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Agronomist, Matt Sheppard (IMAG Consulting), has reported slaters attacking an emerging canola crop at Forbes, in the Central West Slopes and Plains district of New South Wales. Matt says up to 10-15 slaters were found per metre row, and when searching at night they were observed directly feeding on canola plants. The damage consisted of chewing through the plant stems as well as damage to some cotyledons. The affected paddock has a heavy load of stubble and will require re-sowing due to the extent of feeding damage. Agronomist, Natalie Thornton (Elders), has reported problems with slaters attacking wheat seedlings near Inverleigh, in the Western district of Victoria. In recent weeks, high numbers of slaters have also been reported by other agronomists from numerous paddocks across the Western district of Victoria.

Although slaters have not previously been considered a pest of broad-acre crops within Australia, it is best to keep an eye on them. In the past few years, there have been isolated cases where slaters have caused damage to crops in New South Wales and Victoria. Feeding results in uneven rasping-type damage that often appears as ‘windows’ of transparent leaf membrane. Contrary to common belief, slaters are crustaceans, not insects. They have a hard skeleton on the outside of their bodies and many pairs of jointed legs.

Slaters are known to be a minor pest in South Africa, where they often attack lupin and canola crops. They are generally controlled via cultivation but problems have worsened under minimum-tillage. Peter Mangano (DAFWA) has recently received reports of slaters damaging canola plants in the south of Western Australia. Problems appear to have occurred in paddocks containing a large amount of stubble. Peter says crumbly clay soil surfaces and cracking clays seem to favour the survival of slaters.

One particular species, the ‘flood bug’ (Australiodillo bifrons), has caused significant damage to cereal crops around Moree and Mudgee in northern New South Wales. The flood bug is a native species, approximately 7-8 mm in length and 4 mm wide. They are oval shaped and have a flattened body, with light coloured legs. They have the unusual behaviour of moving in ‘swarms’ which can consist of >100,000 individuals. The slater species observed by Matt is not the flood bug, but is a species that is more closely related to the commonly found introduced garden slater, Porcellio scaber.

There are no insecticides registered against slaters in broad-acre crops, and reports indicate they are relatively unaffected by most foliar applications of both synthetic pyrethroids and organophosphates applied to control other crop establishment pests, even when applied at very high rates. This is probably because they hide under cover and avoid sufficient contact with the insecticide. There are chemical baits registered for use against slaters in horticulture, and reports suggest some success with chlorpyrifos baits in Western Australia.

Click here for further information on slaters and for images of the flood bug click here.

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