sustainability through science & innovation

Slugs

Agronomist, James O’Brien (Landmark), has recently reported various species of slugs causing damage to newly sown pastures around Timboon, in the Western district of Victoria. James stated that slug numbers are very high in the region, following a big slug season in 2011 and a ‘green bridge’ over summer that favoured their continued survival and breeding. The slugs are causing most damage to late sown direct-drilled pastures on heavier soils. James noted that most early sown pastures were able to reach sufficient size to cope with the slugs when they became active in late autumn. Baiting has been effective; both the iron chelate and metaldehyde based baits have performed well. Agronomist, Alistair Tippett (Landmark), has reported slugs attacking canola in a large paddock in the Anakie-Balliang region, also in the Western district of Victoria. The slugs are causing typical rasping damage to canola at the cotyledon – 2-leaf stage.

In the western district of Victoria, some feeding damage has also been observed in emerging wheat, particularly where slugs were a problem last season. Most growers have already baited canola paddocks prior to, or at, sowing with good control being achieved, although follow-up treatment may be required in the next couple of weeks if conditions stay wet and cold. Researcher, Michael Nash (University of Melbourne), suggests growers need to be actively monitoring at the moment given the recent rainfall and sensitive, emerging cotyledons. Michael says slug damage generally does not cause plant death once canola is at the 4-leaf stage.

Michael says slug numbers are typically lower than last year. There are fewer brown field slugs (Deroceras invadens) being observed in western Victoria this season, with blacked keeled slugs (Milax gagates) and grey field slugs (Deroceras reticulatum) dominating. A new GRDC project aims to better understand the distribution of slugs through the collection of Australian populations, especially from New South Wales. Michael is requesting consultant and grower help. He would like records of slug populations, including latitude and longitude, and the species name. If possible, direct collections of individuals would be even better. These can be placed in a vial with plant material on which they were feeding and sent directly to Michael. If you are able to assist, please contact Michael by phone on 0417 992 097 or via email at manash@unimelb.edu.au.


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