SLATERS have been found causing extensive damage in a paddock of germinating canola near Amelup, in the Great Southen,
The slaters were active in patches of the paddock which had heavy, cloddy soil and ring barking or chewing through 20 per cent of seedlings.
The paddock contained many dead slater carcases which indicated the population had been present in the paddock for a while.
Slaters survive on organic matter on the soil surface and if the organic matter dries out the slaters cannot survive.
The heavy stubble load on the reported paddock aided their survival over summer.
Department of Primary Industries and Regional Development entomologist Svetlana Micic said in some years, slaters could be difficult to control.
She said at crop germination, the only option was to bait or to spray.
"Baits registered for slater control have better efficacy than baits registered only for mollusc control," Ms Micic said.
"The application of residual insecticide sprays have had some efficacy in protecting a germinating canola crop from slater damage.
"However, as slaters are nocturnal and shelter under stubble it can be difficult to get good spray coverage for their control."
When looking for slaters, growers should check for bare areas, seedling stumps, or chewed and shredded seedlings, usually in patches and areas with higher stubble or pasture residues.
Slaters feeding on plants usually causes an uneven rasping-type damage which can appear similar to slug and snail damage.
They can chew the tops of emerging cotyledons or leaves of crop seedlings, leaving only the seedling stumps.
While slaters rarely damage crops, crop damage can occur when numbers build-up.
"This happens when there have been a few wet summers in a row combined with heavy stubble loads on paddocks," Ms Micic said.
"If slaters are easily seen, that is at least three per 10 square centimetres, this suggests numbers are building up and control measures should be put in place before canola is seeded into the paddock."
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