Pasture / Winter Crops – Redlegged Earth Mite; RLEM (𝘏𝘢𝘭𝘰𝘵𝘺𝘥𝘦𝘶𝘴 𝘥𝘦𝘴𝘵𝘳𝘶𝘤𝘵𝘰𝘳)

Guidelines

1. Determine the risk of RLEM for each paddock before making management decisions.¹
2. Rotate insecticide Groups.
3. Do not apply consecutive sprays of products from any one insecticide Group.
4. Avoid prophylactic pre-emergence/bare-earth sprays in autumn.

* Refer: CropLife Expert Committee on Insecticide Resistance Mode of Action Classification for Insecticides.

Further detailed information about registered products and chemical windowing strategies for RLEM is available at: https://ipmguidelinesforgrains.com.au/important/uploads/Science-behind-the-RLEM-IRMS-in-Australian-grains-and-pastures_October-2024.pdf

4. Monitoring and timing of sprays:
   1. Monitor RLEM activity carefully, particularly in the first 3-5 weeks after sowing.
   2. Only apply chemical if damage has reached economic threshold levels and/or the risk of RLEM is elevated.
   3. Use the hatch timing tool to estimate RLEM hatching in autumn.²
   4. Optimal timing of spring sprays can be calculated using the TIMERITE® tool.³ Follow the recommended best spray date and ensure RLEM is the dominant mite species.
5. Placement of sprays:
   1. Apply perimeter sprays where infestations are concentrated on the edge of paddocks.
   2. Spray the entire paddock when RLEM numbers exceed thresholds or risk is elevated. However, with pyrethroid products, recent research has shown that the risk of Group 3Aresistance can be minimised through the application of foliar pyrethroids in a 50 m strip with 10 m spacing.⁴
6. Cultural practices:
   1. Decrease pasture foliage through grazing or cutting hay/silage to reduce RLEM numbers.
   2. Keep paddocks and fence-lines free of host weeds, such as capeweed.
   3. Sow crops and pastures that are more tolerant to RLEM, such as chickpeas.
   4. Encourage predator survival by judicious use of insecticides.
   5. Burn stubble prior to sowing to directly kill RLEM and its eggs.

Notes regarding the application of insecticides:

1. There is known RLEM resistance to Group 3A and Group 1B insecticides in Western Australia, South Australia, and Victoria. Resistance is expected to expand across these regions.
2. To ensure the most effective control of RLEM:
   24111322. Follow the recommendations in the RLEM Best Management Practice Guide https://ipmguidelinesforgrains.com.au/important/uploads/Redlegged-Earth-Mite-GRDC-24111322.pdf
   24111323. Product labels should at all times be carefully read and adhered to;
   24111324. Full recommended rates of registered insecticides should always be used; and
   24111325. Ensure good coverage of the target area to maximise contact.

References

1. The online RLEM seasonal risk tool developed by Cesar Australia considers multiple risks and management tactics https://cesaraustralia.shinyapps.io/rlemseasonalrisk/
2. The Hatch timing tool developed by Cesar Australia to aids early season monitoring and prediction of RLEM risk at crop establishment https://cesaraustralia.shinyapps.io/RLEM-hatch/

³ TIMERITE® predicts the best spray window and ideal spray date in spring to control RLEM https://www.wool.com/timerite/

4. Strip spraying delays pyrethroid resistance in the redlegged earth mite, Halotydeus destructor: a novel refuge strategy – Maino – 2021 – Pest Management Science – Wiley Online Library