- History of high mite pressure.
- Previous crops that hosted earth mite populations (e.g. pastures).
- Cool, dry or wet conditions (slow crop emergence and seedling growth).
- Weedy crop and/or crop edges hosting RLEM that may move into germinating crop.
|Following a crop with reduced hosting capacity for RLEM (e.g. faba bean, narrow-leafed lupin and lentils).|
- Following a crop in which RLEM reproduction is low, or where RLEM have been controlled in prior to summer diapause (e.g. chickpeas, winter cereal, albus lupins).
- Rapid emergence and establishment of seedlings.
- Repeated production of field peas in a district increases likelihood of pea weevil.
- Poor pea weevil control (high carryover populations).
- History of pea weevil in the district.
- Proximity to oversummering sites (e.g. shed, trees).
- No history of pea weevil in the district.
- Area-wide implementation of a range of pea weevil management strategies.
- Wet winters in breeding areas of central Australia + suitable weather conditions that bring moths from west to east result in spring migrations.
- Repeated influxes of moths over long periods, results in need for continuous monitoring and potentially repeat infestations.
- Broadleaf weeds hosting cutworm and helicoverpa that then move into the crop as large, damaging larvae.
- Hot weather in spring (can cause small larvae to burrow into pods).
- Wet harvest weather (pods are ‘softer’ for longer and susceptible to damage right up to harvest).
- High beneficial insect activity.
- Dry winters in breeding areas (low population source)
- Absence of frontal wind systems that provide opportunities for migration.
|Aphids and virus|
- High rainfall (>500 mm) or irrigation district.
- Proximity of crop to ‘green bridge’ as a potential source of aphids and virus. For example, lucerne, medics, clover, volunteer pulses and broadleaf weeds.
- Wet autumn and spring (promotes growth of weed hosts).
- Sowing into standing stubble reduces aphid landing.
- Seed dressings may provide some benefit against persistent viruses.
- Rapidly closing canopy that ‘shades’ out unthrifty, virus infected plants – limits further transmission.
- Sowing virus resistant cultivars and certified virus-free seed.
- Early sowing allows flowering before aphid populations peak.
|Slugs and snails|
- Annual rainfall >500 mm
- Above average spring–autumn rainfall
- No till stubble retained
- Previous paddock history of slugs and snails
- Summer volunteers and weeds
- No sheep in enterprise
- 450-500 mm annual rainfall
- Tillage or burnt stubble only
- Sheep on stubble
- <450 mm annual rainfall
- Tillage and burnt stubble
- No volunteers and weeds