Non-Chemical Management Options

To reduce the risk of developing pesticide resistance it is important to use a number of methods to manage RLEM. The options include using RLEM resistant plant varieties, grazing management, encouraging natural predators and limiting soil movement.

Use of RLEM resistant plant varieties

If you are planning on sowing new pastures or crops and there is a high risk of RLEM attack, it may be viable to sow RLEM resistant plant varieties.

In pastures, Prima gland clover and Casbah Biserrula offer high levels of RLEM resistance.

For more information on these varieties and their management go to:

NSW Department of Primary Industries

WA Department of Agriculture

QLD Department of Primary Industries

Seedmark

Planttech

Grazing Management

Populations of RLEM have the ability to increase in numbers quickly over the season. However, the numbers of RLEM is dependant on the carrying capacity of the pasture. The more dry matter there is, the more mites it can support.

In a trial by the Western Australian Department of Agriculture it was found that heavy grazing in spring reduced RLEM populations by up to 99%.

For further information on grazing management go to Australian Wool Innovation website.

Encourage natural predators

There are currently no biological control agents to control RLEM. However, there are a number of natural predators which can attack RLEM, helping to keep their populations low. These include native and introduced predatory mites and the European earwig Forficula auricularia.

There is no evidence that Timerite itself as a spray date detrimentally affects the populations of non-target species including predators of RLEM. Research by CSIRO Entomology found that control of non-target species including Bryobia mite, Tyrophagous mite and pasture snout mite varied greatly between years. In 1999 Bryobia mite actually had greater numbers in the sprayed paddock versus the unsprayed paddock, while in 2000 there was a 67% reduction in Bryobia mite numbers.

However, broad spectrum pesticides sprayed at anytime can kill non target species, so it is important to be careful when encouraging natural predators. Ways to encourage natural predators can include avoiding the use of broad-spectrum pesticides. There is also evidence that shelterbelts can increase predator numbers and enables them to recolonise adjacent paddocks which have been sprayed.

Limit RLEM Movement

RLEM can move within and between paddocks through adult locomotion as well as aerial dispersal of diapause eggs.

Adult RLEM can move 7-16m in their adult lifetime. They will also move through unfavourable host crops to reach more suitable hosts. Borders can be used to limit movement of RLEM by using plants which RLEM can not reproduce on (like red lentils or chick peas) or by using border sprays. However, these borders need to be greater than 10m wide to be effective.

The diapause eggs of RLEM remain in the cadavers of the female mites, which lay on the soil surface over summer. The RLEM cadavers are about the size of a grain of sand. They can easily move with soil through wind erosion and through mud attached to farm machinery. To avoid RLEM egg movement it is important to avoid bare soil over summer; use shelter belts to minimise wind erosion; and maintain machinery hygiene in the same way you would for minimising weed seed movement.