The UK climate is particularly favourable for the breeding and multiplication of slugs.
There are 46 species in the UK but there are three key arable and potato pests:
• Grey Field slug (Deroceras reticulatum)
• Round back slugs (Arion spp.)
• Keeled slugs (Milax / Tandonia spp.)
Slugs within any population have variable lifecycles. Typically anywhere between 2 and 4 cycles per year. Slugs from the same batch of eggs may also grow at very different rates, some remaining very small whilst others reaching full size very quickly. It is believed that this is a survival strategy based on food supply and environmental conditions. Grey field slugs have a maximum life span of 9-12 months and are the most important slug pest in OSR and cereals.
Key crop impact
Cereals - Slugs will cause seed hollowing and an individual slug can kill up to 50 seeds in the first week following drilling. Smaller slugs are more damaging and will actively feed in the top 2 cm of soil. Additional damage on shoots and leaves can occur and cereals are vulnerable until GS21.
OSR - This crop is very susceptible to damage. As the seedling develops the growing point is exposed above ground and is therefore at risk of damage. The crop is most at risk until the four leaf stage so early protection is critical.
Potatoes - The critical period for damage is early tuber bulking when slugs will enter the tuber and cause significant cavities. Be aware there are varietal differences in susceptibility to slug damage. On susceptible crops ensure a suitable durable pellet is applied during the risk period and critically before canopy closure to ensure some forward protection is offered.
Slugs are random feeders - they literally stumble across their food source during periods of activity. There is no evidence that they are attracted at a distance to a specific food source.
Once the slug encounters potential food it uses chemical sensors to establish if it is appropriate and will then test the food before feeding. Attractants added to slug pellets have no real benefit but the inherent palatability of the pellet is critical to ensure the slug consumes a lethal dose.
Tip of the iceberg
The slugs causing visible damage are just a small proportion of the actual population. The bulk of the population remains in the soil profile out of sight, it is impossible to completely eradicate slugs.
Slugs do have natural predators with the most important being ground beetles which will prey on both the slugs and their eggs. Parasitic nematodes are also found in most soils. They carry bacteria which are toxic to slugs. Slugs are also very susceptible to changes in environmental conditions, especially anything which impacts the soil moisture conditions in the top 5cm.
What risk factors are important?
Moisture and temperature are the two most influential factors. Cool, wet conditions are favoured by slugs in order to thrive. Hence mild and wet spring/autumn conditions provide ideal conditions. Even in a dry season slugs can quickly repopulate and thrive at the first arrival of rain.
Crop type - previous cropping and cover crops can all have an effect on slug populations
Soil type and drainage with water retaining soils like clays and silts, and poorly draining soils providing higher moisture levels.
Cultivation method has an effect with direct drilling, delayed drilling dates, little soil disturbance (no till) all providing good conditions for slug populations.
Crop residues, organic matter and weeds will provide cover and protection for slugs.
Nearby hedges, wasteland and ditches are refuge areas for slugs to migrate from into cropped areas.
Understanding slug pressure on an individual farm basis is essential and taking an integrated approach to slug control will prove to be the most efficacious, far more reliable than just using slug pellets alone.
There are several critical considerations for any successful integrated slug management programme.
Impact of Crop Rotation
Slug damage is much greater following leafy crops such as OSR. The leafy structure creates moist soil conditions and can leave significant crop residues on the surface post-harvest, creating an ideal habitat for slugs in terms of food and shelter.
Do avoid planting very susceptible crops (salads and leafy vegetables) after OSR.
Late drilled cereals can be at greater risk as it often takes longer for the crop to grow out of the susceptible growth stage.
Production of firm seedbeds makes it more difficult for slugs to move, and will also help crops grow quickly, minimising the critical period of risk.
Small grey field slugs are responsible for much of the seed hollowing in cereals and they typically feed in the top 2 cm of soil. If the seed bed is cloddy and loose, growers are advised to drill cereal seed deeper than normal to reduce seed hollowing.
Some growers are now adopting the practice of rolling newly drilled crops at night hoping to kill slugs on the surface.
Key aims of cultivation
Impact on slugs
Monitor Slug Activity
When using slug pellets it is important to apply the slug pellet early to minimise damage.
Application needs to be timed to coincide with favourable weather conditions, producing a moist surface soil layer and when slug numbers are confirmed.
Growers are advised to utilize slug traps to monitor populations (details on slug trapping can be found in the section Tools).
The Sluxx HP pellet contains ferric phosphate. It has a different effect on slugs when compared to metaldehyde. Growers will see that slug pellets have been eaten but will not see many dead slugs on the surface.
When slugs eat a Sluxx HP pellet they quickly stop feeding and retreat underground to try and recover. They do not recover and will die underground.
Growers are advised to monitor crop damage as an indicator of slug activity along with remaining numbers of slug pellets. In high pressure situations it may be necessary to apply more than one application. Sluxx HP has a label which allows up to 4 applications per crop.
It is important to calibrate the applicator when changing brand and type of pellet.
Download an aplication settings guide for SluxxHP here.
Each brand may have different characteristics in terms of size and ballistic properties, which lead to potential variations and discrepancies if not callibrated when changing between pellet.
Further information and applicator testing can be found at www.nsts.org.uk/Tests/Slug
Sluxx HP is the culmination of 10 years field experience and continuous product development. Growers and Agronomists have confidence in its performance and have made it the bestselling ferric phosphate pellet in the UK market.
The Sluxx HP formulation has a number of significant benefits which differentiates it from other pellets in the market, therefore it carries the Ferric Field Technology quality mark.
What does this mean for you?
Slugs are random feeders. They literally stumble across their food source during their periods of activity. There is no evidence to suggest that they are attracted at a distance to a food source. Once the slug encounters potential food it uses chemical sensors to establish if it is appropriate and will then test the food before feeding.
Attractants added to slug pellets have no real benefit, but the inherent palatability of the pellet is critical to ensure the slug consumes a lethal dose. SluxxHP is made using processed durum wheat flour which makes it very palatable to slugs.
As you can see from the photographs below Sluxx HP pellets have a very uniform size and minimal dust content. This ensures good spread-ability up to 32m and gives a consistent number of baiting points.
Sluxx HP has a patented formulation which includes a food industry preservative to prevent moudling and ensure the active ingredients remains available and active even during wet weather conditions.
This is important as it enables the pellet to be more effective when slugs are most active.
See it in action in the video below.
SluxxHP can be seen on the left, an alternative brand on the right. A distinct difference in quality and absense of mould on Sluxx HP pellets is clear as time progresses over 7 days.
Slug monitoring is essential to understand what is happening at field level and slug traps can be used to monitor activity.
Guide to using slug traps:
For wheat: a catch of 4 or more slugs per trap indicates a possible risk, where soil and weather conditions favour slug activity
For winter oilseed rape: weather conditions during the short period between harvesting cereals (especially wheat) and drilling may not suit trapping.
It may be worthwhile to trap in standing cereals up to 10 days before harvest, particularly if you plan to broadcast seeds into standing cereals or stubble (e.g. Autocast). In the 7-10 days before cereal harvest, or in stubble.
A catch of 4 or more slugs per trap in standing cereals, or 1 or more slugs/trap in cereal stubble indicates possible risk.
Potatoes and Field Vegetables: a count of 1 slug per trap indicates risk to the crop
It is important to check the settings of your applicator when changing brand and pellet type.
Click on the sheets below to download an Applicator Settings Guide for each of our pellet brands.
Each brand may have different characteristics in terms of size and ballistic properties, which lead to potential variations and discrepancies if not adjusted when changing between pellet.
Further information and applicator testing can be found at www.nsts.org.uk/Tests/Slug.
Integrated Slug Control - Classroom Module
Complete our online 15 minute module for a complete guide to integrated slug management.
Originally created for the BASIS online learning platform, where BASIS cpd points may be obtained on completion. More info here: https://basis.vbms-training.co.uk/
Click the image to start.
National Slug Trapping 2020
Oil Seed Rape
As OSR drilling starts, our technical team will once again be monitoring sites around the country. Check back in the coming weeks to see their results.
In June our regional technical specialists were out monitoring slugs in different potato crops across the UK. Using baiting points, comparing irrigated and non-irrgated sites for slug pressure during the critical control point, from 50% canopy closure.
With the drier weather, few slugs were found during the critical timing period.
Check out the results in the map - click on the location points for more info.
Talk to your advisor or distributor.
Read and watch more ferric phosphate related news below.
Contact our technical experts on 0845 373 0305 or send us this quick form.
Find out more about Sluxx HP
Slug Facts with Dr Gordon Port
Hear all the facts you need to know about slug behaviour from Dr Gordon Port. Including most common species in UK crops and their feeding habits
What makes a good slug pellet?
Dr Gordon Port explains the characteristics that make a good quality and effective slug pellet, based on years of in-depth slug research and understanding of slug behaviour
What makes Sluxx HP different?
Neil Beadle explains what makes Sluxx HP such an effective, high quality slug pellet
Slug Tracking Trial
Certis UK regional technical specialist Geoffrey Bastard along with Professor Keith Walters of Harper Adams University explain how we investigated the behaviour of slugs once they have ingested ferric phosphate pellets
Download our SlugWatch app to measure slug pressure in your area.
The app provides the opportunity to view location-specific slug activity data, along with information on weather conditions, helping you to make informed decisions on slug monitoring and applying slug pellets.
Available to download for Android and IOS
'Get Pelletwise’ is the campaign of the Metaldehyde Stewardship Group (MSG).
The group’s aim is to promote and encourage best practice with metaldehyde slug pellets, amongst agricultural users.