Integrated slug control The UK perspective. Caroline Nicholls,

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1 Integrated slug control The UK perspective Caroline Nicholls,

2 Key species in the UK Grey field slug (Deroceras reticulatum) Garden slug (Arion hortensis and Arion distinctus)

3 Grey field slug Populations have a mixed age structure so damage occurs when the weather is right Breeding peaks in April-May and September- October They can start to lay eggs within 16 weeks of hatching They lay eggs in batches of Up to 500 eggs per slug may be laid over several weeks

4 Damage in cereals Seed hollowing is most damaging 1 slug can kill 50 seeds in the 1st week after sowing Weight for weight, smaller slugs destroy more seeds

5 Damage in cereals Crops are most vulnerable to leaf shredding and feeding on shoots up until GS14 (4 true leaves)

6 Damage in oilseed rape Seedlings are most vulnerable as the germinating point, unlike cereals, is above ground Once the crop has 4 true leaves it is much more tolerant

7 UK issues Metaldehyde in water courses

8 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

9 Understanding risk Moisture and temperature Optimum temperature for slugs is 17 o C Active between 5 o C and 20 o C Grey field slug active even at close to freezing

10 Understanding risk Soil type Slugs are more abundant in heavy soils with high clay or silt content

11 Understanding risk Previous cropping Leafy crops increase risk as they crease moist soil conditions Crops with long growing periods increase risk to the following crop

12 Understanding risk Crop residues, organic matter and weeds All provide a source of food and shelter to slugs Slugs prefer soft nutritious provided by young ground plants especially in damp conditions

13 Understanding risk Cultivation Direct drilling and delayed drilling increase risk Open, damp, cloddy seed beds allow slugs easy movement and provide shelter

14 Understanding risk Crop type Autumn crops are slower growing so more vulnerable Barley and oats have an extra seed coat so are less vulnerable

15 Understanding risk Other risks Small fields surrounded by ditches Headlands are close to vegetation and are often compacted with poor drainage Wasteland Hedgerows Green fallow Lack of nutrients, poor drainage and weed competition result in slow crop growth

16 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

17 Cultural control Cultivation Weed control Beetle banks

18 Cultural control Cultivation Seed bed preparations are more important than chemical control Ploughing reduces slug populations Cultivations will increase slug mortality Firm seedbeds reduce slug activity A fine seedbed protects seeds If cloddy, increase sowing depth to 4-5 cm

19 Cultivation Cloddy seedbed Fine seedbed

20 Cultural control Reducing weeds in the previous crop and in the seedbed of the new crop reduces food and shelter for slugs

21 Cultural control Beetle banks are good habitats for carabid beetles which prey on slugs Peak predation is usually June to September (UK)

22 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

23 Monitoring for slugs Sampling using refuge traps Put out traps before cultivation when the weather is mild (5-25 o C) and soil is moist Traps are 25cm across with chicken food under Place 9 traps in each field Leave over night

24 Thresholds Crop Threshold (average no. slugs/trap) Winter cereal 4 Oilseed rape (standing cereals) 4 Oilseed rape (cereals stubble) 1 OSR Monitor regularly until 4 true leaves Winter cereals Monitor from sowing until first tillering

25 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

26 Biological control Phasmarhabditis hermaphrodita Nematode parasite

27 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

28 Chemical control Always integrate with cultural control Ferric phosphate Causes slugs to stop feeding Die below ground within 3-6 days Effectiveness should be measured by feeding damage

29 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

30 Application method and timing Broadcasting pellets is better than admix with drilled seed Admix pellets if soil is cloddy Apply just before susceptible growth stage when weather favours slugs Use traps to monitor activity

31 Application method and timing PhD project on slug distribution by Emily Forbes, Harper Adams University

32 Application method and timing PhD project on slug distribution by Emily Forbes, Harper Adams University

33 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Biological control Chemical control Application method and timing

34 Understanding risk Moisture and temperature Soil type Previous cropping Crop residues, organic matter and weeds Cultivation Crop type Small fields Agronomic factors

35 Strategies for slug control Understanding risk Reducing risk through cultural control Monitoring for slugs Bioloical control Chemical control Application method and timing

36 Thank