Slaters

Farmer, David Johnson, reports that slaters have caused extensive damage to oat and wheat crops near Moree, northern NSW. Samples have been sent to the Australian Museum for identification. Slaters are commonly seen in domestic settings and generally not regarded as a pest of broad acre agriculture in Australia.

Agronomist, Sarah Gleenie (Cotton Growers Services) reports that slaters have recently damaged cereal crops on a number of properties in the Moree region. Sarah says slaters have been a minor pest problem in the past where they have been observed attacking emerging cotton plants. Agronomist, Tracey Farrell (NSW DPI), has also reported slater damage on a wheat crop at a property near Walgett, northern NSW. Tracey has not heard of slaters being a problem in broad acre agriculture prior to this year.

David says the number of slaters per cereal plant was staggering and that individuals could be seen crawling up the plant and feeding mainly on the tips of the leaves. Sarah believes stubble retention and the amount of trash within paddocks seems to be correlated with slater numbers. However, in David’s situation there was relatively little ground cover and stubble retention had not been employed in the affected paddocks. Re-sowing of some crops has been required due to the extent of feeding damage sustained.

Slaters feed mainly on decaying organic matter and can be beneficial at low population densities. At high densities, they can damage new seedlings and fruit, such as strawberries in contact with the ground. Agronomist, Sam Gall, says the slaters leave feeding damage of "windows" of transparent leaf membrane, similar to lucerne flea damage.

Slaters are woodlice, belonging to the large group Isopoda. 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 oval, flat and segmented, growing up to 17mm long.

Slaters are an agricultural pest in South Africa where they often attack lupins and canola. They are generally controlled via cultivation but problems have worsened under non-tillage regimes. Peter Mangano (Department of Agriculture, WA) has received some unconfirmed reports of slater damage to canola plants this season in the south of Western Australia. The cases have been at sites close to townships and the extent of damage attributable to slaters is unknown.

Although slaters have not been considered a pest previously, it is best to keep an eye on them. Slaters need damp conditions and will die if exposed to open and dry situations. Similar circumstances could occur in other regions or with other pests where stubble retention and minimal or no-till practices are employed.

This new insight into slaters gives cause to question the effects of other formerly innocuous invertebrates in broad acre cropping. We may be observing a shift in the importance of pest species with changes in farming practices. For example, Ken Henry (SARDI) received a report earlier this season in South Australia of black Portuguese millipedes (Ommatoiulus morelettii) causing suspected damage in canola. This species predominantly feeds on organic matter and Ken says they have not been a problem of broad acre crops in the past.

If you hear of any news or observe slaters attacking crops please send your reports directly to Paul Umina and/or advise your local agronomist. We want to determine whether or not this is an isolated situation.