Red legged earth mite (RLEM) are a common pest of legume pastures in South Australia. Up to 80% of seedlings, and a similar amount of spring dry matter yield may be lost on infested paddocks. Using a Timerite® spray will bring benefits this year and in forthcoming seasons.
RLEM are small mites (1 mm long) with black bodies and red legs. They spend most of their time on the soil surface, moving up on to plants to feed. When feeding, RLEM make holes in the cells on the upper surface of leaves and suck out the sap, causing a ‘silvering’ of the leaves. RLEM have numerous hosts, including clover, plantain, wheat, oats and canola and weeds including ox-tongue and capeweed.
Average populations of RLEM across trial sites have been assessed at 21,000 mites/m2. This is of significance, as it has been calculated that approximately 12,000 mites/m2 can use as much energy as 1DSE/ha.
For a short time in spring, after RLEM have finished laying normal winter eggs on pasture, but before they produce their over-summering eggs, there are no eggs present. This is the ideal time to spray because eggs are impervious to sprays. Controlling mites in this period means that the whole population can be affected, reducing mite numbers for the following autumn.
Timerite® provides farmers with the date for a single spring spray that controls RLEM through to the following autumn. Your Timerite® spraying date can be accessed on-line at http://timerite.wool.com/. If spraying within three days either side of the optimum spray date is not possible, it is still possible to achieve reasonable control by spraying within a two week period leading up to and including the optimum Timerite® spray date.
Research consistently shows control of mites in pastures and crops leads to increased financial returns. Eliminating RLEM from pastures will result in increased pasture growth in spring when 40 per cent of the growth occurs.
The following table outlines the RLEM control costs and income from a paired paddock trial with half the paddock sprayed on the Timerite® date and the other half not sprayed. It is clear that the improvement from spraying versus not spraying, in this case, resulted in a 19% increase in income.
| Sprayed Paddock | Control Paddock | |
| Net wool income ($/ha) | 117 | 98 |
| Net lamb income ($/ha) | 212 | 170 |
| RLEM spray ($) @ $10/ha | -10 | 0 |
| Income ($/ha) | 319 | 268 |
The reductions by 7000 mites/m2 in the example represents a reduction in energy consumed by the mites and a potential to increase the holding capacity of the paddock by nearly 50% due to the reduction in the damage to the crop.
You do not need to have very high mite numbers to consider spraying. But if you cannot see any mites in your pasture it is probably not worth spraying. It is still necessary to check for mites in the following autumn, because the spray may not always reduce RLEM to levels where they cause no damage (particularly to emerging seedlings).
The Timerite® spray date is unique to each farm and will remain constant from year to year. Spraying dates across SA generally occur in mid to late September. For details on your Timerite® spraying date go to AWI website and search "Timerite".
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