Slugs: loving these conditions!

Monitoring slugs in October will allow for smarter management in 2017.

Black keeled slug (left) and grey field slug (right) (Source: cesar)

 

The wet winter and spring in many areas of NSW and Victoria is undoubtedly a boon for slugs, and in some areas, snails as well. Heavy stubble loads at the end of a good season will exacerbate the risk in paddocks as we head into 2017.

Slugs feed actively throughout winter and spring whenever moisture allows. For example, the grey field slug (Deroceras reticulatum) reproduces when temperatures are between 4°C and 21°C (optimal temp is 16°C), and soil moisture is greater than 25%. So even if conditions dry off now, slugs have had extended opportunities for breeding this season.

Our advice

Crop monitoring for the presence and distribution of slugs (and snails) within paddocks will help you plan for 2017.  Monitoring in October, particularly, before the soil dries out is critical. This is particularly important in areas where slugs are less frequently a problem.

Refuge traps for grey field slugs should be placed on the soil surface and then checked for the presence of slugs after a few days. Alternatively, feeding activity of both grey field slugs and black keeled slugs (Milax gagates) can be assessed by distributing bran-based baits from corner to corner of paddocks and checking the following morning for dead slugs. This is best carried out immediately following a rain event.

Baiting to control slugs in spring can be useful but is sometimes not effective because there are ample alternative food sources. At the end of the season, reducing crop stubble (e.g. baling) will reduce slug habitat and over-summering options. For those considering baiting for slugs or snails this spring, be mindful of withholding periods.