Insect pest risk
|High risk||Reduced risk||Low risk|
|Paddocks rotated out of pastures.||Intensively grazed pasture (reduces mite survival).||Rotation with weed-free non-crop hosts reduces mite populations. Non-host examples: lentil, chickpea, wheat, barley, lupins, and linseed.|
|Weed hosts controlled at least 2 weeks prior to crop emergence.|
|Diamondback moth (also known as cabbage moth)|
|Drought stress increases aphid population growth rate and reduces the crop’s ability to compensate for flower and pod abortion.|
|Native budworm (Helicoverpa punctigera)|
|Dry winters in breeding areas contribute to a low population source and the absence of migration opportunities.|
|Slugs and snails|
|Late sowing into cold soil reduces plant growth and increases vulnerability to insects and slugs.|
Economic damage from insect pests is most likely to occur during establishment and from flowering until maturity. Major pests are in bold.
Rutherglen bug is best known as a seed-feeding pest, attacking grain as it develops and fills. However, in some seasons, large numbers of nymphs and adults can cause damage to establishing crops. RGB populations can build up in summer weeds, and move into the establishing winter crop, feeding on and killing small seedlings. Large numbers of RGB moving out of canola stubble also pose a threat to nearby establishing summer crops.
|Slugs and snails*||Damaging||Damaging|
|Helicoverpa armigera (NOT IN WA)||Present||Damaging||Damaging||Damaging|
* Snails may also cause grain contamination at harvest
**Early colonisation by virus infected aphids
|Present||Present in crop but generally not damaging|
|Damaging||Crop susceptible to damage and loss|
Key IPM considerations for canola
- Monitor regularly, recording both pest and beneficial numbers. Review checking data for population trends.
- Tolerate low-moderate early damage, as canola can compensate by setting new buds and pods if sufficient growing time remains.
- Biopesticides used in vegetative canola prior to flowering will preserve beneficials:
- Consider the use of spray oils where aphid populations are low to moderate (repeat applications required).
- Where pests invade from adjacent fields consider spraying only borders rather than the whole field.
- Control some pests (e.g. lucerne flea or mites) in preceding pasture or broadleaf crops.
- Use selective products when spraying for aphids (e.g. pirimicarb) to preserve beneficial insects.
- Seed dressings may be the most effective control for some soil insects, as well as the least disruptive to natural enemies.
- Earth mites RLEM and BOM can occur in mixed populations. There is evidence that RLEM and BOM species have different susceptibilities to chemicals. Determine species composition before making spray decisions.
- Pest populations are often regulated by competition from other pests within farming systems. For example, applying chemicals with specific activity against red legged earth mite (e.g. bifenthrin) can lead to a substantial increase in lucerne flea numbers through the removal of competition.
- Increasing pesticide usage to control RLEM may not solve pest problems but select for pests that are more difficult to kill e.g. Balaustium mites.
- RLEM has been found to have high levels of resistance to two synthetic pyrethroids – bifenthrin and alpha-cypermethrin. This resistance has been found to have a genetic basis, persisting after several generations of culturing in the laboratory. See the RLEM Resistance Management Strategy for more information.
- Some BOM tolerance to registered rates of insecticides in Northern NSW.
- Resistance found to synthetic pyrethroids in DBM, H. armigera and green peach aphid.
- Green peach aphid has variable resistance to pirimicarb in WA, and potentially to synthetic pyrethroids and organophosphates nationally. See the GPA Resistance Management Strategy for more information.