Slugs and snails threaten in south

Snail numbers are building, especially in parts of South Australia.

Snail numbers are building, especially in parts of South Australia.

FARMERS with broadleaf crops in southern parts of Australia are being urged to continue to monitor for both slug and snail activity.

Both pests can virtually decimate emerging broadleaf crops, with canola particularly susceptible.

Crop pest monitoring service Pest Facts said high rainfall zones tended to be the worst impacted by slugs, while snails are often most severe on alkali soil types.

Paul Umina, of Pest Facts, said it could be difficult to accurately assess numbers of slugs, due to the fact they feed at night.

He said farmers should trap if they wanted an accurate number count.

Landmark Naracoorte agronomist James Heffernan said farmers would attempt to get a good handle on slug and snail numbers following this week’s forecast rain.

“The slugs and snails should get a little more active then so we will get the traps out and get a better feel for numbers,” he said. 

“There have already been high numbers of snails observed on pulse and canola stubbles from last year.”

He said farmers in the mid south-east of South Australia and the far west Wimmera in Victoria were factoring in the cost of putting out bait for the pests.

Growers have a choice between higher cost bait, with better longevity following rain or in cold conditions, that can cost up to $40 a hectare or generic formulations of the same active ingredient at around $10-12/ha.

Dr Umina said slugs have become a massive problem for the grains industry, especially in the Western District, but added cultural controls could help cut the load.

“It may not be popular for other reasons, but burning can give you some control by delaying breeding, especially with grey field slugs,” Dr Umina said. 

“Rolling paddocks after sowing makes it harder for slugs to find seed, reduces surface clods used as moist refuges when slugs are surface active, and improves crop establishment when used in combination with cultivation.”

Dr Umina said baiting needed to be done prior to crop emergence for best results. 

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