www.grdc.com.au W [email protected] | [email protected] E Deroceras slug (Deroceras field Brown panormitanum) field slug is 25 to 35mm long, The brown all over with no distinct and usually brown markings. It is mainly surface active but to shallow depths. It is more can burrow part of is a frequent common when pasture pair can lay A breeding rotation. the crop up to 500 eggs per year. rey field slug or reticulated slug field slug or Grey ) reticulatum (Deroceras reticulated slug is field or The grey to long and light grey 35 to 50 millimetres mottling. fawn in colour with dark brown a year. generations up to three are There in autumn and spring, It will generally breed favourable this if conditions are however, any time – a pair can species will breed It is up to 1000 eggs a year. produce mainly surface active and is a major pest and pastures. of crops Black keeled slug (Milax gagates) The black keeled slug is 40 to 60mm long with a ridge down and black or brown up to its back. This species can burrow to escape underground 20 centimetres in drier problematic the heat. It is more such as South Australia, environments, south- throughout although it is widespread eastern breeding and Western Australia. A pair can lay up to 200 eggs a year. Pest species theThe main pest species in Australia are slug and the black keeled slug, but field grey recorded field slug has also been the brown than one species in high numbers. More within a single paddock. may be present

ns PHOTO: Michael Nash +61 2 6166 4599 | 4599 6166 2 +61 F regio n +61 2 6166 4500 | 4500 6166 2 +61 T T 2604 | 2604 ACT ster d We n The eggs of the black keeled slug, laid in a clod of moist soil. Slug eggs hatch to six weeks. A pair of black within three keeled slugs can lay up to 200 eggs able to but some species are per year, up to 1000 eggs per year. produce Life cycle both therefore, hermaphrodites, Slugs are individuals of a mating pair lay eggs. and whenever moisture They will breed suitable – conditions are temperature mid-autumn to late spring. generally from Each pair will lay eggs in batches. laid in moist soils and will hatch Eggs are to six weeks, dependent within three Juveniles look like smaller on temperature. versions of the adult. ustralian growers spend an average Australian growers $8.7 million annually on slug control. The incidence of slugs has increased practices. with changes to cropping Cultivation and stubble-burning previously kept numbers down, but the widespread adoption of minimum till and stubble slugs with more has provided retention favourable habitat. Surface-active slug species such as the crevices in field slug find brown and grey the soil during dry summer conditions to avoid heat and drying out. They emerge and moist to breed when conditions are most active at slugs are field feed. Grey between 4°C and 20°C. temperatures a n d management tion an T 2600 | PO Box 5367, Kingston 5367, Box PO | 2600 ACT treet, Barton Barton Street, , Souther n

No single control method will be No single control an integrated completely effective; is needed. approach The grey field slug, or reticulated field slug, or The grey the slug, and black keeled slug are field main pest species, but brown slugs can also pose a serious threat. Moisture availability is a key Moisture of slug populations. regulator lugs need moisture and shelter Slugs need moisture to thrive. Cool wet summers and an abundance of stubble provide ideal conditions.

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s no single control method will provide complete protection, an integrated approach is best. an integrated approach protection, complete method will provide As no single control problem. n the higher rainfall zones where zero till and stubble retention is practiced, slugs are an increasing an increasing slugs are is practiced, till and stubble retention zero zones where In the higher rainfall ntifica Slug ide Norther FACT SHEET FACT

slug control slug march 2013 march south eastern Darling Downs. problem for growers on Queensland’s on Queensland’s for growers problem western regions, but are also a significant western but are regions, threat to growers in the southern to growers and threat regions of Australia. They pose the biggest regions lugs are present in all major grain growing all major grain growing in present Slugs are barley, oats and canola crops annually. oats and canola crops barley, $25.9 million in lost production across wheat, across $25.9 million in lost production ustralian grains industry, costing on average Australian grains industry, most damaging invertebrate pest for the terms of economic loss, slugs are the sixth terms of economic loss, slugs are seful Resources) has found that in (see Useful Resources) , costs of invertebrate pests in grain crops The current and potential The current A GRDC report, losses can occur. and this is the time when major economic however, seedlings are the most vulnerable seedlings are however, lugs will eat all parts of a crop plant, Slugs will eat all parts of a crop numbers are relatively low. relatively numbers are major economic losses, even when slug ttacks on emerging crops can cause Attacks on emerging crops ustralian grain growers in recent decades. in recent Australian grain growers and have emerged as a serious pest for lugs are a major pest of crops globally, globally, a major pest of crops Slugs are The black keeled slug can burrow up PHOTO:s Mic h ael Nas

to 20cm underground to escape the PHOTO: Mic h ael Nas heat and so it survives well in drier The grey field or reticulated slug is a major pest of Australian grain crops and pastures. environments. Its burrowing behaviour It is 35 to 50mm long and ranges from light grey to fawn in colour with dark brown also allows it to attack germinating mottling. Under favourable conditions, this species will breed any time. A pair can seedlings underground, making damage produce up to 1000 eggs a year. difficult to detect.

Hedgehog slug (Arion intermedius) At the break of season, monitor for the slugs present. To counter this, sample more presence of slugs. The most effective time than 10 refuges per 10 hectares. A significant pest species in Europe and to bait is at sowing, followed by rolling New Zealand, the hedgehog slug has been Where unexpected crop damage is to consolidate the seedbed. However, recorded in a number of high-rainfall (more occurring, inspect the area after 10pm this cultural practice may not fit with a than 600mm) locations. It is up to 25mm on a mild, calm night. zero-till operation, so assess the scale of long and grey in colour with a yellow foot. It the problem and make the management As well as looking for slugs, check for other is distinguished by its breathing pore at the decision appropriate to your operation. pests such as European earwigs or beetles front of the mantle (the section at the front that could cause similar damage. of the slug that covers the internal organs). Baits are most effective when paddocks are bare, so if there is retained stubble, control When monitoring is not practical from a Crop damage may not be as good. time or resource perspective, an alternative option is to put out lines of bait to gauge Slugs can be underestimated as pests During the winter months, continue to populations, especially in areas where slugs because they are nocturnal and shelter monitor for any plant damage during occurred previously. during dry conditions, and therefore are not crop emergence. Repeat baiting may be generally visible during daylight hours. required during crop establishment. Baiting Control methods They will attack all plant parts but seedlings in spring is generally not effective because Effective control involves a combination of are the most vulnerable crop stage and can there are ample alternative food sources. measures: chemical, cultural, and biological. suffer major economic damage. In Queensland, seedling canola, soybeans Populations as low as one grey field slug and sunflowers are the crops at greatest Chemical control per square metre can inflict severe damage risk, particularly on creek flats where there Baiting is still the only chemical control option. on a canola crop at establishment. is zero till and overhead irrigation. Apply baits after sowing and before crop Grey and brown field slugs are mainly Monitoring emergence to protect emerging seedlings. surface active, requiring moist refuges at Three types of baits are registered for the the soil surface such as volunteer crop The foundation of any IPM program is control of slugs. plants and broadleaf weeds. monitoring, but accurate estimation of slug numbers is difficult because slugs are hard to 1. Baits based on metaldehyde (there are Black keeled slugs are a burrowing species, find, populations are often clumped and their many products available), some of which and can feed directly on germinating seed. This activity is dependent on moisture availability. often makes damage more difficult to detect are registered for all slugs and some for compared to the surface-feeding species. One monitoring method is to create surface grey field slugs only. Metaldehyde is a refuges in the form of terracotta paving Schedule 5 poison and is highly toxic Control approaches tiles, carpet squares or similar. These can to birds and mammals. Spread evenly give an indication of slug activity and the and avoid heaping to avoid attracting No single method will provide complete relative number of slugs present. A 300mm off-target animals. control so an integrated pest management by 300mm refuge represents approximately (IPM) approach is required. 2. Baits based on methiocarb (Mesurol®), 1m2 when soil moisture is favourable (more which is registered for all slugs. than 25 per cent). Concentrate monitoring By understanding the system’s complexity Methiocarb is highly toxic to carabid and working on pest control year round, a on areas where slugs have been a problem beetles, one of the few predators of reasonable level of control can be achieved. in the previous autumn in order to assess slugs in Australia and New Zealand, population activity, especially after rainfall. In the summer months, remove refuges by which it kills by secondary poisoning. controlling weeds and managing stubble Check the refuges early in the morning, 3. A bait based on iron EDTA complex through grazing. as slugs seek shelter in the soil as it (Multiguard®), which is registered gets warmer. If summer weed control is not possible, for grey field slugs only. Multiguard® look to control weeds at least two months Keep in mind that monitoring does not provide Iron EDTA complex bait is snail and prior to seeding. an accurate guide to the total numbers of slug-specific and has low toxicity to PHOTO: Mic h ael Nas PHOTO: Mic h ael Nas The brown field slug has not been PHOTO: Mic h ael Nas Patchy emergence of this canola crop considered a major pest species but is evidence of extensive slug damage. has nevertheless been recorded in high Slugs will attack all plant parts but Baiting can continue at this time, but numbers and can inflict serious damage. seedlings are the most vulnerable. Damage it will only serve to minimise further It is mainly surface active but can burrow to the cotyledons in canola seedlings can damage; it will not be able to retrieve to shallow depths. mean major economic losses. lost yield.

mammals and birds. It has no impact important than kilograms of bait per hectare. cover and thus food and shelter for slugs. on predatory insects such as carabid Higher bait densities may be required where Keep paddocks as weed-free as possible, beetles, iron complex baits and so is the high slug populations occur (more than especially if there is a wet summer. 2 recommended IPM option in Europe. approximately 20/m ) . Current research Cultivation is effective in reducing slug is investigating this further, but preliminary Different species have demonstrated numbers as it destroys their habitat, however, results suggest that a minimum of 250,000 different levels of tolerance to metaldehyde, this is not an option in zero-till operations bait points per hectare may be required. where the aim is to conserve soil moisture. so researchers are testing if black keeled and/or brown field slugs may be more Bait failures are often associated with Stubble burning is another option but, tolerant to baits containing metaldehyde unfavourable weather conditions. More again, is not always desirable nor failsafe, than grey field slugs. than one bait application may be necessary. as a hot burn is required. The different responses to bait may also When slugs are actively breeding, no current Rolling after sowing to consolidate the be due to behaviour. Consider placing control measure will reduce populations seed bed is an important component of below established thresholds. For canola, baits with the seed when sowing, when an integrated slug control program. Rolling this is as low as one slug per square metre. black keeled slugs are present and easily improves the establishment of many crops move along drill rows. For grey field slugs, Cultural control and reduces surface clods that provide broadcasting baits is more effective. habitat for slugs. Heavy rolling can reduce Some crops, such as canola, soybeans soybean emergence but lighter (selective) The biggest issue with baits is the and sunflowers, are more susceptible to rolling can be carried out in well structured slug damage than others. application rate. Don’t underestimate the soils. Rolling is also at odds with a FIGURE 1 Xxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxxxxxxxx. size of the slug population just because If planting a susceptible crop, increase minimum till philosophy, so decide whether they are not visible. Always use the highest seeding rates in paddocks where slugs have the size of the slug problem means the possible label rates or adjust the rate to the been present and follow good agronomic outcome justifies a change of approach. perceived size of the slug population. practices to get the crop established. The best approach is to incorporate The number of baits per hectare is more Controlling weeds removes vegetation appropriate cultural controls for your PHOTO: Mic h ael Nas courte s y: michaeal n a s h

Grey field slug (Deroceras reticulatum) Brown field slug (D. panormitanum) Terracotta paving tiles can act as surface Black keeled slug (Milax gagates) refuges for slugs and are useful for Hedgehog slug (Arion intermedius) monitoring slug numbers. Check the tiles FIGURE 1 Slug distribution in Australian grain-growing regions early in the morning when it is still cool, These results are from an initial GRDC-funded SARDI survey of pest slug distributions but bear in mind the clumping behaviour throughout grain growing regions of Australia 2011 to 2012. WA was not sampled due of slugs, and their dependence on to drought conditions; historical records from 2002 to 2007 indicate WA distribution. moisture, may mean that samples are not always an accurate representation of the Darker colours indicate more attractive areas for slug populations. Circles indicate areas total number. where damage from slugs was reported.

your name and full address; telephone your name and full address; number and email address; the date and location of collection specimen was found, the (where with GPS coordinates); preferably soil type; tillage or paddock history (zero/minimum history); and cropping cultivation regular and attacked; crop description of the damage (photos are optional but useful). – – – – – – orting Slugs Reporting Send slug specimens (in a jar with leaves) to: moist paper and some crop Michael Nash CESAR Bio21 Institute Melbourne University 30 Flemington Road Parkville VIC 3100 03 8344 2521 or 0417 992 097 – – – – – – urrently the research team has had the research Currently species kill rates on some encouraging expect South Australia. They of snails in in high rainfall to be even better results at the site at moisture zones. However, and other factors the time of application in determining role will play an important an economic are whether or not these measure. control Building a database for the Building a database slugs reporting future: can to researchers Submitting specimens and of slug numbers help build a picture regions the grain-growing damage across is dependent of Australia, although this on local weather conditions and tillage systems used. Building such a database into the future. researchers will benefit Place collected slugs in a jar with moist leaves, then post or paper and some crop courier the specimen to Michael Nash at the University of Melbourne. See Reporting details. Slugs for address following information along with the Provide the specimen:

PHOTO: Michael Nash A- echnologies GRDC Project Code DAS00127, CSE00046 dentification and control of pest Identification and control slugs and snails for broadacre Australia (1.7mb) Western in crops DAFW www.grdc.com.au/ Useful Resources Bulletin4713-SlugSnail Back Pocket Guide Slugs in Crops GRDC-BPG-Slug www.grdc.com.au/ and potential costs of The current invertebrate pests in grain crops GRDC-Report- www.grdc.com.au/ InvertebratePestsCosts IPM T www.ipmtechnologies.com.au Carabid beetles can provide biological slug can provide Carabid beetles easily killed by Because they are control. use or pesticide some pesticides, reducing can insecticides avoiding broad-spectrum complex EDTA Iron support their activity. and will slug and snail-specific baits are predators. not harm such beneficial The nematodes invade the animal and an The nematodes invade six to five within it kills bacterium associated acts as an incubator days. The dying slug and, on the death of the animal, massive to released numbers of new nematodes are slugs. infest more The nematode species capable of occur naturally slugs already controlling but not in sufficient numbers to provide adequate control. Field trials will take place in Victoria this season to determine if applying nematodes prior to the season to the soil and in-furrow as predicted. will be as effective Hugh Brier, Paul Horne, Svetlana Micic, Michael Nash, Acknowledgements: Hugh Brier, Gavin Ash, Aisuo Wang. m.au .coretext.co A

[email protected] 02 6933 2739 Charles Sturt University (Nematode project information) (Nematode project Aisuo Wang [email protected] Charles Sturt University (Nematode project information) (Nematode project Gavin Ash [email protected] 03 8344 2521 University of Melbourne Michael Nash [email protected] [email protected] 08 9892 8591 DAFW Svetlana Micic [email protected] 03 9710 1554 IPM Technologies Paul Horne or Jessica Page [email protected] 07 4160 0740 QDAFF Hugh Brier more information

produced by www Disclaimer or views of the Grains Research and Development Corporation. contained in this publication suggestions or opinions do not necessarily represent the policy Any recommendations, professional advice. independent, No person should act on the basis of the contents of this publication without first obtaining specific, Sheet may identify products by proprietaryThe Corporation or trade names to help readers identify particular types of products. to this Fact and contributors We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to. Other products may perform as well as or better than those specifically referred to. do not endorse or recommend the products of any manufacturer referred to. We cost or expense incurred or arising by reason of any person using or relying on the information in this publication. damage, The GRDC will not be liable for any loss, RESEARCH ON UNREGISTERED PESTICIDE USE CAUTION: Any pesticides or of unregistered products reported in this document does not constitute a recommendation research with unregistered for that the authors or the particular use by authors’ organisations. pest and region. crop, All pesticide applications must accord with the currently registered label for that particular pesticide, protected and may not be reproduced in any Sheet is copyright form without written permission from the GRDC. All material published in this Fact Copyright © great promise in the laboratory. in the laboratory. promise great extended to slugs. The research is showing extended to slugs. The research biological control for snails has been biological control of several species of nematodes as Research demonstrating the effectiveness demonstrating the effectiveness Research use of carabid beetles. spectrum insecticides is essential to make spectrum insecticides reducing pesticide use or avoiding broad- pesticide use or avoiding reducing s they are easily killed by some pesticides, easily killed by some As they are conditions that favour slug populations. conditions that favour are predatory and they do well in the same and they do well in the same predatory are on plants. Both larvae and adult carabids on plants. Both larvae ground-dwelling pests and those that live pests and those ground-dwelling arabid (or ground) beetles feed on both beetles feed Carabid (or ground) in limiting slug populations. Predatory insects and organisms play a role play a role insects and organisms Predatory needed for successful crop establishment. successful crop needed for control Biological however, in some scenarios all controls are are scenarios all controls in some however, PM strategy, IPM strategy, into a broader operation