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Slaters commonly feed on decaying stubble and other organic matter within crops, however, in high numbers they can attack newly emerged seedlings


Slater damage to canola seedlings (Source: Allan Edis)


Where have they been reported?

Slaters have been observed in large numbers (both juveniles and adults) feeding on canola seedlings in the Central West Slopes & Plains of NSW (south of Temora). Slaters were directly observed crawling up and attacking cotyledons. This was particularly evident at night, which is when slaters tend to be more active due to the cooler conditions. Damaging populations of slaters have been reported attacking a canola crop around Forbes, also in the Central West Slopes & Plains. The majority of damage is reported to have occurred in areas of the paddock that have the highest amount of stubble and trash. Additionally, slaters have been observed building up in some paddocks around Elmore, in the Victorian Northern Country, and issues in emerging canola crops have been reported in the north-east of Victoria.

About the pest

Native and introduced slaters have become an increasing pest of broadacre crops and pastures over recent years. This has been closely linked to minimum or no-tillage and stubble retained cropping practices. Crop stubble provides a cool, moist habitat that aids slater survival; slaters will die if exposed to open, dry conditions.

There are three main slater species that can be broadacre pests. The common slater originally introduced from Europe, Porcellio scaber, is the most widespread species in Australia. The Pill bug, Armadillidium vulgare, is also a European species and occurs commonly across Australia. This species is characterised by it’s ability to roll into a ball when disturbed. The flood bug, Australiodillo bifrons, is a native slater that forms large swarms of tens of thousands of individuals. There have been increasing numbers of reports of the flood bug in parts of NSW, particularly in areas prone to flooding.

For detailed information on slaters, including their occurrence, lifecycle, behaviour, damage symptoms and management strategies, go to slaters.

Our advice

Monitor crops closely before deciding whether action needs to be taken. It is important to remember that the presence of slaters within a paddock (even in high numbers) does not necessarily mean they are an issue. They only become problematic if high numbers are seen feeding on the crop, in addition to widespread damage symptoms.

Most problems with slaters tend to occur in emerging canola, although they have been recorded attacking wheat, oats, lentils and pastures.

Insecticide sprays aimed at other crop establishment pests are generally ineffective; many of the active ingredients are relatively harmless to slaters. Slaters also hide under cover and thus can avoid contact with insecticide sprays. There are chemical baits registered for use against slaters in horticulture, and there is evidence to suggest some success with chlorpyrifos baits in Western Australia.

Stubble management prior to sowing is the most effective strategy to reduce slater numbers. Slater populations can be suppressed by reducing stubble loads, or disturbing stubble in summer, exposing insects to the hot soil. Some growers have had success managing slaters ahead of canola rotations by burning crop residues. This was observed again this year in some paddocks near Temora.

Dead slaters after burning stubble (Source: Allan Edis)


Sources of field reports of cowpea aphid

Wes Amor – Sales Manager, Bayer (NSW Riverina)

Jim Cronin – Agronomist, Landmark (NSW Central West Slopes & Plains

Allan Edis – Agronomist, Landmark (NSW Central West Slopes & Plains)

Greg Toomey - Agronomist, Landmark (Victorian Northern Country)

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