Insect pest activity this week
Invertebrate insect reports to the PestFax team this week have generally been slow this week as a result of the warm and dry weather conditions slowing crop emergence across the state. In previous years, warm starts to the season have led to different pest pressures on germinating crops.
Growers and consultants are urged to use the PestFax Reporter app to report any findings or ask for help identifying unusual pests.
Australian plague locusts
- Tammin
- Kulin
Jessica Cole (DKT Rural Agencies) has reported that there are Australian plague locust (APL) nymphs south of Tammin and they are starting to chew on 1-2 leaf oat seedlings.
Ben Whisson (ConsultAg) reports that APL are still active in the Kulin area.
APL information can be found at the department’s Diagnosing locusts and grasshoppers in crops and Australian plague locust: overview pages.
Mites
- Woodanilling
- Albany
Kim Adams (Landmark) has found first instar bryobia mite on germinating canola at Woodanilling. The canola is being monitored. At this stage it is out-growing damage, however, with weather conditions being above 20°C it is expected that bryobia mite may be an issue this season. Especially if there were clover or broad-leaved weeds present in the paddock prior to sowing.
Entomologist Svetlana Micic has observed very low levels of blue oat mites and redlegged earth mites in shaded areas of pasture paddocks on the south coast of Albany.
In previous years feeding damage from balaustium mite to moisture stressed seedling cereal and canola crops has also been an issue. Correct identification of bryobia and balaustium mites can be very confusing when they are at the first instar stage. Balaustium mites cause white tipping of cereals whereas bryobia mite are only found on canola and cause white lines.
For more information about diagnosing and managing different mites refer to the departments;
- Diagnosing bryobia mite
- Diagnosing balaustium mite
- Diagnosing blue oat mite
- Diagnosing redlegged earth mite pages.
Vegetable beetles
Crop protection officer Alice Butler (DPIRD) has found some vegetable beetles at a DPIRD trial site at Kendenup. The wheat and barley plants at the trial have not germinated yet.
Lab trials conducted by DPIRD 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.
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 insecticide information refer to DPIRD’s Autumn Winter Insecticide Guide 2017.
More information about vegetable beetles can be found at DPIRD’s Diagnosing vegetable beetle damage.
Weed web moths
- Geraldton
Chris Pinkney (Agrarian Management) reports that around the Geraldton district weed web moth caterpillars have been seen feeding on the few wild radish plants that have survived summer spraying programs. At the moment this is not a concern as long as they do not migrate into and feed on nearby canola crops when they emerge.
Caterpillars of weed web moth look very similar to diamond back moth, particularly when they are small. This means they are easily confused in the field. Weed web moth caterpillars are grey-green and pale brown in colour, with a distinctive black head. They are slender, grow up to 15mm long and generally have a dark line down the middle of their back with three rows of dark spots on either side. Caterpillars tend to wriggle violently or crawl around rapidly when disturbed.
In addition to canola, weed web moth caterpillars are known to attack lupins, lucerne and a wide range of broad-leafed weeds. They shred the leaves of seedling crops and may cause complete defoliation, which can lead to plant death.
For more insect information contact Svetlana Micic, Research Officer, Albany on +61 (0)8 9892 8591 or Dustin Severtson, Development Officer, Northam on +61 (0)8 9690 2160.