Earwigs and vegetable beetles in canola
- Ongerup
A grower at Ongerup is having problems with earwigs and vegetable beetles in his emerging canola crops. As the grower’s canola germination is patchy it is difficult to distinguish between seedling damage or death caused by the insects or whether some seed had simply not germinated yet.
European earwigs are a recurring pest on properties. These pests do not just cause damage to canola at the emergence but have also been known to strip canola at the 10 leaf stage to the stem.
Lab trials conducted by DAFWA entomologist Svetlana Micic have shown that vegetable beetles will cause damage to crops if day temperatures are 20°C and above. As soon as the cold, wet winter conditions prevail ie day temperatures of 15°C and below, damage by the vegetable beetle is expected to cease.
Vegetable beetles can build up to very high populations under no-till systems and high stubble residues.
Insecticides especially chlorpyrifos or alphacypermethrin applied at the highest registered rates do have efficacy against European earwig as a contact only. However European earwigs can be difficult to control as they hide under stubbles. Sprays applied at night have worked better than sprays applied during the day as earwigs are more active at night.
Vegetable beetles are very tolerant of insecticides. Svetlana says that currently registered insecticides for use on false wireworm (includes vegetable beetles) on canola such as chlorpyrifos (500g a.i) at 1.0-1.5L/ha with some labels stating that the application should be incorporated into the top 50mm of soil, have suppressed damage from vegetable beetles, however, many growers and agronomists have reported these rates did not cause vegetable beetle mortality rather beetles were 'subdued' and this allowed the crops to out grow the damage.
For more insecticide information refer to DAFWA’s Autumn Winter Insecticide Guide 2017.
Further details about these pests can be found at DAFWA’s Diagnosing European earwig and Diagnosing vegetable beetle damage.
For more information contact Svetlana Micic, Research Officer, Albany on +61 (0)8 9892 8591 or Dustin Severtson, Development Officer, South Perth on +61 (0)8 9368 3249.