The onset of cool, moist conditions during autumn, ‘wakes’ snails from their dormancy, after which they begin to search for food. The optimal time for snail baiting is during a window of opportunity after snails become active – but before egg laying commences.
Growers with a history of snails on farm in south-eastern Australia can monitor for the commencement of snail activity by spreading a trail of bait near fencelines and checking for dead snails the following morning.
Ideally, paddock baiting should occur once snail activity begins but prior to egg laying.
This is advantageous for two reasons.
Firstly, baits are far more effective at controlling adult snails than juveniles as there is an increased likelihood of the larger snails (> 7 mm) encountering baits.
Secondly, there is less alternative feed and less complexity to the landscape prior to sowing, which increases the chances of snails encountering baits.
Be aware that some baits are far more stable than others under adverse weather conditions, such as cold temperatures and significant rainfall. Rainfall (> 35 mm) erodes bran-based baits rapidly and reduces efficacy, with these products sometimes requiring re-application after only 1 week in wet conditions.
Applying baits at an adequate density is essential for effective control. Aim for no less than 30 baits per square metre, in order to ensure there is enough product on the ground for all snails to encounter a bait. Where necessary, a follow-up second baiting may be applied, especially where snail density is very high.
For more information on snails, including baiting guidelines and biology, see these resources:
Managing snails – latest research findings and recommendations
PestNotes southern: vineyard snail, white Italian snail, pointed snail, small pointed snail