Snails – What is Your Baiting Strategy?
At this point in time baiting is the only effective broadscale chemical control option that we have for snails.
Timing of baiting is critical to achieve effectiveness and to ensure you get the best bang for your buck. Snail activity increases during the autumn with dewy mornings and with the odd shower of rain. However just because they are moving doesn’t mean they will go to baits and graze. They need to be in grazing mode before they will eat.
What makes them want to graze? Well, we don’t fully know - but we do know they need to re-hydrate after a hot dry spell before they will graze.
How do you check that they are in grazing mode? Test baiting a small area is the answer. This is done by marking a couple of areas and baiting where you know snails are present. Snail responses may vary in different paddocks so spread 2-3 square metres with a high rate of baits. Come back and check these baited areas each morning to monitor activity. If they are ready to graze they would have gone to the baits, grazed and died. If you can’t find dead snails around baits then don’t waste your time and effort baiting your paddocks as you will not see satisfactory results.
Baiting needs to occur once you have deemed them to be in grazing mode as there are limited opportunities to control them before they lay eggs and start the cycle over again. As mentioned baiting is seen as the most effective form for the control of snails. There are however several cultural practices which can be implemented to help control. Burning excess stubble and cultivating paddocks can really help restrict snail numbers and can be used as a multi-strategy approach in your program.
Photo 1. A mixed population of White Italian and Small Conical Snails aestivating on a fence post. this photo was taken on the 27th March 2019. I checked to see if the snails were alive or dead – they were alive, but very dehydrated. When the shell was crushed, the snail body was only just damp and withdrawn right back into the shell. These snails will have to rehydrate before they will graze. If you squash a snail shell and you have a wet squashy mess on your fingers, then they are hydrated and probably ready to graze.
Photo 2. Small Conical Snail that is well hydrated and had been grazing on a placebo bait (no active ingredient). As you can see the bait has been ingested and is inside the snail’s gut. This is an example of a snail which is in grazing mode and is ready for baiting.
Once you have determined that the snails are ready to graze you must ensure that you are implementing the right baiting strategy. The rates for baiting needs to be determined by the level of risk. Don’t cut your rates where high numbers of snails are present, you need to have enough baits to allow all the snails to feed and get a lethal dose. After a couple days, go back and check where you have baited to ensure that you have controlled the snails and there are still a few baits present. If you can’t find any baits and/or live snails, you will have to re-apply as it is likely that all the baits were consumed before all the snails were controlled. Please refer to the ‘test baiting’ method again to determine thresholds and your control strategy if required.
For any further information please don’t hesitate to contact myself or any of the Western AG team.
Article produced by - Andrew Heinrich, Western AG Naracoorte