Mites and lucerne flea are active
Redlegged earth mites
- Tambellup
- Gnowangerup
- Condingup
Redlegged earth mites (RLEM) have been causing damage to canola crops at Tambellup, Gnowangerup and Condingup.
Many of the reports received of RLEM causing damage in germinating crops have had insecticide applications of synthetic pyrethroids (SP’s) and organophosphates (OP’s). Crops are being closely monitored and RLEM will be tested for insecticide resistance. In the meantime the growers are planning on applying Pegasus® but only if canola cannot outgrow feeding damage.
If you notice RLEM surviving applications of insecticides please contact DPIRD technical officer Alan Lord or DPIRD research scientist Svetlana Micic to discuss and arrange for paddocks to be tested.
Most RLEM are expected to have hatched in the Great Southern region of WA. RLEM typically hatch after rain and 10 days of mean temperatures below 20oC.
For the central and northern agricultural regions hatchings are predicted to have occurred by late May to early June.
A RLEM hatch timing tool is now available. This tool, developed by Cesar Australia with investment from GRDC, helps to aid decision making by predicting when eggs will hatch in autumn, which indicates when to increase crop monitoring. The map above shows predicted RLEM hatchings for WA by the tool at 5 May 2022. Cesar Australia is keen to ground truth its hatching predictions. For more information refer to the 2022 PestFacts south- eastern article Predicting redlegged earth mite hatch dates.
For more information on RLEM refer to the DPIRD Diagnosing redlegged earth mite page.
Bryobia mites
- Gnowangerup
- Esperance region
Jack Batchelor (Nutrien Ag Solutions) has found Bryobia mite causing damage to canola, which was sown after pasture, at Gnowangerup. Post-sowing pre-emergent (PSPE) sprays of bifenthrin at 200mL/ha were applied straight after seeding. It is highly probable the mites hatched post spray application.
Bryobia mite have been found in canola crops across the Esperance area.
Adult bryobia mites are reddish-grey with a pie-shaped body, red legs and two long forelegs. For more information refer to DPIRD’s Diagnosing bryobia mite page.
Balaustium mites
- Esperance
Balaustium mite has also been reported in canola at Esperance.
Balaustium mite causes minor damage to crops that are growing well. This pest tends to retard crop growth in moisture stressed crops. Its only recommended to control this mite if crops are not out-growing damage.
The adult balaustium mite has a brownish / red body, red legs and looks similar in appearance to the redlegged earth mite. If viewed under a magnifying glass or microscope short, stout, velvety hairs can be seen covering the body. The adult balaustium mite grows to almost twice the size of redlegged earth mites. Several generations can occur each year.
Feeding by these mites cause distortion to cotyledons and a silver or white discolouration on leaves. Damage is more severe when seedlings are stressed (for example, cold, waterlogged or very dry conditions). For more information refer to the DPIRD Diagnosing balaustium mite page.
Lucerne flea
- Nyabing
- Borden
- Ongerup
Lucerne flea have hatched this week and caused patchy damage in canola seedlings near Nyabing. They have also been found in pasture paddocks near Borden and Ongerup.
The lucerne flea is a Collembolan or 'springtail'. Adult lucerne flea are approximately 3mm in size and green-yellow in colour.
It is expected that growers who have had lucerne flea issues in the past can expect to have hatchings occurring. Lucerne flea numbers this year will depend on what the population was in spring 2021.
Control of lucerne flea, if crops are not out-growing damage, relies on OP spray applications. Be careful to check the label as some formulations require green plant material to be effective. The PestFacts WA team receives reports each year of spray failures which can be linked to insecticide choice and a lack of green plant material.
For more information about diagnosing and managing lucerne flea, refer to DPIRD's Diagnosing lucerne flea page.
Correct identification and control measures
It is easy to confuse the micro pests such as mites and lucerne flea so growers and consultants are urged to correctly confirm the identity of the pest before making management decisions. Correct identification is critical for applying the correct management option.
Identifications can be made by using the DPIRD MyPestGuide Crops app which includes images and information of mite pests.
Alternatively, you can send images for confirmation through the PestFax Reporter app.
For registered insecticide recommendations for mites and lucerne flea refer to DPIRD’s 2022 Autumn/Winter Insecticide Guide.
For more mite and lucerne flea information contact Research scientist Svetlana Micic, Albany on +61 (0)8 9892 8591 or Technical officer Alan Lord, South Perth on +61 (0)8 9368 3758.
Article author: Svetlana Micic (DPIRD Albany).
Article input: Dustin Severtson (DPIRD Northam), Cindy Webster (DPIRD Narrogin) and Lizzy Lowe (Cesar Australia).