal growth, flowers and leaves
• Yield loss occurs when larvae burrow into pods.
• Feeding holes in pods are evident and parts or whole seeds are consumed, resulting in reduced yield and quality
• Helicoverpa punctigera migrate from inland breeding areas into cropping areas in spring as their hosts dry off. The timing and size of these influxes can vary from season to season.

Monitor crops 1-2 weekly until podset, increasing frequency when moths and/or larvae are detected. If border sprays were used to control pea weevil, start sampling well into the crop. Repeat sampling at 5-10 sites across the field (more sites give a greater level of confidence). In years of large moth influxes or wet springs where crops continue to flower/pod – monitoring should continue until pods are dry and no longer able to be penetrated by larvae.

• Visually examine leaves, buds & flowers for eggs and small larvae. Start looking for eggs mid-August or when the crops start flowering and moths are detected.
• Use a beat sheet (wide rows) or sweep net (narrow rows) to sample for larvae.
• Assess pod burrowing by looking for holes and splitting open 20-40 pods and look for larval damage.

Record number, sizes, and crop development stage. Calculate number/m² to compare with appropriate thresholds. In southern grain regions, average number of caterpillars per 10 sweeps of an insect sweep net is the standard for comparison and thresholds.

• Trichogamma wasps parasitise helicoverpa eggs and Microplitis, Heteropelma, Netelia sp. and other wasps parasitise helicoverpa larvae.
• Predatory bugs such as Geocorris and Nabis prey on eggs and small larvae while Cermatulus and Oechalia also attack larger larvae.
• Ants and spiders also eat helicoverpa eggs and larvae.
• NPV is a virus which only infects Helicoverpa species. It occurs naturally but can also be applied to enhance disease levels.

• Control broadleaf weeds in and around the crop. Helicoverpa larvae can develop on weeds, moving as large, damaging larvae to podding crops in spring as the weeds dry off.
• Set harvester up to screen out damaged seeds
• Advance crop drying (swath or desiccate) is an alternative to a late spray in an uneven crop, or when the crop continues to put on green leaf in a wet finish.

• Field peas: 1-2 larvae in 10 sweeps
• Lupins: average of 5 or more larvae per m² with beatsheet
• Chickpeas (kabuli): 2-3 larvae in 10 sweeps
• Chickpea (Desi  type): 5 larvae in 10 sweeps
• Faba beans: 2-3 larvae per 10 sweeps or 4-8/m² with beatsheet
• Lentils: 2 larvae in 10 sweeps

• Aim to control larvae before they enter pods – target small larvae <7 mm.
• Synthetic pyrethroids are very effective but their broad spectrum activity has a negative impact on any beneficial insects present.
• Commercially available NPV gives up to 80% control in chickpeas.
• Bt is effective against helicoverpa.
• There is usually a range of rates on the insecticide label to allow for varying conditions such as the size of the caterpillars. The choice of rate should not be solely driven by the lowest price. Also consider impact of chemical use on other pests and beneficial species.
• Refer to the impact of pesticides on beneficials table.
• Inspect crops after spraying to ensure chemical applications have been effective and detect further infestations until the crop is no longer susceptible.

• Field peas: do not delay necessary pea weevil treatment and treat both pea weevil and native budworm with one spray.
• Control of native budworm with synthetic pyrethroids can promote the outbreak of aphids when natural enemies are killed.
• Where both native budworm and corn earworm (Helicoverpa armigera) occur (north of Dubbo and in irrigation areas), be aware that insecticide resistance in corn earworm can affect the efficacy of SPs and OPs in mixed populations.

Industry publications provide up to date information about regional pest issues.