Don’t let your farm become sluggish

Conducive conditions such as high stubble loads for shelter, rain events and cool conditions, specifically between four and 20 degrees has led to an increase in slug numbers across the Wimmera and Mallee.  

Additionally, the adoption of minimum tillage and stubble retention provides the ideal habitat for slugs, with moisture the key for slug number increases.

The challenging part of slug management is first identifying and monitoring activity. Populations of slugs are hard to monitor and identify due to their nocturnal nature, making dawn and dusk the times when crop inspections should take place.

Refuge traps, such a terracotta tiles, flowerpot bases or carpet squares are useful for ascertaining slug populations. Place refuges in a ‘W’ shape in suspect paddocks and check them in the morning.

Monitoring slugs in this way will not provide an absolute assessment of slug density, but will provide an indication. Slugs attack emerging crops, especially canola which are more susceptible to damage. While seedlings are the most vulnerable, slugs will eat all parts of the crop.

In the 2013 GRDC report entitled ‘The current and potential costs of invertebrate pests in grain crops’, an estimated $25.9 million in lost production was reported due to slug damage.

Slugs will take the opportunity to breed and feed whenever there is sufficient moisture, usually between mid-autumn and late spring. When conditions are too dry they will find crevices in the soil to shelter.

Once laid, eggs will hatch within three to six weeks, but that will vary depending on conditions.

If populations are as low as one grey field slug/m² and causing significant damage, especially in canola crops, monitoring numbers and conditions are advised.

An integrated pest management approach (chemical, cultural, and biological) needs to be used for slugs as no single control method is completely effective.

For more information on slug management, including baiting and other control measures, read the GRDC slug identification and management factsheet.

This article was published in the Stock and Land 18 May. 

Photo source: Michael Nash, SARDI.