Species identification has been underlined as critical to the effective control of slugs in the high-rainfall zone (HRZ) of the southern cropping region. A GRDC-funded evaluation of various management strategies to reduce slug damage has shown that different species become active and feed on crops at different times, and therefore control tactics need to be carried out according to the emergence of each individual slug species.
The evaluation of slug management strategies – a fast-track project instigated by the GRDC’s Regional Cropping Solutions Network in the HRZ – has been conducted by Southern Farming Systems (SFS) in the western district of Victoria.
SFS CEO Jon Midwood says the project evaluated a range of management strategies. He said the major slug species causing crop damage were the grey field slug and the black keeled slug, while several other species also occur in the HRZ.
Mr Midwood says the most common control strategies included burning of stubble, light cultivation, rolling and baiting post-sowing (although this was often undertaken when damage had occurred and baiting was seen as the only option). The project involved three trial and demonstration sites and treatments were based on a draft strategy developed by Dr Paul Horne from IPM Technologies, using knowledge of life cycles, behaviour, habitat and predators of the major slug species.
Mr Midwood says the SFS trials highlight the importance of species identification: “For example, the grey field slug was mainly surface active, whereas the black keeled slug burrowed up to 20 centimetres underground to escape the heat and find moisture.”
Mr Midwood says the importance of species identification related to the emergence of each species as the autumn break developed. “At the very early emergence stage of the canola, only grey field slugs were causing plant damage, but as moisture penetrated the soil profile with increased rain, the black keeled slugs became active. “Just applying the initial bait treatment post-sowing and prior to emergence isn’t going to control the later emerging species. So the different slug species need to be accurately identified to choose appropriate control strategies.”
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A fact sheet on Slug control is available at: www.grdc.com.au/GRDC-FS-SlugControl
A back pocket guide on Slugs In Crops is available at: www.grdc.com.au/GRDC-BPG-Slug
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