Eastern false wireworm - adult and larva.
False wireworms, striate, eastern and southern
Pterohelaeus and Gonocephalum spp.
Damage
- Larvae feed on decaying vegetable and crop residues in the soil.
- They also feed on newly germinating seed and the growing points of seedlings, which results in patchy stands.
- Damage is most common in early planted crops where crop residue has become scarce.
- During summer, adults may damage young plants, by surface feeding or cutting of the plant at or near soil level.
- Damage by both larvae and adults may necessitate re-planting.
Risk period
The risk from adults is highest in summer. For larvae the risk is highest for early (September-October) planted crops.
Damage may occur if early plant growth is slowed by cool damp weather allowing larvae to remain in the moist root zone. As soil dries they retreat below the root zone.
Monitoring and thresholds
Detection can be difficult - either hand sift 10 soil samples (30 x 30 cm) or place 10 germinating seed baits (GSB) throughout the paddock. One larva per sample warrants control. See monitoring for soil insects.
Management
High mortality of false wireworms can be caused by cool wet weather from autumn to spring. False wireworm beetles are more damaging to seedlings where stubble is buried by cultivation than in crops that are directly drilled into the surface retained stubble. This is because the surface feeding beetles remain feeding on the stubble and not the crop.
- Prepare ground for even and rapid germination.
- Use of press wheels at planting provides some control.
- Clean cultivation during summer dries out topsoil and eliminates weeds that provide food for adults.
- Larvae can be controlled by insecticide applications at planting or insecticide treated seed.
- Control of adults is obtained by baiting with insecticide treated cracked grain broadcast evenly over the surface at or immediately after planting.
- Where broadcasting is not possible, the bait may be laid in trials spaced no more than 2 metres apart.
Natural enemies provide little control.
Cutworm larvae on the soil surface.
Cutworms - Agrostis spp.
- Brown cutworm - Agrotis munda, Bogong moth - Agrotis infusa, Black cutworm - Agrotis ipsilon and Variable cutworm - Agrotis prophyricollis
The common name of cutworm is derived from the larval habit of severing the stems of young seedlings at or near ground level, causing the collapse of the plant. Cutworm larvae typically shelter in the soil during the day. They curl into a ´C´ shape when disturbed.
Damage
- Cutworm larvae can sever stems of young seedlings at or near ground level.
- Sometimes the young plant is partially dragged into the soil where the larvae feed on it.
- Larvae may also climb plants and browse on or cut off leaves.
- Crop areas attacked by cutworms tend to be patchy and the destruction of seedlings in one area may cause cutworms to migrate to adjacent fields.
- Risk period is spring and summer - one generation per crop.
- Weedy fallow prior to sowing can lead to cutworm infestation.
Monitoring and thresholds
- Inspect emerging seedlings twice per week.
- Treat seedlings when there is a rapidly increasing area or proportion of crop damage (greater than 10% seedling loss).
- Treat older plants if more than 90% of plants are infested or more than 50% of plants have 75% or more leaf tissue loss.
Control
- Cutworms are attacked by a range of natural enemies such as parasitoids, predators and diseases.
- Controlling weeds prior to planting will reduce cutworm infestations.
- Insecticides are used when damage warrants their use. For current chemical control options see Pest Genie or APVMA.
- Spot spraying of identified patches may suffice. For best results, spray late in the afternoon, close to feeding time.
Black field earwig
Black field earwig - Nala lividipes
Black field earwigs are a sporadic pest of sorghum, usually in areas with heavy, black soils.
Damage
- Eat newly sown and germinating seed and the roots of crops below ground, resulting in poor establishment.
- Chew the stems of newly emerged seedlings above ground.
Monitoring and control
- Monitor crops after planting until establishment.
- Use germinating seed baits or digging and sieving to detect adults and nymphs prior to planting.
- Control if more than 50 earwigs in 20 germinating seed baits.
- Grain baits containing insecticide applied at sowing offer best protection.
- Insecticide seed dressings provide some protection.
- In-furrow sprays are not effective in protecting against dense populations.
- Earwigs prefer cultivated soils rather than undisturbed soil (zero til).
- Use press wheels at sowing.
- For current chemical control options see Pest Genie or APVMA.
Photographs
Black field earwig sourced from:http://www.dpi.qld.gov.au/26_8123.htm
Cutworm sourced from:http://www.dpi.qld.gov.au/26_8114.htm
False Fireworm sourced from:http://www.dpi.qld.gov.au/26_8135.htm
