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PestFacts WA

Monitor for slugs now to prepare for next season

A black keeled slug (bottom) and reticulated slug (top).
A black keeled slug (bottom) and reticulated slug (top). Photo courtesy of DPIRD.

Growers and consultants in the south coastal areas of WA are urged to monitor paddocks for slugs this spring. Assessing slug numbers and distribution in paddocks at this time of year will prepare growers for slug management next year.

The Bureau of Meteorology’s seasonal outlook for October to December 2022 is indicating 25-65% chance of exceeding median rainfall for the south west land division. Above average rainfall mid-spring may be conducive for increasing slug populations. For more climate information refer to DPIRD’s Seasonal Climate Outlook October 2022.

The two main slug species present in WA are reticulated slugs and black-keeled slugs. For more information on diagnosing these slugs visit DPIRD’s Identification and control of pest slugs and snails for broadacre crops in WA page. 

Tips for monitoring for slugs

Paddocks with a history of slug activity and which were not baited earlier in the season are likely to have slugs present.

Reticulated slugs over summer hide under surface refuges such as rocks, whereas the black keeled slugs will burrow underground. Both species of slugs will survive hot summers, but black keeled slugs which have burrowed underground will also survive in paddocks if burning occurred.

Survey your paddocks and find out where your slugs are to target baits. The best time to survey for slugs is nine hours after sunset when temperatures are at 7°C and humidity is between 80-90%. Slug activity can be monitored with refuges (for example, carpet mat, wet hessian sacks or tiles) placed out in paddocks and checked the following morning.

As slugs often have a patchy distribution in paddocks it’s important to use multiple refuges. Fifty monitoring refuges are recommended when paddock size is 40 hectares due to variability of Australian conditions. Or run a line of baits out one day and check for any dead slugs the following day.

Monitoring is encouraged in wet conditions when slugs are active.

Slug management

If you do detect slugs in your maturing crops, take note of the paddock, as this is where they will be in 2023.

At this time of the season, slug control options are limited as there is ample green feed available for slugs and presents an alternative to baits.

Monitoring during spring provides an understanding of the success of any management practices in 2022. It also identifies the slug risk for next season’s establishing crops. Plan to bait next autumn, after sowing, to protect emerging crops.

Best practice management of slugs requires an integrated approach.

 

For more information on slugs visit:

For more information contact Research scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.

 

 

Article authors: The original articles, both titled Springtime slug monitoring, are from PestFacts SA October 2022, written by SARDI’s Rebecca Hamdorf and Dr Michael Nash and PestFacts south-eastern September 2022, written by Julia Severi (Cesar Australia) and reviewed by Dr Michael Nash (SARDI).  This article was modified by Cindy Webster (DPIRD Narrogin) and Svetlana Micic (DPIRD Albany) for relevance to Western Australia.