Optimising Slug control

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Emily Willis
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1 Optimising Slug control Michael Nash SARDI Entomology

2 To manage we must understand. To understand, science counts. First we must identify. Together we can make science count!

3 Factors for success! An integrated approach is needed cameras are another tool to be added to the IPM tool kit Recognize the risk factors and resulting pest threat vary between seasons understand what is going on by orchard by year Bait needs to be surface applied to protect truffles product choice should take account of orchard conditions, species present and environmental effects

Know your enemy Grey field slug (Deroceras reticulatum) Light grey to fawn colour Dark brown markings Up to 50 mm long Mainly surface active Milky-white mucus Reproductive maturity 138 days 21-22

4 Know your enemy Grey field slug (Deroceras reticulatum) Light grey to fawn colour Dark brown markings Up to 50 mm long Mainly surface active Milky-white mucus Reproductive maturity 138 days days for eggs to hatch Optimum 18 C Median Slug weight each week (g) Optimum soil water 25% Opportunistic annual life cycle m 2 damaging to canola 5 damaging to cereals???? MAR-2003 Nash MA (2003) Honours thesis, La Trobe University. GRDC UHS76 27-APR MAY JUL AUG SEP OCT NOV-2003 Date sampled (every forth week displayed)

Black keeled slug (Milax gagates) Black / dark grey in

Reproductive maturity 240 days 40 days for eggs to hatch

underground Feeds at surface AND below ground < 1/m 2

5 Black keeled slug (Milax gagates) Black / dark grey in colour Sharp ridge (keel) along back mm long Reproductive maturity 240 days 40 days for eggs to hatch Optimum C Annual or Biannual lifecycle Burrows underground Feeds at surface AND below ground < 1/m 2 damaging to canola?? 1-2 damaging to cereals???? Metaldehyde LD /- 63

6 What is known: Smaller up to 35 mm long Brown with no distinct markings Mainly surface active Clear mucus when disturbed More common in pasture Reproductive maturity days for eggs to hatch Optimum 20 C Annual lifecycle???? Prefers warmer conditions Brown field slug (Deroceras invadens)

7 What is known: Distinct stripes Mainly surface active Clear mucus when disturbed Reproductive maturity???? 18 days for eggs to hatch Optimum 20 C Annual lifecycle???? Prefers warmer conditions *Lifecycle information is suggested and more work needs to be done. Striped field slug

What is known: Hedgehog slug (Arion intermedius) Yellow to grey in colour with dark grey head 15 20 mm long Yellow mucus Optimum 16 18.

8 What is known: Hedgehog slug (Arion intermedius) Yellow to grey in colour with dark grey head mm long Yellow mucus Optimum C Self fertilization Annual lifecycle (NZ) Autumn breeding (NZ) Copyright 2002, Royal British Columbia Museum Damage thresholds not established but not considered a serious pest in Europe Picture 2003J.K. Lindsey

9 Climate data collection and slug activity monitoring DAS00160 Sensors: Temp & RH (ground) Soil Temp Soil moisture Leaf Wetness (ground)

10 Slug abundance western Victoria 2015 (wheat) Time to complete life cycle

11 Slug abundance western Victoria 2016 (barley) Time to complete life cycle

12 Soil Moisture 0-10cm Volumetric Oct Nov Oct Nov

13 South Australian slugs wheat 2016

15 Bait degradation

16 Bait life recommendations Rainfall erodes physical integrity of bran-based baits Mould on products did not influence bait consumption nor efficacy Reduction of a.i. by rainfall (metaldehyde & iron chelate) is most important - individuals are more likely to consume a sub lethal dose Don t use current Iron based baits when >10mm rain is expected Temperature, not UV light, degrades metaldehyde baits Commonly used bran products need to be re-applied < 2 weeks, more expensive products will last 3-4 weeks. - Work out the cost benefit yourselves!

17 Product comparisons: 2015 > 35mm 2016 = 22mm * Significantly different P < 0.05

18 Bait Basics Dry Process Steam Process Wet Process Bran (Chook food) Flour (pasta) Before 1980 dust size s cost rain fastness palatability [ metaldehyde]

19 The chief obstacle to improving chemical control of slugs is not the lack of molluscicidal materials but the difficulty of getting them into the animal (Briggs and Henderson, 1987). Chance of encounter: 1. slug activity 2. attractiveness of bait 3. number of baits per unit area Consumption of active: 1. enough bait 2. adequate concentration 3. palatability

3. number of baits per unit area 50 45 40 Western Victorian Practice already applied May and June 35 30 bait number to achieve 80% chance of encounter 25

20 3. number of baits per unit area Western Victorian Practice already applied May and June bait number to achieve 80% chance of encounter Multiguard Sluggoff Meta Slugger Slugger*2 Slugger Metarex [6%] Iron EDTA [3%] Metaldehyde [1.5%] Metaldehyde [5%] Metaldehyde kg/ha Bait per M2

Average length of bait pellets (mm) 8 Bait Ballistics Dependent on pellet size and shape Smaller pellets more likely to land closer to the spreader 7 6 5

21 Average length of bait pellets (mm) 8 Bait Ballistics Dependent on pellet size and shape Smaller pellets more likely to land closer to the spreader Amazone Test 6 Bogballe Test 4 Kuhn Test 7 Vicon Test 6 Pre-spread Distance from centre (m)

22 Pellet distribution Twin spinner fertilizer spreader bait pattern Data accessed 4 Feb

23 Uniformity of distribution outcome Calibrate spreader for specific bait Consider narrower passes (bout width) Consider the spreader being used Single disk lopsided spread of bait >1000 rpm breaks up bait Consider product size and density Does the bait break up easily Look at the end results

24 Cost of Slug control Product A.I. g / kg Label Rate kg / ha Baits / m 2 Pellet Efficacy after rain (35mm) Ability to spread Distance (base on twin spinner machine) spread Metarex flour Similar Good 22-24m Metakill flour Reduced Good 18-20m SlugOut granule Reduced Good 24m Meta bran Reduced Poor-fair* 20-24m Slugger bran Reduced Poor-fair* 20-24m Pestmaster bran Reduced Fair* 20-24m Eradicate bran Reduced Fair* 20-24m Mesurol bran Similar Poor* not tested data/assets/pdf_file/0004/ /Snail_and_slug_baiting_guidelines.pdf

25 Further considerations for successful slug control Cultural methods: Leaf removal Tillage to get truffles deeper Precision pest management : Irrigation regulation in patches of high slug densities Targeted baiting

26 Initial slug numbers pre treatment Average per tile post treatment Nov 2013

27 Suggested rules for control Remove moist refuges Bait in problem areas as needed in the spring depending on soil moisture Follow up monitoring after baiting, watch for a wave of slugs mid late May especially if wet? Is this to late to bait!

28 Baits for other pests Chlorpyrifos baits available in Argentina for pill bugs & home made baits for earwigs in Aust. Alternative to foliar applied Lorsban that creates more pest flares (e.g. Nash et al 2010) Targeted response to difficult to target resident pests But are slaters, earwigs and millipedes pests?

29 Questions/Discussion

Where now for slug control without Draza?

Where now for slug control without Draza? Gordon Port Mollusc Centre of Expertise School of Biology Newcastle University Where now for slug control without Draza? Slug species and damage Slug life cycles