Over the years, agriculture has progressively moved to more conservative farming practices, such as no-till, less burning and less tillage. While this has improved soil structure and erosion, it has also created ideal habitats for snails and slugs. We have better soils, but we pay the price of these pests becoming more of a problem in our farming systems.
Snails and slugs are an issue because of the damage they cause by eating emerging crops. If you’re wondering about the potential impact on your crop, look for typical evidence like chewed leaf margins and irregular holes, plus keep an eye on emerging crops, as slugs can chew cotyledons off at ground level. Cereal crops are likely to survive this, but damage to germinating canola and legumes when they’re at the cotyledon stage can mean crop failure.
Snails need moisture to be active, so rainfall events usually trigger increased activity. Snails’ pace may seem slow, but in the right conditions, snails have been recorded to move up to 30m in seven days. If they’re in high numbers, that’s quite a path of destruction! Snails will start reproducing between April to September, so it’s best to bait before this egg-laying period to keep your crop snail free.
Slugs are usually more problematic in higher rainfall areas, wetter seasons, and paddocks with heavy soils that retain moisture or crack. Slugs feed on crops at all stages but cause the most damage to seedlings.
Grey field slugs feed mainly on the soil surface, feeding on plants at ground level and consuming cotyledons, leaves and stems, sometimes severing seedlings.
Black-keeled slugs feed similarly at the soil surface but also burrow below ground to feed on germinating seeds.
Slugs are mostly inactive during summer. The black-keeled slug burrows to depths of 20 centimetres or more to survive the heat, whereas the grey field slug seeks refuge under rocks, logs or summer weeds and debris or by moving into cracks in the soil. Soil-penetrating rainfall and cooler temperatures increase slug activity on the soil surface in autumn and winter.
So what snail and slug bait should we use?
Besides the generic metaldehyde products such as old ‘Meta’, Imtrade’s Metakill is an excellent fit for paddocks. Metakill is made by Imtrade, and the baits are a higher loading active of Metaldehyde – 50g/kg compared to the 15g/ka of standard ‘Meta’. Metakill is also a smaller sized bait, with better rain tolerance and a more compact pellet.
Key features of Metakill:
– Imtrade has made Metakill pellets highly resistant to weathering. Baits will be present in paddocks for longer, which will help prevent most re-baiting situations.
– The smaller pellet size means more baits per square metre. Trials have shown a much higher number of baits per square metre, around 100,000 baits per kg of Metakill compared to 32,000 of Meta. Having more baits per meter is important as snails and slugs have a higher chance of encountering them and can consume them quickly.
– Being a higher-loaded active, snails and slugs do not have to ingest as much bait for it to be effective.
Another option is Imtrade’s Transcend.
It’s a snail bait with a high strength of 50g/kg of Metaldehyde but also 1.5g/kg of Fipronil. The addition of Fipronil gives the bait the extra punch of controlling earwigs, slaters, millipedes, as well as slugs and snails.
Transcend also had great rain-fastness and longevity. This will save you, as in the right conditions, you would only need one application of bait each season. Imtrade says they are leading the market regarding both rain fastness and accuracy of baiting, in terms of the number of baits per m2. Transcend’s smaller pellet size, and higher active loading means you can use less to achieve the same effectiveness per hectare. For example, to achieve a spread of 400,000 baits per hectare (recommended baits rate by GRDC research), you will need a rate of 4kg per hectare of Transcend, compared to 15.4kg of standard Meta (15g Metaldehyde). Another benefit of the Fipronil in Transcend is that only the targeted insects are affected. This is very important for a good IPM strategy, as it leaves all of the good bugs alive in the paddock, unlike broad-spectrum sprays of chlorpyriphos.
Look to apply Transcend just after sowing to provide maximum protection from the emerging crop and long residual protection.
Remember, if snails are a big issue for you, it’s a good idea to have an integrated management plan to control them. This can be achieved by using baits, rolling/cabling stubbles or burning stubble.
For more information on snail issues, get in contact with us today.